advertisement


Slowing down a Rega P9?

J

Jazzyguy

pfm Member
Hi,

I have a P9. When I purchased it brand new it ran almost right on speed (about 0.5% fast measured with a KAB speed strobe which is great.

Now a few years later it runs at the same speed still. However, trying to upgrade to the White Belts, the table now runs about 2% SLOW.

I would assume that Rega adjusts the motors to the belts they're shipped with by moving the motor closer or farther away from the subplatter. It seems there are adjustment screws on the deck holding the motor.

Can I simply adjust the speed of the table myself by loosening the screws and adjusting the position of the motor on the deck slightly? Or will this interfere with any anti-vibration adjustments that are made in the P9's separate PSU at the the factory?
 
Did you try to listen at slower speed? Maybe it would sound little better since correctly running P9 is hardly listenable for longer time unlike all their cheaper models (admittedly not so many share this opinion but some do ;) I only attempted this little trolling because all alleged speed problems with Regas in the past (too fast) However , slowing down P9 may serve it well.....
 
limono said:
Did you try to listen at slower speed? Maybe it would sound little better since correctly running P9 is hardly listenable for longer time unlike all their cheaper models (admittedly not so many share this opinion but some do ;) I only attempted this little trolling because all alleged speed problems with Regas in the past (too fast) However , slowing down P9 may serve it well.....
Click to expand...

Please stay on topic. Can you help me or no?
 
To hear it from the horses mouth as they say post#2 would give you the best answer. Let us know how you go. It is interesting that the Rega white belt does this. I fitted one on mine with decent improvement but i have no way of accurately measuring it's current speed. Can you notice the difference? And is 2% slower but steady anything to be concerned about? I am sure Paul will see this soon and be along to assist.
 
You do have a way of measuring speed accurately! "Google" turntable strobe or go on Vinyl Engine, and download the image of a strobe disc. Print it, cut it out, make a hole in the middle and put it on your TT. Then watch it spin lit by a normal incandescent or neon bulb, which goes on and off 50 times a second. Very exact.
 
I read in a review that you can adjust the speed via the power supply and that rega set it for each individual motor when manufactured
 
Old belts - still accurate.

New belts - 2% slow.

I'd say the belts are the problem & don't even think about moving the motor position!

Try another set of White belts (you could have bought a bad batch). I'm sure Mr Darwin will be along soon at assist either way.

Cheers,

Rack.
 
Can't see how moving the motor position would help as the relative difference between the pulley and platter diameters wouldn't change. Similarly differences in belt thickness would also be irrelevent. Maybe there are differences in friction/rolling resistance between the two belts?

Rich
 
PaulMB said:
You do have a way of measuring speed accurately! "Google" turntable strobe or go on Vinyl Engine, and download the image of a strobe disc. Print it, cut it out, make a hole in the middle and put it on your TT. Then watch it spin lit by a normal incandescent or neon bulb, which goes on and off 50 times a second. Very exact.
Click to expand...

Thanks for that, i am sure i have a strobe disc somewhere.
 
rbrown said:
Can't see how moving the motor position would help as the relative difference between the pulley and platter diameters wouldn't change. Similarly differences in belt thickness would also be irrelevent. Maybe there are differences in friction/rolling resistance between the two belts?

Rich
Click to expand...

The effective diameter of the pulley varies with the thickness of the belt as the inner face of the belt compresses slightly when bent round the pulley, as well as the outer face stretching. Obviously the effect is proportionally greater on a small pulley, thus different thicknes belts give slightly different speeds.
The motor position shouldn`t make a difference unless belt tension / slip is a factor.
 
I don't see how you can measure to 0.5% & 2% with 100% accuracy using strobes at best they give you ball park guide

imo the most accurate way is to time it
 
Have Fun said:
I don't see how you can measure to 0.5% & 2% with 100% accuracy using strobes at best they give you ball park guide

imo the most accurate way is to time it
Click to expand...

Timed also to back up the strobe. The numbers match each other. The 0.5% and 2% numbers are correct. No doubts on that. Strobe was a KAB strobe includes a separate battery operated light source which I used with a precision stop watch. I also used a regular paper strobe as well. All the numbers match there as well showing a relative speed difference between white and black belt setup. White belt setup is 2.5% slower than the original black.
 
Moving the motor, stretches the belt which makes it thinner, it then runs further down the V which actually makes the deck even slower. Teh exact opposite of the same action on a flat belt/crown pulley.
 
Jazzguy,

Would I be correct in thinking that you are in Canada and that my colleague Simon Webster has been in contact with you ?

If that is correct then Simon is away on vacation at the moment but will of course be happy to continue to help address the issues raised on his return.

FWIW 2% is considerably outside the tolerances that our measuring equipment is even calibrated for, the maximum variance we have ever been able to measure with any belt/ pulley combination on a P9 would be less that 0.75% maximum and that is before we finally position the motor and trim the power supply to ensure total accuracy.

Paul Darwin
Rega Research
 
Thank you Mr. Darwin,

Yes Simon was excellent enough to quickly respond and together we are working to resolve the speed issue with the white belts. Excellent and unsurpassed customer service as usual. Out of curiosity, I just thought I'd ask Rega users if anyone has successfully adjusted the speed of a Rega table (P9 in particular). I realize Rega would probably recomend I not touch it and I would be too afraid to try anyway. If not adjustable, then the table runs excellent with the black belts still. By the way, I've been immensely enjoying this table for 5 years now and will probably continue to do so for another 20+.
 
You must log in or register to reply here.


advertisement


Back
Top