Brinkmann Bardo vs Transrotor Fat Bob Reference

03-15-11: Melbguy1
I received this reply directly from Transrotor in response to a question asking why they decided on the belt, as opposed to direct drive approach:

"We chose the belt drive because we think it is the best way not to bring resonances from the motor to the platter. The negative aspect of the belt drive (the belt slip) is compensated by the magnetic drive, the TMD"

I trust the Transrotor turntables are good sound products based on what was commented from earlier posts. I also think the TMD is a clever idea for belt-drive. But I'm surprised by their response to why they chose belt drive. Isn't direct-drive in itself a form of magnetic drive? Just think of the TMD is driven by coils instead of outboard motor using a belt. And if the DD motor is spinning at 33rpm, half Hz, isn't it innately quieter than one or three motors spinning at, say, 300rpm to 1800rpm, isolated by a belt or not? The only noise issue with DD is the quality of the bearing, which applies to ALL turntables. This is just another case of someone who does not understand the workings of direct drive. Let's face it, building quality DD table is expensive and, more importantly, requires a lot of knowledge in electronics beyond just mechanical engineering. I have no problem with them saying they simply prefer the sound of belt-drive, instead of using the, by now, really tiresome argument against DD. The horse is dead, stop beating on it.

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Melbguy1: "It is really simplistic to simply say direct drive is superior to Transrotor's TMD. That is like saying Lexus is superior to Rolls Royce."

I did NOT say direct-drive is superior to anything. I own all three drive systems: belt-drive, idler-drive, and idler-drive. All three are capable of good sound. But when it comes to direct-drive, I hear the same argument against it over and over again, i.e., if the platter is directly attached to the motor then therefore it will have vibration and no way of isolating it. My view is that the motor and platter share the same bearing and it has only one single moving part which is running at such slow speed at 33rpm that vibration isolation is not even needed. I see the mechanical simplicity as a plus and hence my fondness of it. Of course there are other issues that can haunt a DD system such as cogging, servo speed, magnetic shielding, etc... and those are valid objections. Nobody said it's perfect.

The TMD system is very clever and to me more elegant than their FMD or the one used in Clearaudio Statement or EAR Disk Master. I have no doubt it is a quiet table and offers the mentioned good sound and I am happy that you're enjoying it. Hell, I would like to try one myself. Again, my comment was directed at TR's response to the DD motor/platter isolation issue, which is a non-issue to me, and hope people can just move on to addressing other meaningful analog issues. I am certain people will bring up the same argument again and again... just like life.

Audioquest4life: "In fact, the combination of TMD and outboard motors used caused quite a stir in a German magazine a few years ago due to the extremely low measured distortion; comparably lower than some direct drive models."

Do the said direct drive models use the same bearing as the TMD? I rest my case.

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Lewm: "I would be wary that the TMD system adds unwanted compliance where there is already some unwanted compliance from the belt itself."

Maybe this is the reason the EAR Disk Master uses noncompliant gear belt to lessen the compliance in sum with the magnetic force. TR can probably use something less stretchy like mylar tape or film. I was enchanted by the TMD too and still think it's a great idea.

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Melbguy1, no worries. There's no best or worst and whatever in between is why we called this a hobby. It doesn't matter what drive system you use. Whether it's belt drive or steam engine drive, as long as it meets your need. Most important of all, enjoy the music. :-)

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TMD = Transrotor Magnet Drive

Using a ring bearing surrounding the platter bearing underneath the subplatter driven by a belt. The ring bearing holds the magnets that attacts the magnets in the subplatter above. This ring bearing is still mounted on the same plinth as the main bearing.

Diagram of TMD

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FMD = Free Magnet Drive

Using a belt-drive motor pod underneath the turntable. The motor pod holds the magnet that attracts the magnets in the subplatter above. FMD differs from TMD is that FMD is completely mechanically separated from the turntable above. Similar system in the Clearaudio Statement and EAR Disk Master.

Diagram of FMD . . . and . . . more pictures.

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Lewm: "Life could have been simpler if they just made a direct-drive turntable instead"

That's what I've been saying! But audiophiles always have a hard time grasping the concept of direct drive that it is "magnetic drive" -- instead of driving the top platter with another set of magnets, it can be driven by magnetic field generated by coils, which is a stator in a motor, and this system is called, voila, direct-drive! Granted it comes with its upside and downside but, yes, life could have been simpler.


Regarding the TMD, I am curious why the secondary bearing, the ballrace bearing (maybe the technical term is angular contact bearing"?) is attached to the platter bearing, at least according to the diagram. Wouldn't it be better to have the collar bearing decoupled from the bearing shaft to have better isolation? Perhaps, I am not interpreting the drawing correctly.

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Audioquest4life: "In regards to the TMD, below the bearing assembly is a ceramic / steel spindle, that has a viscous pool of oil that runs up the spindle and is used to lubricate the spindle when the patter turns, thus physically isolating the bearing from the spindle."

Thanks for the info! The oil pool makes sense. Very cool.

Also thanks to Manitunc for your insight.

Audioquest4life: "I prefer not to deride, discredit, or participate in lengthy debates about the implementation of other drive technologies, in the end, it is all about the music, and what makes "ME" happy. I cannot afford to waste my time on trivial matters, when I have so much music to listen to. I do appreciate your technical insight of the implementation of various drive methodologies concerning turntable."

I agree with you but what I wrote above was never intended to be a debate. I really have no interest in talking about the sound since that's so subjective. If someone likes or dislike the sound it is of no interest to me. All the pornographic flowery prose--wide soundstage, imaging, neutral this, neutral that, blah, blah, blah-- from magazines is a big turn off for me. Since I am a gearhead and I am only interested in the technical aspect and it's fun to discuss those things for me and I regret my questions have bruised some egos. I am used to the diyaudio.com forum with like-minded people so I guess I carried some of the old habits onto this forum. My mistake is that I automatically think audiophiles enjoy talking about technical things. Obviously, I am wrong. This site is more about consumer reports so I've been barking on the wrong tree. I just want to say that when I question the implementation of a design it is in no way discrediting people's effort or someone's purchase. I have bought some equipments before with questionable features or engineering that were either a work of genius or Rube Goldberg but they never bother me because they are just toys for me and never as an investment. Audio is just a hobby but for some it's an investment and status symbol and there's nothing wrong with that. As far as enjoying the music, I can just as comfortable listening to my car radio as a high end system. But the mechanical and engineering aspects of audio tickle my fancy and it's fun.... except this is not the forum or platform to do it.

I just looked up top and realized Melbguy1 is the opening poster(!!) and that I might have hijacked the thread so I apologize for his departure. Come back Melbguy1; I'll stay out of the way! Ok? Please?

Once again, enjoy the music.

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