Powerline noise / P10


#1

I bought a P10 about a month ago, and am very, very happy and amazed by how it improves my system. There is one interaction with my system that I am asking about not as a complaint, but more out of curiosity. I have a computer front end (a homebuilt Zuma, for those familiar with Chris Connaker’s design on Computer Audiophile). it is a wonderful music source, but has one major drawback — it spits back electronic noise big-time (RFI or EMI, I don’t know) back into my home’s wiring and is picked up by the amp. I can actually here the buzz it creates being modulated as I scroll on the computer’s screen!

Fortunately, long before the P10 came on the scene, that issue was solved. I have an outboard battery Black Lightning power supply by Red Wine Audio. When the switch for the supply is in “charge” mode, my system is still drawing power from the battery but still susceptible to the AC grunge as it charges the battery – I can hear it. But when I flick the charger off, the AC is physically disconnected from my system, which is then on pure battery, and it is dead quiet.

Now, finally, here is my question. My entire system, except the computer, is plugged into the P10. The P10 is plugged into a dedicated 20 amp line. Unless the Red Wine power supply is in pure battery mode, the AC noise is still getting thru to my amp. I don’t understand how this can happen, given that the AC signal, grunge and all, is being broken down and regenerated. ??? Thanks in advance. – David


#2

As you’ve discovered if there is a electrical connection between items noise finds a way along it. A power regenerator at best acts like a filter that only lets thru 60Hz (or 50Hz) and suppresses everything else (tho that’s not how most are built). The problem is that any normal feedback technology loses effectiveness as the frequency goes up. So it’s hard to make a power regeneration system (or any kind of power supply) that blocks all high frequency noise. Some power supplies advertise “never connected” but unless they use mechanical relays and batteries they are still connected and high frequency hash get’s thru.

Then there’s the whole ground loop issue…

The folks at PS Audio obviously have more practical experience with regeneration than I do and can correct me.


#3

Thanks Ted! I’ll be interested to hear the other answers as well. – David


#4

Welcome, davidz1!

An incredibly frustrating problem. I do not know what else to try, given you already have the compute plugged into a separate circuit. This strikes me as the best option.


#5

Elk, thanks. The moral as I see it is that computers are incredible power line polluters (hey that rhymes). I wouldn’t think of using one without battery isolation. – David


#6

A good rhyme it is.

Computers can be messy, although not every system picks this up. I don’t know why.

In your case, it can’t be because of airborne RFI as the battery power supply eliminates the problem.

I assume you have posted at Computer Audiophile - anyone there have suggestions or an explanation.


#7

Actually, Elk, I haven’t posted on CA, given that the outboard battery supply fixes the issue – I only do “sit down” listening on pure battery. Once I got the P10 and noticed the noise coming thru (while the battery is in charge mode), it posed the theoretical question of why that should still be the case. Thanks for your interest.


#8

Perfectly reasonable. :)


#9

As Ted correctly pointed out much can come through on the ground, which is common to everything and not regenerated or changed in any way. Also, and I am guessing here, there may be some airborne noise coming in if the charger has any type of switching arrangement. The P10 will provide consistent, low output impedance, regulated power without distortion products. It won’t, however, help with airborne or ground delivered buzzing. As you have noticed.


#10

Thanks, Paul. As noted above, I’m pleased this is just a theoretical issue. The P10 continues to amaze, big time, the more I listen. Speaking of big, it certainly is that! I got a new hip last August and am currently limited to nothing heavier than 40 lbs. I had to call in some favors with a buddy to do the heavy lifting. – David


#11

The computer is dumping it’s noise through the ground (most likely) why not just put a cheater plug on it to lift the ground?


#12

This may help.

But return and ground are tied together at the junction box, and the connecting cables will probably carry the noise in any event. For example, the shield of the coaxial cable used for S/PDIF connects the ground plane of the PC with the ground plane of the DAC.


#13

Erik - thanks for the suggestion. But since the battery isolation fixed things, I haven’t bothered trying anything else. -David