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Transformer noise including Powervar

First, all transformers make acoustic noise. That is their nature. But the manufacturer should know how to limit or dampen these vibrations to keep them pretty much inaudible.

The transformer in a power conditioner or power amplifier will make audible noise for primarily one reason: improper AC input. All transformers require a constant specified voltage and frequency just like all other electronics. The AC input requirements are specified on the rear of the unit.

If one feeds the unit improper voltage or frequency, the magnetized plates in the core of the transformer do not operate properly and rattle…hence the noise. And this information comes from the chief engineer at Powervar.

Powervar and many other power conditioners do not regenerate the AC sine wave or regulate voltage or frequency. The AC that goes in comes out less AC TRANSIENTS and AC NOISE.

With that being said, there are many AC line sources that can cause transformer noise including DC on the mains. If you are interested in understanding what they are and becoming educated on the subject, I suggested highly that you read the following article and focus on section 3. “Adverse Mains Conditions”. Go to: http://www.plitron.com/PDF/AES.PDF The article is excellent.

So if you are going to use a Powervar, you should feed it proper AC sign wave. The AC can be full of transients and noise but it has to be the correct voltage and frequency. The Powervar will clean the transients and noise but it is not going to change the sine wave. One can only do that with a regenerator and that comes with a price of course.
drdokman1
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shadorne
7,477 posts
 
DC offset seems to be a big problem for tranformers especially when driven to saturation. If possible, the best is to unplug the offending device that is feeding DC offset back to the mains (AC or DC motor or another power supply like a chopper power supply for a PC).

If manufactuers used more costly transformer designs that were less easily driven to saturation then DC offsets and acoustic noise would be much less of a problem.
mdhoover
695 posts
 
Jea48: Thanks for the links. Now if I just knew how to read the diagrams.....
"The thing to remember is that you MUST know what you are doing - this is the AC line we're talking about here, and obviously, the DC blocker is NOT UL approved."
-Palasr
Palasr: That would disqualify me from this endeavor, at least for now. DANG!
drdokman1 OP
7 posts
 
Ludimagis:

Might be something on a particular circuit only causing the problem.

Perhaps the transformer is not dampened enough or perhaps it has been damaged. Tighten it down?

Thanks for your response.
drdokman1 OP
7 posts
 
Here is another spectacular article about DC offset and its affects on the AC sine wave. Transformers hate DC offset.

http://www.soundstage.com/maxdb/maxdb071998.htm
ausjoe
98 posts
 
Drdokman1
Good post! I Hope this isn't straying too far off topic. EI frame transformer magnetic fields brought up a thought i've been thinking about ie. separating the Amp from the preamp. I've heard 3 feet to be a minimum to avoid magnetic field effects fom the power amp. That would require a awfully large space around your amp, perhaps even removing it off the component rack. This, at least for me, would result in at least 1.5 meter interconnects which doesn't fit in the shorter is better camp. Recently i came across quarter inch stainless steel plate. Would this when added to shelving be enough to shield the preamp from the EI frame transformer? If not are there any other solutions beside distance.
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