60Hz hum...Do amps have built-in EMI filters? (paging Mickey and other pros)

[Gear_Junky]

A friend of mine, who is an electronics tech but knows nothing about guitar amps, has been telling me about these EMI filters. He sent a link:

https://775mv.com/

There are units meant for installation as well as for inline plug-in.

My first question is logically: wouldn't our amps already have this circuitry in them?
How effective can these things be? With my new preference for single-coil pickups I certainly wouldn't mind a working solution, especially if it works better than just shielding the guitar itself.

[mickey]

I can't speak to high end "boutique" type amps, but I seriously doubt if you'll find anything like those in your typical assembly line amp.
Adds too much to the unit co$t.

[mozz]

What kind of amp are we talking about? Most older tube amps, no. Newer tube amps and transistor probably have some sort of one. It may be cheap enough to get UL listed. A lot of the EMI protection is meant to stop noise from going out on the AC line. They also stop noise getting into the amp. Today a lot of noise comes from mini flourescent bulbs, LED bulbs. You can't really listen to any shortwave broadcasts with a inside antenna because of all the noise. Your single coils are pickups. Any noise or hum they pickup is from something nearby or faulty wiring.

[Gear_Junky]

I can't speak to high end "boutique" type amps, but I seriously doubt if you'll find anything like those in your typical assembly line amp.
Adds too much to the unit co$t.

Awesome, thank you, Mickey. Appreciate the quick response. Do you think a unit like this can be effective (and without sucking tone)? As my friend explained (and his application of this has more to do with seismic equipment than music), you're not filtering out the 60hz from the musical input, only from the power supply. He said that if this was made as an in-line pluging device, then the power cord run from the filter to amp should be as short as possible. Meaning it's probably better to install one inside the amp than to have an external box that several amps could share.

[Gear_Junky]

What kind of amp are we talking about? Most older tube amps, no. Newer tube amps and transistor probably have some sort of one. It may be cheap enough to get UL listed. A lot of the EMI protection is meant to stop noise from going out on the AC line. They also stop noise getting into the amp. Today a lot of noise comes from mini flourescent bulbs, LED bulbs. You can't really listen to any shortwave broadcasts with a inside antenna because of all the noise. Your single coils are pickups. Any noise or hum they pickup is from something nearby or faulty wiring.

In my case I have a Crate Palomino V16 (like in my avatar) and a couple of SCXD's. Not vintage. But I think Mickey is right - the Palominos were definitely on the budget side of things. Likewise the SCXD.

[mickey]

What kind of amp are we talking about? Most older tube amps, no. Newer tube amps and transistor probably have some sort of one. It may be cheap enough to get UL listed. A lot of the EMI protection is meant to stop noise from going out on the AC line. They also stop noise getting into the amp. Today a lot of noise comes from mini flourescent bulbs, LED bulbs. You can't really listen to any shortwave broadcasts with a inside antenna because of all the noise. Your single coils are pickups. Any noise or hum they pickup is from something nearby or faulty wiring.

I'd never realized the newer LED light bulbs were such noise sources. Gonna have to dig out my old Heathkit SW-7800 receiver (0 to 30 mHz in 30 bands). Been too long since I was messing with stuff like that!

[Partscaster]

What kind of amp are we talking about? Most older tube amps, no. Newer tube amps and transistor probably have some sort of one. It may be cheap enough to get UL listed. A lot of the EMI protection is meant to stop noise from going out on the AC line. They also stop noise getting into the amp. Today a lot of noise comes from mini flourescent bulbs, LED bulbs. You can't really listen to any shortwave broadcasts with a inside antenna because of all the noise. Your single coils are pickups. Any noise or hum they pickup is from something nearby or faulty wiring.

I'd never realized the newer LED light bulbs were such noise sources. Gonna have to dig out my old Heathkit SW-7800 receiver (0 to 30 mHz in 30 bands). Been too long since I was messing with stuff like that!

Hey Mickey,

if they are on dimmers, it could be the dimmer aspect effecting the LED noise.

From TGP: re LEDs on dimmers.

"The dimmer acts like a pot, and there is one involved, but the pot is actually adjusting a very small time delay circuit that's controlling a phase-shift power controller. Without going into a lotta detail, just know what you're hearing is switching noise. If it's off or all the way on, you won't hear it. Any point in between, you're screwed.

If you can't lose the dimmer, you're probably limited to noise gate solutions or something EH came out with a bit ago called a "Hum Debugger". Rather than a gate, the Hum Debugger is a highly tuned filter designed specifically for common power line noise. I don't have one, but my understanding from people who do and whose opinion I trust say it works like a charm. Also has the advantage of not having a "gating" effect that lets noise though when the signal is above the noise threshold, and sounds real obvious when switching on/off. Might want to look into one of those."

[golem]

Just got to say I have the EHX Hum Debugger. It works well for the noise issues I have in my house.

[mickey]

Hey Mickey,

if they are on dimmers, it could be the dimmer aspect effecting the LED noise.

From TGP: re LEDs on dimmers.

"The dimmer acts like a pot, and there is one involved, but the pot is actually adjusting a very small time delay circuit that's controlling a phase-shift power controller. Without going into a lotta detail, just know what you're hearing is switching noise. If it's off or all the way on, you won't hear it. Any point in between, you're screwed.

If you can't lose the dimmer, you're probably limited to noise gate solutions or something EH came out with a bit ago called a "Hum Debugger". Rather than a gate, the Hum Debugger is a highly tuned filter designed specifically for common power line noise. I don't have one, but my understanding from people who do and whose opinion I trust say it works like a charm. Also has the advantage of not having a "gating" effect that lets noise though when the signal is above the noise threshold, and sounds real obvious when switching on/off. Might want to look into one of those."

I don't have a dimmer on my property! Learned the hard way about dimmers with a house I bought in Nashville in 1980.
Mozz sounded like the new LED bulbs were as big a noise generator as dimmers.
I need to get out my old shortwave receiver & check it out because all I have are LED bulbs.

[mozz]

A pocket AM radio works good as a noise sniffer.
Some LED bulbs are bad, some are rather quiet. Now if you are talking hum, that's different than noise. You might need to do some shielding, dummy coils, or stacked humbuckers.

[Zipslack]

Didn't check the specs on the linked products, but can guarantee they don't do anything for 60 Hz. They would be MUCH bigger. Most equipment is concerned with radiated and conducted emissions for UL/CSA certs. Most of the time you're not worried about frequencies below 100KHz or even 1MHz.

If you think you need an EMI filter due to 60 Hz coming in from your guitar, you don't. You need shielding and/or noiseless pups.

[JimyTheAssassin]

Oh man. I’ve heard about electrical noise practically my entire life. My dad has been a ham radio operator since he was in his early teens. He hates switching power supplies in neighboring houses and flickering street lights. And he knows how to sniff them out too. He’s even asked neighbors if they have one of those “touch lamps”, the kind that you touch to change the light intensity.

Anyways there’s noise and then there’s Hum. Noise would be something an EMI filter will help. I know there’s a number of external options that can help, not to mention some good power filtering from something like a monster power conditioner.

Hum on the other hand might take more to hunt down. Figure out if it’s 60hz or 120hz first. If it’s 60hz then it helps to eliminate where its originating from. Bad tube, bad ground, ground loop? If I had to guess with the palamino, some servicing might be in order and that might get rid of your excessive hum (although some amps always had some to begin with).

Tests ; start the amp with nothing plugged in and volume 0. Is it humming?
Turn the volume up. Did it get hum or increase hum. If so check the tube or tubes preceding the volume. If not move on down the line removing preamp tubes to see if the hum disappears.
Clean the tube pins and try it all over again.

Never remove the power tubes for obvious reasons (and you would burn your fingers).

If the hum changed little to none in the previous Exercise, then the ground connections may need checking, cleaning or resoldering a cold solder joint. I have a feeling the palamino is star grounded and uses clips to connect board sections together. Those are all points to check and clean. you would need to verify if you want to make extra sure thus isn’t your actual issue.

[JimyTheAssassin]

I forgot to mention in the above description. Isolating an increase in Hum to a particular tube position doesn’t necessarily determine that it’s the tube itself. You can certainly try swapping tubes to see if there’s a change, but it does indicate the issue lies within the circuit or components Surrounding the tube. That could take many forms but it still helps to isolate where to look so you’re not wasting your time.

Anyways like I kinda said; this is all good to know but sometimes you can bypass all of it by just servicing your amp and it’s connections, jacks, pots, tube sockets etc. start there first and worry about the rest afterwards

[andrewsrea]

Theoretically, the better made amps have a lot of EMI elimination treatment. Those special units are most likely, snake oil.

Amps convert the 60 cycle AC to DC (as in, zero cycles) by using rectifying diodes, chokes, resistors and capacitors. For good amps, transformers are shielded and the physical layout of parts have considered EMI.

IMHO, the power within amps range from minor inherent hum (from cheap or broken amps) to inaudible by the human ear.

If nothing is broken in the signal chain, or super-cheap, most of your audible 60 cycle hum comes from you guitar pickups. There are digital pedals which you plug into your amp (guitar and pedals plug into it) that sense 50 to 60 cycle hum and electrically cancels them. I haven't tried them myself and don't know how effective or if there is latency.

Occasionally you'll get hum from a failing vacuum tube.

So, the majority of hum sources won't be treated by a power conditioner.

[glasshand]

I keep thinking, if only we had ended up with 30 Hz AC, life would be a lot simpler. That's real near the lower range of human hearing, and lower than the low E on a bass guitar, so filtering it out would be easier. Apparently incandescent lights work less efficiently on lower frequencies, so that may have been part of the reason the frequency didn't go lower.

[andrewsrea]

For the most part, I've beaten the hum and noise demons (there - I've just jinxed myself!).

My amps have healthy rectification, I am not near any radio stations (a problem in my 1st house), not near any power distributions, close enough to the transformer to get reliable and stable power, but far enough away to avoid EMI, my pedals are well shielded for RFI & EMI, I don't have many florescent lights (mostly LED now) and my studio is in the basement, where the cement walls and surrounding dirt on 70% really block out radiation and sound.

Speaking of, my studio is a quiet 62dB ambient noise with the air conditioner on and about 55dB all other times (A weighted & averaged).

That only leaves me to my guitar playing ability that needs attention.