Vinyl Asylum

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In Reply to: RE: I am not sure of your meaning.. posted by kentaja on December 18, 2016 at 11:38:45

What you say about the loss of "slam" and other qualities commonly attributed to idler drive turntables, when using an AC supply, is worth noting. Both the Garrard 301/401 and the Lenco L75 use induction type motors, definitely not AC synchronous. I think the Garrard motor may be even more power hungry than the Lenco motor. Just to keep the terminology straight, the name of the power supply made by Phoenix is "Eagle". So far as I understand it, the tach made by Phoenix Eng is called the RoadRunner and apparently can be used on any turntable so long as it is possible to mount the two speed-sensing devices, one stationary beneath the platter and one on the underside of the platter. I think that's what John is doing. When you use the Eagle with the RoadRunner tach (which isn't required, so far as I can tell), it can feed info back to the Eagle so the Eagle can compensate for speed variation, up or down. My thought was that because the sensing is done only once per revolution, the corrections can only occur once every 1.8 seconds for a 33 rpm LP. This is where I would look for a change in the character of the sound of an idler driven by such a power supply, more than what might be due to watts alone. If I buy an Eagle, I may listen to it for a while as is before setting up the Roadrunner, to find out if I can hear any added or differential effects of the latter.

Direct-drives differ from one another as to how speed is sensed and corrected. For example, the Kenwood L07D and the Yamaha GT2000 seem to do it once per revolution, whereas the Denon DP80 has a continuous sensor (and uses an AC synchronous motor, to boot). I am not sure how Technics does it, even though I own one.

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