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Speed Stability

I have been fretting about the speed of my vpi for about a week now. I do not have a test LP or a strobe mat but I feel that if there is a speed issue. I am hearing the pitch fluctuate up and down on notes that are held out. I have compared some recordings to a CD version and have gotten mixed results. For instance:

On the first track of John Coltrane Quartet Ballads, I noticed that the ending note on the the first track tended to sway like an old VHS tape compared to the solid pitch of the CD version.

a first pressing of Dark side of the moon compared to my anniversary CD copy resulted in no significant changes in pitch that I could hear.

I guess what Im trying to get at is could that be a issue with the speed of the pressing itself, or could it be that some records show off a problem with my rig more than others. I hope it hasnt just started to be a thing thats just in my head. I think my next step is to take the Coltrane over to my fathers direct drive technics and see if the pitch continues to sway or not.

I would appreciate any input on the situation. Thanks

Darren
macd
tonywinsc
583 posts
 
I want to think that some labels did a better job of centering the hole in albums than others. I am almost curious enough (but not quite) to measure the hole position of a group of records to see just how far off they are and how much they vary. Maybe someone has already done that- perhaps even by label so we could all know which ones are better for critical listening.
ghostrider45
449 posts
 
Nakamichi built a couple of very complex turntables (TX-1000 and Dragon} back in the early 80's that centered the record to correct for off-center spindle holes.
tonywinsc
583 posts
 
I noticed while playing records over the past week that the European and Asian pressings seem to be punched true-ie. no visible swaying of my tonearm. US pressings however, seem to be a mixed bag. Some records are true and some I see the tonearm swaying quite a bit. Still, with the exception of the pure test tone section of my test record, I cannot hear the runout in the music.
dougdeacon
3,338 posts
 
Jeff L,
We didn't take any photos. You might find them online somewhere. Remember I was talking about RMAF 2008, not 2009.

Tony,
Further to what Mosin said, speed variations occur over every possible time span, from the length of an entire LP side to a nano-second or less. A strobe will usefully measure variation that occur over longer times, but becomes less useful (and eventually useless) in measuring variations of shorter duration.

The particular time-domain errors we listened for (and did not hear) on Mosin's Saskia table at RMAF are far too short-lived to be evidenced by any strobe device I've seen. A signal analyzer would reveal them but a strobe's resolution is far too coarse.

More fat to chew...
tonywinsc
583 posts
 
Then it would stand to reason that the position of the record relative to the platter can affect playback quality. What I mean is, if the turntable has a certain rhythm (wow and flutter characteristics) then it must be possible to turn the record relative to the platter, ie say in 10-15 degree increments and effectively match, or optimize the record's eccentric hole tolerances to your turntable and find the best playback position. Sounds like an interesting experiment. Has anyone tried this?
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