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Adjusting the speed on a Rega P9 if it changes due to the new belt

Hi Myles, my only advice would be to actually buy the belt, fit it, let it run...then see for yourself it runs at perfect speed or not and don't listen / read stuff written by largely anonymous keyboard warriors (which I have searched for and not found) and perhaps avoid posting on other forums before you have actually established the facts for yourself. We have spent years and years researching and developing new materials, new production processes, new finishing processes, consistency testing, reliability testing, longevity testing and would never bring a product to market unless it offered a significant improvement on what has gone before and at a sensible price (in this case a couple of quid more). To imply or suggest otherwise is merely scurrilous.
 
The drama of it......
Why don't you just contact Rega via email or phone?
Why the full colour reveal on here?
 
Why dont you just contact Rega via email or phone?
Why the dramatic reveal on here?
It’s gone.

I contacted Analogue Seduction by email and got nothing helpful. This idea of the slower speed is already on the internet. I was just searching for how to adjust the speed. The full colour reveal was to say I don’t intend anything scurrilous. No malicious intent. Far from it. I’m a big fan of Rega.

I apologize to everyone reading this thread. My hope at this point is that the admin will close or even delete the thread. And if not, I’ll stay out of it unless directly addressed.
 
I
I contacted Analogue Seduction by email and got nothing helpful. This idea of the slower speed is already on the internet. I was just searching for how to adjust the speed. The full colour reveal was to say I don’t intend anything scurrilous. No malicious intent. Far from it. I’m a big fan of Rega.
I didn't see any harm in this thread. And Paul Darwin from Rega responded to the thread this morning so that seems like good info to have in case anyone else pokes around for an answer.
 
Unless the belt slips, I don’t see how it can affect the speed, unless I’m missing something. I suspect any posts suggesting something like the OP relates, are likely mischief making and best avoided, certainly not passed along.
 
Unless the belt slips, I don’t see how it can affect the speed, unless I’m missing something. I suspect any posts suggesting something like the OP relates, are likely mischief making and best avoided, certainly not passed along.
I don't see how it would happen either, unless the belt was tight enough to slow the motor somehow. But now we have a thread with an answer from a reputable source. That's better than threads the OP mentioned, populated with armchair engineers and speculation. :)
 
Unless the belt slips, I don’t see how it can affect the speed..

I'm sure that a belt of differing consistency could effect the speed. Bending the belt takes energy so a softer belt might make the deck run faster for instance. Take it to extremes, you could fit belt so stiff the motor would not be strong enough to turn the platter at all.
 
Hi Myles, my only advice would be to actually buy the belt, fit it, let it run...then see for yourself it runs at perfect speed or not and don't listen / read stuff written by largely anonymous keyboard warriors (which I have searched for and not found) and perhaps avoid posting on other forums before you have actually established the facts for yourself. We have spent years and years researching and developing new materials, new production processes, new finishing processes, consistency testing, reliability testing, longevity testing and would never bring a product to market unless it offered a significant improvement on what has gone before and at a sensible price (in this case a couple of quid more). To imply or suggest otherwise is merely scurrilous.
That's what I said -
I'd ask on Hoffman - that's where I read about it. However, I'd let the belt bed in first, or even just buy an Edwards Little Blue Belter which doesn't give you that feeling of wading through treacle!
 
The speed control reference of the P9 power supply is based upon two quartz crystal oscillators, 3MHz for 33.33RPM operation, and 4MHz for 45RPM. There are adjustment potentiometers fitted, however, these are for precisely setting the two independent phases that are provided by two high current, low distortion (<0.03% THD) FET amps, as well as voltage gain pots for adjusting the output of same. These adjustments are specifically intended for tuning the motor such that noise is virtually eliminated.

IOWs, the P9 motor will run near silent at a perfect 250RPM for 33.33 records, or circa 337.5RPM for 45s, respectively.

As to final speed adjustment, P9 has its motor bolted to the plinth top in such as way as to allow fore/aft adjustment, the position of which will not only control belt tension, but also belt running 'depth' within the drive pulley 'V'-groove; i.e. a round belt running within a 'V'-groove allows for the effective pulley circumference to be somewhat variable via given combinations of belt cross section, belt tension and modulus of elasticity.

Regardless, should adjustment be necessary, such is best left to a qualified Rega technician (or perhaps a dealer tech who has received explicit instructions from Rega Service).

Rega P9 motor mount, note the LH bolt passes through a slot:
3170980-b2a3d44f-rega-p9-flagship-plinthmotormatched-power-supply-ttpsu-combo-2000-upgrade.jpg
 
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There are two pots at the aft right corner of the PWB inside the P9 supply box - same case as the old A1 amp. However, the range of adjustment is extremely small.

Depth in the pulley V-groove will have a more appreciable effect as described in a post above.

However, absolute speed is less important than speed stability. For example, one can usually hear 0.5% constant speed error on a well known piece of music - musicians will hold an edge here. But it is subtle - you hear a slight pace discrepancy, not tone difference.

However, 0.5% wow will sound horrible and painfully obvious.

A small constant speed error - very few tens of a percent - is essentially irrelevant. Speed stability, on the other hand, is super-important.
 


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