Direct drive vs belt vs rim vs idler arm

Lewm,
To clarify a few points -
My comment that the best DD I've heard thus far is the SP10mk3 is based on listening, not torque numbers. The Krebs modified SP10mk2 is in my view easily outperformed by a well set up Garrard 401. The L07D has always been one of my favourite DD's, but recent listening tests have led me to disappointment. The L07D was standard with the stainless mat which according to the literature is supposed to provide shielding. It is possible the L07D may not have been operating optimally. I say this because in my experience the power supplies in these vintage decks should be completely rebuilt and calibrated - not just the caps but all resistors should be replaced. For example in my outboard power supply built for my Marantz 7 tube amp, after 12 years I had it recalibrated by my tech. In that short time several mil spec resistors had drifted in value, despite being mil spec and overrated. The caps were ok but replaced with superior caps.
With regards to servo technology, I think we are in agreement in recognising the issues around servos. Significant advances are available in speed response and accuracy, notwithstanding devices now switching at a trillionth of a second. The chips used in the 70's decks are obsolete, non programmable and slow. As an analogy, my Marantz 7 outboard supply, despite using regulation far more sophisticated that the ubiquitous LM317 and its like, would now be obsolete, the use of stacked op amps for regulation would be an example of using different new technology that can be utilised for providing better solutions to old problems.
With regards to the Bill Thalmann/Krebs changes - my understanding is that Krebs has sent his own power supply to Thalmann because he couldn't get it to run, so I assume that he doesn't know how it works and any mods are more likely parts replacements or tweaks rather than a redesign.
I'm also pretty sure in another thread Krebs has stated there are no changes to the servo operating parameters and design.

To suggest the Technics Sp10Mk3, when properly conceived and implemented, cannot during playback recreate an accurate portrayal of an analog recording possessing the appropriate pitch, scale, speed consistency and balance is purely absurd. Numerous random variables come into play when evaluating such precision instruments, let alone vintage designs, especially when individuals are listening in foreign environments. In order to effectively and objectively evaluate two turntable platforms side by side, one must recreate the conditions present identically, period. Arm for arm, cartridge for cartridge and including associated equipment. Even then, doing so may prove less than absolutely precise. Frankly, based on what one individual described above "Tones are changing multiple times, depth and physical presence does not exist" this may indicate the logic / control / drive circuit requires a comprehensive scope bench test followed by servicing. Had these individuals bothered to examine the block diagram and troubleshooting guide printed in the service manual? Bear in mind, the Mk3's were intended to be used for extended periods of time while exhibiting utmost precision and stability during playback, namely in commercial environments, and thus were readily serviceable in the event of a malfunction. Over the years, in addition to the Technics Sp10Mk3, I've personally evaluated, studied and tested numerous other admired vintage designs at length, including the Micro Seiki RX5000 series and RX1500's with flywheel and many idler drive based ie. Lenco L75, Garrard 301/401 and various obscure direct drive based designs for that matter and in my experience none of these classics are entirely devoid of some type of inherent compromise. Fortunately, however, with today's technical resources and understanding of applied engineering principals, including material application, certain vintage based designs can still prove more than relevant and worthy of our praise.

Peterayer, please PM me directly if you wish to know the extent of Artisan Fidelity's electronic service and mechanical upgrade services available for the Technics Sp10MK3 and how it differs from Bill Thalman's services and Krebs modifications.

I asked my iPhone, "How many angels can dance on the head of a pin?" Siri then went into a lengthy dissertation on angels and arrived at the conclusion that angels are non corporeal and therefore have no dimensions in space; ergo an infinite number of angels can dance on the head of a pin.

Dover, I am gratified that you've apologized to the L07D. Yes, the stainless steel "platter sheet" ought to go a long way to block EMI from the motor, but the addition of a second shield (ERS cloth, mu metal, TI Shield in my unit) under the platter sheet removed a kind of subtle glare that I did not know was present until it was eliminated by the added shield. The idea to try it came from the L07D Owners website; it turned out to be worthwhile. I don't know what was in the rest of the system that caused you to blame the L07D for a loss of "contiguity" among bass, midrange, and treble, but it would have to be a system (from cartridge to speakers) with which one was otherwise very familiar, in order to be able to blame the TT. Good point about the increased speed of modern day chips, but what is the evidence that these parts make a meaningful difference in design of a servo for a TT? The Grand Prix Monaco is state of the art in servo design, and no one is knocking down the doors to buy one (so far as I know). Bill Thalmann is much better equipped than I to discuss the servo mechanisms in these tt's, but I take his word that the circuitry is pretty sophisticated by modern standards, and in some cases he is able to upgrade discrete transistors to "modern" equivalents.

Otherwise, I am on the side of both Chris and Richard, although they are professionally competitors with each other. Both are fighting the good fight, IMO.

Perhaps I missed it in the six previous pages of this thread, but there is an issue with belt drive suspended tables that is often overlooked. If the motor is mounted somewhere other than the subchassis along with the platter, then belt tension varies with suspension movements. There's no getting around this. Even if the belt has less stretch than rubber, the belt becomes part of the suspension. It's part of the suspension anyway in this case.

Suspensions are designed to compensate for acoustic impact on the table and they're tuned to a low frequency. When one sets up a suspended table it's made to bounce straight up/down. This straight bounce only occurs if you push on the suspension precisely, and in the right place usually equidistant from the springs. Hit the suspension in the "wrong" place and the perfect bounce becomes imperfect. Sound waves don't obey the rules dictated by a suspension and will hit the table in unfortunate ways.

I read a diatribe here about the Goldmund Studio and how the Delphi was so much better. It's true that the Goldmund DD's had an unfortunate suspension, but at least there was no belt involved. This was something that everyone came to realize and it became di rigueur to defeat the suspension.
Okay, we're not talking about the stock table any longer, but a Goldmund thus modified was far superior to a forgiving Delphi with its mushy sticky mat and speed variations. Even without the suspension defeated it was a more precise deck capable of extracting more information. The methacrylate platter was a prototype for platters/mats that are designed for physical properties compatible with vinyl.

It's no coincidence that Japanese statement decks of the late '70s early '80s were virtually all direct drive. When the CD was introduced in '80 they were phased out. The "superiority" of belt drive was sold to the public because that was the only option for a small manufacturer. They didn't have the technology or the motors to duplicate the Japanese decks, so they did what they could.

Belt drive has come a long way and some are much better than those offered in the '80s. Now, well into the resurgence we come full circle. Before '90 VPI had the HW19 and the TNT was just introduced. Now their top deck is Classic Direct, go figure.

Fleib, Your points are well taken; I am no fan of suspended tables, but suspension vs no suspension is yet another choice, in addition to, not instead of, belt-drive vs DD. As you note, a suspended DD turntable would not be subject to the belt stretch you mention. But in fairness to TT's of the suspended/belt-drive class, none of the current examples that I know of still mount the motor on the base, rather than on the suspended element. The old SOTA tables were guilty of that flaw; my Star Sapphire Series III was just awful on sustained piano notes, as a result. For years, I thought the muddy piano sound was part and parcel of vinyl reproduction. Modern SOTA tables are no longer built that way, and old ones can be modified, according to my reading.