While we are talking about power conditioners...

nacho459

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While looking at the $600 IEC cable thread http://www.groupdiy.com/index.php?topic=11352 I was wondering, what value caps do they use in the Furm@n power conditioners? I know it's just the box, switch, lights, etc. but I remember years ago when I opened one up the only thing I saw inside actually doing "filtering" were some caps. I guess they let RFI, etc. go to ground, and let the 60Hz AC through.

If this is so why not just put a cap on the IEC inside every piece of gear. I never really understood the "power conditioning" thing, and all but two pieces of gear I own (Behr1ng3r headphone amp, and a Lex1c0n reverb unit) are really quiet.

Maybe a cap inside the old headphone amp would clean up those low level noises in the phones.
 

Mendelt

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Dunno how things are done in real powerconditioners. But I guess just a cap to ground isn't enough. This will form a CR lowpass filter combined with the load resistance. So the corner freq of the filter will be dependant of the load and the filter will allways filter some of the 60Hz because you're charging and discharging the capacitor at 60Hz

I guess it would be more efficient to put a capacitor and inductor in series to ground in there. If you use an inductor with a low DC resistance you can tune that filter so that it will allmost let through all the clean 60Hz power and just filter out all the nasty harmonics at higher frequencies.

I don't think using a powerconditioner before behringer equipment with cheap psu's will clean things up a lot because you're still feeding the psu 60Hz AC. When that's rectified you'll still have a 120Hz signal with lots of nasty harmonics and switching noise from the diode-bridge. All that has to be filtered out by a bunch of underpowered psu caps.
 

JustinS

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I worked at a local studio before and after they installed a power conditioner & there was definite improvement - most obvious in tube stuff, guitar amps especially, but definitely there in solid state gear (I swear the mixbus got quiter... but that's just a vibe measurement, and we know how reliable that is). I have to say though, that this studio is in an old inner city building that I don't think has particularly good grounding systems...

Justin.
 

BYacey

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I don't think those were caps that you saw. Metal Oxide Varistors are what they use in power conditioners. Essentially they are two high power zener diodes back to back, and if the voltage exceeds the zener point, they conduct clamping the transient spike. If sustained high voltage is maintained across them they burn up.

Usually they put one across the hot and neutral, and from neutral to ground and hot to ground. This clamps all potential spikes.
 

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