Direct drive vs belt vs rim vs idler arm

Richard,

Do you have any theories other than eccentricity as to why the results with the Feickert are inconsistent?

That's my main one....although I suspect that fluctuation of mains power could affect the sensitivity of the sine-wave generation frequency?
It appears that results are better late at night.....and without air conditioning on?.....at least chez moi :-)

Regards

My posts are not in sync as moderators are really taking their time . My last posts took something like 20hrs to come up. Seems the A'gon forum is run with a degree of paranoia that is just unbelievable...... I don't how I can take part in a meaningful discussion with such a long delay. ...... so frustrating. Anyway now that I've had my rant I think Tonywinsc hit the nail on the head when he said that our turntables are holding speed an order of magnitude better than the capability of the records. As I said the pitch waver from my supposedly well centered test record was easily heard. Even my belt drive tt while not quite as good as the dd was quite good compared to error caused by disc eccentricity . Halcro & Richardkrebs wrt worse results from tests of longer duration, could it be the stylus heating up when playing for a longer period and perhaps increasing the amount of friction which in turn might be throwing the servo out ?? Just speculating, in reality I have no idea.

Good read guy's, as some here are well aware off centre record holes including test recrds are problematic especially for us that are sensitive to variations of pitch and are acutely aware of it. With a off centre spindle hole,as the stylus traverse through the grooves changes in velocity occur which of coarse with change pitch , low in the beginning of the Lp to high as the stylus traverse toward the label, then add this to a table that can't keep speed when the needle is in the groove.

You can fix the off centre hole by checking the run out and carefully open up the hole with a needle file to centre it. Then you simply mark with a pencil on the label which part of the elongated hole butts up to the spindle for next time.
Option 2 is to drill/mill the hole oversize. Then centre the record to minimise runout. You can make it easy by making up a washer with a spindle hole, and once you are happy that you have found the true centre, then push the washer over the spindle and glue it to the record. Now you have a record with a true centre.
PS As Tony has pointed out, dont assume the record is round, it isn't. You must play the record and work out how far it's out by measuring the lateral movement of the stylus.
PS2 : As this advice is free, there is no responsibility on my part if you screw up.

Dover,

Then centre the record to minimise runout.

Can you please explain what you mean by this?
Thanks.