EMI Filter: Cor Com 5VK1?

[mike_mccue]

Hi,
I have just opened a parcel of surplus CorCom 5VK1 EMI Filters that was left to me a few years ago by an older technician friend. He had bought them at surplus for some project that I never really understood the nature of.

We are no longer in contact. He left me to care for several parcels of his old parts and such and now it's time to clean up the storage.

So, I have 18 of these units:



CorCom K series DataSheet


I don't really know what there are or if I can find a use for them in the Do it Yourself projects I enjoy.

I'm assuming they are filters to be placed on the AC power supply of various appliances. Can I use them as a filter stage in a Guitar Amp power supply before the rectifier?

Any other useful suggestions?

Thanks,
mike

[Old Tele man]

...they're excellent for clearing up "noise" coming IN on the power line as well as for reducing "noise" going back OUT to the power line (as caused by switching power supplies).

[mike_mccue]

I'm not that familiar with switching power supplies, but I think I can imagine how they would be hooked up on a power transformer type supply.

Is there someplace I might find some schematics of how these are implemented in a circuit?

thanks,
mike

[jrfrond]

The three pins on the right correspond to the AC input wiring. The two on the left are AC output to the switch, transformer, etc.

I use CorCom AC Filters on new builds, but I use the ones with the integral AC-IEC input. The filter shown must be wired either to a separate IEC input, or a 3-wire AC cable.

[mike_mccue]

Thanks John,

That was what I was thinking seemed like the correct hookup. I'm glad to have it confirmed.

I also assume that with this form factor that the circuit is basically set up to use chassis ground and if that was not the case the 5VK1 would need to be islolated from the chassis and circuit ground connected to the 5VK1 canister. Is that correct?


Here's an *opinion* question for anyone out there:

Is there any merit to bolting one of these inside a "players" Silverface era Fender Amp?

thanks again,
mike

[Enzo]

None that I can see. They remove high freq noise from the mains, and that is not usually an issue with tube amps. This thing is what they stick in those "filtered" outlet strips for computers or whatnot. That and a varistor or two to control spikes.

Personally I would use them for anything with a computer circuit in it and not much else. So synths, processors, MIDI stuff and like that.

But certainly won't hurt anything.

[mike_mccue]

Thanks for elaborating.

best regards,
mike

[jrfrond]

I just need to elaborate on something. Enzo said that these filters are not normally needed in tube amps, and he is correct. However, I make my livelihood in the heart of NYC, and we are bombarded with every for of RFI and EMI known to mankind.....seriously! When I build new amps for NYC players, I use the filter as a precautionary measure.

Our RFI and EMI is so high that we were once contracted by KRK to troubleshoot NYC-specific RF problems when they introduced the Expos? 8 studio monitors. THAT should tell you something!

[Enzo]

In special situations, of course they are useful on most anything. In most cases RF doesn't make it through the power transformer in an amplifier. RF is more a problem for shielding and grounding. My shop is a few blocks away from an AM radio transmitter, and RF is all over the place here. Shop visitors are amazed when I touch something to a tube grid and the radio comes out their speaker.

Power line hash is different, that does come through the mains. I used to work where the trafic light at the end of the block had a noisy triac for one of the lamps. I could tell when the light was green for Washington Ave because there was this power line buzz whenever it was on - or perhaps it was the red facing the other way, don't know which was which.

[mike_mccue]

That's great stuff to consider thanks to both of you for posting the additional info. My day job is a free lance sound person for TV and film. We use wireless systems far too frequently and have to be aware of the density of traffic wherever we work. New York is legendary for the fact that you can be stepped on terribly in one place and in a shadow and clean in another. It's wild up there.

Enzo, Thanks for speaking about the noise on the ground. That seemed interesting to learn about.

best regards,
mike

[Bruce / Mission Amps]

OK I did come out of the two radio biz and like Enzo lived 400 yards from Denver's KOA 50KW transmit vertical antenna array for 22 years and I do do know what RFI is!
I'd say about 99% of the time, using something like this in electric guitar, tube amps is total overkill.... and although painful to say, 'cause they look awesome, ...
worthless for the types of noise and hums you're normally going to run into.
I'd dump them all on Ebay and buy some cool NOS tubes with the revenue and really be happy with what you do with them.

[mike_mccue]

"I'd dump them all on Ebay and buy some cool NOS tubes with the revenue and really be happy with what you do with them."

That's probably what I'm going to do with them. I'm really glad I know what they are and when to use them. I can always grab a single one at a later date if a project comes up.

best regards,
mike