VPI ADS Versus SDS

In my experienced opinion....

I have never really understood the need for an SDS or other similar type of device.    The only REAL reason for such a device is to reduce the voltage to the motor during record play.  That can be easily achieved using a Variostat.  The VERY minor fluctuations in frequency is insignificant compared to typical off-center spindle holes/  I have no trouble with pitch on my 20+ year old VPI Aries.  I use a Variostat to start the table at 120V and during "dust-off" and reduce the voltage to around 75V during playback.  I reduce the voltage to zero to stop the table rotation.  I don't use ANY on/off switch except to turn on/off the Variostat.

Yes, it is a very little bit more involved, but hardly worth mentioning.  It just becomes a habit.

The results speak for themselves.  Not picking a fight or comment war, just stating my OPINION.

bpoletti

I have never really understood the need for an SDS or other similar type of device. The only REAL reason for such a device is to reduce the voltage to the motor during record play.

That may be true for you. But for anyone who sometimes plays 45s or <shudder> 78 rpm discs, an SDS can offer a convenient way to set exact speed.

The reason for many controllers,  A/C sycro motors, is to stabilize frequency.  The reason some have voltage drops is to lower the vibration of the motor.  Also a big plus is to vary the frequency to get the right rpm.  Lots of things vary the rpm.  A two phase unit would be nice for the hurst motor Vpi uses.  Get rid of the cap and dial in the phase.  

To believe that speed stability is not critical is to Completely miss the point!!!  

Enjoy the ride
Tom

I don't miss the point, and you didn't READ my comment.   MY OPINION is that speed stability is about off-centered spindle holes, not A/C frequency.  I am very sensitive to pitch fluctuations and only experience them with off-center spindle holes.  

The controllers clean up or reconstruct the AC signal, regulate it as to frequency and lower the voltage.  My experience is that they provide a degree of improvement and clarity to the sound much as does the addition of a flywheel or a heavier platter (providing more flywheel).  If you have a revealing system and a discerning listener, the improvements are obvious.

Having said all that, the speed of a belt driven TT may still drift from 33 1/3 because of aging bearing lubricant, an aging belt and/or needle drag.  Other factors?  Hence, many users welcomed the Roadrunner tachometer which measured average platter speed over a period of about 3 revolutions.  When brilliantly mated to the electronic drive as was done with the Falcon and later the Eagle, the frequency would be adjusted slowly, but quickly enough as to be done right and not noticed by the listener.   It is a "set it and forget it" system.  (This differs from the instantaneous correction, as in Asian direct drives with relatively light platters, which, according to many people results in a deterioration of the sound.)

IMO nothing has approached the Roadrunner-Falcon/Eagle system which, unfortunately, is no longer available, and not even on the used market--for no one is parting with them.  And just for the record, these were sold at a much lower total price than the competing VPI systems and IMO were built to a much higher engineering and physical standard.  VPI has literally spent years trying to come up with something comparable, but with no apparent success.

As for this new Australian device noted above, despite the pretty page filled with hype, very little information is actually given regarding its actual use, particularly about its "tacho" or "strobe" system, nor about any incremental cost for them.