Doc's Mod - please explain

[tommyh]

Folks,

On my HM the single coils (especially) sound a bit dull at the indent on the TBX tone and as you turn up the treble the get a bit thin. On a previous thread, heem6 suggested I ought to do Doc's Mod as on the wiring page. So I've had a look and have a couple of questions if anyone can help:

What is the effect of Doc's Mod?

Looking at the diagram - comparing it to the 'official' wiring diagram above - it looks like it is drawn upside-down (I'm not quite sure what the 'doodle' in the middle underneath is, sorry if I'm being thick) with the 'hot' wire therefore coming into the middle 'upper' and the 0.22uf cap going to ground off the 'bottom left' (if you turn Doc's diagram the other way up to orientate like Fender's).

If so, this means that the 4.7Mohm resistor goes completely and not only is the 82K replaced by a 220k but instead of going to ground it runs between the 2 left terminals - I guess this might be quite a big tonal change - have I got the wiring right?

Cheers, T.

[nickwellings]

Yes it is drawn upside down but that does not matter. Not sure what you mean by "the doodle underneath"

IIRC TBX never uses a 4.7M ohm resitor anywhere??

All you have to do is hold the pot so it looks like in the picture (upside down) and then wire as displayed. You can use the thin wires on 220k resistor itself to bridge bottom right and top middle (bottom pot, right hand terminal to top pot middle terminal). .022 cap goes to ground of pot and top right hand pot terminal. Input (or output if you like) centre of bottom pot.

The doc mod IIRC basically gives a more natural sweep of tone. There was a discussion on the FDP board where it was originally made up, about the improvements.

A stock TBX acts like a normal pot from 1-5 and then opens up more high end quite abruptly from 5-10. I think with the mod, it is a smoother taper.

I have it on an HM, and a normal TBX on a few others. I really should compare. FWIW, I do the MOd on all my TBXs now.

Also, I am pretty sure it is not the ONLY mod to tbxs.

[tommyh]

Nick - thanks. I get it now (the 'doodle' is the rest of the pot - shaft etc showing that it's upside down - D'oh!). I ought to look at the guitar rather than the diagram! But thanks for you explanation - that's really helpful. Cheers, T.

[heem6]

Nick, I'd be interested in what differences you can hear between your stock and modded TBX's.

The guys who came up with this mod were saying that the 82k resistor "throttled" the sound and that substituting the 220k resistor "opened things up."

[nickwellings]

I will try and have a fiddle on them, Jim, and see if I can notice any differences.

[tommyh]

Nick - so I took the backplate off and - what d'ya know - it is exactly like the Fender wiring diagram - ie there is a 4.7Mohm resistor running to ground in parallel with the cap (I even checked the colours - a bit difficult to see but it looks to be correct)! Cheers, T.

[enigmachrysalis]

Do you guys know if this mod will work if you use humbuckers in the neck and middle (sc sized of course)?

If it is functional, is the tone worth it, or is this strictly for improvement in singles?