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I have sucessfully used the Corcom filters in power supplies that I have built. Here is a photo of a 20 amp version. Note that it hase two common mode chokes, four capacitors and a resistor inside the shielded case that is like a small brick. It will blow away any isolation transformer I have ever seen as far as noise but provides no additional safety for line to ground shocks.[/quote]


With many thanks to the now deceased Timonium Fair Grounds Hamfest I have a cache' of of some very nice Corcom filters ranging in size from 3-amps. to 40-amps.

Besides my isolation transformer -- my audio and video systems are "peppered" with Corcom filters. You can still get filters on eBay at low cost and they are worth every penny.

RFI/EMi noise is sneeky and until you expunge the noise with the devices discussed in this thread you will never know how much better your system can be until you install the devices. There are a number of manufacturers that now include Corcom (or another brand) filters within their kit for those very reasons.

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Walt

Right on as far as noise being sneaky. There are basic things you can do but at the end of the day you just have to gut it out to find the source or sources. Yes, that is correct. There can be multiple causes which makes it even more difficult and therefore it requires a lot of hard work and patience.

The utility RF won't get through this.

Probably not much more than an "audiophile" spec power supply filter.

http://apelectric.com/generac-powerpact ... er-switch/

Just stick one of these in the corridor outside the DCDiy room at CAF and feed a power cord into the room.

ray

I have a 24 kW whole house Genrac (thank you PEPCO for outages). The waveform is a lot worse than your normal line voltage. Thanks to PEPCO glitches I have also put UPS's on all of my computer, video, and audio equipment except for the power amps.

Good solution for outages but as you say the waveform and voltage consistency is very bad compared to utility power. In my new house I'll also have a backup generator with the understanding that it will keep the house warm and the beer cold but not for use with sensitive equipment. It will probably be a Generac 22 KW model as that seems to be at the price break for larger systems. Most UPSs also have bad waveforms, even the "sine wave" models. BYW, if you ever do a cost analysis of using a backup generator it usually takes about 5 - 7 days of fuel to equal a whole month of a Pepco bill. But when the power is out, who cares?

Part of the generator noise problem is that the Generac uses a generator with brushes (they went bad in my generator once). I got the 24 kW one since it was the smallest SAE (Sound Absorbing) generator Generac had. It was also large enough to run the whole house air conditioning. In my current audio/visual system I have UPS's for the HTPC, Projector, and miniDSP DA8. With all the digital signal processing going on I afraid of what an interruption to the power might do.

I have tried using the Corcom type filters in the past but I did not like the effect on the sound. Cleaner perhaps but also less perceived dynamics and just plain sucked the life out of music. Virtually every passive AC conditioner (probably heard a couple dozen different manufacturers units over the years) has done this. Sort of like placing a couple ferrites on your line level interconnects, makes things sound boring. The big (15A or 20A) balanced power conditioners are least objectionable IMHO. I admittedly don't have a lot of experience with the regenerator types such as the ones from PS Audio, and seeing how the new 15A-20A ones cost $8k to $10k, I probably will not get the chance. Maybe I just like noise?

Interesting observation. The better Corcom or similar filters have very low impedance at power line frequencies and minimal effect on power transfer. I wonder what the physical effect is that causes what you hear. That would be a tough thing to track down.