Not An Audiophile – The Podcast featuring podcast episodes with Mark Dohmann, designer and manufacturer of Dohmann Audio. This extraordinary designer of high-end turntables answers every question that’s ever been asked about turntables, design, engineering and sound.
Podcast transcripts below – Episode 022
TRANSCRIPT
S2 EP022 Turntables – Mark Dohmann of Dohmann Audio
Mark Dohmann answers our top five questions about turntables
Mark Dohmann: I figured that I was the guy rocking in the corner muttering, analogue’s better, analogue’s better. You don’t know what, you don’t know what you’re missing. Oh, he’s one of those analogue guys, you know, like, poor thing, you know. Let’s just tighten the straps on the vest a little bit more.
Andrew Hutchison: Foreign welcome back to not an Audiophile A Podcast. This is episode 22 season 2 and today we have Mark Dohmann on the line and also Brad Serhan asking probing questions on the side. Mark answers all of my questions regarding all sorts of lesser known aspects of turntable setup and answers our perhaps top five questions about what really matters in turntables. And of course also talks about his own turntables, the Dohmann turntable.
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So Mark.
Mark Dohmann: So back in the 80s, 82, I put a, a badge on my first turntable.
Andrew Hutchison: Yes.
Mark Dohmann: Called the Continuum.
Andrew Hutchison: Yep.
Mark Dohmann: And it was Dohmann. Same spelling as the current company name. Ah, D O H M, a double N with the O with the umlaut. And we had a dream of being a turntable manufacturer. and come 1985 there was a fork in the road with the music industry. It’s called the CD rom. And that sort of really, I mean the massive amounts of investment in CD and getting people to convert their catalogues, it was, it was ah, you know we called it the writing on the wall. Yeah, yeah. And whilst it didn’t lessen my passion for analogue, it did sort of become sort of like a very difficult road ahead if you could use it. And it wasn’t clear, the picture wasn’t clear. so yeah, it was an interesting time. I mean I just saw a joke recently on somebody saying that each generation was told to get rid of the prior generations. Technology. Yes, indeed. You know, the other new generation is saying let’s buy vinyl and get rid of all that digital stuff. So yeah, I mean how things turn.
Andrew Hutchison: I have very strong memories of two things related to the record popularity or three things if you include the fact that I was pretty glad to see the back end of it in some ways because I lived in a house with a timber floor and I could not work out how to be able to play the system at the level that I would like without getting, you know, acoustic feedback, etc. which your turntable clearly would resolve. And we’ll come, we’ll discuss that briefly in a second about your isolation system. But And then the second one was in retail in hi fi. Retail in the 90s just how it went from. We actually at the start of the 90s were still selling quite a few turntables but by the end of the 90s it was it was. I remember distinctly having a Rega Planar 3, the last one sitting on the shelf. It had been there for two years and no one had shown it the slightest bit of interest. And I think I sold to half price that the next person that came in the door and that was that. Until the third thing about 2010 or 11, I got sick and tired of sending inquiries for turntables to the opposition who were stalking them. Yeah, I’m like, I gotta put record players back in the shop. Yeah. What is going on? So in that, in that tracking that period of, of lack of popularity. So, so what, what did you do in that was. There was a. Obviously you did something else in the late 90s because there were no one. It was not even the. I mean I would say it was 0.0001% of the high end market were interested in turntables in, in the year 2000, would
00:05:00
Andrew Hutchison: you say?
Mark Dohmann: Or am I. Oh yeah, yeah, totally. it was We’ve in the industry referred to as the dark ages. Yes. and what I figured, that I was the guy rocking in the corner. analogue’s better. analogue’s better. You don’t know what, you don’t know what you’re missing. Oh, he’s one of those analogue guys, you know, like poor thing, you know, let’s just tighten the straps on the vest a little bit more.
Mark Dohmann: So it was challenging because I mean it, it’s hard to bottle up enthusiasm for something that is a real passion. so every core conversation. Somehow I managed to steer it onto the topic of why vet records sound better.
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Mark, can you talk about your isolation system in the turntable
can I talk to you Mark, about your isolation system in the turntable? The. It’s something to do with earthquakes I believe.
Mark Dohmann: not so much earthquakes as any vibration really. And in industry if you’ve got any sensitive measuring equipment, like in a laboratory. We still deal with the university sector here and some of the other allied sectors who have very sensitive measurement equipment. That is a microscope or say for instance they want to measure the quality of a surface with a surface roughness tester or There’s a bunch load of instruments, lasers if they’re doing any laser interferometery where they shine beams at the various angles and get the reflected energy, come back and look at the interference patterns on a, on a screen. Yes, they, they’re literally the footfall in the university laboratory, or engineering department. Typically at the bottom of the building, the concrete transmits a lot of vibration. You know one would think that hey I’m on three foot thick concrete that that’s going to stop anything moving. But turns out a truck on the road, on the western highway will interfere with your, your imaging. Two kilometers away.
Andrew Hutchison: Two. Oh. Two kilometers. Okay.
Mark Dohmann: Yeah, yeah, yeah. It’s really weird. I remember when we, we saw that this is a couple years back, somebody was doing some very sensitive measurements out west. And literally they could tell when the trucks rumbled through you could see it disturbing the. The measurement gear. And they were looking at you know, will this mechanism that you’re talking about which is called A minus K, comes from Inglewood, California.
Andrew Hutchison: Yeah.
Mark Dohmann: developed by a very bright individual, called Dr. David Platus and David and now Eric Runge, the senior engineer there. have been at the forefront of removing those vibration signatures from very sensitive equipment all m. Over the world. And they use a, a passive mechanism. Now in the world of vibration there’s a bunch load of alternatives. some are they what they call active.
Andrew Hutchison: Yep.
Mark Dohmann: Which is like a loudspeaker, a ah voice coil. And he. As you can see your, your loudspeakers push in and out to music signal. If you invert the music signal 180 degrees. You can use the speaker to cancel out the music.
Andrew Hutchison: Yeah. Sort of like like noise canceling headphones. Yeah, absolutely. Only in a slightly different application, but yeah.
Mark Dohmann: So those systems are actively listening.
Andrew Hutchison: Yep.
Mark Dohmann: And then they’re actively feeding back a reverse signal to the incoming signal and attenuating the level of vibration that that comes in. And they’re very, very effective as well. And then you’ve got the classic, air bag suspension systems where they literally get a, a balloon or a bicycle tire and inflate it with, with air and then they bleed the air out so that the rubber eventually starts to become very compliant.
Andrew Hutchison: Yeah.
Mark Dohmann: And by monitoring the air pressure they can adjust the amount of bounce.
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Mark Dohmann: And the lower the, the bounce, the more isolation they develop. So all those sort of general platforms for isolating vibration, you know, rubber mounts, oil air systems, active voice coil based systems, or piezo devices. And then you’ve got your passive spring based systems. I, felt that the minus K was the best performance.
Andrew Hutchison: Yep.
Mark Dohmann: In that. Now when I say I felt that way is when you ask a manufacturer for their nomograms, say. All right, show me your data. They give you some graphs and they publish the, you know, disturbing frequency. And then they show the peak acceleration in excitation mode, the resonant frequency of the device and then a slope as it peters up to a lower amount of energy, what that curve looks like and have a standard test that they do that with. And it was for my looking at things when I looked at the active and the air and you know, the other alternatives, it was very difficult to compare apples with apples.
Andrew Hutchison: Yeah.
Mark Dohmann: Because sometimes the manufacturers, they wouldn’t publish the, the same information to the same standard.
Andrew Hutchison: Yeah, yeah, indeed.
Mark Dohmann: And, and, and so it became this exercise in converting their graphs and finding out where 0.0, 1 of hertz was, where 1 hertz was with 10 hertz was, where 100 hertz was. And then looking, you know, on the x and Y scales and saying, ah, there it is. Now I can superimpose their graph onto this graph and, and see which one has actually got the better performance. And when you went through that exercise, you realize that the minus K system was actually the best performance.
Andrew Hutchison: Okay.
Mark Dohmann: It had the lowest resonant frequency. I mean these guys can get down to 0.3 of a hertz. Now what does that mean in earthquake terms? You’re probably shaking a little bit higher than 0.3 of a Hertz.
Andrew Hutchison: Yeah.
Mark Dohmann: So if you were to shake the system at 0.3 Hz or 0.5 Hz, it would wobble, it would excite. And you’d say, there’s no isolation going on there. Yeah.
Andrew Hutchison: Yeah.
Mark Dohmann: But if you were to disturb it with a 1 Hz frequency already pulled out 98 of the vibration. If you disturb, with the 2 Hz frequency, you’re pulling out 99.95. If you’re disturbing it with say a 5 Hz frequency, it’s completely washed off till it’s infinitesimal. so in comparison to the original.
Andrew Hutchison: Yeah. So the truck that’s 2km away is obviously inaudible. You couldn’t. It works perfectly now. Yeah. But you. Well, not, not once it’s sitting on the minus K, though, it’s, it washes it off. It’s gone. Yeah. So interestingly, I just think, example, there’s.
Mark Dohmann: A university here in Australia that in the bowels of the building, they have a beam collider.
Mark Dohmann: And they’re using, an airbag suspension system.
Andrew Hutchison: Yeah.
The minus K system stops dead vibration getting into the, the plinth
Mark Dohmann: And on a big girder system. And they have to ask all members of the faculty that are currently in the building and students to stand still really, whilst they take one of their measurement shots. And once the process is over, which only takes a couple of seconds, they announce over the klaxon, hey, it’s all good, everybody can return to normal activity.
Andrew Hutchison: Yeah.
Mark Dohmann: You know, we’re measuring things right. Right down at the limits at an atomic level. So in a hi fi system in a normal home, if you can provide that level of isolation, it really benefits a turntable which is very sensitive to vibration. So that’s what we’ve done is we’ve partnered with a Californian company and to this day, I still love their technology. It’s, it’s, you know, still being chosen through very complex tender processes to achieve the best performance. You know, these things are going into universities, they’re going into defense, aeronautics. You know, amazing the amount
00:15:00
Mark Dohmann: of places where we in the biolabs, where minus case are being caught and yeah.
Andrew Hutchison: For the obvious reason, if you’ve got to have the faculty stand still for 10 seconds, it’s, it’s, it’s, you know, I mean, I couldn’t believe it. Hey, interestingly so, okay, so you’d write, obviously your isolation, the minus K system, the way that you stop, literally stop dead vibration getting into the, the plinth, if we call it that, of your of your turntable, it’s obviously a key design feature. But where, where does that. When do you have thought the opposite. Which is say say Rega’s, Roy Gandhi’s methodologies, if you like where he m. He goes sort of stiff and light and no suspension. So what, how does that, what do you have a thought on how that might. I mean I realize different price points. I mean where he’s his most.
Mark Dohmann: He’s got, he’s got some, some very expensive tables as well.
Andrew Hutchison: Yeah, yeah.
Mark Dohmann: And which are you know, the ultimate expression of that engineering philosophy. Which is valid. Totally, valid. what it is is that to get a suspension system to go low enough is really hard. So typically if you’re going to run with rubber or Palmer type systems and you go open up your Barry controls or you know it’s now owned by another company or your Lord catalogs, and you look through and you look across and say yeah, there’s a postradine mount. It’s. Let’s look at its nomograms. Oh crikey. That goes low that. Wow. For a polymer mount, getting down to three and a half hertz.
Andrew Hutchison: Yeah, yeah, yeah.
Mark Dohmann: Wow, that’s impressive. And so you choose that rubber mount.
Andrew Hutchison: Yes.
Mark Dohmann: Right. Now that’s a horizontal and vertical and you think that’s the best performing currently on the market. Now to beat that you have to go to an air system. So you gotta then have pumps and bladders and you know, pressure monitoring and then. Okay, cool. Wow. I can get that down to 2 hertz. You know, wow. I can actually get down to one and a half. That’s impressive. So you’re starting to, to try and get down lower and lower. It’s becoming more and more complex.
Andrew Hutchison: Yes.
Mark Dohmann: so the, the Rega pathway of saying. Right. To solve that is, is such a complex task. We’re going to go the other way. We’re going to go stiff and we’re going to mount everything rigidly.
Andrew Hutchison: Yeah.
Mark Dohmann: Which is a absolutely admirable approach. And if you were to excite the mechanism, we’re just going to ignore that. We’re not going to store that energy.
Andrew Hutchison: Yeah, yeah.
Mark Dohmann: So it will have an effect on the sound. And so chasing the tail of trying to remove the vibration versus saying look, we’re going to live with it and we’re going to adapt to its disturbing effects and we’re going to lighten our chassis, system. We’re going to use aerated materials and we use carbon fiber to stiffen the, the Outside skins. But we’re not going to store any of that energy because I don’t want it interfering with, with my system. What it does, it doesn’t remove the base energy. No. from the feedback loop, but it doesn’t store.
Andrew Hutchison: Yes. Yeah. So that’s, And that’s I guess the catch with making a heavier, sturdier turntable that, that, it, that the suspension system becomes heavier.
Mark Dohmann: And heavier and heavier and.
Andrew Hutchison: Yeah, yeah, well, yeah, that’s like if you.
Mark Dohmann: Yeah.
Andrew Hutchison: That’s a bit like building a more powerful car or whatever. You know, it ends up being a and weighing over 2 tons or whatever because everything has to be bigger and heavier to deal with the power and the heat. But yeah, but, but your turntable, you, you completely, you, you just resolve that problem by this incredible isolation system. So really then you’ve got free reign over how you might make some of the other components up the top. You know, as far as, yeah.
Mark Dohmann: You can have a heavy platform. I’ve still got the same problem that Rega is facing is what do you do once you get over the 100 hertz hump? I’ve still got exactly the same problems.
Andrew Hutchison: Oh.
Mark Dohmann: Ah.
Andrew Hutchison: So the range of isolation is from 0.3 up to about 100. Is that that?
Mark Dohmann: Yeah, yeah.
Andrew Hutchison: Okay.
Mark Dohmann: She starts, starts petering out. and that, that, that curve. Right. So you have to look at just like your loudspeakers and, and Brad’s loudspeaker. That
00:20:00
Mark Dohmann: careful crafting of the crossovers to make them seamless so that you’ve got a continuous, path.
The minus case systems take out the big heavy bottom end energy
Mark Dohmann: Of vibration management. The minus case systems take out the big heavy bottom end energy. But then what do I do with the other energies that are in, in the chassis? I still have to look at it like Rega looks at it. Yes. or any of the other turntable designers out there look at those problems and then I have to develop a strategy for that. And so yeah, it’s, it’s, it’s not a. Just a whack a minus K under a table and you’re good to go.
Andrew Hutchison: That’s right. It’s not. Yeah. You don’t take a, a, I don’t know, a expensive project turntable and whack it on a minus K and suddenly have a helix 2. That doesn’t work that way.
Mark Dohmann: No, no, no.
I was talking to a client about, about turntable mats
Andrew Hutchison: Speaking, of stuff with turntables, you’re clearly the guy to ask.
Mark Dohmann: how about that?
Andrew Hutchison: Well, about anything really to do with turntables. I got a Feeling that you’re going to have an answer and a balanced answer by the sound of it. so I was talking to a client the other day about, about turntable mats and they had a, they had a mat. They had changed the mat on their turntable to a cor. And the cork mat did not have a rebated area for the label to sit.
Mark Dohmann: Yep.
Andrew Hutchison: And it reminded me and I, I suggested. I, I felt that was probably a bad thing, from a common sense point of view. so is, is the job of a platter mat? I have others, I have other questions. This just happens to be the one that jumped in my head. This is slightly uninteresting in a way. But a lot of platter mat people change platter mats willy nilly. It’s a sort of, it’s a bit. Yeah. It’s how you hot rod your turntable. Right. So yeah, mostly they ruin the turntable. They put on some light sort of slip, mat type of thing or they, or they put a cork mat with no rebate or whatever. Does the, the grooves. The, the more the, the ridges, the, the peaks of the grooves that, the main face of the How am I describing this? The peaks of the grooves and valley. Yeah, yeah. So the peaks are suddenly not, they’re not sitting on the platter mat anymore. Or do we not want that? What, what part of the record do we want to have touching the platter mat, do you think?
Mark Dohmann: Well, there’s, there’s two. Well there’s a number of ways to look at this problem. one is to look at it from perspective of say Ed Meitner of EMM Lab, who was the one of the key developers in the SACD system.
Andrew Hutchison: Okay.
Mark Dohmann: And he’s known for his expertise in digital. But Ed, is an absolute legend in the industry. and, and certainly somebody that I pay attention to and respect. it developed a turntable where there was no mat. In fact there was no platter.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: And he, he clamped the record just in the center.
Andrew Hutchison: Yes.
Mark Dohmann: And he had evidence to show that a free floating record.
Andrew Hutchison: Yeah.
Mark Dohmann: you know, the needle still dropped down in the groove and hopefully the record was flat and everything and it would track. That was the best, acoustic impedance match, to, to the stylus. So you can go from that and it’s a valid point all the way across to a really liquid gooey mat that tries to smudge itself up into the grooves and with a clamp. So if you listen to both Those styles, they’re very broad interpretation between those two points. So mat’s definitely make a difference to the sound.
Andrew Hutchison: Yeah.
Mark Dohmann: And are a really effective tuning mechanism. That’s why, you know, we get hold of a mat and we put it on our record player and then go oh wow, that sounds so much better.
Mark Dohmann: Valid experience because within a person’s unique system which they’re curating for their own, enjoyment and they get used to a certain sound and there might be something about that signature in their system which they’re finding. Oh, ah, that’s just a bit of a niggle there. It’s not really sounding right. And changing a mat all sudden resolves a number of those issues. Yeah, yeah, yeah. that map then becomes the, the, the new reference, the new standard for them.
Andrew Hutchison: Yeah.
Mark Dohmann: For them as part of it.
Brad Serhan: It’s a tuning
00:25:00
Brad Serhan: fork.
Mark Dohmann: Yeah, it’s a tuning now. They might then change their speakers down the track and then there’s something out. Oh, that didn’t quite. Oh, it’s missing that. I’ll try another mat. And they try another mat and it. And it changes the sound again and it rebalances for them their system. So there’s no 100% correct answer that this is the mat and it’s the only map and it’s the only way.
Andrew Hutchison: Okay.
Mark Dohmann: It’s a continuum of experience. And in. When you’re voicing and building a turntable, you eventually settle for a type of acoustic interface, a matte or no matte or.
What is that mat doing to the sound? Is it trimming high frequencies
So what is that mat doing to the sound? Is it trimming the high frequencies? Is it boosting the bass or is it making the mid range more prominent by m tapering off either end. And so ideally you’d strive for neutrality and removing of any really annoying spotlighting signatures. So for instance, if you had a really, really hard platter like something that’s you know, hitting into the glass and ceramic scale.
Andrew Hutchison: Yes.
Mark Dohmann: you possibly find a nice felt soft or wool or some, you know, natural material, would, would really blend well with, with, with that mat. If you were using say something that has a brightening signature M, you might find that a really soft compliant rubber mattress would, would bring it back into balance. So if you have a look at the, the schools of turntable ism. yeah, as you look at the 70s and you saw the wonderful direct drives, very high quality coming out of Japan and this is, you know, from Panasonic to Micro Seiki to all the.
Andrew Hutchison: Yeah.
Mark Dohmann: The Kenwoods and The Pioneers and the Yamahas. And what was the predominant type of mat that went on that turntable?
Andrew Hutchison: No, rubber.
Mark Dohmann: Yeah, rubber. M. And some were liquid filled and everything.
Andrew Hutchison: Yes, various. they would come. Some were quite What’s the word? Yeah, super compliant. I mean obviously the oil leaks out of them or leeches out of them over the years and they go hard and. And that’s a thing if you know this. At this point it is, Yeah, the aluminum platter are fairly light. Say a Japanese belt drive turntable with a relatively light aluminum platter. I mean these are the ones that I get annoyed when someone brings one of those in with a, With a, you know, with a slip mat on it that clearly weighs one gram. And therefore that aluminum must be ringing its head off really compared with when it has the rubber mat on it. But that ringing, it might, it might be adding some kind of exciting illumination in the mid range or something when you hit the right notes, you know. So I guess it’s. It is a taste issue to some degree. So that. Well, that will put that to one side.
Les Davis from Davis Audio is using a constrained layer for his mat
Brad Serhan: Mark, a quick question.
Andrew Hutchison: Yes, Brad, Fire away. You’ll go ahead.
Brad Serhan: I have to declare my bona fides with Liz Davis from this Davis Audio.
Mark Dohmann: And yep, Les
Brad Serhan: Les, is using a constrained layer type of material with his latest mat, which is a sort of double the. The thickness of the old one.
Mark Dohmann: Mark.
Brad Serhan: You might remember calling it the Soul Mate. So, and that. That’s using constrained layer. what’s your take on sort of that sort of thing?
Mark Dohmann: with regards, very, very valid approach. Constrained layers are ways of tuning. And I know Les does a fabulous job with his sandwich, constructions. So for, I suppose the audience who might not be an audiophile, constrained layer is literally a sandwich. Imagine, a bologna bread. You take a. Take a first ah, slice and you put on a bit of butter and then you put a bit of cheese and you put a bit of ham, you put some tomato and then you put another slice of bread on top. That is actually a constrained layer. it’s made of different materials and each of the different materials create a different flavor. But combined, that sandwich is tasty. Well, we hope it is.
Andrew Hutchison: I mean, what sort of cheese though? We’re talking. I mean.
Mark Dohmann: Yeah, well, yeah, you know. Yes, we can, we can definitely go into the weeds on this one. Yeah, so it’s constrained layers. Ah, I love constrained, layers. And people know me, know that I like a sandwich.
00:30:00
Mark Dohmann: so. So, Yeah, there’s there’s a lot of merit there. Again, they’re very turntable devices. And you can’t say that that mat’s going to be perfect for everybody, but definitely give them a try and find out where you’re at. What, what are we trying to solve is that the vinyl sits on the mat and the mat has that sandwich material or it’s contiguous material. And then you’ve got your main platter and that’s either made of some sort of polymer or, aluminium alloy or, you know, some other material. Yeah, acrylic or whatever that wood. It’s just totally fine to have a wood platter. so your needle, excites itself in the groove by being moved left and right and up and down as the record rotates. But when it jumps from one side to the other, it gets ricocheted back and forth inside this groove and it creates a mechanical, noise like literally banging, crashing against the sidewalls of the groove. If you were to envisage oneself as a tiny human being and Brad becomes tiny person and Andrew becomes tiny person and we, we all step inside the, Inside the lp. So we cut a hole in the floor and we step up through and into the vinyl room. Now where we’ve got the ceiling, which is the. Where the needle is, ricocheting and making noise. And we’re in a, you know, a one to two millimeter thick, room. Yeah, it’s very, very wide. And Brad walks around to the other side of the room and Andrew and I on this side and we say, hey, Brad, can you hear us? And we hear.
Andrew Hutchison: I feel as if you and you and I, Mark, were on one side of the room and Brad was on the other, that the room would tip over. But I mean, it’s.
Mark Dohmann: All right. So we, we can locate each other where Brad.
Andrew Hutchison: Maybe I’ll stand in the middle and sort of, you know.
Mark Dohmann: Well, it turns out the middle is a very, very noisy area.
Andrew Hutchison: Okay.
Mark Dohmann: because the reflections of the sides of this round room and the ceilings and everything tend to congregate around the middle. Now why do we know that you, can do the measurements and some of the, analogue guys are now publishing those measurements for, all. Which is wonderful. but that problem’s been around since the 1930s. built the record so that, that understanding, has been there in the industry. And the mat will dampen the amount of movement in the floor.
Andrew Hutchison: Okay.
Mark Dohmann: So therefore it reduces the amount of echo in that final room that we’re.
Andrew Hutchison: Standing in as long as the as long as the. And this is back to my original sort of concern is that the face of the record is m in many cases with many mats is not actually touching the plat the surface of the platter mat. It’s the outer lip and the inner label.
Mark Dohmann: Yeah. Ideally you’d want the suspending it if you like the cutting surface to be well mated to Internet. Yes, yes, that’s heat but that’s my opinion.
Andrew Hutchison: Well to me that makes, makes a lot of sense though. Right. So anyhow, look we’re going to take 2 second break and we will be right back with my, my questions on cartridge compliance and how that might relate to the you know, the specification if you like or the type of tone arm. so something I’m a bit vague on. So. All right, thanks Mark. Thanks Brad. Back in a second.
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Mark Dohmann from Melbourne has question about cartridge compliance
And we’re back back with Mark Dohmann from Dohmann Turntables based in Melbourne and these days manufactured in Melbourne. And of course Brad Serhan also on the line from Serhan Swift loudspeakers made in Sydney and myself from dellichord made in Brisbane. We’ve really got all three eastern board states covered I guess hence we’re on the phone and not sitting in the one room because it’s 10,000km from here to Melbourne or at least it feels
00:35:00
like it if you drive your car. so Mark, I, I’ve got a question about cartridge. Oh you hear the word cartridge compliance thrown around. I mean everyone the specs. If you buy a new cartridge, it has a bunch of specifications frequency response and output and, and perhaps you know if it’s a moving magnet it might have a resistance or impedance value of the coils. It’s really resist I guess DC resistance but, but it also have output related perhaps to speed and also tracking force suggestions etc. So I’m, I’m not sure. That there’s a compliance. I mean, just tell me what is, what is cartridge compliance? And then how does that equate or how should you try to match that with a particular arm, if you’ve got any thoughts on that at all?
Mark Dohmann: Oh, absolutely. Yeah, yeah. This is, this is a, an age old discussion. and very, very valid. The problem has existed since the early, era of vinyl. Talking back in the 20s and 30s.
Andrew Hutchison: So pre micro groove.
Mark Dohmann: Pre micro groove, the problem was there. then in micro groove it became more apparent. So if we come into sort of what I call recent memory. 1960s,’70s.
Andrew Hutchison: Wow. How old are you?
Mark Dohmann: I’m 150. In dog years? yeah.
Andrew Hutchison: I think you’re older than that in dog years. Your mental arithmetic is terrible.
Mark Dohmann: Yeah. so the problem is, for compliance. So I, use an analogy of a car.
Mark Dohmann: So you go into say zagame and you see this beautiful Italian Ferrari with you know, engine and, and you know, naught to 102.3 seconds and all these wonderful specs.
Andrew Hutchison: Yes.
Mark Dohmann: And you go, all right, I want to buy that car. And then you get in it and you drive it out the the driveway onto the road. There’s tram lines on, on the road. And you feel every tiny speck of dust on the, on the road. It comes straight through your seat and you go, I couldn’t drive to Brisbane in this thing.
Andrew Hutchison: No, no, no.
Mark Dohmann: All right, so, so then you, you take it back and you go next door and you buy the family SUV with suspension setting of, you know, comfort.
Andrew Hutchison: Yes.
Mark Dohmann: So you get in it and you drive down that same tram line road and go, I can’t feel a thing. But then you want to go take a corner and you have to start turning the corner 1km ahead in the hope that you gotta make it around the corner.
Andrew Hutchison: Yeah.
Mark Dohmann: Ah, that’s why they invented Safari.
Andrew Hutchison: Yes.
Mark Dohmann: So the suspension softness, the amount of give to an input is, is, is literally what we’re talking about here. So you can have cartridges that are built like a Ferrari.
Mark Dohmann: Ah, you can have cartridges that are built like that family SUV with the comfort setting.
Andrew Hutchison: Okay.
Mark Dohmann: And as opposed to some cars now you can punch a button and go to sport mode.
Andrew Hutchison: Yes.
Mark Dohmann: You can’t do that with a cartridge. It comes from the factory as either sport or comfort. Or maybe in the middle. so moving coils and moving magnets and say the derivative moving irons and some of the, you know, the smaller variants. Yes, the moving magnets and moving irons tend to be built like the family, SUV on comfort setting. And some are even built like an American 1950s Boulevard cruiser. Even softer than that.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: And most moving coils are up at the other end. They’re at the Ferrari.
Brad Serhan: All right.
Mark Dohmann: And they’re really, really. So if you don’t match the body of the car to the suspension, m I, E. The tone arm, which is now sitting on that cartridge suspension, you can get a situation where, the wheels won’t stay on the road, they’ll skip and they’ll bounce and the whole car leaves the road for that split second before it bounces down again.
Mark Dohmann: You need to put a bit of luggage in it. You need to have a bit of weight of an engine, you need the weight of the passengers, etc. To get it to sit about the middle of its suspension.
00:40:00
Mark Dohmann: Travel correspondingly in the family suv, you load too many cement bags from Bunnings and you put a boat on the roof and you know, four adults in it and everything. And all sudden she’s bogged down so, so low. It starts bumping the suspension.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: Against the stops. Which makes for, so you’ve got to balance the amount of mass that you’re moving for the cartridge suspension. That’s where this argument comes in into play. Now the common understanding which has been around say 50 years is a formula which gives you a number and that’s the rule. And you’ve got to stick by that rule. And you plot your graph. You say for that cartridge you need to buy this toner. So that is a theory. And it became Dogma.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: And yeah.
The old formula says the following: 60 grams effective mass
You could light up a few Dogma forums.
Andrew Hutchison: That’s, that’s, it’s never happened in the hi Fi business. There’s no surely.
Mark Dohmann: So sometimes you found a designer.
Andrew Hutchison: Yeah.
Mark Dohmann: Who went against Dogma. Right. And, and everybody would look at them go, oh, that person is wrong. They are wrong. Because the formula says the following.
Andrew Hutchison: Yes.
Mark Dohmann: And then you’d go and listen to that iconoclastic designers.
Andrew Hutchison: Yep. work Dogma for real work. Yes.
Mark Dohmann: Wow, that sounds amazing. But what you found was some of those, innovative designers didn’t publish their figures because they knew it would light up the formula guys.
Andrew Hutchison: Yeah.
Mark Dohmann: That would say, oh, you’re wrong, you’re breaking the law. You know, the law says so what they did is they under declared the mass of their tone arms.
Andrew Hutchison: Okay.
Mark Dohmann: Tucked it away, were impecific about it. You know, you can’t see, you know, where’s the effective Mass. I can’t find any effective mass of this this time arm. It’s not published. Well, you’d weigh the thing and it’d be sitting up at 40 plus, you know, 60 grams.
Andrew Hutchison: Right.
Mark Dohmann: Complete and utter heresy.
Andrew Hutchison: Yes.
Mark Dohmann: But you’d match it with a Koetsu cartridge.
Andrew Hutchison: Yeah.
Mark Dohmann: Moving coil and go. Wow, that sounds absolutely amazing.
Andrew Hutchison: Okay, so the Koetsu is the Ferrari. It’s got Ferrari suspension in it.
Mark Dohmann: Is.
Andrew Hutchison: That is. Yeah. Yep.
Mark Dohmann: Yeah.
Andrew Hutchison: And the heavier compared to.
Mark Dohmann: Well, with a Shore V15 Type 5, which is the family SUV.
Andrew Hutchison: Yes.
Mark Dohmann: Soft suspension.
Andrew Hutchison: So you’ve got your Ferrari cartridge, your Koetsu collectible Japanese handmade cartridge and you. So the. What you want with that is a lighter effective mass arm. Is that what. Ah, you want the opposite.
Mark Dohmann: You want, you want a heavier. Yep.
Andrew Hutchison: so you’re saying 60 grams is light then is as far as effect.
Mark Dohmann: No, not light. That’s, that’s a heavy arm in, in the other schemes, but normally the, the rule says you don’t go above 20. See. Oh, and, and, and these guys like the FR64s from Fidelity Research, some of the big sumiko and some of the, those, the glanz and those, you know, venerable, the Ikedas and so on. They were heavy, you see.
Andrew Hutchison: Yep, yep.
Mark Dohmann: And they matched well with the Japanese moving coil school. The high end is becoming dominant. mode like the moving coil is still very, very, very popular, indeed amongst the guys who are pushing analogue, performance. So you need a heavier arm, than what’s accepted. So if we were to calculate, and measure the acceleration at the headshell versus the excursion at the head shell.
Mark Dohmann: And mechanical engineers would do those sorts of things. you might find that those old calculations, the, the rules don’t apply.
Andrew Hutchison: Okay.
Mark Dohmann: And you’re actually observing the system under test. The sut. or device under test. Dut. And you’re measuring something completely, different than what the formula from the 1950s said is the rule. So observed results, real world results are actually the only thing that matters. So you can throw
00:45:00
Mark Dohmann: out that old formula.
Andrew Hutchison: So. And in turn while you’re throwing it out, you could throw any cartridge on any arm, and have a listen to it and see what you think. Is that the gist of it?
Mark Dohmann: Oh look, that’s, that’s one way of doing it. Or you can, I mean there’s a gentleman who I have a lot of respect for, Alexei from korf Audio. That’s Korf audio.com and Alexei has kindly finally published things that we’ve been secretly doing for a number of years. it’s now out in the open. and he provides a wonderful little calculator and you punch in some values and you push, calculate and it gets you a predicted mode. Yeah. And it shows you the importance of those. And it basically proves that you can run a much heavier arm, than previously thought acceptable. Okay. Imagine, a marketing comes through from one school of engineering. And in turntables, we’re talking and tone arms and we’re matching a sure V15 Type 5 which back in 1970 was the bomb And we need a super lightweight tonearm to, to match it so that it’s very compliant suspension, would work beautifully in the groove and track impossible amplitudes.
Andrew Hutchison: Yeah.
Mark Dohmann: Like it was, it was the, the proof that this is superior way of engineering. That tonearm that it was mated to, built by a British company called SME, was an absolute work of art, like in, in fine mechanical, engineering and lightweight technology.
Andrew Hutchison: Indeed.
Mark Dohmann: And made it with that cartridge. Wow.
Home arms have to be light, right? Yeah. Okay. Okay, so now that became the accepted understanding
Okay, so now that became the accepted understanding in a lot of people’s mind when they went to a hi fi shop. They saw these lightweight performance systems and it became embedded that home arms have to be light. And if your turnaround looked heavy, it wasn’t as good as the one that was light.
Andrew Hutchison: Okay.
Mark Dohmann: Now, if you can imagine that took hold.
Andrew Hutchison: Yes.
Mark Dohmann: In the consciousness. Whereas in the real world, if you’re running a moving coil now, the, say, the Frank Kuzma Sapphire tonearm is pushing up at 60 grams. other arms are pushing up to 90 grams. And we start an argument and then we have to answer the questions. It’s okay to do that. Yeah. Because if the record is flat. Yes. You know, not always the case, but.
Andrew Hutchison: You know, with our aforementioned record mat and clamp, it is.
Mark Dohmann: Yeah.
Andrew Hutchison: And it’s not warped.
Mark Dohmann: Pretty flat.
Andrew Hutchison: Yep. Pretty flat.
Mark Dohmann: Yeah. it doesn’t become a problem.
Andrew Hutchison: Okay.
Mark Dohmann: So the actual problem that we were trying to solve, which was what we called an 812 Hertz issue, we were trying to get the thing to resonate between those two bands because it was above warp. Wow. And it was below, music frequency. And that was the sweet spot that we had to sit the, the resonant system into.
Andrew Hutchison: Yep.
Mark Dohmann: It’s quite okay to push that down, you know, drop it down to five, you know, four. Around. Around there with a super heavy, And music still plays.
Andrew Hutchison: Yeah. speaking of.
Young: I heard amazing acapella speakers at Munich last year
So a room that m. I quite enjoyed at Munich last year. I don’t know whether you, you, you’re probably too busy assuming you were there and I’m sure you were.
Mark Dohmann: Yeah, I was. Yeah.
Andrew Hutchison: I, I You would have been busy working, but I was just flitting around entertaining myself and I So there was a room, very nice room, which I mentioned in another episode. rooms, you know, great sound we heard. I was the wrap up episode of 2024 where we’re talking about the best sound we heard all year. Best sound I heard was these amazing acapella speakers which of a giant wave guided. Yeah, horn. But they’re sort of. There’s very plasma tweeter short, stumpy. yeah, you obviously know more about them than I do. I know how they sound. They sound freaking amazing. But the turntable the guy was using had a tone arm about three feet long. Well, at least, at least it looks like that from, you know.
Mark Dohmann: Yeah.
Andrew Hutchison: In. Yeah. Because it’s a big room that it was set up in. And I was. Yeah, I did walk up to the turntable and take a nice picture of it which we should put on the website. But the point is, say it was 2 foots. We’ll speak in metric, say 7 or 800 mil long. So what, what’s your thought like was the effective mass of that by definition is high or.
Mark Dohmann: Well.
Andrew Hutchison: And what’s the advantage in a three foot arm?
Mark Dohmann: Yeah. Okay, well, the advantage, what they’re trying to solve there is they’re trying to create the most linear path. See, the record was originally theoretically cut in a straight line.
Andrew Hutchison: Yeah.
00:50:00
Mark Dohmann: And it’s, it’s a horizontal lathe and the cutting head is on a linear track. And one would assume that the engineer who cut the record made sure that the line of the cut was from the outside edge directly to the center of the spindle.
Andrew Hutchison: Indeed. Yeah. Yeah.
Mark Dohmann: If we assume that that is the truth on that basis. And I’ll explain a little bit why that sometimes isn’t the case. sometimes the engineers are a bit sloppy and they cut it 2 or 3 millimeters ahead or behind of that ideal path. Okay. so you know, as an average we’re going to get somewhere near the middle if we make a really long time. I’m just saying we make it three meters long. Tone arm.
Andrew Hutchison: Well, now that’s the thing I’d like to see.
Mark Dohmann: All right. And you’ve got, you know, three meters away, you’ve got the pivot point and then three meters forward of that you’ve got the stylus, the Arc that, that three meter, long tonearm, would deliver is almost a straight line. Yeah.
Andrew Hutchison: So that’s, Is that what they’re. So it’s a geometrical line.
Mark Dohmann: They’re trying to. Yeah, they’re trying to reduce now with a headshell. Most people, when they look at a turntable, they’ll see a pivoted tone arm. and then the, the where the needle is, is sort of kicked off to the left. So it’s sort of m. Now what they’re doing there is they’re trying to get two points on the arc where that, it is actually square to a straight line perpendicular to a straight line. Now those are what we call null points. And the null points can vary a little bit around around 60 millimeters and around about 108 millimeters from the center of the spindle.
Andrew Hutchison: Okay.
Mark Dohmann: So there’s, there’s, there’s two null points. Now you can play with those a little bit by offset of that angle and length of the tone arm.
Andrew Hutchison: Yep.
Mark Dohmann: So the effective mass we know is not a problem anymore because you can have a heavier, heavier cartridge. So having a 3 foot long or 800 millimeter long tonearm is quite acceptable from an effective mass point of view.
Andrew Hutchison: How to cut you off for a sec. Effective mass, obviously it’s counterbalanced. You’re still tracking it at one and a half or two grams or whatever. But so the effective mass, I mean if three, sorry, eight or MM long, is going to have to be made, made m. Out of titanium or something to keep the effective mass low. Or, or you could make it out.
Mark Dohmann: Of a bruise, make them out of violin bows or you know, those sorts of things that they tension up over that distance.
Andrew Hutchison: Yeah, yeah.
Mark Dohmann: Because we’ve got a thing called Young’s modulus. So if you get a ruler, like a metal ruler, say a meter metal ruler, and you put it on your kitchen bench and then you start pushing it out over the kitchen bench. Eventually you’ll see the ruler start to droop.
Mark Dohmann: The further you push it out. That’s a point where the, the material’s weight versus the material’s stiffness starts to interact and the weight overcomes the stiffness to various degrees.
Andrew Hutchison: Indeed. Yeah.
Mark Dohmann: So in an ideal world it would be infinitely stiff and be infinitely light. but we can’t have that. So we’ve got to compromise it somewhere along the, the, the, the rules of the materials science.
Andrew Hutchison: Okay.
Mark Dohmann: Or the structure, like building a bridge, across the harbor, Is, is dealing with that problem.
Andrew Hutchison: Yeah, yeah.
Mark Dohmann: Okay, so the 800 millimeter long tonearm, the only issue is, your partner’s acceptance of the device in the house. So.
Andrew Hutchison: So actually that’s, that’s so clearly, Yeah, you won’t be buying one of those.
Mark Dohmann: Yeah, yeah, it’s the limiting factor.
Andrew Hutchison: Yeah. But for those that you know, live. Live by themselves, they could potentially have quite a long tone arm. and there would be a small advantage in, in alignment.
You choose your alignments based on the predominant um, musical styles
But and so speaking of alignment, if you’ve got a more normal length arm, which apparently average is 6 inches. No, that’s sorry, 9. 9 inches.
Mark Dohmann: Yeah. There’s some shorter than that.
Andrew Hutchison: I was something shorter than six. But getting back to tone arms.
Mark Dohmann: So the point stream of 12. So. Yeah. So yeah, yeah.
Andrew Hutchison: In relation to everything. Sorry, I’m so.
Mark Dohmann: No, there was no double entendre there.
Andrew Hutchison: No, no, no, no. Because this is serious, a very serious discussion about tonearms. So let’s say you’ve got your standard 9 inch HM arm. When you’re aligning a cartridge.
00:55:00
Andrew Hutchison: What do you aim for? Do you. I’ve heard rumor, and maybe some innuendo that, that you should really align it for the inner node or the. Basically for perfect, Perfect alignment on the last track. Is that a, is that, is that a thing? Because that’s where alignment irregularities potentially, I guess are at their highest. Which from what you were suggesting about the way the record’s been cut would in fact be the case. Because if the engineer has messed up slightly and is not aiming at the spindle, that would, that would be.
Mark Dohmann: There would be those alignments. Yeah. There’d be a bigger misalignment on a straight line. Yeah, yeah. Correct. Yeah. So all those alignments are predicated on a perfect world where the tangential cut is actually right through the center of the spindle. So we can’t do anything about that. That’s the, the material, that’s been handed to us. So we, we’re aligning for a bell curve. the average.
Andrew Hutchison: Yeah.
Mark Dohmann: And within those alignments there’s some 1930s alignments and then there’s some 1960s alignments and there’s some, some sort of late 90s, early 2000s alignments. And what we mean by that is that how much forward of the tangential line. What we call the overhang and how much offset, how many degrees offset will define where you hit those tangent points. And some people who like listening to Long classical pieces.
Andrew Hutchison: Yeah.
Mark Dohmann: Find that the records got a lot of information towards the label.
Andrew Hutchison: Yes.
Mark Dohmann: And it’s typically where the orchestral crescendo and you know the whole story comes together and they’re going off the ultimate sonics there.
Andrew Hutchison: Yes.
Mark Dohmann: we’ll use alignments that favor that last little bit to try and reduce the, the very steeply escalating distortion figures towards the end of the record. Yeah.
Andrew Hutchison: Okay. Yeah.
Mark Dohmann: Now, others who listen to more contemporary, modern, indie, that sort of stuff and, and want lower distortion across the, the maximal surface of the area. Knowing that the records often don’t get cut deep into the label.
Andrew Hutchison: Yeah.
Mark Dohmann: Direction. they want to reduce the distortion at the start and in the middle more. So you choose your alignments based on the predominant listing styles. If you’re listening to classical and punk and everything like that, you’re probably going to go for an average somewhere. So the, the four are , Lofkin, which were contemporaries back in the 1930s. They did some maths. And then we’ve got a Stevenson which was out of the uk. very, very favorable towards more of the classical longer cuts. And then we’ve got a uni din out of Germany which again is a valid alignment. Now no one is perfect. They’re all trying to reduce distortions that are inherent in the mechanism. So choose your, your favorite and stick with it to fiddle with it between records. So that then means what tools do you use to do the alignments? And I’m a favor of what I call Tronkey based.
Andrew Hutchison: Well, hang on, just bear with us a second. Mark. the line has gone very choppy, which is kind of frustrating. just, just, just, just run clear here. Yeah. Okay. Just, just, just wind back one or two sentences and
You were about to talk about alignment gauges I think. There’s, it’s as simple as
You were about to talk about alignment gauges I think.
Mark Dohmann: Oh yeah, yeah. yeah, alignment gauges. There’s, it’s as simple as you can print them off the Internet on, on a one to one ratio on your inkjet printer at home. Poke a hole in the label area and stick the template on and align the cartridge. It’s really simple. As you progress through learning the various geometries, you can invest in more serious tools. some of those tools include protractors that mount onto the platter and have little grid lines on them and they’ve got extension arms that you locate over the rear pivot of the tone arm. And, and you have to build that, that system, up and they’re, they’re again precise tools. in that world. I really like the arc protractor, style
01:00:00
Mark Dohmann: purely because it means that I’m traveling a lot and I can carry those tools with me relatively easily because they’re flat and they don’t require any identification of the rear of the pivot. Because the arc protractor is just literally an arc that’s scribed on a mirrored surface. And if you touch down the needle at the front of the arc and move the tone arm to the inside of the arc and it touches down at the same point, you automatically define the rear pivot. It’s just automatically defined well in the triangle.
Andrew Hutchison: Yeah.
Mark Dohmann: So it’s, it’s just, it’s just a way of reducing complexity.
Andrew Hutchison: Yeah.
Mark Dohmann: And increasing the quality of the measurement. So for me arc protractors are an excellent tool. I also love using the, the more complex tools such as Smart Tractor and so on, that comes out of Germany and the ficut Tractor and there’s a bunch of them there that, that are just like jewellery. You’re opening a box. Beautiful array of alignment tools and. And yeah they’re also excellent. But for me being on the go and having to set up turntables at shows etc, I just run, run the arc protractor system from Wally Tools. That’s just a personal preference. was good friends with Wally the originator and I’m now great friends with of Wally Tools who’s making those tools. So for me, Yeah, yeah.
Andrew Hutchison: And, and relatively simple. so when you, when you, you tighten up the screws and because you’ve got your alignment right, do you, are you a believer in doing them up with a, you know to continue the three foot seam, a three foot long spanner, do them up to M200 foot pound. Or are you, or are you more that you just, just just nip them up kind of thing or is there, is there anything in that?
Mark Dohmann: Ideally you should be able to And then they’re not inexpensive but a small torque calibrated Torque driver.
Andrew Hutchison: Yes.
Mark Dohmann: So that you can create a setting and you can reach that setting perfectly every time. That’s the ultimate expression. if however you’re you know on the go and somebody says oh can you just have a look at my cartridge and can you realign it for me and you say have you got any allen keys or got a screwdriver handy? You’re Left without that tool and you have to do it. so my advice is you don’t use the long part of the Allen key. You use the short part as the torque.
Andrew Hutchison: Yes.
Mark Dohmann: Settings. And you just gently tighten. You don’t put your wrist into it or your elbow. Yeah, yeah.
Andrew Hutchison: So just, just tight.
Mark Dohmann: Yeah. And now I have had examples of galvanic, bonding occurring between cartridge screws and cartridge bodies in humidity, tropical environments.
Andrew Hutchison: Yeah.
Mark Dohmann: And one thing I could advise is is in those sorts of environments use some sort of a, An oil agent, you know, something that retains itself on the screw.
Andrew Hutchison: Yeah, yeah. Yep.
Mark Dohmann: just before you assemble. And not that it drips everywhere but just gentle causes a film to reduce the amount of potential for welding to occur. Because you’re thinking not of yourself but thinking of the next person who, who’s going to change the cartridge.
Andrew Hutchison: Yeah, yeah, yeah.
Mark Dohmann: so yeah, that’s, that’s the only thing. Don’t over tighten and, and, and try to match your materials so that they’re not too disparate on the galvanic scale.
Andrew Hutchison: Do you lead out cables? There’s and I don’t want to talk cables because you, you manufacture turntables and But you must supply, I presume you supply a lead with your turntable. Do you feel. I mean the vast majority of turntables at the semi affordable end of the market have fairly, fairly rudimentary cables. Is there much in it? I mean there’s very. Is a, in the case of a moving coils, audio or the power are the audio. So a tiny, I mean we’re talking, you ah, know, obviously you know a tiny amount of signal from a moving coil cartridge. So one would think the lead was important. Is that.
Mark Dohmann: Yeah, it’s critical. Absolutely critical in my opinion.
Andrew Hutchison: Yeah.
Mark Dohmann: And I’ll tell you why. So, it’s not
01:05:00
Mark Dohmann: uncommon to find multiple junctions of joints within a tone, arm wiring system. So it’s still very popular to provide what we call a din, connector. It’s five little pins in a an array in the bottom of the arm. You mean in the stubborn phono standard?
Andrew Hutchison: Yeah.
Mark Dohmann: All right. So there’s many standards in the DIN world.
Andrew Hutchison: Yes.
Mark Dohmann: But the one for phono is a particular type and they usually allow the end user to purchase and interchange different tonearm, wires and just plug it up into the underside of the tone arm. It’s got a great convenience factor. I’m not a, I’m not against that. because it’s, it solves a lot of problems and provides a lot of convenience and it still sounds great. However, if I’m building for ultimate, you know like trying to push the, the tech as far as I can get it.
Andrew Hutchison: Sure.
Mark Dohmann: Then I know I can’t easily overcome the cartridge clip interface which is a clip onto the pins of the cartridge.
Andrew Hutchison: Yep.
Mark Dohmann: Because it’s quite difficult to solder or for our American friends sarder, the harsh the, the, the pins onto the, you know. But it has been done.
Andrew Hutchison: I was going to say. Is that a thing? Because it sometimes occurs to me, you know, you could give them a bit of a clean up and you could tin them pretty quickly. But have you ever, have you ever soldered the, the headshell wires to the car?
Mark Dohmann: Guilty as charged.
Andrew Hutchison: Okay.
Mark Dohmann: But it’s a revelation. No. Well, it does improve it, but it’s not advice. It’s definitely not convenient. And you can actually wreck the cartridge because the, you put too much heat into the pin, you’ve melt the other side of the pin off.
Andrew Hutchison: This is my concern is that it disconnects itself internally.
Mark Dohmann: Highly. Highly. not recommended.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: So the, the better thing is is to try and simulate that connection.
Micro arcing is actually a distortion artifact that they want to remove
Now again we’ve taken the little pill and we’ve shrunk down the mini persons. So mini Brad, mini Andrew, mini Mark are standing there looking at the, the cartridge pin. And the cartridge clip. And Brad says to me, mark, that’s as rough as can be. It looks like craters are on that beautiful shiny surface that we just saw a second ago. Wow. I couldn’t believe how rough that surface is.
Andrew Hutchison: Yeah.
Mark Dohmann: And I say hey, Brad, have a look inside the cartridge clip. And we both look into the cartridge clipped. And horror of horrors, it’s just as rough. Now when we push those two surfaces together, there will be times when the peaks touch.
Andrew Hutchison: Yes.
Mark Dohmann: And the valleys don’t. And the valley to valley. in these little craters is a small area for an electrical potential to jump across and make a contact that is intermittent.
Andrew Hutchison: Okay.
Mark Dohmann: Micro arcing.
Andrew Hutchison: Bloody hell.
Mark Dohmann: If.
Andrew Hutchison: Yeah.
Mark Dohmann: We were working for a company that was trying to separate noise from data.
Andrew Hutchison: Yeah.
Mark Dohmann: Or noise from any signal. That micro arcing is actually a distortion artifact that they want to remove. So contact enhances typically a gel like substance like they’re calling DC4 or one of those sort of greases. Conductive grease.
Andrew Hutchison: Yes. Yeah, yeah.
Mark Dohmann: And you put a bit of that between those two surfaces and you reduce that arcing okay. And, and in, in, in super, you know, pushing the envelope systems, you can hear the difference correspondingly at the other end. if you’ve got a DIN connector halfway through the arm or you’ve got multiple connections through the arm, that problem just keeps recurring. So in the ultimate sense you only want the cartridge clips and then you either solder the wires directly onto the amplifier, which again is inconvenient, or.
Andrew Hutchison: Yeah, I haven’t seen.
Mark Dohmann: no, but it’s obsessive. You know what I mean? Like you’re going to the next best thing. What’s the next best thing? What’s the next best thing? Of course the next best is contact enhancer on a, A really high quality,
01:10:00
Mark Dohmann: RCA or xlr.
Andrew Hutchison: Yeah.
Mark Dohmann: Okay. Then the metallurgy, the pin and you know, the, the, the thickness of the plating and the you know, blah, blah, blah.
Any thoughts on the cable itself that runs from the DIN connector
Andrew Hutchison: Any thoughts on the cable itself that runs from the DIN connector at the base of the arm to the, to the.
Mark Dohmann: Yep. so we over many, many years played around with lots and lots of different cables. Now most of the time the tonearm manufacturer will have done that work and say we recommend the following.
Andrew Hutchison: Yeah.
Mark Dohmann: So for instance, on the reed tone arms, they’ve got a silver option. which is beautifully done. And that sounds better than the copper option.
Andrew Hutchison: Okay.
Mark Dohmann: in some cases a, ah, copper, construction will outperform the silver sonically.
Andrew Hutchison: Yep.
Mark Dohmann: so it’s really. And I know for the listeners it’d be difficult to say. Well Mark’s not actually, you know, putting a stake in the ground here. Well, I can’t. It’s because it, it, it is, it is case dependent.
Andrew Hutchison: Yeah. I was going to say, not just case dependent but the case of the cable I guess. Is it Yeah. You know, talking with Matthew Bond on a couple of occasions in other episodes, he, he seems to be as much concerned if not more so with dielectric than And the materials that’s made from.
Mark Dohmann: Is that so. For instance, the Frank Schroeder uses a natural wool, fiber like almost like a cotton wool. But it’s wool.
Andrew Hutchison: Yeah.
Mark Dohmann: And, and he, he gently lays the wires in that fluffy matrix.
Andrew Hutchison: Yes.
Mark Dohmann: Down the middle of the tone arm because of the effects of plastic dielectrics that he’s trying to avoid.
Andrew Hutchison: Avoid.
Mark Dohmann: Yeah.
Andrew Hutchison: Okay.
Mark Dohmann: So, so you know the, the tone arm design is the guys that actually they really do their homework on that. Others just buy a 10 kilometer reel and pull it off the reel, flip it Away you go.
Andrew Hutchison: Yes.
Mark Dohmann: Still works all right. But for the guys who are really pushing the high end.
Andrew Hutchison: Yeah.
Mark Dohmann: You’ll often find they’ve gone to incredible lengths to source and specify the internal tonearm wiring and the array.
Andrew Hutchison: Okay. Complicated. Hey, we, we’re sort of getting towards the shank of the conversation.
The turntable is by far the most important component in a sound system
I’m interested to hear your top five, observations, I suppose, from so many years of playing with turntables. What are the top five things that you think affect the sound the most? And I. I guess we’ve covered perhaps many. Well, some of those. I mean, you know, obviously the cartridge plays a big role in the character of the sound.
Mark Dohmann: But.
Andrew Hutchison: But where do you sort of. The systems that I’m interested in is sort of turntable itself versus the tonearm, versus the cartridge, versus the lead, versus the whatever. Do you have a. Do you have a. Do you have an order of concern? For instance, would you buy your turntable and put a Rega RB330 on it and get a substantially better result than you would if you stuck it on a P3? Which. Okay, I guess. I guess you would.
Mark Dohmann: Right. But, I can. If you come to Melbourne, I can take you to, ah, a listener who has done exactly that.
Andrew Hutchison: Oh, okay.
Mark Dohmann: RB 300, on a helix 2.
Andrew Hutchison: Yeah.
Mark Dohmann: And that rig is getting hammered day in, day out, from morning till after dinner. It’s in a, family area where the kitchen and communal meals are shared and there’s vinyl spinning, all day every day.
Andrew Hutchison: Yeah.
Mark Dohmann: And the project commission, was I want an ARM that anybody can come here and play a record with. And I don’t want to ruin my records, but I want it to sound great.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: You know, that’s. That’s pretty much bulletproof, tonearm solution, nice moving coil on it. And, it fits in a beautifully decorated room. So aesthetically it was matching and. And everything. The system’s quite discreet. Small integrated amplifier, from, Creek Audio, believe it or not.
Andrew Hutchison: Okay.
Mark Dohmann: another.
Andrew Hutchison: Another popular, guest on the show.
Mark Dohmann: Yeah.
Andrew Hutchison: so the You. So by. By, you’re insinuating that the turntable is by far the most important component as far as sound quality in the system.
Mark Dohmann: You have to give each component its own space. the turntable is trying to get out of the way.
Andrew Hutchison: Okay.
Mark Dohmann: And. And deliver, you know, signature free, conditions for the arm, to perform. Now, the Rega RB300 is no slouch. It’s a great tone up.
Andrew Hutchison: Yeah.
Mark Dohmann: And
01:15:00
Mark Dohmann: you can hot rod them, you know, with wiring and blah blah, blah, blah. Yeah. different counterweights and you know, and they can handle a big moving coil as well. There’s no issue.
Andrew Hutchison: Okay.
Mark Dohmann: they lack some of those fine adjustment features. Azimuth and you know, easily done on, on someone and BTA on the fly and blah, blah, blah. So that you choose them for, for their elegant simplicity.
Andrew Hutchison: Yeah.
Mark Dohmann: Ah, yeah, yeah.
One of the signatures that comes through a lot of tables is bass feedback
Now on the, on the turntable side, one of the signatures that comes through a lot of tables is bass feedback.
Andrew Hutchison: Okay.
Mark Dohmann: So you’ve got your speakers, you know, booming away, listening to some, some lovely music that’s generating a lot of bottom end. And if you remove that feedback through isolation, it cleans the bass up where you start to hear articulation and the instruments intent and the musicians intent from playing bass because, you know, it’s an absolute foundation of the music. So isolation for me is a, is a must have because of its impact on cleaning up the bottom end. Now you can have a beautiful bottom in warmth and a thickness and a fullness.
Andrew Hutchison: Yeah.
Mark Dohmann: Which is actually that signature of bass feedback, without it being Uncomfortable.
Andrew Hutchison: Yeah, yeah.
Mark Dohmann: Right. It can be pleasant.
Andrew Hutchison: Yes. A pleasant coloration, I guess.
Mark Dohmann: Yeah. If you’re trying to compare it to the original tape or master tape, then you go, hang on, it’s not on the tape so why should it be on my, my record?
Andrew Hutchison: Yes.
Mark Dohmann: so that, that’s for me a foundational aspect. there’s a thing called, you know, in turntableism they talk about P.R.A.T. pace, rhythm and timing. it’s hard to describe but basically it’s the ability for you to snap your fingers and tap your toes to the, to the music because the intent of the musician is conveyed. And some systems wash a lot of that off and leave you with a beautifully smoothed or you know, a tonally homogenized, rendition.
Brad Serhan: Amorphous m mass of bass.
Mark Dohmann: And there’s nothing wrong with that. Whereas other systems make you all sudden stop talking and pay attention to the musician because you go, wow, what’s he doing there?
Andrew Hutchison: Yes.
Mark Dohmann: So P.R.A.T. for me is, is since mucking around with the old idler drives. In my youth, there was a company out of Tasmania called Commonwealth Turntables or Commonwealth Electronics. And in the 50s, through the early 60s they were building transcription level radio station quality, works of art. And in the late 70s, early 80s they were throwing them out onto the nature strip. young, audiophiles who couldn’t afford the expensive linn Sondek, would find these old pieces of junk and lovingly restore them and go wow, this sounds amazing. and P.R.A.T., since that day sort of been imprinted on my ear.
Andrew Hutchison: Okay.
Mark Dohmann: So that is a very important thing for the turntable design to achieve that.
Brad Serhan: And Mark, I ah was going to ask some questions which is sort of deviating from what Andrew is saying about five points. But you know back in the 70s 80s when I was playing around with turntables I had the older Technics SL23.
Brad Serhan: I think that was a belt drive actually. But there’s quite a few techniques with Direct drive. Then I had a. Had the old arm turntable to. Because I was getting feedback or howl around from the techniques.
Mark Dohmann: Yeah they
Brad Serhan: Turntable had the suspension system then went to a. Funny enough to a Rega 3 but that. That was isolated on the wall to some extent and then to a Linn sondek. I’m mentioning all these is because the in and also had an Orpheus turntable.
Mark Dohmann: Ah. Yep.
Brad Serhan: Which you probably ended up was designed in Melbourne and it was an Idler rim.
Mark Dohmann: Yep. So yeah.
Brad Serhan: And I unfortunately let that go. It ended up being how I sort of came up with the brand Orpheus loudspeakers. But that’s beside the point.
Andrew Hutchison: The.
Brad Serhan: I unfortunately let that go. But sort of covering all those. What was. So the either rim had the advantages in the base end. Is that what you’re contending?
Mark Dohmann: Well it had. It had a It was. It was like the direct drive of. Of the era. There were some direct drives in industry but these were fast startup, high torque. So when the needle was in the groove and a large modulation came along the affected. That modulation wouldn’t create drag.
01:20:00
Brad Serhan: Drag.
Mark Dohmann: Yes.
Brad Serhan: Yeah.
Mark Dohmann: That would. Would affect the way the platter slowed down and sped up. Just had enough oomph to push through any modulation. Thus delivering the full impact of the. The music signal and style and dynamics. Yeah, yeah. It was a direct coupling of the. The motor to the platter.
Brad Serhan: Right. So there was noise coming through. Was that a problem?
Mark Dohmann: one of the issues that they suffered from was was rumble and motor. Motor noise coming through. And you put up with that because of the. The great dynamics and slam and punch and. Right. Yeah. The P.R.A.T.. So I had a gentleman who. Who’s an absolute legend in the industry and and is one of the you know most knowledgeable people on idler systems. Robin Wyatt from the US And Robin came to a show and listened to the Helix and he said Mark, I swear this was a Rim drive.
Robin P.R.A.T. says this turntable is the only belt drive he’s heard
This turntable is the only belt drive that I’ve heard P.R.A.T. out of.
Andrew Hutchison: Yeah.
Mark Dohmann: Oh, really? And that compliment from Robin, you know, it made my day. Yeah. Yeah. Because that’s. That’s what we strive for. And you do that with high talk. Yeah, it’s a. It’s a trick and a short belt length and, you know, those sorts of things that we’re trying to emulate what a rim does.
Brad Serhan: Yeah.
Mark Dohmann: but without conveying the noise of that motor into the system. So we. We decouple, using various tricks, which is that. That mechanical area after 100 hertz.
Andrew Hutchison: Yeah.
Brad Serhan: Yes. Right. The thing is just veering off a little bit is that back in the 70s, and 80s.
When did people start to judge turntables subjectively
The question I was going to ask you, was, you know, when did people start to judge turntables subjectively? You know, because there was that sort of around the late 70s, if I remember rightly. people were sort of just. That used to measure the wow and flutter and rumble. And that was basically. Basically it. And you’ve been judging the sound of a turntable by maybe the combination of the tone arm and the cartridge. but when did that. I remember the English magazines, I think was starting to sort of talk about it when Linn. linn started to come to the fore or their marketing did. You know, did. And there’s a lot of talk about P.R.A.T. with the linn.
Mark Dohmann: Yeah, it was.
Brad Serhan: Did you. I don’t want to make you walk the plank, but. Yeah. Did Linn actually have, from your point of view, that sort of PRAT look.
Mark Dohmann: I put my hand up. I’ve loved linn’s, since the first day I heard them. I had a lecturer, at uni who was an owner. And, of course, audiophiles identify each other, pretty quickly, you know. and. And he’s. I said, oh, wow, you got one of those. And then he said, yeah, come over and have a listen. You know, bring your mates. And so we went over and had a listen one time, and that was through some audio research, amplification and 18 inch Hartley monitors. on an open baffle, concrete. baffle, you know, it was true. audiophile. and the Lin Sondek with the, moving coil and heavy, ARM FR 64. And I just sat there and went, wow. Now, the lens mid M range for me is still absolutely lovely, sound. the extension down the bottom and the extension at the top. that’s where we’ve really worked hard to. To get more, Right. But yeah, to this day, if somebody’s running a linn. They’re happy campers. They’re making good music, they’re fun. Yeah. Yep. The whole idea of a linn is that you’ve got it for life. and I, I’ve. I’ve really. You know, and even as it. I should speak about the. The diamond team, it’s not only me. we’ve also embraced that. That, you know, it’s a turntable for life. And you. You’ve got an upgrade path through life to always keep you at the. The latest iteration. So yeah, there’s a lot to be. You know, we have a lot to thank linn for being pioneers in the industry.
Brad Serhan: Right, right. But you would have been. When did you start to like.
I started building turntables because I couldn’t afford to live
Brad Serhan: One last question and going back and.
Mark Dohmann: I started building turntables because I couldn’t afford to live.
Brad Serhan: Right. Okay. And that was around 82, as you.
Mark Dohmann: Said I was before then. Oh, okay. Okay. So. Yeah, yeah.
Brad Serhan: But, were you obviously up the question but were you aware of difference is the differences in sound due to materials? used
01:25:00
Brad Serhan: this, you know, for the chassis, etc, you know.
Mark Dohmann: Well, yeah, yeah, that came about because a. I heard the source first and, and marveled at it. And then somebody else had an RD11S and then somebody else had a micro seiki. And you know, all of a sudden as I’m starting to hear these, better examples of. Of tables, that all of a sudden changed, you know, my approach to analyzing what they were then hunting around finding parts and. And building the first couple of iterations. And then all of a sudden I had a turntable that I’d built. And then the. The hi Fi store that I was frequenting kept on saying, why don’t you buy a decent turntable? And no, no, I’m happy with what I got, you know. Or what is it that you’ve got? Oh, I made it myself. And they’d all giggle and had a laugh and oh yeah, another one of these DIYs. And then finally one of them said, well, why don’t you bring it in? You know, let’s have a shootout. Shootout M. Guns drawn like a western. and I, did. And they heard what I heard. And then that store said, can you build more? And that was the start of Dohmann
Andrew Hutchison: Wow.
Brad Serhan: I like the way you said they.
Andrew Hutchison: Heard what I heard.
Mark Dohmann: That’s.
Brad Serhan: I love the way you played that.
Mark Dohmann: So. No, that’s literally what happened. Yeah, it’s still clear in my mind. That was, you know. And that’s not me being smart, Alex. Or Anything. It’s just, I had the might of a large Australian Airlines engineering division behind me. it wasn’t, wasn’t fair. You know, like I didn’t play fair. you know, there was some, some serious materials, monkeying around that went, went into the, the first of them and you know. But that again, taught me a lot. About what? Each element, it’s a whack a mole game. Fix one thing, one side, something else pops up on another. So it, it’s a, it’s a, it’s actually way more complex than I. Even today I’m still learning. it, it’s a complex beast.
Brad Serhan: The more you know, the less you know.
Mark Dohmann: Yeah, I totally agree. Yeah, Yeah.
Andrew Hutchison: I will take a two second break guys, and we’ll come back and Mark will wrap up these order of importance, top five, suggestions. Back in a sec.
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Brad Serhan: Thank you very much, Hutch.
Andrew Hutchison: And and of course Mark is the the figurehead and the founder of dohmann turntables. But as he alluded to, there is a team of people. So he’s not going to take all of the acclaim, for their amazing sounding machine. And you were talking about isolation and P.R.A.T. and how the two are sort of connected. I remember a demo you did at the Melbourne show, not last year but the year before. you had the turntable running into some enormous amplification and a giant pair of Wilson Benesch loudspeakers. And you were playing it very, very loud. And I could not believe how well the thing was tracking. It was so tight and clean that there had to be a tape machine, you know, or something hiding away. But you know, I, I was pretty sure that that the ah, a, that the stylus was in the groove and in turn the record that we were listening to was coming, you know, was the record that was on the turntable. It just I’ve never heard anything like that. I mean if that’s what the Helix does, then that’s very unusual. I think in A turntable and I guess that’s to some degree down to that, that minus K isolation system.
You implied that the arm is perhaps less important than the cartridge
But getting back to the other. So you’ve, you’ve alluded in my quest to, to, to steal information from your head. Well you implied by the client that you’ve got with the RB300 arm but a moving coil cartridge that perhaps the arm is perhaps less important than the cartridge. And obviously we’re saying the turntable.
Mark Dohmann: No, no, no.
Andrew Hutchison: Is that a leading question?
Mark Dohmann: Yeah, I’m going to clarify. Arm is absolutely crucial and the science behind arms is still to this day a ah hotbed of innovation
01:30:00
Mark Dohmann: and. for instance there’s arms that are you know as expensive as my turntable, that customers are mating with the turntable so they spend you know 100 grand on the, on the turntable and they’ll put 100 grand into the arm.
Andrew Hutchison: Okay. And then, and then what cartridge would they be bolting that becomes a taste issue or.
Mark Dohmann: Yeah, they’re typically predominantly moving coils and they’re predominantly you know diamond cantilever, and you know complex body assemblies ah magnets and and you know they’re really at the, the leading edge now. They’re also European and Japanese. They’re the predominant two the centers of manufacture of those high end moving coils. But that doesn’t mean that you can’t fit a optical cartridge or you know as expensive a moving iron or moving magnet. so Yeah the arm however is a very critical part of the equation. So you can start from an RB300 but you will hear the difference between that and something like an origin live which you can you know scale up through. you know you can go up into the carbon fiber constructs. You can go to the science into the Wilson Benesch geometry GMT tone arm technology which is absolutely first class most modern thinking and technologies applied as well as listening to you know the, the super precision sat, technology out of Swedish analogue technologies or some people go vintage rebuilds.
Andrew Hutchison: Yeah.
Mark Dohmann: but you know you have to find a really competent person to rebuild the tonearm if you’re going vintage rebuilds but you can buy new ea sorry not eat which is a good brand m. Brand new Ikeda and brand new glanz which are that s shaped what I call classical 70s Japanese. Yes school.
Andrew Hutchison: Yep.
Mark Dohmann: they are ah sometimes on the most expensive rigs. Yeah.
Andrew Hutchison: So you’ve got okay, so you’ve got your hundred thousand dollar turntable, you’ve got your hundred thousand dollar arm. you, you have your $26,000 cartridge. do you or do you not clean the record?
Mark Dohmann: if the record is dirty and a lot of us buy second hand and you know, we go crate diving and so on and the music is so important and it’s only limited access to that. You take that record and you run it through, you know, cleaning routines, ultrasonic machines. and it’s amazing what those machines can do to resurrect, poorly, cared for vinyl. And it makes it listenable. brand new records, some of them need a clean because they, they’re full of mould release and from the pressing and you can.
Andrew Hutchison: That’s the concern, isn’t it? Yeah. That they is real nasty crud building up on your very expensive stylus. So I, I guess that’s a concern.
Ivor told people not to clean records and let stylus clean them
But we’re talking about Linz earlier and there’s the, the, the. And I, I of course was at school this particular day when Ivor was out at a hi fi show telling people not to clean their records and let the stylus clean the record. But that, that is, that, that’s the old tale of yore that he used to tell people that is that, is that just a great bit of simplistic, marketing?
Mark Dohmann: No, look, you can, you can make a mess if you, if you clean the record the wrong way.
Andrew Hutchison: Yeah.
Mark Dohmann: you can create more problems than you’re setting out to solve. So I do see the reason why he would have, would have said those things. if a record is cleaned and, and it’s in good nick, then you know, just a light brush, get the main dust boogers off before play helps. And you shouldn’t have an accumulation of anything around the stylus after that. That play.
Andrew Hutchison: Yep.
Mark Dohmann: A lot of records we buy, they had, you know, people put. I’ve heard apocryphal stories of people using boot polish to make them shinier. you know, you don’t, you don’t know what’s been done to it before you got it.
Andrew Hutchison: Okay. Yeah. Well, yes, I mean you’d want to. I would have thought of. That’s where your, your two arm, model. You could have the second hand record arm. and, and cartridge. it’s not so much a different arm, for different. Whatever you.
Mark Dohmann: Yeah.
Andrew Hutchison: Like
01:35:00
Andrew Hutchison: a 78 or whatever. A monocard.
Mark Dohmann: Yeah. So you don’t put hours on you.
Andrew Hutchison: Exactly. On your good One most expensive.
Mark Dohmann: Yeah.
Any thoughts on cleaning the stylus? And um. I had a final question
Andrew Hutchison: any thoughts on, cleaning the stylus? And Oh, I had another final. I had a final question. But yeah, we’ll talk about cleaning stylus as well. I mean, it’s hard to buy a decent stylist brush these days.
Mark Dohmann: Yeah, look, the dishwasher had a nice one. And the best brush, Lyra. Lyra. cartridge. Make a little bottle of what they call spt.
Andrew Hutchison: Yeah.
Mark Dohmann: and a little tiny little brush. And that’s an excellent, very purified way of doing it. Don’t use solvents. Don’t use alcohol.
Andrew Hutchison: No.
Mark Dohmann: Don’t use anything. And I’m also, not a fan of the little gooey,
Andrew Hutchison: Yeah. Little bowl of sticky stuff. Yep.
Mark Dohmann: unless it’s guaranteed to show no residues left on the, on the stylus after use. So there are some there that do that. But the way to use them is not by hand. it’s to put it on a very stationary surface, gently lower the stylus into it and gently lift the stylus out.
Andrew Hutchison: Yep.
Mark Dohmann: involuntary, hand tremors and those sorts of things. You’ve got to remove any of those things when you’re near a diamond. Okay. All right. Because you can, you can, you can wrench the diamond off its mount if you’re okay.
Andrew Hutchison: Yeah, yeah. So, yeah, I’m really annoyed. I can’t think of the other little tweaky question I had. But it may come back to me.
There’s a lot of contention about cleaning records
Mark Dohmann: But I think we’ve covered four. So we’ve got a.
Andrew Hutchison: Well, I think. Well, I think the cleaning thing was kind of m. Is that, I mean it’s. There’s a lot of contention, I guess about cleaning, but let’s move past that because, I mean, I think the record has to be clean. But yeah, you’ve got to clean it in such a way that you don’t actually make it worse. And I think most. I mean, hilariously, some YouTube videos are quite. You know, they get a carbon fibre brush and they literally sweep all of the dust that’s sitting on top of the grooves into the grooves and they’re. And sort of then announce that they’ve cleaned the record. which clearly, is not a, A not a great plan.
So tracking force and its relationship to vertical tracking angle
Quick question. Mark. So tracking force and its relationship to vertical tracking angle. And then in turn, what tracking force do you feel is, is ideal or is that an arm related thing? Because obviously most cartridges say like, you know, 1.6 to 1.9 or something like that. Yeah, grams. do you. But doesn’t so a lot of people go on about vta. We haven’t mentioned VTA and the whole just. Or maybe once it got alluded to. But, but when you look at, when.
Mark Dohmann: You go through your alignment parameters, remember we’re dealing with a vision for a perfect world. But we’re living in an imperfect world.
Andrew Hutchison: Oh yes, we are.
Mark Dohmann: So we, we, we say on the package that it says say two grands nominal. and the suspension system is classified at certain setting. And again if we were to measure that with a calibrated instrument, it might have a slight variance left or right of that nominal value.
Andrew Hutchison: Yeah.
Mark Dohmann: So therefore we do have sometimes the need to vary left or right of that nominal value on the other parameter in order to achieve a perfect, or more perfect outcome. So I’m not a fan of running say a nominal value of 2 grams and pulling it back to 1 gram in the groove. I don’t, don’t see that. I, try to stick with the manufacturer’s recommendations because they know what they’re doing.
Andrew Hutchison: Yeah.
Mark Dohmann: And they’re recommending this value to seat the suspension at the right.
Andrew Hutchison: Yeah. now, for instance, central position, I assume.
Mark Dohmann: Yeah. In the, in the coil. In the, in the, in the, in the engine. One of the difficulties is, is that if you increase mass or decrease mass, you can change the angle of the stylus in the groove, which is the stylus rake angle, which does have a dependency on the vertical tracking angle vta. The two are different. I won’t go into full detail here.
Andrew Hutchison: But okay, so rake and VTA are ah, two different things.
Mark Dohmann: They’re slightly different, but they are, they are buddies. in the, in the fact that adjusting the vta you will, you’ll change the way the, the stylus edges, if it’s a fine edged stylus, will, will sit in the groove and its contact points. But if you go down that path, you know what’s important. Then you’ve got to head to the other parameters which are azimuth and then finally zenith.
Andrew Hutchison: Crikey.
Mark Dohmann: Now, zenith can only be measured
01:40:00
Mark Dohmann: under a microscope. And the cartridge manufacturer, you assume that it’s 90 degrees to the, to the cantilever when viewed from above. However, you can have variances in that stylus on that zenith angle of, you know, a poor example would be 15 degrees 14. 15 degrees off the perfect zero.
Andrew Hutchison: Yeah. Okay.
Mark Dohmann: now manufacturers tolerances are allowed, you know, plus or minus, say 3 degrees, which they publish. But 15 degrees is a horrid mismatch. so we’re getting into the, you know, in the upper echelons of expensive cartridges. if you have one of those misalignments that needs to be factory corrected.
Andrew Hutchison: Okay.
Mark Dohmann: some factories are reticent to address that problem because they’re buying a bucket of, styluses from another manufacturer. And in that bucket there’s only a percentage that are perfect, and then the rest of them are left to right of that perfect line.
Andrew Hutchison: Okay.
Mark Dohmann: so I, I’d say that within the realms of their, manufacturing process. Because remember, they don’t make the diamond and they don’t make the can lever. They assemble it.
Andrew Hutchison: Yeah.
Mark Dohmann: Into the things they make. I haven’t passed mentioned that in a perfect world, you’d send your cartridge to an expert who would be able to knock off the diamond and re. Glue it on perfectly.
Andrew Hutchison: Okay. Yeah. All right.
Do you have a preferred cut or shape or, you know, shape
so actually, speaking of diamonds, do you have a. Do you have a. Yourself a preferred cut or shape or, you know, shape?
Mark Dohmann: Look, I. I think. I mean, you’ve got your replicants from Ortofon, which are the. The most severe.
Andrew Hutchison: Yeah.
Mark Dohmann: But also the most, accurate compared to the original cut, if the original cut was perfect. and then you’ve got your, micro lines, the Shibatas and some of those more exotics. I would suggest the microline is my favorite because it’s the most tolerant.
Andrew Hutchison: Yeah.
Mark Dohmann: Of the fine, profiles. I mean, the most tolerant would be a conical, elliptical is a little bit, less forgiving. And then the micro lines are less forgiving. But within that echelon, microlines, when they wear, they wear in a friendly fashion.
Andrew Hutchison: Okay.
Mark Dohmann: Replicants, when they wear they. They wear faster because they’re more severe.
Andrew Hutchison: Yep.
Mark Dohmann: so you get a more glorious sound for a shorter period. If I’m paying that much for a cartridge, I’d like to strike a little bit of a balance. And the micro lines for me are very good.
Andrew Hutchison: And why. Why, I do like a micro line. I have to say. I, I just. Just from the sound quality point of view. I didn’t realize they wore better, but, So what? It’s always. It’s. It’s the time. The forever question. How the hell does a diamond wear when it’s just rubbing up against vinyl?
Mark Dohmann: Or how does a hard granite rock turn from a sharp pointed object to a round pebble under a stream?
Andrew Hutchison: I knew you’d have an answer. It takes a while though, right?
Mark Dohmann: It takes a while, but that, you know, It’s just that, Atomic exchange.
Andrew Hutchison: Yeah. Yeah.
Mark Dohmann: Between the two surfaces. So you definitely got heat pressure and you polish. I mean, you get a smooth bit of A4 paper. Right. You wouldn’t think that you could abrade anything with it. And yet I can take that little bit of a four beautiful white perfect place.
Andrew Hutchison: Yeah, yeah, yeah.
Mark Dohmann: And rub it on a car polished surface and cause scratches in that car polish.
Andrew Hutchison: Oh yeah, absolutely. Yeah, yeah. In fact, someone that was working for me once cleaned a piece of Perspex for me with a, with a, with a piece, of paper towel. Scratch the other crap out of. I said, what’d you do that for? Oh, I didn’t think it’d be a problem. And I think he even dampened it. No, maybe not. But anyhow, it really scratched it. Paper towel on Perspex is, is nasty.
There is an issue with wear associated with microline turntables
I, oh, another question jumped into my head. I have many questions. I, No, I think we’ve, I think we’ve actually kind of, kind of covered it. So you like a microline and Yeah. So the wear. Yeah, the, the analoguey that you’ve made with the, with the stone and the, and the river. Yeah, river stones or something is, Is, is, is a, is an easy one to grasp, but that’s that indeed there is a, there’s an issue there with wear. And I, I guess the the heat thing is the other weird thing. I remember once, demonstrating a turntable on a Friday afternoon, pretty, close to 5:00. they said, yep, love that, I’m going to take it. I walked out the front, sold them a turntable and turned, the lights off and went home. I, I came, came in on, Monday morning. In fact, I think it was a long weekend. So maybe I came in on Tuesday morning
01:45:00
and at some time later that day I walked out into the demo room and there was this tick, tick, tick. And I’m like, ah, no, I’d left the, I left the turntable, in the runout groove for three, three to four days.
Mark Dohmann: Yep.
Andrew Hutchison: now it, it clearly gets hot because there was a little twirl of vinyl.
Mark Dohmann: Yeah.
Andrew Hutchison: Oh God, the brain just failed to work. Swarf? Yeah, little, little bit of vinyl. Swarf. A nice little. As if it had come off a lathe.
Mark Dohmann: Yeah.
Andrew Hutchison: so how does that happen? I mean, I guess that’s. I mean this diamond is literally cutting a, its own extra groove. so how much heating do you think happens when it’s just one pass? Obviously if it sits there for four Days it gets really hot.
Mark Dohmann: But some, some discussions, you don’t play the record again, for half an hour.
Andrew Hutchison: Okay.
Mark Dohmann: To, to allow the, the matrix to, to re, reassimilate. because the pressure, is you know, equivalent to tons of pressure on a surface. And the vinyl heats up and then it magically springs back. So if you rerun your diamond through that same point continuously, eventually the lag between the rebound and the heat buildup gets shorter and then eventually you start gripping the material and pulling it away from its matrix and you end up with that little bit of swarf after 4, 4 days of continuous playing.
Andrew Hutchison: Yes you do. I was, I was, I was horrified. And the stylus was destroyed. yeah, it obviously was coated in, you know, sort of. Yeah. And it heated up, you know, Vinyl detritus. Yeah, it was, it was, I mean I’ve only done it the once. but that was enough to. So it’s actually an interesting exercise because I was genuinely, I was quite, I was quite pleased with my efforts because I mean it was such a, I think I might have taken a photo. Such a beautiful piece of suave. but anyhow, it was an OM5, so it was kind of irrelevant. Just drop that in the bin and put another one on. No, no, I know. M M10 maybe. Om M10. elliptical quality.
We haven’t spoken much about Dohmann Audio turntable
so look, I, I think we’ve covered a hell of a lot of ground, Mark. I mean we haven’t spoken probably as much about your turntable as people expected. We were going to. It’s kind of well known. Obviously there’s tons of information at Dohmann Audio. Helix 1 is the spectacularly top of the range 1, but Helix 2. Would you briefly describe the differences? I mean only one arm board arrangement.
Mark Dohmann: Sure. So what we did is we reduced the footprint and it’s one arm. but that arm board can be with four screws lifted off with the arm settings and cartridge settings all intact. And some of our customers, due to size constraints on their shelf, run a Helix 2 but have a number of arms, swap in and swap out as they, you know, desire. So it still has that flexibility.
Andrew Hutchison: it’s still got the minus K.
Mark Dohmann: Still got a minus K, but a, a smaller version of it.
Andrew Hutchison: Okay.
Mark Dohmann: And it has a lot of similarities. Look, we had a recent review hi Fi plus magazine. we won the turntable cost no object category with the Helix one.
Andrew Hutchison: Yeah.
Mark Dohmann: and then they reviewed the Helix two, two years later and gave it the turntable Cost no object. They said if we didn’t know about the big Brother, you know, this is all the turntable you’d ever need. So we haven’t held back.
Andrew Hutchison: Yes.
Mark Dohmann: On the Helix 2, we’ve given it an absolute, you know, everything we could. It’s got the kitchen sink in it. you know, I’m blessed with some amazing, team members, including my co directors, George Moraitis and Jim Angelopoulos. both Melbourne boys.
Andrew Hutchison: You can tell that from their surnames. Yeah.
Mark Dohmann: my nickname is Dohmann-opoulis. it’s got that family, family values, family culture.
Andrew Hutchison: Yep.
Mark Dohmann: we’ve got, You know, Jim brings some amazing talent to the business. he’s a machine logistics. you know, he, he’s organized, all my racking and shelving and, and support systems and my shipping and, so, you know, forklift and materials handling and storage and packaging. And so we’ve got these, this, this engine that is supporting the creative endeavors and, you know, keeping me as a, the mad
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Mark Dohmann: inventor on the straight and narrow. And then George, has the ability to communicate the language of the product, to the, to the market, plus contribute to the sonic development and the, the, you know, he throws, questions at me, being a physicist, you know, hey, we need to look at this. I’ve been thinking about this. What do you think? Is this a problem? And, and that then gets me going and down a rabbit hole.
Brad Serhan: Right, right.
Mark Dohmann: so, you know, it’s not a, you know, I started off on a kitchen bench as a DIY kid.
Andrew Hutchison: Yeah.
Mark Dohmann: And, and I launched, the Helix, you know, off the kitchen bench into Munich in 2015.
Andrew Hutchison: Yeah.
Mark Dohmann: you know, and then 2018, George and Jim came on board and said, you need professional help.
Andrew Hutchison: Well, yeah, but that was, that was. They were commenting on something else, though, Mark.
Mark Dohmann: I didn’t get it. That’d be slightly aspy. and, and I just welcomed that. Yeah. Because I, I knew what good team, spirit can, can build. And then we’ve got some guys who work with me closely in actually manufacturing and building in house the, the, the assembled parts.
Andrew Hutchison: Yeah, we should put that, you, you make the turntable in Melbourne.
Mark Dohmann: Yeah. So we’ve got, I mean, there’s some bits that we buy from California and, you know, motors from Switzerland and you know, like, you can’t make everything here. No, but.
Andrew Hutchison: No, of course not.
Mark Dohmann: the precision parts, my bearings, you know, Moorabbin Airport, one of the, machine shops there, BS Precision. Those guys are just awesome. I’ve got, you know, other machine shops. Ronnie Harrop, who’s quite famous in engineering teams, Harrops Engineering, Ron’s one of my close friends and mentors in, in fabrication and machining and at the absolute high end, and other machine shops that we use locally and we’ve built up in that Moorabbin and Cheltenham area. You know, ah, water jet cutting, laser cutting, surface, finishing, we’re even. Occasionally we have to drive over to Airport west to buy our aluminium from an aircraft, supplier there. And by the way, you can buy aluminum from, you know, your local extrusion shop and they’ve got acres of it on site. But no, we, we have to drive out to an airport supplier. They give me the certificates. It’s Reynolds Aluminium or Kaiser comes from the usa. It’s X ray quality. It’s, it’s, it’s, it’s way more expensive.
Andrew Hutchison: Yeah.
Mark Dohmann: Than commercial and there’s a reason for that. We have to go to that. So, you know, you look at the product costs and so on, there’s a reason these costs are there guys. You know, it’s not, it’s not easy, building it to that level of, of, of metallurgy.
Andrew Hutchison: Yeah, indeed. And as far as its structural qualities, but also getting the incredible finish that you’ve got is, is an art form as.
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