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PS Audio P12 Review Part 2: Power Testing

solderdude

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It would be strange if the used mains transformers would saturate (and thus hum louder) at 124V and would hum noticeably less at 118V.

Transformers, especially bigger ones all hum. Some a bit louder than others.
 

olderman

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Amir, how about testing your PS audio P300? You indicate that it probably fully regenerates A/C unlike the P12. I can attest to the physical and behavioral characteristics you described.
 
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amirm

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In my experience, if you deal with people in an honest, respectful and polite manner they react accordingly and you get results. I had another result just last week on a faulty home automation product. If I was @Lonetoe I would call PS Audio, say he was about to purchase an item, has read your reviews, is now uncertain and would they cover the return shipping if he was not satisfied?
That's a different matter than saying if you don't like it you can return it. Heavy items like this cost you fair bit to return in addition to aggravation of hauling it to the shipping company store. Companies are counting on this for you to not return it.

BTW, plenty of useless stuff out there comes with this kind of return privileges. It doesn't mean you should ignore reliable data in front of you and go and order it because of that as you said. People research products as to sharply improve their odds of liking something.
 

olderman

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Hey folks. Thanks for all the replies. Here is some more information. The amps are push pull 300B’s made by Deja Vu and they sound wonderful. I have tried many different amps over the years and these are my favorites by a large margin. There is nothing wrong with the amps and they have handled the 124+ voltage from the mains (through an Adept Response power conditioner) for several years now without any problem. There is just an audible transformer hum when you are close to the system. Listening at all but very quiet levels, the hum can’t be heard. It’s just a little annoying knowing it’s there.

There is no ground loop issue and there are no cable faults. I have no problem manually biasing the amps to their correct specs.

It would honestly be great if a good USA made variac would solve the problem — I just have my doubts. It’s a lot less expensive than the PS Audio product, and I already have an excellent power conditioner. But I am not all that excited about a $1000 experiment for something that isn’t all that critical to solve.
Do your amps have toroidal transformers? I understand that they are prone to vibrate when subjected to D/C offset, but it may apply to other types of transformers as well. My Parasound A21 started humming intermittently after 12 years, but a D/C blocker totally cured it. It was cheap, too.
 
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amirm

amirm

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Amir, how about testing your PS audio P300? You indicate that it probably fully regenerates A/C unlike the P12. I can attest to the physical and behavioral characteristics you described.
I have tested it in another review.
 

DWI

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@amirm I agree that the main point you make, which is absolutely correct, is that companies want to get their foot in the door and are counting on you not to return it. I suspect this is often the case.

Anyone who has run an Amazon Reseller business (we did) will know that returns are always low, as long as products are reliable. It's not related to shipping inconvenience, which for Amazon is straightforward. Anyway, my experience in the UK is of free door-to-door shipping and my dealers will usually bring items to me, sometimes I pick them up, without payment.

You can form an opinion something is useless, but if you don't try it you won't know. I saw today on PS Audio that some guy, a strong believer in measurements first, bought a P3 regenerator recently, with the return option, loved it and still does. He was arguing he wanted more measurements to prove it worked, obviously forgetting his incredibly glowing review a few months before.

I try and keep an open mind on everything. If we knew all there was to know about engineering we could close all the research labs. Who would bet against our knowledge of acoustic and audio engineering not increasing over the next 10 years?
 
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amirm

amirm

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mhardy6647

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Well using a variac does make for one big azz volume control. :)
Dude.
You ain't seen nothin' yet... :cool:



1648512448240.png
 

restorer-john

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Dude.
You ain't seen nothin' yet... :cool:

Who on earth does that? Let's put a giant adjustable inductor and hum magnet on a board and use it for a volume control. The contacts on the wipers are a chunk of carbon. :facepalm:
 

Pogre

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I am not all that excited about a $1000 experiment for something that isn’t all that critical to solve.
That'd about sum up my thoughts about it, lol.
 

BlackTalon

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Hey folks. Thanks for all the replies. Here is some more information. The amps are push pull 300B’s made by Deja Vu and they sound wonderful. I have tried many different amps over the years and these are my favorites by a large margin. There is nothing wrong with the amps and they have handled the 124+ voltage from the mains (through an Adept Response power conditioner) for several years now without any problem. There is just an audible transformer hum when you are close to the system. Listening at all but very quiet levels, the hum can’t be heard. It’s just a little annoying knowing it’s there.

There is no ground loop issue and there are no cable faults. I have no problem manually biasing the amps to their correct specs.

It would honestly be great if a good USA made variac would solve the problem — I just have my doubts. It’s a lot less expensive than the PS Audio product, and I already have an excellent power conditioner. But I am not all that excited about a $1000 experiment for something that isn’t all that critical to solve.
Have you contacted Vu to discuss this? He and his guys are always digging into things, so he may have some suggestions.
 

Lonetoe

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Yes I have been in touch with Vu and I may borrow a Variac from him and buy it if works. He has vintage ones of course. I will also try the DC blockers.
 

pinpoint_oxford

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I reached out to PS Audio via email to ask about the new P12 firmware and what it claims to fix and if it relates to the HC outlet. I received a response today that does indicate a fix for some number of units that had issues. I'm not sure if mine had an issue, but I updated the firmware on my unit, which was a painless process overall.
The new software was specifically released to fix a problem in the P12’s internal webpage. It also refreshes the unit’s OS. That’s typically not needed but we have found a few P12s that don’t properly bypass the HC outlets after powering up a unit. Refreshing the OS seems to fix the problem for the very few that have it. In general, we recommend always keeping the firmware of the units up to date.

The following fixes are included:
  • The previous version had an incorrect version of the Web UI that was for P15/ P20s. The correct P12 Web UI is included in this release.
  • Lowered UART buffer size to free up memory.
  • Removed check for jumper on IO board since this code only works on P12s.
  • Fixed small issue where measurements processor would give bad message on screen before regen was ready.
  • Allow waiting properly for regenerator to initialize before moving on from cold startup.
Curious as to why this wasn't just added to the firmware as release notes in the first place, but now we have some official information.
 
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amirm

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"Refreshing the OS seems to fix the problem for the very few that have it. " Seems to?

Seems to me that hardly anyone has tested this issue with HC port so the notion that they had seen a few makes no sense to me either.
 

solderdude

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I reached out to PS Audio via email to ask about the new P12 firmware and what it claims to fix and if it relates to the HC outlet. I received a response today that does indicate a fix for some number of units that had issues. I'm not sure if mine had an issue, but I updated the firmware on my unit, which was a painless process overall.

Curious as to why this wasn't just added to the firmware as release notes in the first place, but now we have some official information.

The only way to know is to redo the test with the heater. :)
 

xaviescacs

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What does "refresh the OS" mean? Restart the computer? From the OS we can refresh some running program, which normally means restarting it, to reload new config for instance. But the OS can't refresh itself in that sense. What do they mean?
 
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