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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
hifimaniac
508 posts
 
Get a KAB speed strobe to dial in the speed. Do you use the SDS power with your VPI? This is a great upgrade if you don't and you won't have to check your speed to often.
ghostrider45
449 posts
 
Is perhaps the spindle hole slightly off center on the Ballads LP? That would generate the wow you're hearing and explain why your DSOM copy sounds OK.
chadlesko
94 posts
 
I second the KAB...but I don't think your issue is speed. Speed will change the pitch but that would be uniform throughout the record. If the record is "slipping", as in the drag of the needle is pulling the record at times, then a fluctuation in pitch will occur. My guess is that your record clamp needs to be tighter or the cartridge is tracking with too much force (most likely the 1st issue).

Spindle hole being off center would contribute...I agree with above...look at record for warp as well. Speed is very important for constant pitch...but not fluctuating pitches.
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