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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: The grounds on loading side might be the key.Posted by Romy the Cat on: 11/30/2015
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 JOHNR wrote:
The common mode noise will lie between 5 meg and 8meg or 8 meg to 12 meg depending upon whether it is forward or backward mode working.  
It does not have much to do with the 30Kilohertz.

The normal common mode noise is megahertz level noise and it of cause will go through any switching filtration like hot knife through butter. Since I observe the ELEVATED common mode noise 9if we presume that it is common mode noise) then it would make scene to recognize PP3000 as course of the common mode noise. It is need to be pointed out that there is hardly anything in PP3000 fasters then PP3000. That was all that I was saying.
 JOHNR wrote:
If you are concerned that placing a 1uF cap across the mains spoils the sound then that surprises me because the cap by itself will alter the lagging power factor in a system by a miniscule amount.  You should be able to add 100uF to bring the phase angle up to 95% lagging  without altering the sound. It looks to me as if your power factor is being corrected to a leading PF somewhere else in your system.

I played a LOT of filtration on AC side and although I was able to get much auditable noise does it has very little impact to what I was hearing and it ALWAYS get worse sound (particularly in very lower bass) in case I get any capacitance on AC side. Regarding the power factor. I am sure that PP have power factor correction circuit at input.
 JOHNR wrote:
The least you should do at this stage is to try the "Y" network of 2 caps.  These will sum the opposing voltages thus will self cancel.  If this reduces the problem then the nature of the interference is essentially proven.    The cap value is not in the audio passband therefore should not affect the audio.
Do you means the "Y" network of 2 caps to the ground? I would not run it in real time but I think as proof of consent it will work wonderfully.
 JOHNR wrote:
A second suggestion is to fit a clamp on ferrite to the power cable on each unit.  If no difference, then RFI is not your problem.
I have it for years.
 JOHNR wrote:
Question: are you by chance connecting each PP3000 to a single external ground rod?
The loads are isolated from source ground and use own grounds. I did try to kill grounds on loading side and make the system to float and it had no impact.

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