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?