I have got some problems with my Powerbase.
It is giving off intermittent ‘trafo’ noise that worries me.
The interval between the humming is about 5secs and the humming last for 3secs.
It continues like this on a permanent basis.
In a quiet room it is quite noticable and prominent.
If I switch on the main load (P10 with or without load) the humming remains the same.
Everything works like it should, so it is only the noise that is bugging me.
If I switch off the power inlet to the PB the noise immediatly goes away (as expected) and when plugged in again it reappear.
Odd. Perhaps it is a loose component, such as an induction coil.
I did some more testing to isolate the problem and what I wrote in my first post is not entirely true.
As it turns out my subwoofers are connected to the secondary output of the PB.
I bypassed my subs from the hi-load output of the P10 on purpose and went direct from the PB instead.
Whether my subs are in standby or not changes nothing, but when I pull the power lead from the PB secondary output, the PB goes quiet.
The noise is less prominent when only one sub is connected.
Well, my conclusions seemed to be a little premature.
It turns out that it is my sub PEQ amplifier that generates the said noise and not the PB after all.
It is damned difficult to accurately locate the noise at this frequency (50 Hz).
I have contacted Brian Ding at Rythmik on the matter.
Very, very difficult.
I will leave it over night and see.
Maybe it is a temporary and local problem on the power line.
I noticed that a thunderstorm just passed.
Thanks Frode, I was really struggling trying to figure out how the inductor could hum like that. Sorry to hear about your sub.
Does the hum go away if you plug the SW into the P10 directly?
Does the hum go away if you plug the SW into the P10 directly?
'No', and here is the reason;
The sub manufacturer thinks it is superimposed DC, but during the middle of the night there are actuallly less dimmers on than what's normal.
However, when I woke up this morning the noise was gone! :)
My suspicion is a shipyard close by. They are feeding power to offshore vessels and I think this may create some problems.
Having said this, I have never observed this before.
I forgot to look at the oscilloscope on the P10 while the noise occurred.
Am I wrong in thinking that one would not actually hear DC on the line. Perhaps it is AC noise from the shipyard due to a poor power factor related to their facility.
Am I wrong in thinking that one would not actually hear DC on the line. Perhaps it is AC noise from the shipyard due to a poor power factor related to their facility.
Transformer humming could be caused by DC.
Oh yes. I was thinking of the speaker. So, is the cone moving?
Oh yes. I was thinking of the speaker. So, is the cone moving?
No, because the humming was present still with the sub amp in standby.
Gotcha. I understand. I hope that it gets better.
It is fine now.
Thanks, wglenn 
Frode
Great news
The p5 I have has a small intermittent buzz , it sounds like it is the toroidal transformer . It does not do it all the time either. But the two P10, s are silent go figure.
I wish the P10 would show DC offset on display and to be able to remove the DC on it’s output…
??? Please explain ?
I have the Vibex Two-6R DC blocking filter standing idle:
http://www.6moons.com/audioreviews/vibex/1.html
It would be interesting if the magnitude of the superimposed DC component could be found - and removed accordingly.