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In Reply to: RE: REVIEW: VPI Industries Prime Turntables posted by John Elison on November 28, 2015 at 10:30:22
John, you know as well as I do that any table made in the "good old days" with electronic speed control sounded like crap, piled on top of garbage.
Give it up already, the Prime is the best sounding table you can buy for under $9000.00 and you know it. I know this makes you stay up at night but the whole world agrees with me, not you.
HW
Follow Ups:
I am on the road until the end of next week, but promise to report back on my Prime using the Phoenix tachometer (Roadrunner) with and without the Eagle and will even run the Prime with the Eagle and the Roadrunner both connected to each other versus not connected to each other. I refrained from including these items in my review of the Prime because I did not want to confuse the issue. Let me say a few things right now. I have a KAB SL1200 that can act as a frame of reference. My Prime runs a wee bit fast as reported in my review of it, after motor warmup 33.595-33.605 rpm according to the Roadrunner. My SL1200 runs 33.334 rock steady after warmup, but the motor in it is controlled direct drive. This information does verify that the Roadrunner is accurate. These numbers for both turntables are obtained without the Eagle in the loop, which can't be used with the SL1200 anyway. In my opinion, Harry's report that Prime turntables that he has checked in New Jersey are running at the correct speed is entirely credible. This is a function of the control being applied by the power companies and it is perhaps true that Florida Power & Light is delivering power that slightly higher frequency and higher voltage too as compared to the power in NJ. I will endeavor to report later on the influence any of this has on the sound of the Prime.
Have you tried moving the motor pod in/out? That will increase or decrease the platter speed, but I don't know whether it'll be able to lower the speed from ~33.6 rpm to 33.33. With the tachometer connected it should be easy enough to find the optimal position of the motor pod.
Yes in my review of the Prime I mentioned that moving the motor does change the speed, but not enough. I would like to have a chance to carefully listen for the difference in sound caused by speed before commenting further. Except for people with perfect pitch, I suspect that it is almost, if not completely, inaudible. On the other hand, my sense is that the difference caused by regulation using the Eagle or the SDS does have an audible effect on the sound.
Edits: 11/29/15
You confirm that the speed you measured is less than 1/10 of 1% above setpoint.I'd say that is well within the margin of error both of your measuring equipment and technique.
.. either that or my reading comprehension is, but looks like he's reporting an error of about .33/33.33, which is 1%.
Still, doesn't seem that big a deal, and without knowing the power line frequency at the time, hard to make an assessment about whether it's an issue. The line frequency does vary, it is only specified as an average accuracy. And negative feedback control systems sometimes degrade the sound of audio components as well, so speed stability and accuracy alone may not be enough to determine the best sound. There have always been turntable designers that felt plugging the motor directly into the power line gave the best sound, and designers that felt it best to regenerate the motor drive signals.
".. either that or my reading comprehension is, but looks like he's reporting an error of about .33/33.33, which is 1%"
Let me prove it... 33.6(avg. high to low)-33.33=0.27.........
0.27/33.33=0.0081 so I'd say less than 1/10 of 1% look go to you?
"The line frequency does vary, it is only specified as an average accuracy"
Line frequency does not vary. I've seen a fusible link blow up because frequency was 2deg. out of phase while syncing a power house (2200KW)to the grid. Talk about a big bang! All turbines in the US run at a 60 HTZ frequency. The grid is carefully monitored to maintain that frequency.
not that it really matters
Edits: 11/29/15
it's .0081
.1= tenths or 1%
.01=hundredths or 1/10 of 1%
.001=thousands or 1/100 of 1%
Let me try...
1%=1 per hundred (thus cent) or 1/100 or 0.01; 1/10 of that is 0.001.
So .0081 is 0.8%, or just less than 1%.
It is very unlikely that the line frequency in Florida is different than the line frequency anywhere else in the United States.
Everything synchs to the grid. Any effort to run at a different frequency creates a rather violent reaction.
And voltage will not have any affect on the speed of these motors.
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