Wiring problem? Help please guys
- Thread starter Diocletian
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Diocletian
BrandNewGlossologist
Re: Wiring problem? Help please guys
Thanks again, I'll give this a go when I get a chance!
Thanks again, I'll give this a go when I get a chance!
octavedoctor
New member
Re: Wiring problem? Help please guys
It does make a difference.
if you wire the pots as potential dividers (as Robert S. is suggesting) , i.e. with the output coming from the wiper (middle) tag and the input going to the track end opposite the one that is grounded then when the volume control is turned down the pickup is shorted out and so is the output of the guitar. This results in less noise from the amp as the input of the amp is also shorted to earth. This is the default wiring pattern for all modern Gibsons.
However if you have both pickups in circuit the second pickup will also be shorted out, so you can't use the two volume controls fully independently. Some people overcome this by putting a 10k to 20k resistor between the end tag and the pot casing creating a buffer resistance between the global signal path and earth. This mod means that the pickups are never fully shorted to earth and this can cause the bleed that is being experienced.
If you wire it the other way, with the pickup signal wire to the wiper and the output from the distal end of the track (as in a Fender Jazz Bass) you don't need this buffer as the track value of each pot forms a fixed buffer resistance between the global signal path and earth. This allows both volume controls to be used independently but only if you use one at a time because as you turn the control down, the impedance shown by the pickup/volume control combination goes up; this is fine as long as the other pickup is operating at full volume as the impedance of this pickup will be pulling down the global impedance seen by the amp but if you try to turn both down the impedance seen by the amp rises dramatically and you get hum...
Possible causes of signal bleed;
Cable crosstalk: using multiple core screened cable to carry the signal from two parallel pickups. i think this is very unlikely as the voltages are so small it is unlikely that inductive coupling can occur, however i wouldn't rule it out and replacing the standard 4-core cable with individually screened cable might be worth as try.
Magnetic inductive coupling: my money's on this, but there's not a hell of a lot you can do about it. This happens when disturbances in the magnetic field of one pickup are mirrored in a neighbouring coil.
Reading back to the OP, I began to wonder how you can tell that you are hearing the neck pickup when you are switched to the bridge position; this would seem to be a very difficult thing to diagnose by listening alone. What tests have you done to establish that this is actually happening?
It does make a difference.
if you wire the pots as potential dividers (as Robert S. is suggesting) , i.e. with the output coming from the wiper (middle) tag and the input going to the track end opposite the one that is grounded then when the volume control is turned down the pickup is shorted out and so is the output of the guitar. This results in less noise from the amp as the input of the amp is also shorted to earth. This is the default wiring pattern for all modern Gibsons.
However if you have both pickups in circuit the second pickup will also be shorted out, so you can't use the two volume controls fully independently. Some people overcome this by putting a 10k to 20k resistor between the end tag and the pot casing creating a buffer resistance between the global signal path and earth. This mod means that the pickups are never fully shorted to earth and this can cause the bleed that is being experienced.
If you wire it the other way, with the pickup signal wire to the wiper and the output from the distal end of the track (as in a Fender Jazz Bass) you don't need this buffer as the track value of each pot forms a fixed buffer resistance between the global signal path and earth. This allows both volume controls to be used independently but only if you use one at a time because as you turn the control down, the impedance shown by the pickup/volume control combination goes up; this is fine as long as the other pickup is operating at full volume as the impedance of this pickup will be pulling down the global impedance seen by the amp but if you try to turn both down the impedance seen by the amp rises dramatically and you get hum...
Possible causes of signal bleed;
Cable crosstalk: using multiple core screened cable to carry the signal from two parallel pickups. i think this is very unlikely as the voltages are so small it is unlikely that inductive coupling can occur, however i wouldn't rule it out and replacing the standard 4-core cable with individually screened cable might be worth as try.
Magnetic inductive coupling: my money's on this, but there's not a hell of a lot you can do about it. This happens when disturbances in the magnetic field of one pickup are mirrored in a neighbouring coil.
Reading back to the OP, I began to wonder how you can tell that you are hearing the neck pickup when you are switched to the bridge position; this would seem to be a very difficult thing to diagnose by listening alone. What tests have you done to establish that this is actually happening?
octavedoctor
New member
Re: Wiring problem? Help please guys
It's not that they are wiring in a fault (although they've done plenty of that in their time) but they have to choose one of two ways of doing it and wiring the pots as potential dividers causes less problems than the other way.
It's not that they are wiring in a fault (although they've done plenty of that in their time) but they have to choose one of two ways of doing it and wiring the pots as potential dividers causes less problems than the other way.
Diocletian
BrandNewGlossologist
Re: Wiring problem? Help please guys
Well, if I tap the pickup with like a screwdriver or something, I can hear which one is making the noise.
Also, if I turn down the bridge pickup completely, and can still hear something, that something goes away when I turn down the other pups volume control.
Well, if I tap the pickup with like a screwdriver or something, I can hear which one is making the noise.
Also, if I turn down the bridge pickup completely, and can still hear something, that something goes away when I turn down the other pups volume control.
Robert S.
Super Moderator
Re: Wiring problem? Help please guys
Just wait for the thank you Artie, it is coming!
Just wait for the thank you Artie, it is coming!
Re: Wiring problem? Help please guys
Man, I couldn't ever figure out why my friends Jackson V was doing that...I wired it all up correctly according to the EMG wiring Diagrams.....and then I tried putting the pickup hot to the third terminal....solved the problem!!
HOW COME NO ONE HAS NOTICED THAT ALL THE EMG PICKUP DIAGRAMS CAUSE THIS PROBLEM?!
Man, I couldn't ever figure out why my friends Jackson V was doing that...I wired it all up correctly according to the EMG wiring Diagrams.....and then I tried putting the pickup hot to the third terminal....solved the problem!!
HOW COME NO ONE HAS NOTICED THAT ALL THE EMG PICKUP DIAGRAMS CAUSE THIS PROBLEM?!
octavedoctor
New member
Re: Wiring problem? Help please guys
Well if the vol controls are functioning independently, it must be wired reverse PD, like a Jazz Bass.
Follow Robert's instructions and rewire as PD's. While you are at it, check for a bad connection between the end of the track and the pot casing. That can cause this problem as well.
Well if the vol controls are functioning independently, it must be wired reverse PD, like a Jazz Bass.
Follow Robert's instructions and rewire as PD's. While you are at it, check for a bad connection between the end of the track and the pot casing. That can cause this problem as well.
blueman335
Mojo's Minions
Re: Wiring problem? Help please guys
When I helped a friend out with his EMG's, as far as the lugs (volume, I think)the diagram from their website was different than the one that came with the PU's. Did they change something, or just screw up?
When I helped a friend out with his EMG's, as far as the lugs (volume, I think)the diagram from their website was different than the one that came with the PU's. Did they change something, or just screw up?
octavedoctor
New member
Re: Wiring problem? Help please guys
As far as I am aware, EMG have always used the PD pattern for volume controls, however EMG play by different rules; because they have a low impedance output if you use a reverse PD configuration it works because even with both volume controls turned down the impedance seen by the amp is only 12.5kohms which is enough for effective input damping. A Gibson with standard humbuckers wired in reverse PD config will present 220K to the amp so the amp sees a lead with an open circuit at the end and you get hum. So with EMGs it doesn't matter so much which configuration you use.
As far as I am aware, EMG have always used the PD pattern for volume controls, however EMG play by different rules; because they have a low impedance output if you use a reverse PD configuration it works because even with both volume controls turned down the impedance seen by the amp is only 12.5kohms which is enough for effective input damping. A Gibson with standard humbuckers wired in reverse PD config will present 220K to the amp so the amp sees a lead with an open circuit at the end and you get hum. So with EMGs it doesn't matter so much which configuration you use.
Re: Wiring problem? Help please guys
still had the same problem though...using high gain, you could hear the neck pickup bleeding through when the bridge was off. after spending 5 hours wiring and rewiring it again and again trying to get rid of that bleed, I'd be extremely happy if EMG would change their schematic to prevent this from happening to a lot of other people.
still had the same problem though...using high gain, you could hear the neck pickup bleeding through when the bridge was off. after spending 5 hours wiring and rewiring it again and again trying to get rid of that bleed, I'd be extremely happy if EMG would change their schematic to prevent this from happening to a lot of other people.
octavedoctor
New member
Re: Wiring problem? Help please guys
you will get this with either configuration. The only reason you notice it with the reverse PD is that you can use both volume controls independently. With a PD config you can't because with both pickups in circuit if you turn one control down it shorts out both pickups. And at high gain there are all sorts of things that can cause crosstalk between pickups; inductive coupling between pickups and adjacent wiring: magnetic coupling via the strings and the earth's magnetic field: acoustic coupling through body resonances...
I think you guys worry far too much about things that really aren't significant problems in the grand scheme of things. I've had acoustic guitar players obsessing over fret buzz and clicks and scrapes that only they can hear and which no audience is going to give a flying firkin about.
It's the same with this; you are the only one who can hear it, and who is bothered by it...
you will get this with either configuration. The only reason you notice it with the reverse PD is that you can use both volume controls independently. With a PD config you can't because with both pickups in circuit if you turn one control down it shorts out both pickups. And at high gain there are all sorts of things that can cause crosstalk between pickups; inductive coupling between pickups and adjacent wiring: magnetic coupling via the strings and the earth's magnetic field: acoustic coupling through body resonances...
I think you guys worry far too much about things that really aren't significant problems in the grand scheme of things. I've had acoustic guitar players obsessing over fret buzz and clicks and scrapes that only they can hear and which no audience is going to give a flying firkin about.
It's the same with this; you are the only one who can hear it, and who is bothered by it...
Diocletian
BrandNewGlossologist
Re: Wiring problem? Help please guys
Well to be honest, I was worried that it would be affecting the tone of each pickup. You know, I'm not getting the pure tone of one pickup, it's always a blend of the two.
I haven't got around to changing the wiring yet, but I will soon! :1:
you will get this with either configuration. The only reason you notice it with the reverse PD is that you can use both volume controls independently. With a PD config you can't because with both pickups in circuit if you turn one control down it shorts out both pickups. And at high gain there are all sorts of things that can cause crosstalk between pickups; inductive coupling between pickups and adjacent wiring: magnetic coupling via the strings and the earth's magnetic field: acoustic coupling through body resonances...
I think you guys worry far too much about things that really aren't significant problems in the grand scheme of things. I've had acoustic guitar players obsessing over fret buzz and clicks and scrapes that only they can hear and which no audience is going to give a flying firkin about.
It's the same with this; you are the only one who can hear it, and who is bothered by it...
Well to be honest, I was worried that it would be affecting the tone of each pickup. You know, I'm not getting the pure tone of one pickup, it's always a blend of the two.
I haven't got around to changing the wiring yet, but I will soon! :1:
octavedoctor
New member
Re: Wiring problem? Help please guys
I hear what you are saying, and I guess it depends on the level at which the redundant pickup bleeds, but i don't think you'd notice any real difference in tone, especially if you are overdriving the amp at high gain.
I hear what you are saying, and I guess it depends on the level at which the redundant pickup bleeds, but i don't think you'd notice any real difference in tone, especially if you are overdriving the amp at high gain.
octavedoctor
New member
Re: Wiring problem? Help please guys
Just fitted a couple of Duncan P.90s to a custom tele and got this exact problem. If i turn the volume of the redundant pickup down and switch it out of circuit and hold a tuning fork to the pickup I get a faint signal coming through. It still happens even if you disconnect the pickup.
My guess is that the pickups are coupling magnetically, so that the signal is being induced in the active pickup coil, but via the magnetic filed of the redundant pickup as both magnetic fields couple via the strings and the earth's geomagnetic envelope.
Just fitted a couple of Duncan P.90s to a custom tele and got this exact problem. If i turn the volume of the redundant pickup down and switch it out of circuit and hold a tuning fork to the pickup I get a faint signal coming through. It still happens even if you disconnect the pickup.
My guess is that the pickups are coupling magnetically, so that the signal is being induced in the active pickup coil, but via the magnetic filed of the redundant pickup as both magnetic fields couple via the strings and the earth's geomagnetic envelope.
