Power supply EMI filter

[rankot]

Did anyone have experience with this kind (or similar) EMI filters?

https://www.aliexpress.com/item/CNIM-Hot-Solder-Lug-Terminals-IEC-320-C14-EMI-Filter-Boat-Switch-Fuse-Holder/32772571050.html


I would like to use it for a PS for my tube amp, but I am not sure if it is necessary to have EMI filtered power in that case?

[amptramp]

It's not necessary and certainly not many amplifiers out there would have it, but the world today is different from what it was when some of our favourite amplifiers were designed.  A few decades ago, we did not have digital chatter on the power lines to the extent we do now when even an air conditioner has digital feeds and a refrigerator can be a network hub.  The only thing about an EMI filter is that it is rather difficult to add any kind of voltage spike limiters or transient suppressors because the current would have to flow through the filter.  But most people don't bother with that either since you can always plug into a power bar with a surge suppressor.

These EMI filters are usually used to avoid conducted emissions but should work equally well against conducted susceptibility.  They don't do much for radiated emissions or susceptibility.  If your amplifier has a high-frequency power inverter in it (most don't), then some sort of EMI filter would be necessary.  At a gig, you are going to find lighting and other power users that do inject some noise on the line (fluorescents can be very noisy).

BTW there is a supposedly true story that a customer at Home Depot once reconfigured a refrigerator on display as a porn hub.  For those who say, "Don't try this at home", I say try it at Home Depot.  "Because they can" is not a good reason to complicate a refrigerator any more than necessary but I am restoring an old AM-FM receiver and one of the things I am adding is an EMI filter, so I say go ahead and use it.

[rankot]

Thanks a lot, nice answer!

[tubegeek]

I've used a similar part at the AC input of a hifi tube amp. I didn't A/B it with no filter, but it didn't break anything either.