Electronic – Isolation transformer to reduce speaker pop


I have some computer speakers which suffer from the following problem:
when switches flip in certain devices in the house, like the thermostat on a radiator or the refrigerator, the speakers will emit a loud popping noise, caused (I believe) by changes in the voltage on the mains.

Would an isolation transformer between the speakers and the mains alleviate this problem?

If so, what capacity isolation transformer should I buy? The speakers are rated at 500W RMS (Logitech Z-5500). I've read that an approximate conversion of 500W to VA comes out to 500*sqrt(2) = 707. If I don't play the speakers at anywhere near maximum volume (certainly less than half the maximum), would a 600VA isolation transformer suffice?

Thanks for any assistance.

Best Answer

I've never had much luck in using isolation transformers to clean up power. I've always had to use an isolation transformer plus something else (filter network, ground breaker, etc.).

If you're looking for overkill, how about hooking up a power conditioner? There are cheap power conditioners that are a waste of money. But if you spend a decent amount on a good name brand, it should provide all the isolation you need from any of the nasty stuff going on elsewhere. If you've got the money, I defiantly suggest using a power conditioner on critical sound applications.

To take it one step further, I find that opening up the speakers and placing ferrites around the speaker wires that actually go to the voice coil helps reduce the noise induced by GSM cell phones. So that might be worth exploring as well. And it's a whole hell of a lot cheaper.