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Stroboscopic disk sets wrong speed for turntable?

Hi all! I am new here.

I have just set up my Clearaudio concept turntable. Unfortunately, the speed of the turntable was wrong so I had to reset it. In order to do this I have used two methods: an iPhone app called RPM; the stroboscopic disk + the iPhone app StrobeLight.
The problem is that when everything is correct at 33 1/3 (both verified with the RPM app and the stroboscopic disk), the songs are playing one semitone lower than what they should. In order to make them play at the correct note, I have to set the speed at around 34 RMP as shown by the RPM app. Also the stroboscopic disk shows that now I am going faster than the 33 1/3, being consistent with the RMP app. How is this possible? Am I doing something wrong or even the stroboscopic disk is not accurate enough? Could it be the StrobeLight app not being an accurate enough light source for the stroboscopic disk? It is just peculiar that both the RMP app and the stroboscopic disk are consistent in saying that I am going too fast. 

Any help is much appreciated. Thanks!
agforte
uberwaltz's avatar
uberwaltz
13,381 posts
 
I agree with Lewm that the battery powered KAB strobe would be the best way to go.
When I purchased his Walker motor controller for my Nottingham TT I first used a generic disc and a AC powered bulb to set speed.

Then a friend loaned me his KAB strobe and lo and behold it showed the AC setup was slightly slow.

Not cheap but highly recommended!
bsmg
296 posts
 
I saw a PBS tv show a few years ago about the nations electrical grid; they stated there are three of them: East, West, and Texas.
bgpowell
70 posts
 
Sorry my memory was a bit faulty, it was a proposal by  the North American Reliability Corporation (NERC), an pro power industry organization.  There is a Federal Energy Regulatory Commission (FERC) which made Time Error Correction mandatory in 2009.  NERC put a second successful proposal to FERC, which is contingent upon the removal of the standard WEQ-006.  Anyway, not implemented yet but there is pressure.
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