Direct drive vs belt vs rim vs idler arm

Richardkrebs
Can you please review the video again.
From 0-24 seconds you can read the 33 quite clearly, but the 33 is moving forward and back, it is not stable.
From about 57 seconds on - he now has a constant load on the platter. 33 is unreadable, but it looks to me as though the surging has ceased.
The conclusions I see from the video are :
Unloaded, it is sort of speed stable but "hunting". Can you not see this ?
Loaded - appears to me to suggest this deck is not accurate with a load ( blurred 33 ) but ironically the long term speed variation seems to have improved with the finger load on it ( less drift ).
To be fair to the deck, the load on it probably takes the deck outside of its error correction operating parameters.

OK just for fun here's something to try on a Linn/Oracle/Clearaudio...take your pick

http://www.youtube.com/watch?v=lwugFlbCOww

I've recorded the KAB speed strobe on my Final Audio Parthenon VTT1 thread drive TT while I bash the record with my knuckle.

Anyone else want to have a go - I used a Carol Kidd record.... from Linn.

I agree with Dover. I watched Ct057's video, blew it up to full screen size, place the point of my cursor on the "33" and it is clearly lurching forward. However, I notice some lurching on my KAB disk which is a result of the disk not being perfectly flat on the LP surface. The warp, if you will, effects the movement of the "33" precisely the same once per revolution. So some of this observed lurching is from the imperfection of the KAB disk itself. But the lurching that is in sync with the finger tapping in the video seems to be the result of the platter motion and motor correction. What turntable is in the video?

Dover, That Carol Kidd LP in the Linn label is a pretty good "audiophile" recording. Don't damage it on our account.

A few years ago, I was in Tokyo and visited a well-stocked audio emporium. Here they had in one room pretty near all of the most expensive digital equipment in the world, to include Meitner, Accuphase, Esoteric, Linn, and Burmeister. The sales people left me alone to listen to any and all of this gear, using the very same Carol Kidd recording, the CD version. I sat there for a few hours and got a very good feel for the differences and similarities in SOTA digital at that time. (I was not blown away.) On the way out, I noticed that the store had for sale the LP version of the Carol Kidd recording; so I bought it. When I got back home, I was astonished to perceive how much better the LP sounded on my system compared to my memory of the CD, even when the CD had been auditioned on such high end equipment. This is not to brag on my system. This is to say that with all its faults, even with the faults under discussion on these interminable threads, analog still "rules".

Incidentally, I do believe, if memory serves, that Mark Kelly showed that belt creep can occur even with a non-elastic belt. Also, a sophisticated AC re-generator for a 3-phase AC motor does not eliminate cogging, as cogging is formally defined. Such a controller can reduce or eliminate motor vibration and noise, where motor vibration and noise are due to phase anomalies in the AC delivery. "Cogging" can be reduced by the other strategies you cited, however. At least this is how I understand the art, and I am no motor expert.

Dover,Ct0517 IMO the timeline is really only good for testing long term speed stability at least the old one was....the Kab strobodisk will and can tell you more on the short term this is what i used in the video...no other turntable that i have used or played with could correct so fast that our/my naked eye cannot see!

for all and anyone interested in what that tt was please contact me offline as i do not want to cause a rukus and or panic..

Lawrence
Fidelity Forward