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PS Audio P12 Review Part 2: Power Testing

Kijanki

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Moving some theoretical numbers around as per the P12 regen unit and if using a unregulated linear supply.

NOTE: Using RMS wattage figures so they match what amp manufacturers quote for power specs:

Example #1 is a 50WRMS/ch amp @ +/- 28.3V rails @ 3.5A peak and using a theoretical 120VAC mains.
Lets say the AC droops to 110V @ a roughly ~9% decrease.
A decrease of ~9% on the rails makes for +/- ~25.75V rail voltages @ 3.2A peak = ~41.4WRMS.

Example #2 is a 100WRMS/ch amp @ +/- 40V rails @ 5A peak and using a theoretical 120VAC mains.
Lets say the AC droops to 110V @ a roughly ~9% decrease.
A decrease of ~9% on the rails makes for +/- ~36.4V rail voltages @ 4.5A peak = ~82.8WRMS.

Example #3 is a 200WRMS/ch amp @ +/- 56.6V rails @ 7.1A peak and using a theoretical 120VAC mains.
Lets say the AC droops to 110V @ a roughly ~9% decrease.
A decrease of ~9% on the rails makes for +/- ~51.5V rail voltages @ 6.4A peak = ~165.8WRMS. (Note rounding error.)

If using the P12 regen unit to maintain a steady theoretical 120VAC mains then I suppose at the power limits of the amp(s) there might be a noticeable sound difference but it's doubtful.

NOTE: @amirm found the P12 to decrease the power output when using the HC output @ ~7% less AC mains voltage.
WRMS is erroneous term. The product of Vrms x Irms is Pavg (average power - a sum of momentary powers). This average power is equal to half of peak power for sinewave. I guess one can make rms of any curve, including power curve, but it would be 0.612Ppeak for sinewave and it won't represent anything useful. It took FTC 25 years to understand it. Many people add "RMS" to signify real power (vs apparent power), but it is already included in "W" (vs. VA).
 
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pinpoint_oxford

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seems to me like you are just denying facts, because its more comforting than admitting to yourself that you made a huge mistake. pretty common.
Not denying facts. I never trust flowery language or ad-copy from a manufacturer website. I also don't believe that most components do anything meaningful, if at all, to affect the sound of a system by that much. You can look at my post history, I believe I've been quite rational in my approach to the P12 and other products. A salesperson did convince me to spend buy audioquest RCA cables before. I did, and realized I didn't notice a difference at all. I'm happy to admit that to myself.

The P12 solves an actual issue I've had with intermittent noise issues and has many other features (like it's smarts and outlet controls) that I like having.
 

MaxBuck

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Not denying facts. I never trust flowery language or ad-copy from a manufacturer website. I also don't believe that most components do anything meaningful, if at all, to affect the sound of a system by that much. You can look at my post history, I believe I've been quite rational in my approach to the P12 and other products. A salesperson did convince me to spend buy audioquest RCA cables before. I did, and realized I didn't notice a difference at all. I'm happy to admit that to myself.

The P12 solves an actual issue I've had with intermittent noise issues and has many other features (like it's smarts and outlet controls) that I like having.
Fair enough. If my system approached 6 figure capital cost, I might regard this expenditure as relatively reasonable. But it doesn't, so for me I don't.
 

JSmith

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I think we should keep in mind @pinpoint_oxford was kind enough to ship this to Amir for testing (thanks for doing so), regardless of whether he wished to keep the product or not, as otherwise this thread and testing wouldn't exist. If he is happy with the product for other reasons apart from the test results, then that is up to him.


JSmith
 

Justin Ayers

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No because *every* review of these devices raves about how much it makes the system sound better. Not one remotely puts down the device. So for a class of audiophiles, it is now a "given" that AC power needs cleaning, filtering, beefing up, etc. Naturally they are in shock that our data says that is not happening. It invalidates so much "everybody knows" folklore that they just can't accept it.

The other thing that makes this heated is the huge cost of the P12 and the fact that it wastes power so it is not like a fancy cable that doesn't do any harm.
My emphasis added.

This testing is a huge service to ordinary (a nice way of saying shallow pockets) shoppers who care about audio quality.

I read the whole thread and this bolded bit is the crux of it all. The testing demonstrates that an 'essential' part of one's audio system does not have to be purchased. That is a big money saver.

Some of us are the type who want to know how to maximize the ROI (return on investment, or cost-benefit ratio), not in terms of resale value (especially if it involves selling snake oil, which some of us won't do).

What is more important, though, than specific preferences of individuals when it comes to buying strategies is what these products mean for the planet. National Geographic just put out an article about the horse conch's pending extinction. It is the state seashell for Florida, so Floridians at least pretend to care about it. The manatee is in grave jeopardy. The state tree is drastically declining. The Florida panther is also on the verge. So, while Florida's politicians and the people who support them with their energy and interest are busy solving problems that don't exist by making things far worse (I won't specify, as it's too off-topic), the symbols of the state are in the process of being lost forever.

Even the National Geographic writer misses the point some, by writing that the horse conch is 'revered' by Floridians. It isn't. If it were revered its protection would have been taken much more seriously and it wouldn't be on the verge of extinction. People feign concern but most are not willing to do the legwork. That's what makes testing like this so special. It's legwork.

Products like this contribute to that. That is not hyperbole. Every unnecessary product carries an ecological cost.

I'll also add that the WHO report just came out that says 99% of people in the world breathe polluted air and that inhaled air pollution is the largest factor in poor health for human beings currently.

Finally, the last important point is that money is an abstraction for the commons, the resources we all share. Every dollar that you spend on a product like this that goes beyond what the product actually provides (as a real service, not nonsense like the placebo effect) is a dollar you should have used for something better. Give it to a sound charity if you won't miss it. Amir has made this point, I think. I believe he wrote that he'd rather buy two good products and give one to someone as a gift than buy one inferior one for the same money. He's right.

Every dollar in your pocket is a dollar you're borrowing from humanity and the ecosystem. It's not really yours and you can't take any of it with you. What you can do, though, is destroy species forever and cause grave harm to the people living and those who will be born, via irresponsibility. Money is not just an abstraction of your life; it's on loan from others', and that includes the creatures and other organisms we share this planet with.

"What also makes this product worth reading about is that the man who created it admits to being directed more by sound than by measurements—within the boundaries of competent electronic engineering, of course. That takes him to some unusual, thought-provoking places where the measurements-oriented people often don't go . . ."

:facepalm:
 

Justin Ayers

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Has anyone done a checksum or anything else to compare the firmware 'update' with the older one to see if the file is the same or actually different? It's a clever trick to release a firmware 'update' as a shield against a lawsuit ('Oh, well... it didn't really do anything for those tests because of a flaw we found and fixed with the firmware update!' — fictitious quote) but sometimes clever tricks are deployed in a not-so-clever manner.

Not including the intentionally-vacuous statements typical of large corporate software updates about 'improvements to quality and stability' is sloppy already, as it implies that nothing was changed — that the release is just a smokescreen/shield. Given that sloppiness, it's not impossible to imagine that the file is identical. Just changing the version number, though, would be enough to change the checksum if it's stored within the firmware file and not some accompanying file (should the firmware update be in multiple files). This goes to my very strong belief that all software should be open source. That doesn't mean it can't be protected by copyright. Closed-source software (and hardware such as microprocessors) boils down to blind faith being the basis of the purchase and use.
 

Geert

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Has anyone done a checksum or anything else to compare the firmware 'update' with the older one to see if the file is the same or actually different?
Don't know if this answers your question:
I think the firmware update did change something with the HC outlet. I turned on my system to listen to some music and noticed two relay clicks now when turning on the HC outlet. One click when the outlet comes on and a second click a few seconds later.
 

voodooless

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Besides, just changing the version number alone would change the checksum. You’d have to do a binary analysis to see how much of the firmware really changed. But even a compiler upgrade or compile flags change might make that exercise very much futile.
 

Shazb0t

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They admitted on their forums the firmware update addresses the relay issue with their HC outlets. In not so may words, but it's there. This a good thing.
 

solderdude

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Needs to be verified (@pinpoint_oxford could do this).
The inrush protection would not work several seconds after the device would be switched on and the load(s) would be switched on later. It would defeat the purpose of having the inrush current limiter.
 

tonycollinet

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Needs to be verified (@pinpoint_oxford could do this).
The inrush protection would not work several seconds after the device would be switched on and the load(s) would be switched on later. It would defeat the purpose of having the inrush current limiter.
Isn’t the inrush limitation about the charging the capacitance into the p12
 

solderdude

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Isn’t the inrush limitation about the charging the capacitance into the p12

Nope it doesn't seem to have one at the input. If it had Amir could have been able to feed the PPP with his power source.
The inrush limiter (an NTC) is in series with the HC-group outlets.
These 2 outlets are in parallel (AFAIK) and have just 1 NTC shared.
This offers the same issue as when the NTC would be bypassed.

When 2 mono blocks are connected to the HC outlet group and one amp is switched on already (or both) the NTC is high resistance for a short moment. Heats up and becomes low resistance.

When one mono block would be switched off and switched on later on the inrush limiter is already low resistance and no longer limits inrush current.
 

Geert

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Screenshot_20220409_171905.jpg
 

pinpoint_oxford

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So I had some time to play around with my space heater and the P12 with new firmware. I believe the circuit is working as intended now, but requires a specific mode of operation; mainly the inrush only works when the outlet is switched on/off via the P12. For me, this is not a problem as my amplifier is the only thing in the HC outlet and I have configured my harmony remote to turn it on/off when listening to music. Anyway.

With the P12 HC outlet off, I plugged in the multimeter and space heater and set the heater to its low (750W) setting. Turning on the HC outlet, once the unit clicks on, I read ~113V from the multimeter and then I hear the second click and get consistent 120V. Seems like the limiter is turning off after a few seconds. From using the P12 to listen to music, I don't hear it click anymore after the outlet is switched on, so I think this is a one-shot thing when the outlet is switched on. So if you keep your amp "On" and use the P12 to turn them on/off, I think you will get the desired functionality of the inrush limit. If you left the P12 outlet on all the time and switched your amps on/off you will not.

I recorded a short video of the testing, since I think that illustrates how it works better.

 

solderdude

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Thanks for checking !

So, after Amir noticed this (the HC group output R) and you checked that this was indeed the case PS Audio found out and corrected this thing.
Had this been working from the get-go the 'loss in power' in the measurements (other than the difference in mains voltage vs rectified) it would never have been noticed.

What's good to see is that obviously the needed hardware (the relay and its drive) was already present.

This raises 2 questions. Was this feature not present because of an omission in programming or left out to ensure the soft start also works when the connected loads are not always switched on.
We can only guess, the product exists for quite some time and if Amir would not have caught this would have gone unnoticed.

In all fairness, no-one ever complained because it is moot and only may reduce 'max' output power with some amps by a measurable but not really audible amount.

I think Paul owes Amir an apology for noticing a bug in the firmware.


Indeed as you say the 'inrush current' limiter ONLY works when the devices connected to the HC outlets are always on and only are switched on and off by the power button of the PPP or the outlet group.
 
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