2. analog
  3. 1317949815

Vintage DD turntables. Are we living dangerously?

I have just acquired a 32 year old JVC/Victor TT-101 DD turntable after having its lesser brother, the TT-81 for the last year.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
128x128halcro
richardkrebs
422 posts
 
Halcro.

The explanation from Marcus confirms my comments re the 14 speed changes in the first revolution.

Here is the relevant sentence...

"That's what the spikes are coming from: it's a superposition of eccentricity and "real" WOW and flutter."

The raw data tells us much about the nature of the platters rotation. We see the "real" WOW and flutter as distortion of the sine wave.

In other words, perfect speed would show just a sine wave symmetrically centred about the 3150hz line on the raw data graph. This then being filtered by their program to produce a straight line at 3150hz for the low pass graph.

cheers.
halcro's avatar
halcro OP
2,664 posts
 
Richardkrebs...
In other words, perfect speed would show just a sine wave symmetrically centred about the 3150hz line on the raw data graph.
Markus Ribi...
A normal measurement of WOW and flutter with a perfectly centered record will NOT show such a wave form, but a more random spiky form instead.
Richardkrebs...
Sharp spikes on the raw trace... this is a servo in action!
richardkrebs
422 posts
 
Halcro.

Perhaps you misinterpreted my last post.
When I said "perfect speed" I did not mean "perfectly centered".

A real world test record, which is off centre, produces the sine wave. Speed errors are superimposed on this sine wave, as Markus says.

So with a real world test record running at perfect speed, we would get the results I described.

cheers.

Go the ABs!
halcro's avatar
halcro OP
2,664 posts
 
Perfect Speed?
Perfect Speed?
lewm
13,294 posts
 
Just a note from the peanut gallery:
Halcro, you and Richard are actually in agreement. The statement from Feickert (or whatever was the outside source) was that record eccentricity will produce a regular irregularity in the frequency, forming a sine wave around the center frequency. Since one is interested in wow and flutter due only to tt platter speed variations, that sine wave must be filtered out or subtracted from whatever is the actual wave form. The remainder would constitute w and f due to the tt only. Ideally, that would leave a straight line, if wow and flutter due to the tt were zero. I think we can all agree on that, including you and Richard.
More to discover