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Eliminating guitar hum
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enginefire
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#1
29th November 2012
Old 29th November 2012
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Eliminating guitar hum -FIXED!!

Does anyone have a solution for this problem?

When recording directly into the daw, my guitar, a telecaster clone, gets a lot of hum whenever it is not turned and angled just right.

I plug the guitar into an old DIY di, just a trafo inside, and then into a FireWire interface using balanced xlr.

Is it possible to add an isolation transformer inside the guitar to stop the hum? would a better di with an ISO trafo like an utc a-20 or a Hammond 804 resolve this? Is there an active circuit that could eliminate this noise?

I don't mind trade offs, I can deal with a lower output or having ti drill extra holes and add switches. Btw the cavity is very well shielded with copper foil and the grounding is good star point already.

Thanks

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29th November 2012
Old 29th November 2012
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Hi
If the pickups and internal wiring are as 'correct' as can be and shielded (see guitar pickup threads elsewhere) then it may be your room that is the problem. You could use a battery powered amplifier and switch off ALL mains in the building, then put different circuits back on one at a time. It could be lights or power from your floor or above / below so NOTHING is ruled out initially. The problem may be a 'neutral' that is inadvertently grounded somewhere in the building on ANY of the connection points (sockets or light outlets) or it could be that live and neutral for a particular circuit are not physically tight together. say for multiple light switching where a live goes one way around a room and neutral goes a different physical route.
If playing with anything to do with the mains wiring, ensure there is someone with you 'in case' and consider getting an electrician in when you have got nearer the problem if rewiring is needed.
Apart from a dedicated 'notch' filter at your mains frequency NO little plug in boxes will really 'cure' the problem.
Matt S
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29th November 2012
Old 29th November 2012
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If the hum is being picked up by the pick-up coil, you may want to play inside a faraday cage... Problem is not in the interface after the pickup.

JR
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29th November 2012
Old 29th November 2012
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If you can turn the instrument and eliminate the hum, then an isolation transformer will do nothing for you. Your pickup coil itself is picking up a magnetic field. You (and your instrument) are apparently too close to some magnetic field-producing device.

Some microphones include a second coil to exactly cancel the hum from the induced magnetic field. Dunno why you couldn't do that with an e-guitar pickup?

Note: A Faraday cage will shield you from RFI, but NOT from a magnetic field. You would need to sit in a mu-metal box to isolate you from magnetic fields. And you would likely suffocate in there. Not recommended.

Of course, the obvious solution (at least IMHO) is to experiment with using your instrument as a "probe" to discover WHERE the magnetic field is coming from. Most likely a power transformer in some nearby equipment.
#5
29th November 2012
Old 29th November 2012
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dai h. is offline
single coils being noisy is normal. One solution is the Chiliachki/Suhr hum canceling coil (this is a product but some people have DIY'ed their own). (As I vaguely understand) it's a low resistance series coil w/the pickups surrounding them and helping to cancel hum (this seems to be more acceptable subjectively compared to other humbucking solutions (specifically the humbucking construction pickups constructed to sound like single coils)--I haven't tried one personally but just from reading and hearing sound samples).
enginefire
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30th November 2012
Old 30th November 2012
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dai h, I will investigate, I have been wanting to avoid changing the pickups to humbuckers, i like the sound of the instrument already, and to avoid having to route a bigger cavity. maybe the Chiliachki/Suhr is small enough already, I will read up on it!

Mr. Crowley, if costs were not an issue, I would certainly investigate creating a Nu Metal pickup cover, this might be just the trick! there are some regular (ol' ?) metal covers on the pickups right now.

I tried out an old navy trafo a little last night (20k to 600, but only flat up to 4k)... it sounded good, i think the hum was reduced, but there was an additional noise, which very well could have been added to the equation when I added a switch and different tone caps, again last night

there are also a lot of power transformers already in the room, but I figured it was easier to fix one guitar than to rewire and extend all the power. So far everything else has been pretty good for noise, even the console no longer dials in the radio in this new (ish) location.
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30th November 2012
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Here's the message for guitarists who are a bit slow.
BUY HUMBUCKERS! BUY HUMBUCKERS! BUY HUMBUCKERS!

I have often wondered why guitarists prefer the sound of their playing with added 50/60 Hz and harmonics when the solution is so easy. Yes, it will probably change the tone, but it will come with no added interference!

By the way, sheilding and screening all the electronics is crucial. I did a guitar recently, it had a humbucker but picked up so much noise on the internal wiring that you couldn't tell it had a humbucker. Sheilding the cavity with copper foil, shortening long wires, and adding screened cable made all the difference. And this guitar came badly wired from the factory!
enginefire
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30th November 2012
Old 30th November 2012
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Ill give the shielded wire a try, when I change the pots on it and redo the wiring (even tho its ok now, but if im changing pots, might as well add the wire mesh grounding sleeve... open on one end of course!)

Ill try lining the pickup covers with copper foil too... i dont know about the humbuckers, if nothing else works then i guess i will have to try that.
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30th November 2012
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Hum buckers do sound different, but I (think) have seen guitars with a switch so you can alternate between single coil and hum bucking when needed.

Maybe you don't need a mu metal cage, but perhaps a mu metal vest could alter the magnetic field near your axe. For playing live the hum bucker is useful if the hum bothers you, most guitars played WFO have hum, that's how you know they are turned on..

In a studio know your local magnetic fields and use a long enough cord for find your happy place..

JR
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30th November 2012
Old 30th November 2012
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drumdrum is offline
And stupid as it may sound, take your phone out of your pocket...

You'd be surprised.. You really would!
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30th November 2012
Old 30th November 2012
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microphonemania is offline
Theres a great quote from a session guitar guy on the Alan Parsons Art and Science of Sound video about guitar and noise/hum (Tim Pierce) etc
It's at: 1:57 on the youtube vid below

ASSR - Guitars (Marshall Edit) - YouTube

Something like and don't quote me "as a guitarist theres always noise...for me it's like how much noise...it's all about disguising noise"

He says his volume pedal has become an appendage to kill noise in between passages of playing....makes sense.
enginefire
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1st December 2012
Old 1st December 2012
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yep i guess i am just fighting against the inevitable... again.
humbucker pickup is the way to go, i know this, but am lazy (in my own very active way). My bass has a humbucker as its stock pickup and it is dead quiet. also has active electronics.

One last stretch... Clip on RFI EMI Filter Ferrite beads?
#13
1st December 2012
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Clip on RFI EMI Filter Ferrite beads may help if you problem is picking up the local radio station. But it will do absolutely nothing about ambient mains-frequency magnetic field pickup. Absolutely nothing.
enginefire
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1st December 2012
Old 1st December 2012
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but at least my guitar cable will look stylish!
ok so i surrender, humbucker upgrades it is, I cant get any work done with this noise.

maybe they make one of those beads big enough to go around my neck, you know, block out the voices
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1st December 2012
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Just get a battery powered Sound Devices 702 and play your guitar here:
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Eliminating guitar hum-field-recording.jpg  
#16
1st December 2012
Old 1st December 2012
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Speedskater is offline
Some guitars work as great interference detector test instruments. Walk around your room (and nearby rooms) find the spots or areas that the hum is the loudest. Check everything that's electrical. New style lights and lighting systems can cause hum. A burnt-out CFL bulb that's still connected is a great noise maker. Check Wall-Warts and TV Set-Top-Boxes.
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1st December 2012
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Now let me see, I can walk around the room finding all the sources of hum, or I can get humbuckers and play my guitar. Nah, why would I do that?
#18
2nd December 2012
Old 2nd December 2012
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Quote:
Originally Posted by Radardoug View Post
Here's the message for guitarists who are a bit slow.
BUY HUMBUCKERS! BUY HUMBUCKERS! BUY HUMBUCKERS!
Really? Do you think it is as simple as that? Cause they sound nothing alike...
Are you in the right business? Or are you a bit slow?
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3rd December 2012
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Yeah you are right! Non humbuckers just sound so good with all that hum on them!
You would be a guitarist then. I'm the one that guitarists are always asking to get rid of the hum in their guitars.
Music is not about being mixed with 50/60 cycle hum and harmonics. It doesn't fit. Period.
However if that is the sound you like, feel free to continue with it. Just don't complain to me when your guitar hums.
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enginefire
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3rd December 2012
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Ah in typical internet fashion this mediocre tread has devolved into bickering and opinion/circumstance as fact and absolute.

I have to say it disturbs me to read replies that cannot remain within the realm of good nature without resorting to jibes jabs ribs or other negativity. Yes we are all under pressure, but we really don't have to resort to being ducks about it.

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#21
3rd December 2012
Old 3rd December 2012
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Quote:
Originally Posted by Radardoug View Post
Yeah you are right! Non humbuckers just sound so good with all that hum on them!
You would be a guitarist then. I'm the one that guitarists are always asking to get rid of the hum in their guitars.
Music is not about being mixed with 50/60 cycle hum and harmonics. It doesn't fit. Period.
However if that is the sound you like, feel free to continue with it. Just don't complain to me when your guitar hums.
yeah, i guess you're right. That jimi hendrix dude really was slow... and all those albums sound like crap.
Imagine all the crappy albums with crappy guitar sounds that were and still are made with all that crappy 50hz hum. geesh.

thank god no one wants a f*cking crappy vintage telecaster anymore.
#22
6th December 2012
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Fighting hum with anti-hum.

Old consumer film projectors (with sound) had the tape heads very close to the BIG transformer for the projection light.
Hum pickup in those heads was a big problem.
They solved it by using a small coil in series with the head's ground wire.
That coil was mounted mid-air on a bendable support.
By bending/twisting it (phase/amplitude) you could cancel out the hum.
Not just hum, but all the crap that was picked up by the head.
Just wondering if this was ever used inside guitars.

I am also thinking: coil, FET, coin cell, for active hum cancellation.
Leo..
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6th December 2012
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[QUOTE=LeeYoo;8515577]Fighting hum with anti-hum.
....They solved it by using a small coil in series with the head's ground wire.
That coil was mounted mid-air on a bendable support.
/QUOTE]

It's called a Humbucker and is used in guitars that don't hummmmmmm. Some people don't like them because the second coil can change the character of the sound. Some people don't like bananas either. Its a matter of taste.

The Humbucker was first produced by Gibson in 1957 and granted a US patent in July 1959.

For some guitarists I've heard, a coil that bucks all of the output from their pick-up would be a good thing, however it would be a really "hard sell".

Anti-hum is your friend, in fact, so is anti-matter
#24
6th December 2012
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Hi
For those more inclined, I believe that a 'problem' of humbuckers is that they materially mess with the 'sound'. How about having a humbucking coil which picks up the '(usually mains induced) noise but then rather than having it simply in series to 'cancel' the hum, put the bucking coil signal through a low pass filter with moderate sharp cutoff at say 240Hz (or lower if it is for bass) and use this to cancel the hum. In this way the majority of the wanted signal would be unmolested. At present the humbucking coil is not frequency band limited. Having the filter adjustable and switched out on occasions of 'low interference' should please most.
Matt S
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6th December 2012
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Given the cost of a good guitar, the cost of applying such an active hum cancellation system would be a relatively low-cost option. A phase control and a signal level control might be needed to occasionally trim the cancellation, although that could be automated with a tiny processor that would store control values and perform a new cancellation with the touch of button when needed.

A quick search found that it's been done commercially in the Fender Elite and the Ernie Ball "Silent Circuit". Both apparently use an independent coil (usually called the "dummy coil") and active cancellation. The Ernie Ball version seems to have high praise from the "I wouldn't be caught dead playing a humbucker" camp. Even the "hard-core" humbucker haters, seem to be able to accept the active cancellation method.

Here's a link to the Fender Elite circuit.

It uses a simple resistive summer and does not use any bandpass filtering on the "hum" channel.
#26
6th December 2012
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Hi Lotus 7
I know how a humbucker works, but The Ernie Ball "Silent Circuit" in your second post is what I was thinking off.
A pickup circuit that doesn't pick up sound, but just picks up the airborne crap.
And feeds that back into the guitar circuit as anti-sound.
Didn't know there was that much info about it on the net.
Time to get the soldering iron out.
Leo..
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7th December 2012
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If the hum bucking coil was properly designed the hum bucking would not be stepping on the signal so much, but apparently wanted string sound is canceling too.

The second coil, needs to be away from the strings, but not so far away that the hum does not track well.

this sounds promising.

one coil sound but with less hum...

Sounds like a good concept.

JR
#28
7th December 2012
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Just brainstorming.
How about three small coils in a triangle, spread out over the guitar body (not too far from the pickups).
Something like those telephone suction cup pickups.
When connected in series, it will give a virtual center where the pups are.
Leo..
#29
9th December 2012
Old 9th December 2012
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I had the same problem with my strat and tele. Shielded the control cavity with copper tape and changed the ground location. Totally fixed it.
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enginefire
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9th December 2012
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How did you change up the grounding? I will give that a try.

In the meantime I resolved the problem by using an SG knockoff instead. two humbucking pickups, no more hum. no more tele sound either, but that is the trade off
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