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Topic: Need some expert electronics information |
Jerry Roller
From:
Van Buren, Arkansas USA
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Posted 23 Jun 2016 8:54 am |
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Does anyone know if it is possible to somehow run from a single coil pickup into or thru a humbucker pickup before it goes to the amp to get the sound of the single coil but hum free benefit of the humbucker? I have a Hum-X which in some cases helps but not always.
Can anyone help with this? I think Travis Toy has some kind of device under his guitar but I have no idea what it is.
Thanks,
Jerry
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http://www.littleoprey.org/ |
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Jack Stoner
From:
Kansas City, MO
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Posted 23 Jun 2016 9:32 am
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| Supposedly if you have a D-10 with single coil pickups and have the neck selector switch in the position that both necks are on, having both pickups in the circuit sort of acts like a hum bucker. |
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Jack Stoner
From:
Kansas City, MO
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Posted 23 Jun 2016 9:32 am
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| Supposedly if you have a D-10 with single coil pickups and have the neck selector switch in the position that both necks are on, having both pickups in the circuit sort of acts like a hum bucker. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 23 Jun 2016 10:08 am
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What Jack said, but it will only work optimally if the single-coils are identical and phased 180 degrees (out-of-phase) relative to each other.
On an S10 you can get good results by mounting a single coil PU - ideally identical to the one on top but connected in reverse - inside the body and connect it via a switch when the hum becomes a problem. The problem may be to get this extra PU mounted with the same orientation as the one on top so it picks up the same noise-field, while also keeping it from picking up rod-noise etc from the mechanics. |
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Bob Hoffnar
From:
Austin, Tx
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Posted 23 Jun 2016 10:32 am
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I would look into the Alembic Bass "dummy" pickup system for informed insights. The have been using it for over 50 years.
I think the D10 thing might be an illusion that comes from the output dropping in half when you turn on both necks.
I'm not sure that the direction of the pickup windings make much difference. In my experiments it didn't change anything.
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Bob |
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Jerry Jones
From:
Franklin, Tenn.
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Posted 23 Jun 2016 2:05 pm
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I think an identical coil connected through a differential amp will work.
Added this:
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Jerry Jones
Last edited by Jerry Jones on 23 Jun 2016 5:18 pm; edited 1 time in total |
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Bruce Derr
From:
Lee, New Hampshire, USA
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Posted 23 Jun 2016 5:12 pm
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| I've been wanting to try something along those lines for a long time. Buffer your favorite single-coil pickup, then mix in a cancelling noise signal from a separately buffered dummy coil. Maybe it wouldn't have to be an identical pickup if its buffer had a gain adjustment. It would be an interesting experiment. Essentially a differential amp but with variable gain for the inverting input. |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 23 Jun 2016 5:19 pm
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Jerry, Bruce,
Neat idea, perhaps make it rotatable like a directional antenna. In effect, that just what it is.
In theory you should be able to get a deep null.
Craig
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"Make America Great Again". . . The Only Country With Dream After Its Name. |
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Bruce Derr
From:
Lee, New Hampshire, USA
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Posted 23 Jun 2016 7:52 pm
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Jerry, that's pretty much the topology I had in mind, except with part of R2 variable for gain adjustment. If it turns out the amount of gain needed for cancelling noise doesn't change much once adjusted, a trimpot would do; otherwise a pot with knob. I hadn't thought it through as far as identifying a suitable opamp, etc. so I'm interested in your choice of the 4250.
Craig, a directional noise pickup might be necessary but I wonder if a simple round coil, positioned vertically, might be adequate if its signal level was adjustable in the buffer. Maybe even the right off-the-shelf inductor would work. The idea would be to have relatively omnidirectional sensitivity, and adjust for minimum noise using the gain knob.
Maybe you could cobble together a prototype to try! You could call it the L'il Buzzy.  |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 23 Jun 2016 8:14 pm
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Bruce,
With my luck, it would distort and I'd end up with Li'l Fuzzy. LOL
No doubt the hum nulling device would be a trial and error project but exciting to get it working.
Years ago, in rural, PA, I worked for a radio station with a loud studio window air conditioner. We hung a matching mic from the ceiling the same axis as the DJ mic and ran it our of phase to a pot on the board. The DJ could null most of the AC in his headphones. Enough that you couldn't hear it on the air.
The guitar deal would probably work even better.
Craig
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"Make America Great Again". . . The Only Country With Dream After Its Name. |
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Bob Hoffnar
From:
Austin, Tx
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Posted 23 Jun 2016 9:13 pm
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Do the pickups need to be active for the dummy coil to work ?
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Bob |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 24 Jun 2016 12:44 am
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| Bruce Derr wrote: |
| The idea would be to have relatively omnidirectional sensitivity, and adjust for minimum noise using the gain knob. |
A "relative omnidirectional" noise-PU would hardly ever sense the radiating hum-field with the same phase and curve-shape as the regular PU, which means just balancing out signal-strength from the two coils for canceling out the hum will be a real hit-and-miss and largely depend on orientation of the instrument/coils. Might work in a studio where one has time and space to adjust for optimal positioning of instrument and noise-PU relative to each other and the present noise-radiation, but not very practical in most other venues.
Although the noise-PU does not have to be identical to the regular PU, it has to be mounted close to and in plane/orientation with it - literally be tuned to how the original PU picks ut hum. Then the mentioned trim-pot to balance out levels from the two coils is likely to work as intended to cancel out hum at least as well as a regular humbucker PU does.
A decade of running and providing technical support to chains of local radio stations back in the days - around -82 to -95, provided me with plenty of challenges related to solving mains-radiation problems and resulting hum.
When the physical setups could not be changed to avoid the radiation, I more than once introduced noise-pu-coils and canceling circuits. I designed, built and put in place all such solutions myself, so I know very well how to make them work. And if they stopped working properly - as happened from time to time - it was always because others messed with the setups - the "human factor"...
| Bob Hoffnar wrote: |
| Do the pickups need to be active for the dummy coil to work ? |
No, but the chances of getting all factors right in all situations with an entirely passive hum-canceling setup, are quite small compared to what one can achieve with an adjustable active setup.
So, unless a passive setup is built "fixed" - more or less like a regular humbucker PU, it most likely will fail to do its hum-cancelling job more often than not. |
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Jeff Bollettino
From:
Virginia, USA
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