How much does rock-solid speed stability cost?

This is an interesting thread. I also have very strong relative pitch.

One problem I have had a lot of trouble with--and it was mentioned above by Ghostrider45--is off-center holes. It doesn't take much. This effect is most noticable when constant pitch instruments like the piano are playing.

The degree of pitch change increases (grows worse) as the needle approaches the center of the record since the fractional linear speed change causing this increases as the distance to the axis of rotation becomes smaller. So what can be a disconcerting suspicion at the begining of an LP grows into cause for leaping up in alarm to inspect for what the heck is going wrong.

I need to discard a few percent of the records I purchase due to off-center holes...some of them otherwise pristine Shaded Dogs (sob sob).

I have toyed with the notion of actually offsetting the axis of some of my rare LPs by enlarging the hole on one side to compensate. Haven't tried it yet, though.

A slightly bent spindle would also result in this type of periodic change in pitch.

To see if this non-axial rotation is a problem, put a piece of opaque tape on the lid of your TT as a visual reference. Then watch very closely to see if the arm and cartidge are moving slightly in and out as the record plays. It really doesn't take much (depending on how sensitive your are) and it can be hard to see without a fixed visual reference.

I am not that experienced in TT's but find SME's, Basis, and ClearAudio to be very acceptable as regards speed control. Unfortunately, they are also very expensive.

Thanks, everyone, for your thoughtful replies.

Twl, as usual, you are a fountain of useful information. Your explanation of cogging makes sense. I'll do some reasearch into DC motor-based tables. I'll also look into tables with heavy platters.

For those of you that commented on off-center holes, I see that occasionally, but not often enough to explain what I hear.

Violaguy, I am a former musician (trombone), though I haven't played in many years. I played in high school and college. I don't know if I have perfect absolute pitch or not but I'd say I have very good relative pitch, at least. I'm sure I could distinguish between A440 and 441. Thats about 1/8" on a trombone slide. A good trombone player is a lot more accurate than that - I'd say accurate to at least 1/32". I know what you mean about variations in dynamics and overtones. I love hearing the overtone beats of a piano chord, for example. That type of variation doesn't bother me at all. However, that's not what I'm hearing. I'm hearing real changes in pitch. I have heard variations in CDs but always assumed it was due to the master tape. Most CDs are fine. I've found the more overtones an instrument, or voice, produces the less likely it is to cause noticable flutter. It's the pure tones that get you.

From what you all are saying I think it's going to cost quite a bit to achieve the pitch stability I need. I'll keep my eye on the classifieds. (The SL1200 is going back to Crutchfield!)

The 1200 has close to perfect pitch stability--that's why is preferred by a lot of musicians that use "inferior stereo systems". I really like how it flawlessly keeps the beat of complex rhythm patterns of *salsa* music. Most belt drives don't cut it in this department. Something's not right here...

You could be mistaking eccentricity for pitch, as someone else pointed out. Nakamichi used to make a TT that adjusted the record's spindle so that it would play concentric. Perhaps it should be on your short list. Get back to us and send us some pictures!

Psychicanimal, I'm not trying to be contentious but rythmic patterns don't show up the kind of pitch variation I'm talking about. Sustained pure notes do. I listen to mostly jazz and classical which show this effect quite often. I've had the SL1200 for about a week and have played around 50 records on it. Most don't have any eccentricity at all. I vaguely remember the NAK deck. Early '80s, I believe.

Psychicanimal, I thought you might be interested in a recent development. I've been using a Shure V15VMR with the SL1200. I had been using the VTF set at 1.5g, as recommended, when using the dynamic stabilizer and a target VTF of 1g is desired. With this setup I could hear pitch variations on pretty much every record.

Next, I tried disabling the stabilizer and setting the VTF to 1g. Whoa! Much better. Tracking is not so good on warped records, though. This got me to thinking, maybe the stabilizer in subtracting more than .5g. I re-enabled the stabilizer and set the VTF to 1.7g which should give a net VTF of 1.2g, which is near the top of the recommended range for the V15. I suspect the actual VTF is less, but I don't know of a way to verify this. Anyway, the pitch variation is almost completely gone! I still hear it on records with off-center holes, but a good record sounds fine. I've changed my mind on the SL1200. I think I'll keep it:)

Anybody know why this is so? I know the V15 is high compliance. Could the suspension, in a lightly loaded state, been resonating to cause a sound like flutter?