The THD in runs between 5% and 6% here and out stays right at 0.1%. Awesome machine.
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Wow! Now I know why you have multiple P20’s! I thought they were killer amp stands but they are working hard for you!
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For this house it’s 300 feet to a transformer that 3 houses share. Then it’s at least 10 miles to the closest substation.
At my shop I have a 14,400 volt 3 phase transformer in the driveway with 1000 amps of 120/208 3phase power available. Incoming THD is less than 1% and the single phase voltage is rock solid 125v. Sadly no stereo equipment is there except a Sprout / Elac combo for the back room.
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Galen,
Have you tried Shunyata power cables? Does this look like a legit test?
Yes and no. RF is filtered really well with a capacitor to ground at the equipment front end (or some in a power cord), and most power supplies do the same. The test let’s you conclude that the DC bias out of the power supply passes all that noise. We’re looking at the wrong end of the system to evaluate that property.
What we need to test, is the POWER SUPPLY DC properties. Sure, a better cable might act like your supplies noise filter but it shouldn’t. Does the DC change with power cords in any way? This is what we listen to.
To that end RF isn’t as big a problem as power with a chopped off DC component in the waveform or unstable voltage levels. A good regulator (called that for a reason) should mitigate AC line voltage variation, too.
So noise and input voltage “should” be managed by a decent power supply. What we really need to be looking at, is the DC supplied to the components modulating and thus changing the gain of the stages that are set with DC bias voltage. This is where a steady input voltage can makes a difference if we have a too low voltage. The DC can’t change, or the AC analog voltage gain does.
I use the P20 for protection, and it does allow a higher peak current output than a wall outlet. The noise reduction properties “should” be active or passive low pass filters in the supply. Some power cord filtering is certainly fine, but it can’t make or break a good power supplies task to deliver steady systems DC voltage as needed.
DC should have no “noise” or fluctuation and the test doesn’t address what the purpose of the supply SHOULD be, what’s at the END of the system? Where does the noise go, and is it a problem in the DC rail voltages?
Best,
Galen
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This is not oneupmanship, but my P20 distortion in ranges from 7.8 to 8.1% but outputs a constant .01%. I live in the suburbs, 100 feet from a transformer. So, I have no idea why so high but I am happy with the conversion. As for power cables, the P20 is very “sensitive”. You can readily hear cable differences, even within the same manufacture’s family. I have a Shunyata Sigma v1 on it and am trying an Alpha v2. I will post the results later.
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I forgot to conclude that this power cable chase could be remedied with a Galien/BJC offering.
Man, that’s some high power noise! Spitballing here, but have you tried shutting down and/or unplugging everything in the house to see if there is an impact? And if so, put major appliances and users of power back in one at a time to see if there is a primary culprit?
Great suggestion but did that. It’s also on a dedicated 20a line, 10 feet from the panel. My guess is grungy transformer that ComEd won’t replace till it bows. Time for some sabatoge.
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Ha! No kidding. Best thing that ever happened to my power back in IL was when lightning took out the transformer (which was right on the pole in my backyard). Actually TWICE in one week. They had just replaced it the day before it was taken out again.
When they came by, the only thing they had left on the truck was a 75kVA unit, which was considered to be WAY overrated for the application. Power was cleaner and more stable ever after. 
Some of the grunge maybe in your power distribution main panel. My dedicated line distortion dropped considerably as measured by P20, after installing the main lines I ent back a few days later retightened all the connections of every single breaker and wire to bus bar and bus bar to the main panel. I was amazed how loose some of them were as were the main feed cable and bus bar bolts to main panel. Loose connections cause noise. I had read about it and believe it.
Wowsers!
Really bad noise can “lift” the ground reference which modulates the potentially voltage amplitude. We can change the potential voltage value or change the ground reference point. Either can alters the voltage potential value and thus the noise modulates the input voltage if the ground point isn’t constant.
Our total voltage potential is relative to what we reference as “zero”, the ground point. Change that up or down and the potentially value changes right along with it. Get this too bad and poor supplies may have excessive DC ripple. I’d trust measuring DC ripple and potential to verify our imagination is correct.
I use a BAV 10 AWG to the P20 and BAV 10, 12 and 14 AWG power cords to all sources and amps from the P20. I can’t say I hear power cables relative to say a change in speaker cable. I know many report they do, I just don’t hear them myself in my system. I do hear IC and speaker cable changes.
Be aware the a “filter” can’t fix a clipped input voltage like what is exhibited above. It may attenuate NOISE, but not the root signal itself as that isn’t noise. You need to reconstruct it. The P20 also let’s you set a fixed output voltage.
Best,
Galen
Thank you all for your input and suggestions to lower incoming distortion. Will start with the panel and work it back. To be continued.
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What did your system sound like without a regenerator?
It was pretty good already as I had a P12 powering my sources. Swapping out BHK300’s and Spatial X5’s for my D&D 8c’s was an improvement. I never could get the 8c’s to sound “right”. Adding the P20’s ahead of the 300’s was another improvement in overall system sound quality. Adding BAV power cables to the P20’s was also an improvement. I would say that each step reduced background noise and also improved playback quality at any listening level. I listen early in the morning while my wife is still asleep and this system has amazing presence at low listening levels.
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To the interest of how close the step down transformer may be to your home, and my final hop not unlike yours is one house down the way, the issue is that the feed to the pole pig is also carrying noise from many sources. This is not a new issue, and as an FCC general class operator, I have to battle the power company regularly because of hardware issues that generate noise, especially in those areas of the RF spectrum that I transmit within. And now with BPL and Smart-Meter technologies introducing it’s own RF intended to travel over the grid, it is even more important to have technologies like regenerators to address this issue. My P-600 is utilized for this purpose in my transmitting/receiving station, but it doesn’t rectify the RF noise generated and introduced through antenna systems. Only the power company can help with that. It is to be noted, that the FCC requires the power company rectify spurious emissions, but you will have to prove to them it is happening. There are test receivers for this purpose, and if I tell them which pole (each have a unique identification on them) they generally are responsive. Good luck in your issue.
Oh, and BTW, if you want to rule out your own home, you can get any AM portable radio, set the frequency at the top of the dial where no station is, and hold it close to the breaker panel. If you hear noise, you can start flipping the breakers one by one until you either eliminate the noise, or everything gets shut off and you can rule out it is from your own home.
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Interesting…
Thank you.
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I think that’s also the way to tell if there’s an electronic bug present.
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