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The Peter Green mod ?

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The Peter Green mod ?

Postby SecretSam » Fri Sep 20, 2019 7:08 am

I am expecting the answer 'no', but ....

Has anyone succeeded in creating a switchable version of the Peter Green mod (the one where the neck humbucker is upside down and inside out) ?
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Re: The Peter Green mod ?

Postby Wonks » Fri Sep 20, 2019 7:47 am

Of course. But you need a 4-conductor pickup.

The fact that the neck pickup was installed with the screws facing the bridge, not the neck, is purely cosmetic and does not affect the phase at all. There may be a very minor effect on the sound as the screw pole pieces are that bit nearer to the strings in a different place along the string length, but it is very minor. You'll get more of an affect by adjusting the height of the screws.

It's the fact that the magnet was put back flipped that changed the polarity of the output.

All you need to do is have a switch, or a switched potentiometer, that can reverse the ground and signal wire connections of one of the pickups. It's a very simple mod.

If both pickups are screen + 1 conductor types, then you can do it but the reversed polarity position will be very noisy, as the signal is now unscreened.

To get a good PG sound, then you'll really need as close a match for the pickups and guitar as possible. So certainly PAF type pickups. Bare Knuckle's PG set would be ideal - but you'd need to make sure that one pickup had 4-wire connection if you wanted to make the polarity change switchable.

You aren't guaranteed to get a nice sound with polarity reversed pickups, it's all a bit hit and miss. With some pickup combinations, the sound can be very thin and nasally indeed, which is why I'd recommend starting off with classic PAF types with similar outputs. You'll certainly get a different sound using say the popular SD JB and SD Jazz combination.

On a related note, I've been surprised at how there's no standard for pickup polarity between manufacturers. I've fitted quite a few now where the result in the/a mixed position was 'out-of-phase'. Easy enough to remedy with 4-wire humbuckers or two-wire single coils, but on a 2 x single conductor humbucker setup, it's far more complicated.

You then have to take the pickup apart and flip the magnet by 180° along its long axis and put it back together again. A lot harder on covered pickups where the pickup really needs to be repotted with wax afterwards.

So unless you are buying all your pickups from the same manufacturer, with humbuckers, it's wisest to opt for 4-conductor wiring over single conductor wiring (if its an option).
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Re: The Peter Green mod ?

Postby Dave B » Fri Sep 20, 2019 8:10 am

Out of interest, Wonks, did you try that on the Lemondrop? (or did it come like that?)

If so, how did you find it?
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Re: The Peter Green mod ?

Postby Wonks » Fri Sep 20, 2019 8:18 am

I found it in it's case. ;)

The Vintage Lemon Drop came with polarity reversed pickups. The mixed position was quite 'Greeny'. However, there was something amiss with the bridge pickup as it was very thin sounding on its own, and also pretty microphonic. If you can remember, we met up at Max's place and I took it along and he definitely didn't like the bridge pickup.

So that got replaced by a Bare Knuckle PG bridge pickup that I picked up cheap from eBay. However, it turned out to be in phase with the neck pickup, so I got standard LP tones from it. I could have swapped the neck pickup polarity (the PG pickup was single conductor) but I couldn't be bothered as my Jimmy Page model LP could do the 'out-of-phase' mixed sound.

And keeping it 'standard' helped when I eventually moved the Lemon Drop on.
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Re: The Peter Green mod ?

Postby John Egan » Fri Sep 20, 2019 11:39 am

The Yamaha AES 800 had an interesting slant on providing out of phase tones. It 's not the prettiest guitar in the world - vaguely Tele-ish. It has two DiMarzio humbuckers, voiced like P90s and a five way blade switch, which does some "Fendery"coil switching, plus a single volume and tone pot. It also has a third pot which, I think, brings in a third coil out of phase. The ability to blend this in makes for a really interesting sound. Well worth trying out if you can find one.
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Re: The Peter Green mod ?

Postby SecretSam » Mon Sep 23, 2019 9:47 am

Thanks Wonks.

So the gibberish on the interweb about 'magnetically out of phase' is indeed bolleaux ?

It's simply a matter of installing a phase switch and choosing appropriate pickups?
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Re: The Peter Green mod ?

Postby Wonks » Mon Sep 23, 2019 10:04 am

Well, it was the magnet that was reversed, and so made it out of phase with the other pickup. But you an also simply swap the coil end connections around as well. Two ways to do it.

And if you do both, you get it back in phase again. On a single coil, if you do that, then you get a 'RWRP' pickup, often used in the middle position in Strats and the like.

But yes, for a selectable PG sound, then it's just a switch and the right pickups.
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Re: The Peter Green mod ?

Postby Hugh Robjohns » Mon Sep 23, 2019 10:06 am

Is this another case where using the term 'opposite polarity' rather than 'out-of-phase' makes the situation -- and the effect of swapping magnetic polarity or wiring polarity -- far more obvious? :lol:
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Re: The Peter Green mod ?

Postby Wonks » Mon Sep 23, 2019 10:29 am

We've used reverse/opposite polarity a lot here in this thread. But the common description for the PG sound is 'out-of-phase', so sometimes it's easier to just run with it.
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Re: The Peter Green mod ?

Postby SecretSam » Mon Sep 23, 2019 1:01 pm

Fair enough. A polarity switch it shall be.

Thanks very much, Gentlemen
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Re: The Peter Green mod ?

Postby Studio Support Gnome » Wed Sep 25, 2019 10:33 pm

I find myself idly pondering the 90 degree relationship between magnetic and electric fields, and the consequences of the induced fields of both varieties in the various components , the related parasitic effects and whether in fact there would be a difference , beyond simply flipping the polarity of the coil....
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Re: The Peter Green mod ?

Postby SecretSam » Sat Sep 28, 2019 9:55 am

How did that pondering go ?

I suppose a polarity switch could be added to a pickup whichever way up it goes. But a rotating pickup probably isn't a good idea.
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Re: The Peter Green mod ?

Postby Studio Support Gnome » Sat Oct 05, 2019 12:33 am

SecretSam wrote:How did that pondering go ?

I suppose a polarity switch could be added to a pickup whichever way up it goes. But a rotating pickup probably isn't a good idea.

I've not calculated out the effects.... I'm too busy working on 5 concurrent studio designs, and working my Day job....

not even touched my guitar in the last 2 weeks.


some items to consider.

Reversing the magnetic field orientation,.... will change the position relative to the other pickups./

When a magnetic string vibrates in the field, the field experiences variance.
this induces current in the coils below, but also in the string as a wire , both moving in a magnetic field, and with the field itself varying , in a relationship to that movement....
also current in the coil will itself form small magnetic effects... each electric field effect having an associated magnetic field ,at 90 degrees phase, all of which interact... in small ways... some of which sum to zero in the larger sense, but may have effects not he smaller scale on their local neighbouring elements...
then add the effects imposed by other pickups , even though they are not in close field reaction... they create effects in the string, ...

it all gets a bit messy ..... you have multiple conductors, in different physical relationships to the primary magnetic field.... and doing different things....

some of these effects are minuscule compared to the fundamental operation of the transducer arrangement.... but they are there, but will be different for each physical orientation of the agent assembly.

thus the pondering.... how great an effect on the tone might there be , given just single pickup use..... the effect of the gross output phase will be vastly more obvious...

thus my implication that it's a little more complicated than simply which way round the wire coil is connected....
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Re: The Peter Green mod ?

Postby Hugh Robjohns » Mon Oct 07, 2019 2:16 pm

Studio Support Gnome wrote:I've not calculated out the effects.... I'm too busy working on 5 concurrent studio designs....

I don't want to distract you from an important studio design, because I want mine up and running soonest... :bouncy: but this:

...this induces current in the coils below, but also in the string as a wire...

Surely this current can only occur if the wire is in a circuit, but since one end is tied to a post bolted into a non-conducting material that seems unlikely... Or are you assuming someone is touching a string and forming a high-impedance circuit to ground somehow and thus allowing a current to return to the other end of the string in that way?

H
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Re: The Peter Green mod ?

Postby Wonks » Mon Oct 07, 2019 2:17 pm

You've given him a way out!
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Re: The Peter Green mod ?

Postby Hugh Robjohns » Mon Oct 07, 2019 2:50 pm

:D
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Re: The Peter Green mod ?

Postby Studio Support Gnome » Fri Oct 11, 2019 11:15 pm

are you presuming that
1) there is truly zero resistance to ground
2) that Eddy currents are irrelevant
3) that no one plays their guitar
4) Where there is potential difference, (V) and Resistance (R) .....

it may be very very small....

but it is still there.

a bit like your room ;)


and it's not like I've gone all Dirk Brauner and started talking about quantum states and their application to microphones..

just that it was an interesting , very deep rabbit hole for the mind to wander down
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Re: The Peter Green mod ?

Postby Hugh Robjohns » Sat Oct 12, 2019 4:39 pm

:bouncy: I must admit I hadn't considered the possibility of eddy currents.

Small... But beautifully formed...

...a bit like my room will be... One day... :-D
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