Pheonix Engineering Road Runner

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.

@pbnaudio

You may like DD turntables. Many people do, and they certainly have their conveniences. My own opinion is that for a DD turntable to provide the same quality sound as a good belt-drive TT it has to be very expensive. Like the forthcoming VPI DD which will be a relative bargain at $15,000. We have yet to see if it performs as well as its predecessor at $30,000 (?).

IMO the cheaper Japanese models like the Denons you write about have a distortion, hard to measure but easier to hear. It’s kind of a micro-flutter caused by the tiny, but constant, speed corrections. Michael Fremer described it as, "ultra-high-speed hunting and pecking as it over- and undercompensates in the attempt to produce a consistent speed can create a jitter effect in the mid-treble to which the human ear is particularly sensitive, adding a hard, brittle texture to music." I agree.

Beyond that I fail to understand why anyone with a DD turntable and its automatic speed control would want to have a Roadrunner type device. In effect the Roadrunner/Falcon functionality is already built in.

@pbnaudio 

You wrote: "I don't hear the 'servo hunting' your describing rather I hear consistency in tempo, great pace and drive. I do add substantial weight to the platters of these tables by adding copper mats,  this of course increase inertia so if what your describing exist its effect is greatly diminished."

On the basis of what you say,, I believe that you DO hear the "servo hunting" described by Fremer.  You say you add "substantial weight" to the platters.  I presume you do that because the additional weight increases the SQ of the analog playback.  Increased platter weight almost always does.  The difference between what you heard with the light platters and the heavier platters is exactly what Fremer is writing about.  Heavy platters (and other flywheel devices) has always been the advantage of belt-drive TTs (with the exception of super-expensive DD TTs).  Also heavy platters are less likely to ring.

For the Japanese DD TTs you write about, though, the ability to add weight is severely limited by their comparatively weak motors.

@pbnaudio

You wrote: "The motors on these are substantially larger than any of the motors typically used on any belt drive http://www.hurst-motors.com/aabdirectdrive.html this link takes you to the first choice of belt drive manufactures."  

I'm surprised to read that you said that.  The physics of belt drives, with the motor revolving much faster than the platter, permits very small (and very quiet) motors to turn a 30+ pound platter.  In fact, the Hurst motors are among the larger motors used for belt drives.  Excellent sounding belt-drive TTs have been built with clock motors.  The original Sondek motor, for ex., was a tiny one.

As long as you're dragging this out, you wrote earlier: "The reason to put the Tachometers in the turntables to display their accuracy. If you got it flaunt it. :-)"  Are you for real?  You're selling a tach to DD TT owners that does exactly what their TT already does.  So you want them to invite their friends in to watch the tach?  Really??

@lewm

The inertia of a 20 pound platter smooths out the feed back effects.

They sound better with the various controllers because they depend for speed upon the 50 or 60Hz cycle from the electric company. That cycle can now be made more precise with these add ons. Also they drop the voltage (after start-up) which further weakens the already small motors. Weaker motors means less effect upon the heavy turning platter.

The fact that you cannot hear the distortion does not mean it’s not there, just that you cannot hear it. I’d suppose Fremer has a better ear than you do . . . and better associated equipment.

@cleeds,

I've gone a similar route to you, with an original TNT and multi-upgrades over the years.  But I would never give up the lead/acrylic platter.

The PE Eagle is at least the equivalent of the SDS and, in fact, measures better and is somewhat easier to use.  The Eagle (or Falcon) used with the Roadrunner does create a feedback loop and is a brilliant set-it-and-forget-it design.  I sold my SDS when I bought this combo and even made a few bucks on the deal.  The Phoenix stuff was a real bargain in its day.  I hope it is revived by Sota for general sale.

The Roadrunner actually measures a running average of about three complete rotations so that the speed adjustments, when they are made*, are relatively few as compared with the continuing micro-adjustments of the typical DD TT.  The adjustments can't be heard, certainly not by me nor by anyone else who has written about these combos.

*the speed, of course, is MOSTLY controlled by the precision line frequency synthesized in the Eagle.