@DualTriode Does that mean that the P12, which doesn't seem to do anything in terms of improving audio quality, and which is measuring a huge 3 ohm output impedance (300 times the impedance of its manufacturer's spec sheet) might be used without adverse effects say with an amp that uses a switching power supply ?
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PS Audio P12 Review Part 2: Power Testing
- Thread starter amirm
- Start date
All of these great efforts to expose the BS in PS Audio products is useless unless we could make something good, such as to bring many BS Audio users to file a class action suit against PS Audio for false advertising. If we can make an example out of PS Audio, which could make other snake oil companies to reconsider their business practices...
@EB1000 I'm not a lawyer but I would think that's going to be a very difficult thing to do. Don't jump the gun, though. I mean they still sell Carter's Little Pills (they used to be called Carter's Little Liver Pills....) and there are zillions of ads on TV that sell snake oil or at least have some effect but that are not FDA approved !!!! Go to a health food store and you'll see crap like Pennyroyal Oil sold to induce abortions and other things...it's not even FDA regulated like a drug (they consider it a food or a spice) and PennyRoyal Oil is EXTREMELY POISONOUS.....I've seen at least one 18 year old girl die from taking it in order to abort a child (it turned out she wasn't even pregnant in the first place); I tried unsuccessfully at that time to get it off the shelf in the USA...a little too much and it can kill a human by causing massive hepatic necrosis....
DualTriode
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Be mindful, do not get tangled in a web of power cords or trip over the P12 on the floor.
There are Jfet and other devices that are particularly sensitive to power supply quality.
We do not want to limit our toys to operational amplifiers with copious feedback and PSRR.
Thanks DT
There's this in the review, note the bold:
As you see, impedance has jumped to 3 ohm or more than 10 times higher! I should note that I don't know how accurate this measurement is but given the wide differential, we can likely rely on the fact that PS Audio P12 *system* does have higher impedance. I wrote "system" there because P12 introduces yet another AC cord and outlet so naturally those contribute to degrading its impedance. In other words, we are measuring the whole thing, not just some internal impedance.
@amirm @EB1000 What's sad here is that unlike the medical industry where they have at least a host of checks and balances (licensing, medical quality assurance boards, specialty board certification, FDA, lawyers, DEA, etc) there is absolutely NOTHING out there to protect the public from unscrupulous audio electronic sales except e.g. this site.
@Mart68 @amirm Yes, I'm aware of his note, but a measurement of impedance 300 times the spec (0.008 ohms) indicates something is very wrong and should make one pause to check this out more thoroughly....it seems almost impossible unless the unit is broken or other conclusions that I've already mentioned...the P12 I first got from the factory was in fact BROKEN !!!!
DonR
Major Contributor
Doesn't say a lot about the company that ships out a $5500 piece of equipment that is broken. Now maybe twice?
Prana Ferox
Addicted to Fun and Learning
I don't think 'output impedance' as measured here is what we're thinking of with audio amplifiers. Generally the impedance tested is to building ground, the three wire business is to show the different ways the grounding / neutral bonding can be screwed up. (E: from random Googling, see here for explanation: https://www.ecmweb.com/construction/article/20897728/failures-in-outlet-testing-exposed )
You would think you want very low ground impedance (and you'd be right) but '>3 ohms' is not necessarily horrible and it wouldn't surprise me if some part of this silly box's circuitry to reduce ground loops causes a high impedance reading.
You would think you want very low ground impedance (and you'd be right) but '>3 ohms' is not necessarily horrible and it wouldn't surprise me if some part of this silly box's circuitry to reduce ground loops causes a high impedance reading.
@DonR you got that right !!!! at least they were very responsive and replaced mine within about a couple weeks including shipping time...I didn't open the second one and sold it to a famous hollywood person in L.A.
I would not trust the output impedance measurement except in a very general way without knowing exactly how the meter measures it and what it includes. @amirm was careful to state it included other things in the path and that he did not know how accurate the reading. I agree with what he said; in general terms, using it to look at the wall and then to look at the PS12's output, he saw a much higher reading. There could be something about the regenerator's output that is fooling the meter, or something else could be going on.
The thing does not do what its marketing states and that's enough for me to not spend any more time beating a dead horse. Amir has already done a ton of that.
IMO - Don
The thing does not do what its marketing states and that's enough for me to not spend any more time beating a dead horse. Amir has already done a ton of that.
IMO - Don
@Prana Ferox @amirm The device he used was measuring the impedance of the hot line !!! Look at the photo. Here's my thought: Since it's measuring impedance, it's measuring it from H to either neutral or ground. In either case, it's the impedance of the amplifier's output since the amplifier's output IS the hot line on the back of the unit---it's a power regenerator. Therefore, I believe that it IS in fact the output impedance of the power regenerator which is nothing more than an amplifier outputting a 60hz tone, at 120 volts.
Ask Amir to comment since he's the one that measured it. He's not responding to this apparent anomaly in order to clarify any misunderstanding that I have.
Prana Ferox
Addicted to Fun and Learning
Here's the snippets from the tester manual. It's putting a load (or a DC bias, for the ground) on the amp and looking for droop / dissipation time. Remember, this is a cable tester and I'm not sure these measurements on an active device have meaning.
The output impedance can be measured by loading down the amp output to 1/2 the peak voltage and then measure that resistance and that is the output impedance.
OP
- Thread Starter
- #79
I am silent because your answer was in the review and repeated by multiple members. Once more, I don't know how this meter measures impedance or how accurate it is. I just found it curious that it showed much worse impedance with P12.
As to comparing my measurements to theirs, none of us know how PS Audio measured impedance. Unlike me, they are not even telling you the instrumentation they used so we could assess its accuracy. Their stated number could just be computed (theory), at some frequency, and at a point internal to the box. Headphone amp manufacturers for example measure output impedance right at the connection to the headphone jack, not at the end of headphone cable.
Given the above, you can't compare one methodology of measuring impedance against the other.
Also, the big deal in this review was not the impedance measurements but rather, how power dropped in a real amplifier with P12. The claim that the P12 somehow delivers more power kept repeating in the other review thread. So I put it to test and the outcome was the other way around with P12 reducing power by almost 10% -- both peak and continuous. If you were going to ask PS Audio something, this would have been the question to ask. Remember, you listen to audio devices, not the impedance of AC power.
So far Paul at PS Audio has just posted a flippant answer:
Notice how continues to use words as opposed to hard data to counter mine. Focus on this. Ask them to repeat my measurements and show different results. If they can't or won't, then the conclusions of my review stand.
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