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Need Some Assistance With Rega related Issue

A while back I upgraded the Rega motor on my TT. It is a standard Rega uprgade kit.

All was good for a couple of years - i.e. until recently when I tried to play 45rpm albums

The result was terrible - it never reached 45 RPM and experienced huge speed variations

I thought it might be the belt - so I ordered a couple of new ones which arrived yesterday

Although it was better after installing the new belt - it was still bad

I stripped down the TT - cleaned the Subplatter spindle, bearing, brass bearing housing and topped up with fresh oil.

No joy - still sounds bad

I had no problems with the old motor  at 45 rpm  - should have kept it - damn!

Since the speed is adjusted by the pulley - I think it rules out issues with the motor electronics? - because there is no issues at 33rpm - rock solid.

The only difference in load to the motor is an acrylic platter which is a little lighter than the glass platter it replaced.

Any suggestions would be greatly appreciated

Thanks Steve
williewonka
williewonka OP
3,075 posts
 
@mr_m - THANK YOU :-)

Your post prompted me to grap the pulley while it was turning to see if it was loose...

If you prevent the pully wheel from spinning the motor shudders.

The shuddering from the motor was about the same frequency as the weird speed variations I heard when listening to 45rpm albums

I then remembered I had added some extra "mass" to the underside of the platter in the form of a layer of sorbothane to absorb platter vibrations.

The additional torque placed on the motor by using the larger pulley was just too much for it and the motor shuddered causing some crazy "flutter".

I removed the sorbothane and voila! - real 45 RPM !

Many Thanks - Steve
mr_m
1,900 posts
 
Sounds like you found the problem pretty much on your own. But if I had helped in anyway, then you are very welcome!
Cheers, and happy listening!
Tim
noromance's avatar
noromance
9,766 posts
 
Does it sound better at 33 without the Sorbothane?

williewonka OP
3,075 posts
 
@noromance - I can honestly say I think it sounds the same at 33 rpm.

The SRM Tec Deluxe Acrylic Platter for Rega comes with a large "rubberized band" that fits the outside edge of the platter to subdue unwanted micro vibrations in the platter

The original glass platter did weigh more than the acrtlic platter, so I added the sorbothane to the understide of the platter to give it some added "heft" -

Since I did not really play 45 RPM that much back then I didn’t test 45 rpm at that time of applying the sorbothane

Fast forward to today and i now have more 45 rpm albums, That’s when I discovered the issue - I thought it was the belt, but that was not the case.

Thinking back - I had the Mission sorbothane mat on the glass platter and it played without incident. But that was also with the original motor.

Perhaps there is something different about the Rega motor upgrade kit I installed?
- different control circuit - could that effect torque?
- Different motor - could it have less torque?
- who knows

The issue has been resolved to my satisfacton and it is sounding very nice at 33 and 45 rpm,

But it had me wondering there for a while :-).

Regards - Steve
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