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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
flyfish2002's avatar
flyfish2002
94 posts
 
KAB speed strobe + SDS = excellent speed stability in my system (TNT).
dougdeacon
3,338 posts
 
Andrew,

Here's a link to that LP (don't know anything about this seller, just an an example).

One of our nicer sets is a massive Erato box containing all of Vivaldi's opus-numbered sonatas and concertos, from I-XII, with I Solisti Veneti/Claudio Scimone. That's 30 sonatas and 86 concerti if anyone's counting. 20 of the 24 LP's are superb. Four were recorded in a different venue by a different engineer who screwed up the miking, but it's still a great set. Vivaldi by Venetians!

Another good test of TT speed stability is the depth and length of soundfield decays. Most Erato recordings of I Solisti Veneti were made in cathedrals or other large venues, with massive soundstages and near-endless decay periods. This very low level info is easily muddied or smothered by many system errors, including TT speed instabilities.

Apologies to Darren for wandering around your thread. Hope some of this is useful.
blueranger's avatar
blueranger
719 posts
 
The 180 gram reissue of Who's Next is slow. Mike
jj2468
280 posts
 
Doug,
are you able to post any photos of these rooms?
Jeff L
tonywinsc
583 posts
 
After reading these posts the last few days, it got me curious to see how stable my Sota turntable speed is based on listening tests and using the strobe disc. I have a stereo test record so I put that on the platter and then my Sota strobe disk which I clamped down onto the record. I have a 4 inch plug-in fluorescent light that makes a good source for the strobe disc. First, I started the turntable with the tonearm up. I locked in on one rectangle on the strobe disc and noted that it stayed in place for several record rotations. Rock steady stable. Next, I cued the tonearm on the outside lead-in groove of my test record and then locked onto a rectangle again on my strobe disc. As the tonearm dropped onto the record I saw no drift of the strobe disc rectangle. Still rock solid steady. I then played the pure test tones on my test record, 440Hz, 1000Hz and 3150Hz- specifically for flutter measurements. To me and my son, these tones were all steady in pitch. But what we both heard was a periodic shift in the image from center to slightly right. So I go to the turntable and get down eye level with the tonearm and I see the tonearm swaying from left to right. Conclusion: My test record has runout. The hole is slightly off center. I see this same issue on several of my records. So my question is: If the source material has some amount of runout, at what point does spending kilo-dollars for better speed stability yield little to no results? Based on my observations and measurements of my Sota here, what am I missing/overlooking?
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