PurePower wrote:

Hi Max, If you have buzzing that is audible outside the PurePower case, or audible from a listening position, the behavior is not normal. The probable source is a capacitor. Caps can hum in the same way as transformers - the foil expands and contracts and can vibrate at 60 cycles in an effect that is similar to transformer magnetostriction. You should contact us to arrange for service.

PurePower wrote:

In the world or audio you learn new and interesting facts every day.   AC caps (ceramic, electrolytic, polyester and polypropylene metallized foil types) can buzz at various frequencies. This is not nonsense, and is quite normal behavior; it is common sense if you stop to think about it. As the voltage switches from positive to negative in the presence of AC the film stretches and shrinks with each cycle, just as a transformer lamination stretches and shrinks.  Transformers, coils and capacitors  are all capable of acting as little door buzzers.   Unfortunately cap manufacturers do not include specifications for audible noise in their technical data, so those of us using AC caps in applications where audible sound levels are critical have to test each type carefully and specify only those that meet our own QC procedures for audible noise. Interestingly, the tendency to hum is entirely unrelated to the quality, price, or electrical specifications of the cap. So a noisy cap does not indicate a failing or low quality cap at all.   For many of the AC caps in PurePower units we have worked with a small custom manufacturer that has developed a unique folding configuration to reduce the tendancy to vibrate. Several of the hand wound audio grade cap manufacturers have worked very carefully to develop quiet caps through trial and error to come up with the ideal winding technique, and one California audio grade custom cap manufacturer told me it is a skill that varies from employee to employee.   Usually, the sound produced by noisy caps is below a level that is audible outside the component case, but occasionally they can be loud enough to be objectionable.   p.s. It would not surprise me at all if there were capacitors happily humming away inside some very high end audio equipment. Fortunately, the sound level is usually proportional to load, so they would only make noise when the music is loud, and catching them would be like trying to see if the fridge light goes out when you close the door.

I am sorry but stating that capacitive buzz is not nonsense but “quite normal behavior” is nonsense itself. Yes, the film, conductor and dialectic perform micro-movement but if this movements rise to the level of auditable noise then there are ONLY two reasons:

1)    Circuitry is not designed properly

2)    Capacitor is not manufactured properly.

Sorry, to advocate that buzzing capo is a norm is something that you must not do. A vibrating and buzzing cathode in the tube is norm as well?  The film in capacities is the cathode and any good cap manufactures do advertise how firm and tight then wind the caps. The cap that are loose and auditable vibrate are just a defective garbage that need to be trashed. There is no reason to discuss it further.

PurePower wrote:

You point out that if a capacitor can hum it is faulty and wound improperly. You are absolutely correct  - the way a capacitor is wound will determine if it can hum or not. Unfortunately almost all capacitors on the market are wound in a way that allows them to hum - even when they meet all other electrical  specs. Therefore my statement is correct. Most capacitors can hum. Your statement that "If a capacitor can hum, it is faulty and is wound incorrectly" is a legitimate point of view.  I agree with it as a requirement of acceptable capacitor quality. In fact, capacitors that meet the noise free quality level are the very capacitors PurePower uses. The problem is, we had to do a whole lot of testing and visiting capacitor plants to find caps that are wound properly and meet the noise free test because the manufacturers do not publish their audible noise specification. But if you make a general statement that all caps are silent you statement is incorrect. The reason is simple. Most caps are used in applications where hum is acceptable.  Thus most caps do not meet your standards and are not acceptable for use in audio equipment.

Yes, the capacitors are silent and in context of this thread I would insist that if "if a capacitor can hum, it is faulty and is wound incorrectly". Let me to explain.

Capacitors crate nose because of 3 reasons and 3 reasons only. If the sales people who sell your caps tell you otherwise then fire them and find another supplier.

1)    If a cap has to high ESR then drop on this ESR develops Johnson Noise. The Johnson’s is the restive noise not capacitive nose.  However, if the cap has such a huge ESR that a part of the cap begin to act as indictors then it is an absolutely garbage capacitor.  The only caps that I have seen do it were the caps from old Telefunken radio of 1930 and they had no capacitance and huge none-linearity

2)    The dialectic of a cap can exhibit the piezoelectric effect when the electrons in dialectic are exerted under AC in the film. This effect might create some  HF noise and the caps do produce some noise at the frequency they roll of AC. But in your case the caps do not have very minor HF noise but the have 60Hz buzz. (Reportedly and admiringly, as my unit has none of it). In order a cap to have piezo-effect 60Hz buzz the cap shall be huge, I mean it shall be a size of 50-100 PP2000 units combined – it will be the size of a good room.

3)    A capacitor is fatly and VERY loosely wondered. In this case if the conductors have a LOT of room and very bad quality then they might vibrate.  The 60Hz buzz is a vibration, a vibration is mass per amplitude.  Circulate the mass of the cap’s film and you know the frequency – you will have an idea how much the film is moving in the cap – it will be huge if you have 60Hz buzz. With this exertion of the file INSIDE the cap the cap is faulty and need to be replaced with another tight wounded.

I do think that 60Hz buzz did not come from capacitors but from somewhere in the unit. The shunting caps do not care about current and if you use the buzzing caps in coupling application then if a cap buzzes at 60Hz then it will burst VERY soon. So, I do not believe that 60Hz buzzing cap is being used. Sorry, I do not believe into 60Hz buzzing caps and if you have managed to fide them some s then the people who make them have a lot of “talent” to produce them. They need to stat to make dildos but not capacitors…

Paul S wrote:

Since - according to users - PP2000 seems to work better off battery alone, …..

Paul S wrote:

I think you mostly get where I'm coming from and you just don't like it, and your criticism is smart, and your points are well taken; but there are a few things going on here that just bug me that you either seem oddly comfortable with or you just really don't care about it in general terms, at least not any more.  Maybe it would help if I referred to APS as Fremer...

Actually it is not the same.  The Fremer does not do anything that I would care, so there is not point to have interest in him. Shunyata cultivate snakes and this is why I do not care about them but it is not something that makes me to conclude that they have bad cables. The same is with Manley labs. EveAnna told me that she hate Cats. In my book the people who hate can go deservingly right to the hell but it does not make me feel that their lat say phonostage is crap. That all turns my attention off from the specific company but it does not close turn me blind regarding what they might do. In context of this thread I did not have problems with company that cure electricity – I had problem with electricity itself. I kind of feel that for me to find a way to deal with electricity is more important than to find a corporation that would provide this solution.  Pay attention – this thread is for me is about the solution for electricity problem and for you is about to appraise the solution provider. You might be right or wrong in your appraisal but it in my absolutely irrelevant to the problem of electricity cure. 

Paul S wrote:

I do not think I am being "protective" of this site, but I can't think of another "manufacturer" that has so blatantly harvested only the glowing remarks from this site, to literally broadcast from their own place, to use to sell ever more units that they do not test prior to shipping, and all the while it appears that they do not subsequently fix even the acknowledged problems, either. I mean, if I find a tick on my arm, I burn it off, and if I am with a group in the woods at the time, I call it to everyone's attention.  In other words, I actually do tend to be somewhat of a "consumer activist", in some situations.

Do not over estimate the influence of this site. What Purepower does has nothing to do with their recent publicity. 3 years back when I first contacted then I received a number of emails from the people who dealt with them before and was warned about their quality issuers. So, the lack of control of what the do is not their reaction to hyper demands but this normal operation mode. Be advise that by nature of Purepower units (class D drive lead directly) the Purepower  generators are more vulnerable  than other topologies. Still, pay attention that I found reason to continue deal with Purepower despite of it. I do not have accommodation pricing and get no benefits of any kind from this thread. The only motivation I had and have is the Sound that Purepower units produce (when they operate properly).

Paul S wrote:

I hope I have made it clear that I am genuinely (mostly) happy for you and Bill, that your untested, faulty units none the less "worked" +/- as you wished, and that they have somehow worked out for you and Dr. Gaw in terms of the amount of time and money you are comfortable to throw at your electricity problems. OTOH, I am not comfortable giving them money...yet.

And you might be very right as they do improve their units each month. Again, it is not about your, my or anybody else’s ownership of APS but about the sound you, my or anybody else for in the room. I wish I would find a solution comparable to Purepower 15 years ago….

Paul S wrote:

Yes, yes, the "30 day money back guarantee".  But everyone knows that the unit goes bad on day 31.  And, given that APS obviously do not screen units prior to shipping, who really knows what the problems will be?  They sure as hell don't know, and it looks for all the world like they are not really prepared to deal with problems, either.  While I am not saying APS would cut anyone loose on the 31st day, I think it is only sane to view APS' almost random failure rate and their lackadasical "customer service" with some alarm.

I did not see that “unit goes bad on day 31” and I did not see that APS refused to support their units after day 31 and even after the warranty expire. They do it but they do it in own terms, the terms that I disagree BTW. A month ago I suddenly receive an email from APS owner who informed me that tomorrow he will call me and we discuss how my unit might be fixed. It was a month ago and he never called. I kind of accustomed to this behavior from APS - so I just leverage down my expectations and I protected this way from disappointments. ..

Paul S wrote:

How frustrated and desparate am I about the BEP? How soon will I defy my own sense of reason and financial sanity and buy an APS beta?  How long would a sane person wait for some indication of a lower failure rate?

I do not know BEP is. About the “APS beta” – all of the APS Purepower units ARE beta – this is the way how the company operate. They constantly change the things and they (as far as I can judge) do not have TRULY serious engendering or audio assessment recourses. So, they keep fishing, sticking to better solutions and running away from bad one.  They are constantly in Beta mode. It is what it is. I have absolutely no problem to run my unit in Beta mode if it stable and if it deliver the result that I demand.

Bill wrote:

While they may not have tested every unit in the past, they do now. They even send graphs of the testing results with the unit.

Bill wrote:

I spoke with their engineer before sending one of my units back for a problem that turned out to be a blown fuse, probably due to my running the unit at close to its maximum parameters or over, and he stated that they implimented a strict testing and burn-in program due to the costs of paying for the shipping of units that previously needed to be returned.

Bill wrote:

Again, these units have given me the cleanest electricity and sound that I've been able to accomplish over the past 30 years, haVING HAD AND TESTED innumerable different so-caled AC cures in my system.

Bill wrote:

So until you plunk your money down and try one of their units in your system, please refrain from commenting on that which you do not know.