Filter Power Entry Modules

[MarshallPlexi]

Are filtered power entry modules a good idea on a guitar amp? I know that I haven't seen any in the gut shots of the amps that I've seen, but I was curious if this could help to suppress noise. Here are the kind I am talking about:

http://mouser.com/Search/ProductDeta...XvtI3bhw%3d%3d

http://mouser.com/Search/ProductDeta...6AsfwAbVoJk%3d

[Chrome Dinette]

Perhaps someone more knowledgeable will chime in, but I suspect these mostly help with frequencies above the audible range, i.e. RF. That still might be a good thing, but I don't know enough about it.

I used one in a power supply for a low voltage submini preamp I built, but I don't have anything to compare it to.

[MarshallPlexi]

I'm the same way. From a design point of view it looks like a logical thing to address, but it may be one of those things where if it ain't broke don't fix it. Anyone smarter than me have any thoughts on this?

[jrfrond]

It certainly can't hurt. Unless you perform testing by deliberately injecting RF into the mains pre and post-RFI/IEC installation, you won't know. Most guitar amps have been fine without them, but if you want to be on the safe side, there are no issues. Just make sure you select one with the correct current rating.

[defaced]

I've seen them in high gain amps. I think it was either Engl or Diezel that used them. Not sure why they were used, but they were.

[Enzo]

I think in things like guitar amps they are used more to deflect noise issues for electrical certifications.

Those filters stop high freq noise and RF, not really a concern with a guitar amp. They will have no effect on hum.

[Steve Conner]

I've used them on a couple of amp builds, and they didn't really seem to make much difference. I put one on the Crown SXA, and it still makes a little pop when the fridge compressor turns off. Like others have said, I think they're mostly good for keeping RF out.

If you have a PT with a Faraday screen built right into the windings, that's pretty good at keeping the crud out too, and may make a filtered inlet redundant. You can tell these because they have a ground wire coming out of the mess of windings, or a lug marked "Screen".

I am very happy just now because an instrument I designed just passed EMC testing.