Rerurn to Romy the Cat's Site

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visiting capacitor plants to find caps that are wound properly and meet the noise free test because the manufacturers do not publish their audible noise specification.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…

Rerurn to Romy the Cat's Site