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Topic: What would cause this kind of hum? |
Peter den Hartogh
From:
Cape Town, South Africa
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Posted 30 Sep 2011 11:29 am |
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I noticed that my steel guitar pickups (single coils only) hum a lot when they are in their normal position,
i.e. the pole pieces are pointing up (vertical)
When the whole guitar is turned, so the pole-pieces are horizontal, the hum disappears completely.
So I took a spare single coil pickup, connected it directly to my Microcube Amp and tested it for hum.
This time the Amp is run from batteries, so any disturbance from the mains power supply is avoided.
There were no connections to pedals, tuners or effects.
The problem was exactly the same:
- Vertical pole-pieces position = hum
- Horizontal pole-pieces position = no hum at all.
This happened everywhere in the house.
I tried it with different single coil pickups and cables with the same result.
What would cause this kind of hum?
_________________
1977 Sho~Bud D10 ProIII Custom; Sho~Bud SD10 The Professional ; ETS S10 5x5;
Fender 1000; 1993 Remington U12; 1978 Emmons S10 P/P; GeorgeB Weissenborn;
Fluger Cat-Can; Asher Electro Hawaiian; Gibson BR4; Fender FS52; Guyatone 8str;
Fender Resonator ; Epiphone Coronet 1937; Rickenbacher Ace; Rickenbacher NS;
Dynalap 8string; Harbor Lights 8string; Aiersi Tri-Cone; Fender Stringmaster |
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Earnest Bovine
From:
Los Angeles CA USA
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Posted 30 Sep 2011 2:59 pm
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| Play sideways, or put the hum sources on the roof. |
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Paul Arntson
From:
Washington, USA
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Posted 30 Sep 2011 3:29 pm
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Sounds like "inductive coupling" interference.
Any loop of wire parallel to your pickup windings (that is, with the pickup's pole pieces pointed at the center of the circle) that is carrying AC current will cause this. Could be house wiring if the neutral is a separate run from the hot, could be fluorescent ballast, could be transformer out on the pole (all of above has happened to me at some time).
The only real cure I know is a humbucking pickup or hold the guitar weird so it doesn't hum.
You could try sitting in a box of mu-metal shielding, but no guarantees. Or try various locations next to a large piece of iron, where the offending field will be distorted.
One good thing, the hum should decrease rapidly as you get distance from the source, so you might be able to get away from it.
PS I love your avatar. I about broke my monitor trying to swat it. |
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Peter den Hartogh
From:
Cape Town, South Africa
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Posted 1 Oct 2011 12:33 am
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Thanks for the replies, guys. I walked around the house with the "set-up" to find the source. No luck. It hums the same all over. Next step is to go outside and search more.
<----Paul, it is a Humbug.  |
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Paul Arntson
From:
Washington, USA
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Posted 1 Oct 2011 8:12 am
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A friend of mine cleared out his garage (a small building out back of his house) and made a nice studio/performance space. I went over early one morning to record with him and noticed a slight hum. I also was using a microcube, so no chance of power line bleed-thru. We kept turning off circuits trying to find it. Eventually we turned off the main power for his whole house and it was still there. My only guess is that it must have been coming from the power lines or the power transformer out in the alley. The earth beneath you can be part of the loop in some cases (at least in the US, where the return line is grounded.)
Good luck. If you find what it is, please post for general knowledge.
It might also be good to test with a different battery powered amp that doesn't have the built in noise gate that the microcube has.
Thanks and best of luck.-Paul |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 1 Oct 2011 9:56 am
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The best solution for those who are determined to use single-coil PUs, is to wire it to a balanced buffer-amp stage - similar to that used for regular microphones but tolerating higher signal-levels. With balanced (+/-) signal and separate ground, mains-interference will be zero.
Seem to remember that one such stage/wiring was posted on this forum (less than a year ago ? ) so do a search. |
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Peter den Hartogh
From:
Cape Town, South Africa
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Posted 2 Oct 2011 1:14 am
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I borrowed a DI Box (Direct In) from Nic du Toit but that did not seem to help.
Maybe I did not use it properly, so I am going to try it again. |
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Paul Arntson
From:
Washington, USA
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Posted 2 Oct 2011 3:27 pm
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Georg, I respectfully beg to differ. The solution you describe works perfectly for common mode noise, but not transverse. What Peter is experiencing seems to be transverse mode, directly induced in the pickup by an external field. I know that sounds like pompous bafflegab, and I apologize for that, but I think I have the terminology correct.
A humbucker pickup would be more immune to the field Peter is experiencing, sorry to say. There are also "dummy coils", which are pickups without the magnets, placed parallel to and in opposite polarity to the existing pickup.
Last edited by Paul Arntson on 2 Oct 2011 4:16 pm; edited 1 time in total |
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Paul Arntson
From:
Washington, USA
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Posted 2 Oct 2011 4:15 pm
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| oops double post... |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 2 Oct 2011 7:32 pm
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In the front part of my house, we are near the power line transformer outside on the pole. Single coil pickups hum like crazy. Generally, that's what we all suffer from, the hum in the space around us. It varies from location to location, but we will ALL be faced with the problem if we play music. Music venues can be some of the worst environments of them all.
The hum is in the air around you. Wiring, balancing, grounding schemes, etc. won't fix it. Humbuckers are the solution even if they are a tonal step down from the single coil sound. Find the best sounding humbucker and learn to live with the compromise.
Brad |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 2 Oct 2011 8:25 pm
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| Paul Arntson wrote: |
| Georg, I respectfully beg to differ. |
Noted 
The "dummy" coil you mention wired in separately (reversed), alongside a single-coil, to separate buffers, may be the best of all options for dedicated single-coil users. Balancing out the hum is then done by mixing signals from two coils after the buffer stages, so nothing gets lost of a well-loaded single-coil's superior sound. If the dummy is placed in the PSG, a 3-point (stereo) jack must be used. Correctly wired the dummy will then be short-circuited if a regular (mono) jack is inserted, which actually is fine in situations/venues where hum isn't a problem.
Same can of course be done to humbucker PUs that provides access to wires so they can be wired up as two single-coils going to separate active buffers. A humbucker will then sound much more like a single-coil since its impedance in practice will be halved and properly loaded as two halves. |
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Posted 3 Oct 2011 5:57 am
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Wrap the guitar in aluminum foil! 
_________________
--carl
"The better it gets, the fewer of us know it." Ray Brown |
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Greg Cutshaw
From:
Corry, PA, USA
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Posted 3 Oct 2011 7:28 am
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USA infrastructure is very old. In addition to hum around my house, all the line transformers suffer from severe internal arcing and won't be replaced until they die.
It's time to ditch electromagnetic pickups in favor of optical. Honeywell has a patent on an optical sensor that could be used to make a pickup. It might even enhance the string sustain ever so slightly!
Greg |
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Peter den Hartogh
From:
Cape Town, South Africa
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Posted 3 Oct 2011 11:27 am
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I have 2 humbuckers that work well...a 10 string Alumitone on my Bud Professional and a Danny Shields "CrapTrap" on my Remington U12.
All other humbuckers I have in my steels are too muddy.
I experimented with humbucker polepiece adjustments to make them sound more like single coils, but the results were disappointing.
Playing the guitars sideways needs more practice than I thought. 
Where can I get 6 and 8 string Alumitones for lapsteels?
_________________
1977 Sho~Bud D10 ProIII Custom; Sho~Bud SD10 The Professional ; ETS S10 5x5;
Fender 1000; 1993 Remington U12; 1978 Emmons S10 P/P; GeorgeB Weissenborn;
Fluger Cat-Can; Asher Electro Hawaiian; Gibson BR4; Fender FS52; Guyatone 8str;
Fender Resonator ; Epiphone Coronet 1937; Rickenbacher Ace; Rickenbacher NS;
Dynalap 8string; Harbor Lights 8string; Aiersi Tri-Cone; Fender Stringmaster |
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John Billings
From:
Ohio, USA
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Steve Ahola
From:
Concord, California
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Posted 3 Oct 2011 11:08 pm
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I've noticed the exact same thing in my house (condo)- the single coil pickups hum more when parallel to the floor.
I experimented with dummy coils on my regular guitars back in 2003/4. I used P-90 coils without the pole pieces and magnets. Here is a sound sample demonstrating the dummy coil I put in one of my strats:
http://www.blueguitar.org/new/mp3/samples/dummy_coil_strat.mp3
And here is an article I wrote explaining how I added a dummy coil to my Les Paul Jr:
http://www.blueguitar.org/new/articles/blue_gtr/gtr/paul_jr_revisited.pdf
However all of that was "old school" dummy coils which added some compression to the sound by the rather drastic change in impedance. The Suhr system for strats uses a completely different kind of dummy coil that is mounted under the trem plate. A much heavier gauge wire so the coil has a very low DC resistance and when wired in series with the single coil pickup it is very transparent. Here is a PDF of the patent application:
http://www.blueguitar.org/new/misc/patents/pat_20050204905_chiliachki.pdf
The schematic in Figure 5 is interesting as the dummy coil is bypassed with a 10k trimmer (to adjust the amount of hum cancelling) and its own tone control, a 10k trimmer with a 0.047uF cap to ground. With those two adjustments you can come up with a compromise between optimum tone and optimum humcancelling.
Steve Ahola
P.S. I was just thinking of a really cool upgrade for a dual neck console steel like the Gibson Console Grande: have someone like Jason Lollar wind you a pickup that is RWRP (reverse wound reverse polarity) with respect to the stock pickup. When both necks were switched on you would get a humcancelling effect from the two pickups.
_________________
www.blueguitar.org
Recordings on electric guitar:
http://www.box.net/blue-diamonds
http://www.box.net/the-culprits |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 4 Oct 2011 5:21 am
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I like Georg's idea of the dummy coil but with the added step of having buffers for each coil. That would prevent the two coils from loading eachother down and killing the single coil tone. Then Scott Swartz's may be the right tool for this job.
Scott??
Brad |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 5 Oct 2011 9:44 am
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Thinking out loud...
If the dummy coil and dual buffer amp with 9 Volt battery get built into a small plastic-box (to expose the dummy coil to the hum-source), with one buffer acting as a regular, fixed or regulated, impedance buffer and the other, regulated, buffer for the "hum pick-up" dummy coil, the whole box can either have a mounted male jack for plugging directly into the steel and rotated on the jack-connection for optimal hum-suppression, or it can have female jacks and be attached on the PSG leg and be connected via short cords.
A couple of mini-switches and pot-meters to turn on/bypass and set the load on the PU and balance the hum-suppression, should fit on/into a pretty small plastic box (two-third the size of a BOSS stomp-box or something), along with coil, battery, a quad-amp IC and a few resistors and capacitors on a circuit board.
Such a small "buffer/hum-suppression" box can then be plugged into the sound-chain and will do its job on any, non-modified, PSG whenever hum becomes a problem, and be left out or kept in the sound-chain when hum isn't a problem. If there's no hum the dummy coil won't pick any up either, and the PU buffer will still act as a buffer for those who like to have one. |
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