Pheonix Engineering Road Runner

 Peter, your comments lead me to believe that you have probably installed your tachometer on a few Denon turntables that you have restored. I am wondering whether you find that your tachometer is in agreement with the built in strobe device on Denon dd turntables. Which is to say, when the strobe image is stable, indicating 33.33 RPM, is the tachometer reading the expected value?
thanks.

Lewm

Yes indeed - the Denon DD's are very precise - I use the Tachometers on the DP80 Professional and the DN308 Professional.  The reading is 33.333 with the last number varying a slight bit,  they all lock in at "their" speed, which can be 33.334 or 33.332 and some at 33.333  The Oscillators are not adjustable on most of them - only the DP7000  and a few of the DP6000 have had adjustable oscillators.

Good Listening

Peter

DP80 also allows speed adjustment but I think it disengages the servo.

Lew

All the Denon DD’s I work on have Adjustable speed - however as you mention this disengage the servo control. What Im talking about above is the internal oscillator from which the speed control is derived, only the DP7000 allows for adjusting the clock speed (with a small adjustable capacitor) which for the DP7000 is 300kHz.

Good Listening

Peter

IMO a Roadrunner type device alone is a non-starter.  If you keep it visible it will drive you nuts.  For if you have a belt drive you will probably see it vary over time especially as the bearing warms up.  Either it will give you agita over differences you cannot hear or you will jump up and down to correct the speed continually.

The Roadrunner-Eagle/Falcon combination, on the other hand, is a genius combination letting you forget completely about turntable speed and concentrate on everything else.

While I understand there may have been reasons, VPI made a big mistake in not licensing all of this when they may have had the chance.