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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

Showing 2 responses by palasr

palasr
515 posts
 
Try this:

http://diyparadise.com/dablok.html

to remove that pesky DC from your mains supply. Remember, only a few mV of DC can make toroids hum like there's no tomorrow. I used this same basic design when I built my DIY Armegeddon-clone power supply for my Linn, and it cut the mechanical noise in the 1:1 isolation toroid by about three quarters (yes, it's that effective). Check DIY Audio for the abundant debate on HOW this circuit actually works. Pretty spiffy if you ask me. Regards,

-Richard
palasr
515 posts
 
I built the second link Jea48 mentions in his post, which is essentially the same as the link I posted. I kept it simple and used a piece of perfboard mounted on nylon standoffs. Everything can be configured point to point, and takes up no more than 3" square. There are no exotic/expensive parts here, and whole shebang ought not to cost more than $10 to build (including the mounting hardware). 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. I will take some pictures of my DIY Armegeddon, which was based around a Powervar medical isolation device. All I wanted was the isolation TX and the chassis which were nicely adaptable for this use. I removed all the Pi filters and other crap between the AC in and out, and then built the Armegeddon circuit inside the Powervar case (and later installed the DC blocker after the Powervar proved too noisy).
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