Hum filter for single coils?

[Morocotopo]

I just had an idea ( ). Is there a pedal to filter 50Hz hum (or whatever the mains voltage freq is in your country) for single coil guitars? I assume there should be... It doesn´t seem too difficult to design a schem with a tunable notch filter... the only thing I believe should be difficult with analog means is to make the notch narrow enough to not affect the tone, or at least not too much. Oh, another thing is those pesky harmonics... so two, three or more filters. Hmmm, not so easy after all. But, with one of these you could avoid those hum cancelling pickups that never really sound like a single coil, even if they have been trying for some years now, and with each new model they tell you "this one really, really works!"
All this thinking was triggered by the Waves X Hum plugin. Pure magic!! But digital. Not easy to put your desktop in your pedalboard.

[Ripthorn]

If you are worried about the fundamental, a sharp rolloff low pass filter could do some good stuff, since a standard tuned guitar only goes down to about 70Hz or thereabouts.  Also, Suhr has a quiet backplate system that apparently works very well.  As for a pedal, I don't know of one.  The one issue with sharp notch filters for 50 or 60 Hz is that the inductors are typically very large and tend to wander.  You could do something with an active inductance simulation circuit that might work well, however.  I probably wouldn't worry about too many harmonics, especially since the 120Hz harmonic corresponds well to the Bb, so you don't want to notch that out.

[liddokun]

Doesn't the EH Dehummer use notch filtering ?

[biggy boy]

So are you taking about filtering your pedals power supply?
I used an RC filter (resistor capacitor filter) after the rectifier.  You calculate it at twice the supply freq. 100Hz , 120Hz respectively.
I googled  "RC filters" and found a calculator to find the values.

[Ripthorn]

I think he is talking about filtering the hum from the single coils.  That would be 50 or 60 Hz and I think he talking about notching that out along with possibly the harmonics.

[R.G.]

There is a reason that the world is not full of products like this.

60Hz is OK, it's quite a ways down from 82Hz (low E). However, the second harmonic is 120Hz. B is 123.47Hz. The third harmonic is 180hz; there are two notes straddling this one, 184.997Hz and 174.6Hz.To get a filter to notch the harmonics out and not affect the nearby notes too badly depends on what your definition of "too badly" means (thank you William Jefferson Clinton for your additions to the English language).

You can do this kind of thing in a DSP, OK. But it's insanely difficult in real electronics, which DSP is not. Worse yet, what happens when you bend one of these notes? Or don't use a tuner, but do it by ear and lay a note right over the filter?

CBS tried to do an analog copy protection scheme that used very deep notch filters "between" the notes of the musical scale and convince the world that it was inaudible. The world was smarter than that.

[Morocotopo]

So much for my idea. Sigh.

It would be interesting to see what the amplitude of the harmonics in relation to the fundamental is, it might be enough to filter just the fundamental. Of course the amplitude relationship would vary with instrument location, angle, room, city, temperature, player´s mood, lighting fixtures, planets alignment, etc. etc.

How about out of phase cancellation? Mixing an 180 degree out of phase "noise" sample with the signal? Hmmm. Where would you get the noise sample. you ask?
From a unshielded dummy pickup in the stompbox maybe? Or mounted in the guitar, that then would need a stereo out jack to get both signals to the pedal? From a signal generator? From the air with a particle accelerator?

[R.G.]

How about out of phase cancellation? Mixing an 180 degree out of phase "noise" sample with the signal? Hmmm. Where would you get the noise sample. you ask?

Congratulations. You have reinvented the manual hum canceller. See http://www.ethanwiner.com/filters.html
I have one I built. Works OK, but tends to need readjustment as you move around with a guitar. It's deadly effective for sitting in one spot, though. 

And it needs readjustment at each new site for that location's particular hum blend.

[Morocotopo]

Well, you know, stay still, man! Forget about your Angus Young impersonations!

Since I´m 41 years old, the idea of staying still while I play doesn´t seem so bad. Not that I can do anything else really. The "Old Man Single Coil Noise Reducer" is born? The box would have a legend that says: Caution. Do not use on people under 40.

[liquids]

Congratulations. You have reinvented the manual hum canceller. See http://www.ethanwiner.com/filters.html
I have one I built. Works OK, but tends to need readjustment as you move around with a guitar. It's deadly effective for sitting in one spot, though. 

And it needs readjustment at each new site for that location's particular hum blend.

For whatever reason it always seems that there is that 'one' spot, if I spin slowly where most of the hum cancels...sad, though to be stuck there.

I'm truly glad on a regular basis that my ears favor humbuckers, because I can't stand amplifyied hum!  My main guitar was a custom order with miswired humbuckers at the factory, humming oddly and bright as a tele...it was like that for months until I elimintated all the variables I could (was even up to gauge 13+ strings to get some meat to the tone), when I got the courage to  bring it back, and nearly was sent home with a "that's just the way it is" from the small shop I dealty with, till we tried one last thing and discovered the obvious. The hum drove me nuts.  I don't know what I'd do if I liked true single coils!  Worst gig I ever played was with a guy who insisted I play my strat...which is, ironially, now in the shop getting 'humbuckered!'   

My apologies and condolences to 'true' single coil tele and strat players here alike...

Does anyone else find it ironic that for all the crazy sounding crap we can build, there's no analog 'effect' way to transparently get rid of AC hum?  Even R.G. hasn't come up with a satisfactory way, which means it quite simply doesn't exist.   

We guitarist sure do use some old school, primitive electronic equipment for the sake of timbre when it comes down to it, don't we?   

[aron]

Look in the members forum. It's not an effect but a mod to the guitar. It exists.

Look for "Can't see clearly what is on this board...."

[Paul Marossy]

Use a good noise gate. That typically takes care of 60-cycle hum from single coil pickups. And of course, doing all of the things possible with shielding your guitar, etc. also helps. Sometimes quite a lot.

[Scruffie]

http://www.guitarnuts.com/wiring/shielding/shield3.php this sorted all noise on my strat, it's quieter than my les copy with hums, easy to do and it'll get rid of hum while helping to protect you from lethal shocks

[earthtonesaudio]

I think it'd be a heckuva lot easier to try and make your humbucker sound like a single coil.

[R.G.]

http://www.guitarnuts.com/wiring/shielding/shield3.php this sorted all noise on my strat, it's quieter than my les copy with hums, easy to do and it'll get rid of hum while helping to protect you from lethal shocks

Good point! I did this to my strat so many years ago I had forgotten. The difference is dramatic. This is probably the best place to start.

Does anyone else find it ironic that for all the crazy sounding crap we can build, there's no analog 'effect' way to transparently get rid of AC hum?  Even R.G. hasn't come up with a satisfactory way, which means it quite simply doesn't exist.  

I wish it were that definitive, but it's not.

We guitarist sure do use some old school, primitive electronic equipment for the sake of timbre when it comes down to it, don't we?  

We do. But the world has changed. There was not a single high gain fuzz pedal when the Strat pickups were designed, and not for many years after that.

Use a good noise gate. That typically takes care of 60-cycle hum from single coil pickups. And of course, doing all of the things possible with shielding your guitar, etc. also helps. Sometimes quite a lot.

Good advice. We put a very slight noise gate into the V2 series of pedals and made it switchable. The difference can be dramatic in some situations where you'd otherwise get hum and hiss. As for noise gate pedals, the Demeter one is quite good.

[Morocotopo]

Yeah, noise gates help, but I find objectionable that when they open with the signal, the freq of the hum interacts with the notes, generating intermodulation freqs that muddy up the sound...

The shielding and everything sure helps. Done it.

Didn´t know about the Suhr thingie, looks like a nice addition to a single coil guitar.

[bioroids]

About the relation between the fundamental and harmonics in the noise, in my experience is always the harmonics what bothers the most. You can get rid of the fundamental but that doesn't help too much reducing the audible noise. Sadly!

I've heard there are some designs that sound at least 95% of what a single coil sounds, but without the noise. I think that should be enough that anyone in the audience couldn't tell the difference (well, except for the fact that there's no noise!). There's dummy coils and stuff like that too. Maybe worth exploring those options, instead of butchering your audio with notch filters from 60 to 1200hz!

Regards

Miguel

[Paul Marossy]

Use a good noise gate. That typically takes care of 60-cycle hum from single coil pickups. And of course, doing all of the things possible with shielding your guitar, etc. also helps. Sometimes quite a lot.

Good advice. We put a very slight noise gate into the V2 series of pedals and made it switchable. The difference can be dramatic in some situations where you'd otherwise get hum and hiss. As for noise gate pedals, the Demeter one is quite good.

I'm not too sure about noise gate pedals, but I have a built-in noise gate in one of my old ART multi-FX units that works quite well. Some of other ones I have used sucked. I had one from DOD that was especially lame.  

I did notice that the new Visual Sound Jekyll & Hyde pedal has the built-in switchable noise gate. It actually works very well - kudos.

Anyhow, I'm sure that RG's suggestion is right on. My experience is from about fifteen years ago now, a lot has changed since then. I try to avoid using noise gates (and compressors - I hate them!), but sometimes they are the best solution to a noise problem.

Yeah, noise gates help, but I find objectionable that when they open with the signal, the freq of the hum interacts with the notes, generating intermodulation freqs that muddy up the sound...

The shielding and everything sure helps. Done it.

Didn´t know about the Suhr thingie, looks like a nice addition to a single coil guitar.

I never noticed that about a noise gate. The only thing I have really noticed is that some noise gate pedals are just not sensitive enough for my liking. I can't really use them, generally speaking.

I have heard that the Suhr method of shielding/grounding using a dummy coil at the back of the guitar works very well. Good shielding and proper grounding techniques will do wonders. But it's also only as good as your weakest link. On my SpankenStrat, I had to eventually change my single coils to some Fender "Hot Noiseless" types, because even though I shielded the heck out of the guitar and star grounded it, the hum was still there because of the cheap single coil pickups. And for the cost of a decent noise gate pedal, I permanently fixed the problem by putting better pickups into the guitar. 

[Paul Marossy]

with one of these you could avoid those hum cancelling pickups that never really sound like a single coil, even if they have been trying for some years now, and with each new model they tell you "this one really, really works!"

IMO, the Fender "Hot Noiseless" pickups that are in my guitar sound very much like single coils, just without the hum.

I think people generally associate hum with single coils, and when they don't hear that hum, they don't think that it sounds right. That 50-60 cycle hum probably does have something to do with their characteristic "dry" sound, but I'll gladly take no noise and 95% of the single coil sound over being annoyed with incessant humming all the time. I get greatly annoyed by that.

If I insisted on having "real" single coils, I would go the noise gate route.

[Morocotopo]

Speaking of noise gates, a friend gave me a MXR noise gate / line driver, must be 30 years old. Just a threshold control and a XLR out besides the usual out jack. No led. It´s the most unusable thing I´ve ever tried! Don´t know if it´s malfunctioning, but the gate part is awful!