GoodSoundClub - Romy the Cat's Audio Site - Line (grid) Power, waveform symmetry and THD

04-05-2009

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Paul S
San Diego, California, USA
Posts 2,577
Joined on 10-12-2006

Post #:	326
Post ID:	10168
Reply to:	10148

With All the Wonderful Success Lately

Do we finally understand what part of the Bad Electricity problems is [broadband] noise and what part is related to "waveform" issues, such as phase? And do we understand how attempts to deal with either one of these issues might affect the other?

I ask because I have never seen a single corrective device that offers balanced, quiet, phase-perfect power. By "balanced" in this case, I mean that the nueutral/ground is isolated and re-referenced at -60V, while the hot leg is set at at +60V, in the case of 120V AC.

Neither have I seen a full-on "regenerator" that does not employ a digitally-synthesized reference for the reconstruction/propagation of its "perfect" sine waves. Sorry, but I just don't get how this could stay clear of its own noise.

I would not be bringing this up again if it looked like the PP2000 neutral/ground was actually isolated. Obviously, if you unplug the thing, then its ground just "floats". But even in this case, cross-contamination from the loads appears to be possible; likely, even.

Paul S

04-05-2009

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Romy the Cat

Boston, MA
Posts 10,052
Joined on 05-28-2004

Post #:	327
Post ID:	10169
Reply to:	10168

The saga about the tennis playing Jew

Paul S wrote:
I ask because I have never seen a single corrective device that offers balanced, quiet, phase-perfect power. By "balanced" in this case, I mean that the nueutral/ground is isolated and re-referenced at -60V, while the hot leg is set at at +60V, in the case of 120V AC.

Neither have I seen a full-on "regenerator" that does not employ a digitally-synthesized reference for the reconstruction/propagation of its "perfect" sine waves. Sorry, but I just don't get how this could stay clear of its own noise.

Yes, you have seen it. The PS Audio PowerPlant does exactly what you describe: fully regenerating, quiet,\ balanced, etc. I do not know what would be “phase-perfect power” but it is OK.

Paul S wrote:
I would not be bringing this up again if it looked like the PP2000 neutral/ground was actually isolated. Obviously, if you unplug the thing, then its ground just "floats". But even in this case, cross-contamination from the loads appears to be possible; likely, even.

I have no idea what those 3 sentences mean. PP2000 neutral is neutral, the ground is ground, the input ground shall not be lifted. Anyhow, Paul I think you need to make a mental decisions how much you are willing to talk about PP2000 without actually trying it. Sure, you might talk about whatever you wish but how practical is it? Anyhow, just a thought. That reminds me an old joke what two Jews meet and one ask “Can you play tennis?” Another reply: “Perhaps, I do not know - I never tried.”

The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

04-28-2009

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Beav
Posts 5
Joined on 04-28-2009

Post #:	329
Post ID:	10372
Reply to:	2931

Humming

What I have is a subwoofer made by ACI; no information on the amplifier used other than it uses a two prong power cord, no ground. When I hooked it up to the APS 2000 I got a very loud pitched hum. Taking if off the 2000 and plugging it into a wall outlet on a different circuit, I still got the hum, but not so loud or high pitched. Any ideas as to what is causing this both directly hooked up to the 2000 and then only hooked up by way of a subwoofer pre-amp output from the Pioneer Elite Receiver. The sub is used for HT, which in most cases would drown out the hum. However with the new sound formats being used by blu-ray you can get sound quality for music that rivals CDs. If this hum comes through on a quiet passage in a BD concert...well, I'm afraid the unit will receive a "not ready for prime time rating" for me. I am in process of doing a review on the 2000, and so far the only feedback I'm getting is; from ACI why mess with something that works fine without a power reconditioner. From our friends at APS take the PC equipment offline from your audio equipment. This had no effect on the hum. So, my next option would be as the manual states, use the adjustible circuit that removes hum in torroidal transformers of certain designs. I did a review on the 1050 which received high praise from me as it solved a tube amplifier problem that could have cost me thousands in burnt tubes and who knows what damage to the mono amps. I now use a Pioneer Elite Receiver; whigh is the only difference between then and now; that and the location of the house; the ACI subwoofer was in my system at the time of the 1050 review. So why this change?

04-28-2009

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Romy the Cat

Boston, MA
Posts 10,052
Joined on 05-28-2004

Post #:	330
Post ID:	10374
Reply to:	10372

I think you are play wrong game….

Beav wrote:

What I have is a subwoofer made by ACI; no information on the amplifier used other than it uses a two prong power cord, no ground. When I hooked it up to the APS 2000 I got a very loud pitched hum. Taking if off the 2000 and plugging it into a wall outlet on a different circuit, I still got the hum, but not so loud or high pitched. Any ideas as to what is causing this both directly hooked up to the 2000 and then only hooked up by way of a subwoofer pre-amp output from the Pioneer Elite Receiver. The sub is used for HT, which in most cases would drown out the hum. However with the new sound formats being used by blu-ray you can get sound quality for music that rivals CDs. If this hum comes through on a quiet passage in a BD concert...well, I'm afraid the unit will receive a "not ready for prime time rating" for me. I am in process of doing a review on the 2000, and so far the only feedback I'm getting is; from ACI why mess with something that works fine without a power reconditioner. From our friends at APS take the PC equipment offline from your audio equipment. This had no effect on the hum. So, my next option would be as the manual states, use the adjustible circuit that removes hum in torroidal transformers of certain designs. I did a review on the 1050 which received high praise from me as it solved a tube amplifier problem that could have cost me thousands in burnt tubes and who knows what damage to the mono amps. I now use a Pioneer Elite Receiver; whigh is the only difference between then and now; that and the location of the house; the ACI subwoofer was in my system at the time of the 1050 review. So why this change?

Beav,

The “hum” might be from various reasons. If you imply the 60Hz and 120Hz then it most likely some odd ground loops that in case of PP2000 are more complicated. It need to be know if the hum you described is not mechanical nature, what kind it is, how it relates to volume…. the regular things. What surprised me that if people have ground loops with records cartridges then they fight the loops but what they have the same proboems with AC lines then they feel that it is much different…

Actually, Beav, there is something different in your case. I think what you do it wrong. If you are a reviewer and you are in possess of writing a review about the PP2000 then I would advise you do not search online what others say but subject of your review but you your own mind. If you have any technical or exploiting difficulties then take it to the PurePower people as the observation of their compliance to your problems shall be a part of your review as well. I know that many of the audio “reviewers” write their semi-idiotic observation by browsing web and snatching the phrases and opinions from here and there. I do not think that you would do a good service to your or other is you practice it.

So, if you are in possesses of writing a review then you shell not read this thread and shell not ask questions. Your job is to provide answers or to sharpening the questions…

The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

04-28-2009

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Beav
Posts 5
Joined on 04-28-2009

Post #:	331
Post ID:	10376
Reply to:	10374

Response to Romy

Actually, Beav, there is something different in your case. I think what you do it wrong. If you are a reviewer and you are in possess of writing a review about the PP2000 then I would advise you do not search online what others say but subject of your review but you your own mind. If you have any technical or exploiting difficulties then take it to the PurePower people as the observation of their compliance to your problems shall be a part of your review as well. I know that many of the audio “reviewers” write their semi-idiotic observation by browsing web and snatching the phrases and opinions from here and there. I do not think that you would do a good service to your or other is you practice it.

Romy,

The magazine I work for is Enthusiast based. How each Enthusiast chooses to go about problem solving is up to them. I am in discussions with both ACI and PurePower in regards to this issue. The reason I also use audiophile forums is the knowledge base there can be of benefit to my own "thinking". I am not looking of guesses, I am looking for engineering facts; it is an area I am not highly skilled in and so I use what resources I can find to help me solve a mystery. That is my job, how I go about doing my job is my style of writing and "thinking". You may agree or disagree; you are neither right nor wrong. You have an opinion, as do I. I respect yours, and will consider your advice. In the end, I expect I will use every resource I can find to solve my mystery. Hopefully we will all benefit from the effort.

05-25-2009

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anafield
Posts 5
Joined on 02-18-2009

Post #:	332
Post ID:	10582
Reply to:	10376

PurePower 1050 EU Version big bang and dead

Today I was listening music and after about one hour there was a big bang and my hole system was dead.My unit worked well for about 6 months now without any problems, out of the sky it blow up!
The home main fuse of 16 Amps was blown-out but the 10 Amp Fuse on the back of the APH 1050 is still intact.After the shock what happened I hooked up my system with a normal power juicebar and all worked as it shut be.
After listening for about one hour I noticed that my set was sounding much better and smoother.Especially in the upper frequencies there was a more relaxed and open sound, the bass was also more powerful.
For me the APH experiment is over and I will keep the system running without any Power-regenerator.
PS: I looked inside the APH to find out what happened, a couple of 10 Amp soldered Fuses are dead, also the output stage was blown away.At the middle of the power stage there is a small ceramic cap mounted that is bean used in a Sobel-Network on the output of the Digital Amp.This capacitor as I measured it was shorted, my guess is that this sucker caused the problem.

Herman

05-26-2009

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PurePower
Ayr, ON
Posts 44
Joined on 05-26-2009

Post #:	333
Post ID:	10598
Reply to:	10582

Herman's unfortunate experience

The failure Herman had was probably on the input side - not the output.

You will notice 2 things.
1. The system operated normally for 6 months, so it is unlikely an overload issue.
2. The PurePower did its job of protecting the audio equipment (self sacrifice is the first rule of power protection).

The failure was most likely the result of a high voltage transient causing a short circuit of a PurePower input power supply high power mosfet chip.
The description is consistent with a mosfet short. They can fail with a bang. This results when the mosfet is subjected to an input voltage over 450V.

We have documented that utility power frequently contains transient voltages of up to 700 volts that are very short duration - typically less than a
millisecond. They are caused when the utility switches in or out large capacitor banks they routinely use for power factor correction - a necesary
function of power distribution especially in industrial areas. On site testing for power quality at a Purepower customer site in Connecticut by an
independent power quality engineering firm captured a number of these "transient events" over a 3 week period. (We are working of providing this
report in a white paper.)

Normally these high voltage short duration events are too fast to even cause a light to flicker - and certainly are way too fast to trip a fuse, but our
mosfets in the 1050 were super sensitive to sudden overvoltage - and thus were susceptible. Most consumers don't run into this problem or the transients in their neighborhoods are lower voltage - but it only takes one transient and a fraction of a millisecond.

We addressed this problem in late 2008 - and made changes to our 1050 motherboard. Now all 1050 2009 production is as immune to transients as our
model 700 and 2000 always have been.

Not only that - the transients cannot pass through the PurePower double conversion - unlike other types of power conditioners which allow transients to reach
sensitive audio equipment after passing right through. We have no doubt that some audio component power supplies can be harmed
in the same way our PurePower input power supply was.

As to Herman's preference for utility power sound after his unnerving experience, I can understand. We sincerely apologize for giving him such a fright.
But I bet in a blind test he will prefer to go back to listening with PurePower.

Richard at PurePower

05-27-2009

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Beav
Posts 5
Joined on 04-28-2009

Post #:	336
Post ID:	10609
Reply to:	10604

Hum issues

drdha,

Is your hum comming directly from the purepower unit itself?

I've been doing some research on hum issues in general; a goood site for information is linked here http://www.epanorama.net/documents/groundloop/home_solving.html

Previously I reported that when I hooked up my powered subwoofer to the purepower 2000 my sub let out an awful hum. I finallly solved the problem by using a different method of hookup between the sub and the Receiver. It's as quiet as mouse now. In reading up on hum issues (ground loops) I've found that even the experts are sometimes stymied by the cause. It can be with a component or how components are hooked up to the system you have. The best solution I've found is to experiment. Luckily for me I had options with my sub for hookup, had I not the answer would be that particular component is incompatible with a power regenerator, or at least the one I used. If it's a component issue and the rest of the system is benefriting then I would change out the component. If it's a system wide issue I would change out the power regenerator. BAd power is bad power, if you got it, you have to look for ways to treat it. So far I've been quite pleased with purepower in two different systems, in two different locations with both the 1050 and now the 2000. Customer service issues are another story; and only the company itself can address that. Since I solved my own problem by combination of research on the internet and experimentation I in the end did not need to use Purepowers new hum adjustment tool built into the unit. What I like about Purepower is they are always coming up with new ideas to solve age old problems in the power arena. I do believe timely responses to a customer's problem are as essential to a good product as the product itself. Even if the company is having difficulty resolving the problem, giving a status report to the customer is also the professional way to do things. In my real world job I work in the Project Management field, and if I were to fail to give a "stakeholder" in the project a progress report I would not have my job for long. I have found that in general most A/V companies do a good job of communication; those that don't rarely receive my business again. I hope that Purepower will help resolve your problem, keep us informed.

05-27-2009

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PurePower
Ayr, ON
Posts 44
Joined on 05-26-2009

Post #:	340
Post ID:	10620
Reply to:	10604

Hum

Hum is a multi faceted problem. We have identified 4 completely different causes of hum in amplifier power supply transformers exacerabted by AC power problems - and that kind of hum is not even the most common hum audiophiles have to deal with. The no 1 cause is ground loops in interconnects - which is outside our purvue. PurePower can effectively eliminate amplifier transformer hum from AC power supply causes - including DC offset, asymetrical voltage waveform (sometimes called virtual offset), common mode noise from faulty grounds and current waveform anomalies caused by asymetric current draw by amplifier power supplies.
All of these hums are distinct from hums entering the signal path and emanating in the speakers - this is mostly unrelated to AC power issues and again outside PurePower's purvue.

If anyone is waiting for a PurePower technical solution to amplifier transformer hum then please email me with details. We can help with these. richard@purepoweraps.com

05-31-2009

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	341
Post ID:	10668
Reply to:	10620

Buzzing with Schoenberg and the PP2000

Something very interesting happened today in my battle with the incessant buzz in the PP2000. No, it did not go away unfortunately, but I learned something new.

Perhaps inspired by the recent discussions around the original pressings, I decided to spin a few nice old mono recordings.

Now, as has become my habit, I listen with the PP2000 unplugged, as that eliminates the buzzing. And I listened to a few albums. First Sofia Gubaidulina's The Last Seven Words of Jesus on the Cross, followed by Penderecki's Utrenja, and then Tchaikovsky's Symphony Number 4 in F Minor. Incidentally, the second movement is absolutely spectacular. It reminds me very much of the the visit of the Ghost of Christmas Past in A Christmas Carol. Wonderfully nostalgic.

In any event, I happened to be smoking a Salomones by the fire as I was listening. It is a particularly long cigar, and I had a little more to go, so I decided to put on another record. Here I chose Schoenberg's Piano Concerto, as I was seeking something a bit more subtle to follow the at times heavy-handed Tchaikovsky. Now, when I did this, I decided I had better plug the PP2000 back in to the wall, as I was not sure how long it could go on battery power alone.

Well, when I plugged the PP2000 back in, instead of the familiar buzz, I heard a loud growling buzz. The unit itself was actually buzzing audibly as well. This was a low frequency warbling of sorts. Having been assured that the unit was unlikely to blow up by APS and with the cigar already lit, I sat down to listen undaunted. Over the next few minutes the loud warbling buzz continued, gradually speeding up in frequency. After a few minutes it had become a continuous buzzing. A few minutes more and it changed to the familiar extremely high pitched buzz with which I am familiar, and there it stayed.
So now I am wondering if what I am hearing -- the high frequency buzz -- is simply the sound of the PP2000's charging circuit? My upper frequency hearing is quite good, and I sometimes cover my ears from high pitched sounds that no one else around me notices. So is it possible that other PP2000 owners simply are not hearing this buzz because the frequency is too high for them?
Or maybe my unit is defective and going to blow up soon.
Adrian

05-31-2009

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Romy the Cat

Boston, MA
Posts 10,052
Joined on 05-28-2004

Post #:	342
Post ID:	10670
Reply to:	10668

The syndrome of the number 2000?

Reading all those posts about the PP2000 does something strange (I god a few private emails for different people as well) I kind of feel a gully pleasure – my PP2000 still works absolutely flawlessly – means did not blow and sounds good with no noise of any kind. Probably I shall not to run my mouth about it as God will punish me. Anyhow, if you convinced that it is PP2000 problem then pack it up and ship it back. The consumer macrocosm is not a good thing.

Anyhow, there is another interesting idea that I did not try but sounds interesting:

http://www.ep2000.com/

I have no motivation to try it as my PP2000 address all my needs so far but I would like to hear if someone used the EP2000.

The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

06-01-2009

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Bud
upper left crust united snakes
Posts 87
Joined on 07-07-2005

Post #:	343
Post ID:	10672
Reply to:	10670

High frequency explosions

Sounds to me like your switch mode transformer is doing the buzzing. I recently purchased an APC product that charged the battery constantly, so long as it was plugged in. This caused quite a bit of heat and stench, from the hot switch mode power supply. It buzzed all the time and when the battery was being charged it buzzed even louder. I complained and they sent me a different unit, same power, different case (tan and narrow rather than black and fat). This one does none of the above, though when charging the battery it does hum slightly. There is always a turn on buzz, but just for about 10 seconds. The original one had a noisy fan also, to keep it from self igniting, perhaps that is your actual problem?. The new one cost more than the old one and they even paid for the freight.

You should ask your tech support guy if there is a replacement for your APS supply that does not run continuously.

Bud

06-01-2009

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	344
Post ID:	10673
Reply to:	10672

Maybe my PP2000 will blow up after all

Bud wrote:
Sounds to me like your switch mode transformer is doing the buzzing... There is always a turn on buzz, but just for about 10 seconds. The original one had a noisy fan also, to keep it from self igniting, perhaps that is your actual problem?

Yes, it is not fan noise, and I always hear "turn-on noise" but that just seemed "normal" to me. The buzz I have sounds quite abit more like a stressed transformer or capacitor as far as the noise from the unit itself. The thing that puzzles me is that I get sound coming from the speakers. Anyway, I would ship it back to APS if they were willing to fix/replace it and pay the shipping as they did for you. So far though, I have received no help from them, only a few intermittent e-mails saying they would "look into it."
Adrian

06-01-2009

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Paul S
San Diego, California, USA
Posts 2,577
Joined on 10-12-2006

Post #:	345
Post ID:	10674
Reply to:	10673

Management (and production changes) by Exception

Adrian, you have not posted any updates about the unit apart from the hum issues, so I am wondering if the unit remains in your system mostly because you paid so much for it.

For instance, have the HF problems you mentioned earlier been resolved? If so, are they really OK now or have you simply grown accustomed to the problems now?

I would also like to know if you have compared the sound of your system with the PP2000 to that of your system without the PP2000, but with good wall power (who could resist doing this?!?). If so, will you share your thoughts about the comparison?

By the way: Thanks to all of you brave pioneers who have anted up big bucks to play minor roles in APS's product development. Sorry to hang back, but business sucks and my hi-fi budget was an early casualty. Perhaps APS will have some sort of an epiphany of conscience at some point and they will re-group to put out a product that actually works more often than not in the real world. At the least, I hope APS would get and stay focused on end use sound rather than merely reacting to reliability problems.

Best regards,
Paul S

06-01-2009

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PurePower
Ayr, ON
Posts 44
Joined on 05-26-2009

Post #:	346
Post ID:	10676
Reply to:	10668

Close but no cigar

Adrian needs to be in contact with our technical suppport (Damian is the best person to discuss the problems with: damian@purepoweraps.com)

The Purepower 2000 should make no audible humming or buzzing - especially at a normal listening position. If it did make noise due to a faulty component, the battery charging circuit could exacerbate the problem. It is not true that the PurePower unit has a preference for Tchaikovsky over Penderecki - although it does think a Davidoff Gran Corona would be a better match for Russian composers than a Salomones, although it has no notion how to pair a good Cuban with anything Polish.

The PurePower 2000 should sound as good on AC as it does on Battery. If it doesn't our policy is to fix it.

06-01-2009

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	347
Post ID:	10678
Reply to:	10676

PP2000: is there hope?

Well,
I did speak with Damian in Technical Support at APS, and he informs me that this effect is something that they have reproduced in their lab, but only with extremely efficient loudspeakers and certain power supply designs in the amplifier. With a solid state amplifier and regular cone loudspeakers, he says, the effect is not seen. So, I am now assuming that the difference in the power supply design of my amplifiers and Romy's is the key to why I have noise when he does not.

I was assured that they are "a few weeks away" from finding a solution to this problem, but I am not holding my breath, since I have heard that a few times over the past six months already.
Regarding the performance of the unit, I think it is impossible to say anything about it until the issue is resolved, since the correction will likely change the sound again.
Adrian

06-01-2009

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Paul S
San Diego, California, USA
Posts 2,577
Joined on 10-12-2006

Post #:	348
Post ID:	10682
Reply to:	10678

Gettin' a Good'un

Adrian, the more I read on the subject, the more it looks like the "universal" approach to solving power problems is a notion only consumers would swallow.

As for "the difference in the power supply design" between your amps and Romy's making a difference, I agree; but at the same time, remember that Romy fought and clawed his way through 1/2 dozen units or so before winding up with what now appears to be - effectively - a custom-tailored piece, eg., in effect, it's probably a ringer.

Dim bulb that I am, I have just recently started to wonder if maybe one needs to know something particular about one's power problems and one's equipment, alike, in order to stand a fair chance of solving one's own particular BEP with given equipment.

Conversely, does the wide variety of problems one encounters with BEP combine with the various electrical matrices possible with a whole hi-fi system make for problems that are just plain hard to predict, prepare for or effectively deal with in one sell-able unit?

Well, if we need to know more to get the BEP solved with the gear that we actually have, what do we need to know?

Why doesn't someone who knows address the salient issues in plain talk from and for the point of view of a totally neurotic, OCD hi-fi nut (eg, moi)?

I would not mind a little assisted DIY in order to get something like a BEP corrector that actually worked for moi.

Hey, I want a ringer, too!

Paul S

07-06-2009

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	350
Post ID:	10999
Reply to:	10997

Another PP2000 problem: hopeless?

Well, I think the short answer is yes.

What the people over at Technical Support have told me is that this is due to the power supply design of the amplifiers that are being driven by the PP2000 and that it seems to be characteristic of certain types of circuit configurations such as a low powered SET amplifier driving a high efficiency horn loudspeaker. They say this is not the typical stereo set-up and they did not test this when they originally designed the PP2000.

Now, they say they have got this kind of circuit set up in their stereo testing lab and have replicated the buzzing results. Each time I call them they say that they are working on finding a solution to this problem and "getting close" -- but it has been almost a year now with no end in sight. Probably too late for me to return it at this point.

There is nothing you can do to eliminate the buzzing (I've tried) short of changing your stereo components internally.

If the buzz is bothering you, I would just return the unit to them and demand a full refund.

Adrian

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