Wherefore Belt Drive?


I want to initiate a discussion, not a flame war. I have a theory about how belt drive became the de facto standard for audiophile turntables, and your responses, corrections, comments, or confirmations would be most welcome.

According to Linn's history, it was founder Ivor Tiefenbrun demonstrating his Linn turntables in the early '70s that created a new paradigm in LP playback. Until Linn, conventional wisdom held that as long as the platter spun consistently at 33.33 rpm, it was the tonearm, cartridge, pre-amp, and the rest of the signal chain that made the real difference on sound quality. Linn demonstrated that the actual turntable--the device spinning the platters--had a profound effect on the sound of everything that emanated therefrom.

So what did Tiefenbrun's design entail? Chiefly, a suspended design and a belt drive. A suspended design requires belt drive. You don't suspend a direct drive or idler-drive turntable design because then you'd have to suspend the motor, one of the things you're trying to isolate the playback system from. Besides, motors are heavy and escalate the challenges to a suspended design.

Once the audiophile community accepted Tiefenbrun's premises, belt drive became cemented in its collective conscience as the only legitimate way to make the platter spin.

But wait! What if it wasn't the belt drive per se that made his TTs sound better, what if it was the suspension itself, and that the same effect could be achieved by other means, applied to other drive methods?

Turntables present a paradox wrapped in an enigma wrapped in a quandary. You must make a platter spin at precisely 33-1/3 RPM while a microphonic device (cartridge) transmits only the modulations in the groove of the LP. Spinning a platter requires a motor. Extracting the sound from a record requires a microphonic cartridge, but the cartridge must not also transmit any of the motor noise or the vibrations and ambient noise in the room! Both the motor and the sound emitted by the speakers can be picked up by the cartridge, muddying the sound.

Back in the early '70s, there were no real audio racks, no isolation devices, no Black Diamond Racing cones, no sorbothane. Noise and vibration control was unknown and unrecognized. Therefore, a suspended-design Linn, plopped down on the standard walnut veneer-over-MDF shelf of the day, as a matter of course was going to sound cleaner and more musical than any turntable that didn't take vibration control into consideration, be it idler or direct drive, which is to say, all of them. But that doesn't mean the other aspects of non-belt designs were fundamentally flawed.

I postulate that the superior sound of the Linns in the '70s was mistakenly attributed to the belt drive, when in fact it was the suspended design's isolation from feedback and vibration that accounted for the better sound.

Read the posts on this forum from the direct drive and idler drive enthusiasts. DD enthusiasts invariably say that proper platforming is crucial to realizing the potential of a Technics SL12x0 series or Denon 500M. They usually recommend spiking or coning the TT directly into a thick slab of maple or butcher block supported by shock-absorbing, isolating footers underneath the slab.

Read the posts of the idler-drive enthusiasts for pro-level Garrards, Rek-o-kuts, and Lencos, and they invariably say that a handmade aftermarket plinth is essential to realizing the turntable's potential.

The suspended design protects the turntable playback from in-room vibrations and feedback, and reduces introduction of motor noise into the playback chain. But a direct-drive or idler-drive turntable can be isolated too. A good direct drive motor, although connected directly to the turntable spindle, doesn't make much noise at all, and with a 4+ lb. platter, doesn't really have to correct the speed at 4K to 6K times per second. KABUSA has the oscilloscope photos to prove it.

Belt drives have their downsides as well. The biggies: vagaries of belt tension and friction make it difficult to dial in a precise speed; it takes awhile to spin up to speed, which ultimately depends on the flywheel effect of a heavy platter; and the vertically-oriented bearing is being pulled sideways by the belt. The only design I know of that takes this last factor into account is Well-Tempered, which is rarely mentioned on this forum. Also, the shock absorbing aspects of belt drive (at least on lower-end models with lighter platters) reduce the impact of transients and recess the midrange slightly, adding to the illusion of image depth, but actually compromising the natural presentation of the midrange.

So what I'm asking here is, have direct drive and idler drive turntables gotten a bum rap for the wrong reasons? Have they been marginalized and even scorned when in fact, they are equally legitimate drive methodologies that simply needed their own solutions for vibration isolation to bring out their potential?
johnnyb53
Pbb, Your correct, Castle Precision Engineering Was his father's company. With an influence in industrial design, some engineering classes at Glasgow's Strathclyde, and a love for music and musical reproduction he made the Linn Sondek LP12 (sound-deck) because he was so dissatisfied with the TT's that he could go out and buy at the time. Not a bad start. It is about the whole package though, and nobody at the time had the whole package, so Ivor filled the need.
Most of us accomplish very little in life and even fewer make a real paradigm shift. Funny how easy some folks find it to criticize when they have done nothing and show nothing for the rest of us to now critique in retrospect. There are a lot of great TT, IMHO Linn is easily one of them. Besides, what Hifi, or for that matter, any other product, do you know of that can still be purchased and upgraded (improved) by a dealer since 1972? There are a few, I’m listening…

Happy Listening!
Apologies for the ramble, some thoughts ...

Belt drive was an opportunity for the industry to make more money for less, and it was already successful before Linn.

The suspended chassis belt drive is not the secret of the LP12's success, otherwise Thorens would still be a major force in this market.

One of the best regarded tables in the early 70s was the Thorens TD125. Let's say you were quite well off at the time and had one of these. The latest gear from Japan was replacing belt drive with direct drive, so you might upgrade the Thorens for a top of the range DD. You might then feel it wasn't as good, and decide to look at the subject more closely, even to take your old turntable and start to tweak it for improved sound ...........

The Linn empire is built on the single point bearing, the rest of the LP12 is no different to several of it's contemporaries.

The bearing is where the magic is, that's why they were so keen to patent it.

Good marketing too, the dealer training was especially effective. :)

Regards
As an owner of a multitude of tables over the past 30 years; I have owned both belt and DD TT's (only one BSR Idler... as a kid in school before I got my first real "system" at 17) and I have also built four TT's myself (see current one here. http://www.vinylengine.com/phpBB2/album_page.php?pic_id=4196 And Here...
http://www.vinylengine.com/phpBB2/album_page.php?pic_id=4195). I can honestly say that I have loved the sound of my belt drives above the Technics SP-15, Teac TN-400, Denons, Kenwoods and others. The things I have learned in building my own turntables, arms & cartridges is that these things make the most difference: Mass, the more there is the harder it is to move. If you make it out of multiple different shaped pieces of different materials that resonate at different frequencies. Isolate the motor as far from the rest of the TT as possible. Don't use a belt made of rubber just because it's common to see them. We were listening to my current TT the other night and sustained piano notes sounded like they were ever-so-slightly wavering. I stopped the TT (SAMA Motor, VPI TNT Platter, & SDS) and replaced the belt with a knotted piece of upholsterer's thread and my lead-eared partner (bless his heart) asked if I turned up the volume! The cat even turned and stared at the Martin-Logan CLSIIZ's head moving back and forth watching the movement in the recording. It was like I had thrown another $2500 at the phono cartridge. And finally; a fine bearing with smooth surfaces and oils. Lots of different oils. Have Fun No Matter Your Drive Choice!
Cabeau, what's your favorite oil(s)? I've been using the vdH zirconium oxide stuff in my Goldmund DD and I *think* it's lowered the noise floor a lot. . . . . . . .
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Cabeau,

I'd like to know how you got it right with "thread drive" on the VPI. I've tried this with my VPI TNT III w/flywheel & pulleys, using dental floss as well as several kinds of thread. There is an improvement in focus and energy (and apparent volume), but instrument body suffers & a glassy shimmer on the piano tells me it's not speed-stable. The string slips unless it's really tight, and with the string pulled tight the knots ping like table tennis as they circulate. Calling Mr. Wizard!!