Unipivot Verses Other Pivot Designs

karma

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I remember one of my first “Ah Ha” moments in audio. This was in the time period of about 1970. Equipment: A Thorens TD-124 turntable (bought new in about 1965) and an SME 3009 tone arm (bought used but pristine). Issue: Pivot bearing resonance. Design: A gimbal pivot bearing.

Like most audiophiles of the time, I subscribed to all of the major Hi Fi Mag’s which I read avidly. In those days, tone arm reviews appeared regularly. The SME 3009 was certainly considered to be at the top of the heap. I was content that I had one of the best arms around, maybe THE best. One performance issue that was given attention was bearing resonance. Some arms were downgraded because of bearing resonance. The 3009 was not one of them. It was the performance benchmark.

I did not know what bearing resonance sounded like. I had never seen it described. I wondered….. But, why should I worry? I had the “perfect” tone arm.

Then one day I was listening to a familiar record and I HEARD IT!! Only for an instant. I replayed the passage and again I heard it. There must something wrong. This led to a complete review of the arm set up. The set up was fine. Must be mistracking, right? What is this, I thought. This set up never mistracked! I increased the VTF. No help.

Since I have a typical audiophile mind, the idea was in place and could not be ignored. Once I had an idea of what to listen for, I heard this same sonic signature often. Not obvious, not loud, occurred for only an instant then was gone, like a mirage. I realized the signature had always been there but I had ignored it. I changed to another cartridge. It sounded different but the anomaly was still there with the same characteristic signature. I don’t remember the cartridges but they were TOL MM’s. After some experience, I began to be able to predict when the recorded matter would produce the signature. I began to suspect bearing resonance was the culprit. It sounded like what I would imagine bearing resonance to sound. After enough time passed, I was sure of it. Well, the 3009 was not “perfect” after all. I was shaken.

There is a saying that declares a pick pocket only sees pockets. Similarly, audiophiles only hear the latest problem. I only heard bearing resonance. I know you know what I mean.

Before continuing, I should note that the 3009 is not a typical gimbal design. The vertical pivot is a knife edge which I believe is not the resonance culprit. No, I think the offending item is the horizontal pivot which is a ball bearing design.

I concluded that all gimbal bearing designs were flawed and would resonate. It’s the nature of the beast. Some are worse than others.

I could not ignore the problem. Once I was programmed to hear it, I heard it often and it grated. In time I had another turntable and arm. It was a B&O 4004 linear tracking turntable. I loved it. And the bearing resonance had disappeared.

Since I made the change to the 4004, I have never had a pivoted tone arm-until recently. Eventually, I settled on the Eminent Technology ET-2 (and ET-2A) linear air bearing arm. I am convinced that linear tracking is the best solution for a tone arm design. I have good reasons to think this. I have had my ET-2 (A) for over twenty years. Obviously, I love the arm. There is never a hint of resonance which really can't be an issue due to the air gap.

However, I wondered about unipivot designs. But, I had never owned one. I basically liked the idea because the design should eliminate bearing resonance. A couple of years ago I bought a used Oracle Delphi V, fully optioned. It came with a Graham 2.2 Deluxe arm, my first unipivot. It was very impressive in so many ways. I could see right away why the 2.2 was so highly regarded. But, how would it sound? I mounted a Clearaudio Discovery cartridge and proceeded to set up. After so many years using, setting up, and listening to the ET-2, I had definite expectations. After quite a lot of time spent setting up the 2.2 I found myself frustrated. The arm was clearly incapable of establishing a perfect relationship between the groove and the stylus such as was possible with the ET-2. I settled for the best I could get and decided to just listen.

I had proven to myself that a linear design was superior in terms of set up. But, set up is not listening. I listened. I was very impressed. The 2.2 was a gorgeous sounding arm. No hint of bearing resonance. In fact, if I had not had so much experience with the ET-2, I could have lived happily. In truth, the ET-2 was a better sounding arm but the difference was not stark. The 2.2 lacked a little in resolution, detail, and dynamics (but these are the items I pay the big bucks for, so they are significant). But, it was never, never, hard to listen to. In fact it was most enjoyable.

So, what had I learned? Well, first, I found that the 2.2 unipivot bearing did not resonate. This was a big step in the right direction. Next, I concluded that beyond the benefits of the unipivot, a pivoted arm had enough geometrical errors to prevent the cartridge from aligning with the groove perfectly. This causes a loss of detail and dynamics. It has nothing to do with the unipivot bearing which, I thought, performed brilliantly. Rather it is totally because of the pivoted geometry. All pivoted arms would suffer the same lack because they share the same geometry.

However, not all linear arms are created equal. All (except Souther) linear arms that do not use air bearings (the servo types), have a pivot bearing and they are typically gimbals. I would expect all gimbaled arms to have resonate modes, even the best of them (SME V?). The gimbals are the bad guys in this design game.

The Souther linear arms are a mess. When they work they can work well. But, they have enough ball bearings to create a symphony of resonances. They have other problems as well. These are beyond our discussion here. I have never owned a Souther (Clearaudio) but I have worked on and mounted them. I really hate the design.

The remaining pivot design that I know of is the suspended pivot such as used by Well Tempered. I have no personal experience with these in that I have never owned one. However, I have spent many hours listening to the Well Tempered Turntable owned by a friend. It sounded good, no doubt. But, the periodic listening session is not the same as living with it. The design is odd enough to warrant an entirely different discussion. The only comment I have is it uses a pivoted geometry and will have the typical pivoted drawbacks. I truly admire the design because it is so out of the box. Is it equal to or better than a unipivot design? I don’t know.

BTW, I replaced the Graham 2.2 Deluxe arm on the Oracle with a brand new ET 2.5. The 2.2 is now mounted on my pristine Thorens TD 125 Mk1 with an Audio Techinica OC9/2 mounted. This is actually a very nice combo. I use it for the dirty work of auditioning new/used unheard records.

Sparky
 
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mep

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Sparky-I too have used the ET-2 for many years and I still have it along with two pumps and a surge tank. I think the world of the ET-2 arm and it has brought me countless hours of musical enjoyment since the 1980s.

However, the ET-2 isn’t perfect just as nothing built by man is perfect. It has high moving horizontal mass, I don’t like the way the weights are hung off a piece of plastic attached by a set screw. The whole thing wobbles up and down every time you touch the arm. Lots of people claim the ET-2 doesn’t do low bass as well as great pivoted arms, but I never found the ET-2 lacking in bass.

The ET-2 in less than competent hands is a nightmare to setup correctly and will drive the less competent to madness. The spindle and bearing must be kept very clean or the arm will stick. The ET-2 must be perfectly level for it to work. It’s not for the faint of heart or for those with 10 thumbs. Many people don’t have a good place in their listening rooms to remotely hide the pump(s) and their noise. Many don’t want to be bothered with air lines, filters, filter replacements, etc. In short, it’s not an arm for every man.

I now have an SME 312s tonearm and I love it. It is a 12” arm which lowers the tracing errors from a 9” arm. This arm is a joy to use and sounds excellent. It is the first pivoted arm that I have owned that didn’t make me want to replace it immediately with the ET-2.

In summary, just because a linear tracking arm traces the groove “perfectly” doesn’t mean that linear tracking arms are perfect. There are tradeoffs in everything. The people in the analog audiophile market have voted with their ears and wallets, and the majority of arms that are sold and used are pivoted arms. There is a reason for that.
 

karma

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Sparky-I too have used the ET-2 for many years and I still have it along with two pumps and a surge tank. I think the world of the ET-2 arm and it has brought me countless hours of musical enjoyment since the 1980s.

However, the ET-2 isn’t perfect just as nothing built by man is perfect. It has high moving horizontal mass, I don’t like the way the weights are hung off a piece of plastic attached by a set screw. The whole thing wobbles up and down every time you touch the arm. Lots of people claim the ET-2 doesn’t do low bass as well as great pivoted arms, but I never found the ET-2 lacking in bass.

The ET-2 in less than competent hands is a nightmare to setup correctly and will drive the less competent to madness. The spindle and bearing must be kept very clean or the arm will stick. The ET-2 must be perfectly level for it to work. It’s not for the faint of heart or for those with 10 thumbs. Many people don’t have a good place in their listening rooms to remotely hide the pump(s) and their noise. Many don’t want to be bothered with air lines, filters, filter replacements, etc. In short, it’s not an arm for every man.

I now have an SME 312s tonearm and I love it. It is a 12” arm which lowers the tracing errors from a 9” arm. This arm is a joy to use and sounds excellent. It is the first pivoted arm that I have owned that didn’t make me want to replace it immediately with the ET-2.

In summary, just because a linear tracking arm traces the groove “perfectly” doesn’t mean that linear tracking arms are perfect. There are tradeoffs in everything. The people in the analog audiophile market have voted with their ears and wallets, and the majority of arms that are sold and used are pivoted arms. There is a reason for that.

HI mep,

I guess you are right when you say the ET's are not for everyman. But then, neither is high end audio. One must overcome the obstacles to find nirvana. If a person expects to buy perfection off the shelf, putting no effort into understanding and fixing the details and deficiencies, a great system will be beyond reach.

I never said the ET was perfect. Such an animal does not exist and probably never will. The only point of my thread was to use my experience to point out some differences between the various type of tone arm bearings and pivots and to report them. I thought my findings might interest some folks. It just happens that my reference is the ET design.

But, to answer some of your points, I have had zero problems with my ET's. It's true that I have been willing to go the extra mile to optimize my set up as best I can. My arms never stick. Never. True they must be periodically leveled if used on a spring suspended turntable. I re-level mine every six months or so. It's very easy to do. It takes about ten minutes. That is the only periodic maintenance that is needed in my system. And, I should note, I have the high pressure manifolds which have even less gap clearance than the stock one that is used with the low pressure pump. Using the pressure gauge that's a permanent part of my system, the bearing runs at 27 PSI regulated. I think the higher pressure is an advantage.

Dirt is not an issue for me.

I have found no sonic consequences from the counter balance design. In fact, I think the counter balance design is rather clever. As you know, the counter weight is compliant only in the horizontal plane which decouples it from off center record holes. Vertically it is rigid. The threaded shaft makes attaching the brass weights easy for neutralizing tracking force allowing the arm to float above the platter which makes re-leveling very easy without having to change the calibrated VTF.

I have not found any consequences from the so-called high horizontal mass. I think this is just another web fib. If there were a problem then one would expect the arm to skip or thump with off center holes. This never happens.

I too have found the bass performance to be exceptional as well as dynamics. As for placing the pump, it's just a matter of finding a remote closet with a small shelf and running the air line to it, probably through the attic. No biggie. The pump will be silent. I have never replaced a filter but I use industrial particulate and water filters. And the pressure has not varied at all. I know this because I measure it at the point where the air line enters the turntable thus eliminating any air line losses. My shop compressor is located on the other side of the house as far away as can put it. Thus located, it is silent.

For those who do not want to be bothered with this minutia, I say get another tone arm. To a degree, setting up an ET must be a labor of love with the hope of payback. The payback is there. The sound is truly excellent.

All SME arms are terrific. My favorite is the V but I like the others too, in some ways better than the V. But be aware the geometrical errors due to the pivoted design has a price and they cannot be avoided. It has nothing to do with the workmanship and beauty of the arm which, in the case of SME, is exceptional. You just can't get past the flawed geometry. My Graham also sounds very good. But not as good as the ET.

Sparky
 

karma

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HI,
I'd like to add one more thing to my posts above concerning mounting and initial set up. When I bought my first ET, I also bought the optional mounting jig. It took a bit of thought because it was not cheap at $250 in 1990 dollars. But I had mounted enough tone arms from scratch that I thought it might be a good investment.

It was the right move. I still have it and it is still the best way to mount and initially align this arm. I'm certain that without it I would be cussing the unaided mounting procedure as mep mentioned. Since I have never mounted an ET without the jig, I don't know how it would go. I do know the jig makes mounting relatively easy.

I suspect most folks did not purchase the jig because I have never seen them come up used. ET no longer offers the jig. That's too bad. It is a terrific piece of engineering.

Sparky
 

mep

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Sparky-I bought the jig when I bought the ET-2 and I still have the jig as well. I don't know how in the world you would install the arm without the jig and hope it would be correct. The jig is an indispensible tool.

We both agree that the ET-2 is a great tonearm. I'm lucky enough that I have a dedicated room with my workshop room next to my listening room. I had the pumps and surge tank (and my tank has a pressure gage installed on it) in the workshop room so they couldn't be heard in my listening room.
 

karma

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HI mep,
Don't dither. What pressure did you run your ET at? This is important to document for the community as a whole as well as answer my curiosity. Also, what were your results from adjusting the VTA? The ET has one of the best VTA adjustor mechanisms around.

Thanks, Sparky
 

MylesBAstor

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HI mep,
Don't dither. What pressure did you run your ET at? This is important to document for the community as a whole as well as answer my curiosity. Also, what were your results from adjusting the VTA? The ET has one of the best VTA adjustor mechanisms around.

Thanks, Sparky

It does. Do you use the dial micrometer on your arm?
 

karma

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HI Miles,
Good to talk to you again.

I have two turntables with ET2.5's on them. Sota Nova does not have dial guage because it would interfere with the dust cover. But my Oracle Delphi V does have the dial gauge. The dial gauge is not close to essential but it makes the VTA a little easier and looks sexy as hell. This turntable does not have a formal dust cover. I use a silk scarf.

Ah yes, I can be tempted by sexy gadgets.

Here are pics of my Oracle. The stand, which is not shown well in the picture, is a Lead Balloon Version 2 modified to be completely filled with lead shot. The sucker is heavy!! And dead.

Sparky
 
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mep

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HI mep,
Don't dither. What pressure did you run your ET at? This is important to document for the community as a whole as well as answer my curiosity. Also, what were your results from adjusting the VTA? The ET has one of the best VTA adjustor mechanisms around.

Thanks, Sparky

I didn’t realize I was “dithering.” No one has ever asked me that before so it’s not like I was ducking the question. I was using two of the original ET-2 pumps that were sourced from Japan into a gang valve as recommended by Bruce Thigpen. Even with two pumps, my pressure was never that high-less than 5 PSI. I never tried the high pressure route and can’t comment on what changes it brings to the table.

As far as the VTA, of course changing the VTA resulted in different sounds. I simply adjusted it for the overall best balance. There was always a sweet spot for me with VTA where the highs weren’t out of proportion to the bass and everything seemed to snap into focus. I was (and am) never one to adjust VTA for every LP I play.
 

karma

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HI mep,

Thanks. That is helpful. I like to accumulate a lot of seemingly useless information. Some times I learn something.

By knowing the pressure your arm was operating at gives me an idea of the basic performance of your arm. My progression was the original aquarium pump, then the Wisa pump with a surge tank, then my shop air compressor. With both the Wisa and the compressor, I used the high pressure manifold.

Others should not misunderstand. The performance of the arm with the original pump was outstanding, as both mep and I know, despite the low pressure of about 2.5 PSI. With your dual pump set up, 5 PSI could be obtained at low cost. With the Wisa pump I achieved 7 PSI. Now, with my shop compressor, I get 27 PSI. I could get considerably more but that means the compressor would run more often. 27 PSI is a compromise between pressure and compressor duty cycle. By increasing the pressure even more I did not find improvement. I do have a precision pressure regulator on the compressor.

With 27 PSI, all aspects of the sound firmed up. That's the right term. The sound had the quality of being anchored firmly in space. Especially pleasing was imaging and bass response. Resolution and detail was always outstanding. It was something of an eye opener.

I have more to say about VTA but it must wait until tomorrow.

Sparky
 

karma

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HI mep,
I started to write an essay to you about VTA and the ET. But then I remembered you are not using the ET arm. So, I stopped since I don't think you would change back. I think you should but you won't. And your SME is a great arm but it doesn't relate to my essay because it is pivoted. My research into the mystery of VTA shows that pivoted arms do not allow a perfect grove alignment due to their geometry. So, there was no point in continuing. If you are happy, I'm happy.

As for changing VTA for each record, I don't either. I use a standard thickness record for calibrating VTA and, once established, I don't change it. Standard thickness records represent about 95% of my collection.

Because of the precision of the ET's VTA adjustor, and the calibration scales, I could change the VTA for each major increment of record thickness. It would not be that hard. But, that seems to be the path to madness and I'm not game.

Sparky
 

MylesBAstor

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A simple solution my friend uses are variable thickness platter mats; makes it very easy for him to fine tune the sound. Is there some intrinsic reason why this would be considered a no-no by anyone?

Frank

Yes, it compromises energy transfer, coupling of the record to the platter, etc. Think about it. Mats have and affect the sound.

Ringmat I think actually does what you've suggested though.
 

karma

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Yes, it compromises energy transfer, coupling of the record to the platter, etc. Think about it. Mats have and affect the sound.

Ringmat I think actually does what you've suggested though.

HI All,
I agree with Myles. Part of the magic of modern turntables is their ability to absorb reflected energy from the vinyl to the platter. If not absorbed the reflections will smear transients. This has been well demonstrated. Nothing should interfere with that process. I call this the Linn effect but Linn's ideas have been bettered. A vacuum turntable can do a better job. But Ivor deserves the credit for the discovery. I tip my hat to him.

Actually, some great tone arms have extremely good VTA adjustors that make the thickness compensation really easy. They are probably faster than replacing the mat because of their graduated, calibrated scale on the VTA adjustor. The ET, Graham and others have this ability.

Sparky
 

fas42

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Yes, it compromises energy transfer, coupling of the record to the platter, etc. Think about it. Mats have and affect the sound.

Ringmat I think actually does what you've suggested though.
Yes, he's focused very strongly on that as well. The two of us have gone through many iterations of playing with layers of platter material to damp the resonances, as well as experimenting with the level of clamping to balance that damping. What has turned out to be one of the best solutions was to use an old LP as the key mat under the LP to be played. Then, that is balanced by simple layers of cardboard, cork, etc, to fine tune the height: we're talking of adjustments of 1 or 2 millimetres of record height for the sound to snap together.

Frank
 

mep

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HI mep,
I started to write an essay to you about VTA and the ET. But then I remembered you are not using the ET arm. So, I stopped since I don't think you would change back. I think you should but you won't. And your SME is a great arm but it doesn't relate to my essay because it is pivoted. My research into the mystery of VTA shows that pivoted arms do not allow a perfect grove alignment due to their geometry. So, there was no point in continuing. If you are happy, I'm happy.

As for changing VTA for each record, I don't either. I use a standard thickness record for calibrating VTA and, once established, I don't change it. Standard thickness records represent about 95% of my collection.




Because of the precision of the ET's VTA adjustor, and the calibration scales, I could change the VTA for each major increment of record thickness. It would not be that hard. But, that seems to be the path to madness and I'm not game.

Sparky



Sparky-I still have my ET-2, the pumps, the surge tank, and the setup jig. I don’t know if I could ever let them go because the ET-2 has brought me so much musical pleasure over so many years. There are other people on this forum who still use ET-2 arms (Jadis for one), so if you wrote a think-piece on VTA for the ET-2, it would still have an audience.

And I agree with you that changing VTA for every LP is the road to madness and like you, I’m not prepared to go there either. I'm not prepared to say that I would never go back to the ET-2.
 

microstrip

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HI mep,
I started to write an essay to you about VTA and the ET. But then I remembered you are not using the ET arm. So, I stopped since I don't think you would change back. I think you should but you won't. And your SME is a great arm but it doesn't relate to my essay because it is pivoted. My research into the mystery of VTA shows that pivoted arms do not allow a perfect grove alignment due to their geometry. So, there was no point in continuing. If you are happy, I'm happy.

Please write it. I also own a ET2 and all you will say can be applied to the Forsell air bearing - that has an excellent and easy to operate VTA control.
 

Anerol

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Unipivot arms don't work properly

Hello Karma, dear all,

I am not quite sure whether my query requires a separate thread and found this pretty close to my subject.

I have a little collection of tts and arms and enjoy to test new combinations of tts, arms and cartridges. I have now the opportunity to buy a Graham 1.5 in a very nice condition for Euro 1150. Since I am looking at this I have started to ask questions about this arm to friends among which is a renowned cartridge producer and a very active vintage tt servicer. Unanimously, both guys told me that I should stay away from unipivot arms (hence no singular criticism of the Graham) since they don't work properly. I have also been told that some cartridges are damaged by such arms due to the lack of stability.

Having digested this I see so many people enjoying the Grahams and all the other unipivot arms that are around. They can't all be wrong or ignorant of problems.

What is your opinion on unipivot arms and their specific advantages and, if any, shortcomings compared to pivoted arms?

Anerol
 

flez007

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I haven't found any, to my ears unipivot arms in general have a more "fluid" presentation lacking just a tad of control in the very low registers. (I have not heard them all of course and still lusting for a Tri-planar which is NOT a uni-pivot design)
 

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