After getting my new tube power amps, my P10 starts humming when they are powered.
At first, I thought it was 50Hz hum originating from the tube amp transformer, but then I discovered it was actually coming from the P10 itself. It is a mechanical buzz probably in the 50Hz region, but it sounds even, so I don’t think it is caused by superimposed DC on my main incomer. The noise also propagates to my speakers. I also experienced a P10 trip in one instance.
Any ideas or suggestions?
It might be a noisy bypass/regen out relay on the regenerator board, but that wouldn’t account for the noise propagating to the speakers. I suspect you might have 2 separate issues going on. You’re going to have to reach out to PS Audio CS on this one.
I possibly have a similar experience with my P10 powering the BHKS300 monos, and PS audio front end. I hear a continuous low amplitude buzz from the P10 when everything is powered up. Perhaps I should also contact CS.
Thanks.
I put up with a noisy P3 for a long time. Then I got it repaired. Silence. I should have had it fixed when the problem was first evident. If it’s making such a noise to interfere with your listening ambience, get it fixed.
Thx. I have a hard time believing that my P10 worked with my old tube amps on the same outlets, but some moments later when I plugged in my new amps the P10 suddenly became defective?
Seems rather strange to me.
What I can say is that there has always been some low level buzzing, however the intensity escalates when connecting the new amps. I have a recording of the sound as wav.
It sounds like something with your amps is causing the P10 to go under a lot of strain. How big are they? Have you looked at the phase adjustment? The only reason the P120 buzzes like that when powering something is if it is really grunting hard.
Thx. Paul - appreciated 
I will check the P10 phase adjustment and revert with my results next week.
The tube amps are 120W pure class A, but their load is light.
New tube amps
Buzz recorded with iPad 2ft from P10:
Hum
These amps draw 400W each. Two of these is already a significant load, especially as power factor may come into play.
What else is plugged into the P10? What was the load of the previous amps?
The load of my previous amps was only 180W each - a considerable difference!
I think you nailed it, Elk.
I believe the load is just too high for the P10 to handle, along with the other consumers.
Since it is class A they also pull 800W when idle.
I guess Paul has the answer - buy a P20! 
Do play with the phase however. This can make a remarkable difference under the right circumstances.
I guess this graph says it all.
My P10 tripped at the highest load.
There were 3 power amps connected at this time and some auxillary gear, however my subs are not driven by the P10.
A similar session with my old amps. As one can see, a significantly lower Wattage drawn from the P10.
Tried the following this evening:
Toggled between Low Distortion and High Regulation - No difference in buzzing/humming.
Tried phase setting from -10 to +10 - Buzzing/humming intensify at +10. Status quo for all other settings (i.e. constitutes no change in audible level). I have not measured with a dB meter or looked at the THD because the audible level is all what matters, really.
So the outcome was what I expected, overall.
Can you identify the source of the noise inside the P10? To do that you’ll obviously need the lid off whilst it’s in operation. That’s easy enough to do with a P3, but I never had reason to open up a P10 so don’t know the practicality of that suggestion.
The origin and localization at this frequency is very hard to pinpoint by listening, but is this really necessary?
As long as the P10 is at it’s output limit at 1200W and my graph shows that it did indeed reach that level, then I think we can draw the conclusion that the P10 is working as intended and that the only remedy is to increase the capacity or remove loads accordingly. By looking at the ‘evidence material’ is there still any reason for continuing the troubleshooting…(?)
The results from the phase adjustment also back up this the way I see it.
One last test I did in order to confirm this was to turn off one of the tube amps, reducing the load with almost 400W and the noise dropped significantly.
Seems like you’ve figured it out.
Well, I was pretty confident, but today I had an Eureka moment.
While disconnecting my amps from the P10 I discovered that my incomer was going to the Powerbase (support for the P10) and further passed on to the P10. The Powerbase is rated 7.5 Amps.
Just for the fun of it I plugged the incomer directly to my P10, bypassing the Powerbase entirely and VOILA! Dead silence with my tube amps powered!
It still remains to see if this will fix everything during playback, but noise seems to be gone, nevertheless.
I believe the P10 can power the Powerbase so I might try this (but only if necessary).
Wow! Good find, Frode. I had no idea. Yes, the P10 can easily feed the PowerBase
One might draw the conclusion that the noise is coming from the Powerbase, but another possibility is that the excessive load on the Powerbase put some strain on the P10 that again generates the noise. It is very hard to tell just by listening.
Post note:
I am now solo-driving my speakers from the tube amp (bi-amping abandoned).
There are still some mechanical noise transferred on to the speaker ribbons, but it is extremely minor compared with before.
