Wiring a standard pot to split a humbucker.

[jacobtm]

I've got an SG, standard setup with 3 way selector, 4 pots, 2 humbuckers. I've got a Seymour Duncan Alnico II Pro in the neck and a Seth Lover in the bridge.

What I'd like to do is this: have a master volume, 2 tone controls, and have the remaining control split the Alnico II Pro gradually, so that 10 is full humbucker, and 0 is only one coil. I have an idea of how I'd do this, but I'm not sure of it. I'd love it if someone could help me out and tell me if this is right or wrong. Here's my idea:



Thanks alot,
Jacob

[korus]

Commonly used term : Spin - A - Split (eg. see:http://www.seymourduncan.com/support/sum96tip.shtml)

IIRC, output (black) on SD pickups comes from slug coil, hence
there are two options, to use :

1. screw coil (neckmost) - connect wiper of Spin-A-Split pot to neck tone input on the schematics shown (black wire from the pickup)

2. slug coil (bridgemost) - connect wiper of Spin-A-Split pot to the ground - green wire from the pickup (eg. back of the pot) (like the previous link )

BTW on a guitar with less than 24 frets and neck HB the neckmost coil is at the same position/distance (2nd ? harmonic) as tele or strat neck SC, but you should test both then settle for your preference, at least I would.

HTH

[GuitarTechCraig]

I use method 2 on almost all of my humbucker-equipped guitars. I prefer a master volume control and don't mind a master tone, so that typically frees up 2 pots for coil splitting.

By the way, methods 1 and 2 will sound different. In theory, method 2 is the only way to get a true single coil. Method 1 does allow a very small amount of current through the second coil. That's just FYI, as tone is the only important factor here.

[ChrisK]

Use the Red Rhodes tone pot/coil splitter as shown in this post:
guitarnuts2.proboards45.com/index.cgi?board=schem&action=display&thread=1145315219

Use 500K pots.

This gives one both worlds and you then could use one pot each for each humbucker, one for a master volume, and the last one for a master tone (or have two separate volumes as original).

[JohnH]

First, Id like to say Hi and welcome to Korus and GuitarTechCraig. Seems we now have +2 to the number of folk around here who know what they are talking about!

Chris - I agree on the Red Rhodes tone/splitter. I have recently built it into my LP Studio and it has allowed me to get access to coil cuts with no new pots or switches, once I'd converted my pups to 4-conductor.

The variations on the red Rhodes are signiticant. After testing, I went for the left circuit for the neck, which compltely shunts one coil. I made the shunted coil the covered slug coil on this '57 Classic pup. At the bridge, (a 490T) I used the centre circuit, shunting through a 180nF cap. This keeps a little of the bass of the shunted pup.

John

[ashcatlt]

Does this make any practical difference? By that I mean:

a) do you ever actually use the in-between settings, and

b) can anybody else tell the difference.

You've got me thinking I might replace 2 of the pots on my paul with 4-way switches for series/half-shunted/single/parallel.

[UnklMickey]

johnh said:

At the bridge, (a 490T) I used the centre circuit, shunting through a 180nF cap. This keeps a little of the bass of the shunted pup.

the other benefit to this is: you maintain humcanceling in "single" mode.

[JohnH]

unklmickey said:

johnh said:

At the bridge, (a 490T) I used the centre circuit, shunting through a 180nF cap. This keeps a little of the bass of the shunted pup.

the other benefit to this is: you maintain humcanceling in "single" mode.

You would think so, but in practice I found the hum reduction is not really evident. It could be my selected cap was still shunting most but not all the low order signal, and also that alot of hum is actually a higher harmonic 'buzz'

cheers

John

[jacobtm]

Thank you all for the replies and attempt at help. Unfortunately, I'm rather illiterate with this sort of thing. I know tone well, and have a good ear for what I want, and I know how to wire a guitar only by having seen so many schematics and done it so many times that I simply remember which wires go where. I don't actually know the names of the different lugs on the pots, such as the "wiper" that korus spoke of.

Also, the real electrical diagrams are all greek to me, I only spent a few weeks in highschool physics on that stuff, and hardly remember any of it.

If anyone could perhaps dumb down one of their explanations, that would be much appreciated. Also, could anyone reccomend something besides a physics textbook that could help me educate myself on these things so that I needn't always have a dumbed-down version?

Thanks alot,
Jacob

[4real]

chrisk said:

Use the Red Rhodes tone pot/coil splitter as shown in this post:
guitarnuts2.proboards45.com/index.cgi?board=schem&action=display&thread=1145315219

Use 500K pots.

This gives one both worlds and you then could use one pot each for each humbucker, one for a master volume, and the last one for a master tone (or have two separate volumes as original).

I am in the middle of a rewire for my strat project and installed a spin-a-split for the bridge humbucker using the existing tone pot. It works well and saves on switches and drilling but it quickly goes from HB to split around 8 on the dial so operates kind of like a switch instead of a variable control..maybe it requires a linear pot for best effect?

I am interested in the Red Rhodes version. Any recomendations for which of the three circuits best to try? Does it work ok with a standard tone pot as I have on my guitar (it seems to imply it would)...What is the value or range of values for the cap in this circuit (doesn't seem to say) I know John mentioned a 180nF on a version he tried...

Also...any background on this control...a little history on the idea...who is 'red rhodes'...

pete

[JohnH]

4real said:

I am in the middle of a rewire for my strat project and installed a spin-a-split for the bridge humbucker using the existing tone pot. It works well and saves on switches and drilling but it quickly goes from HB to split around 8 on the dial so operates kind of like a switch instead of a variable control..maybe it requires a linear pot for best effect?


pete

Pete - if you are getting sc between 8 and 10 on a log pot for your spin a split- it may be youd be better swapping to the other outer lug - you would then be using the shallow-sloped end of the pot travel instead of the steep end. The spin a spilt only uses two pot lugs

With a log tone pot, this red rhodes idea is also switch-like, because the Hb/Sc end is also the steep end of the travel, so that the tone control end is as normal. Im using it on my LP so I can get coil cuts without drilling for more switches, and without changing to pp pots (Id need long-shaft), rather than to get a blended variations betwen Hb and Sc.

I dont know who RR is. I stumbled across the idea of this pot configuration and asked if it had been done before. Chris pointed out that it had been used on Peaveys I think. I like it however and Im finding it quite easy to control.

John

[4real]

ok...thanks john...

a bit of googling for the curious suggests red rhodes was a pedal steel player of some renown and also worked this out....giving/selling the idea to peavey.

since I have already gone the spin-a-split route, this is just another step along this way so I may as well play around with it also.

I have similar reasons to yourself for using this kind of control....I don't even mind that it "switches" after little travel, all the easier to change from one sound to another.

one benefit of this for my project is that I could convert the tone control to work the neck single coil and have this for the tone of the HB neck pickup. That would give me more flavours by allowing me to adjust the many neck/bridge combinations by mixing a tone effected pickup with non-tone sounds...

I will try a few variations on the cap and see how it goes in this guitar...

pete

[ChrisK]

Firstly, "Red Rhodes" is Orville J. Rhodes who assigned (well, sold, worked for, whatever) the patent to Peavey.

www.google.com/patents?id=YT4sAAAAEBAJ&dq=4164163

This patent issued 22 June 1977, so it has expired, and can be practiced freely for any purpose.

I first heard of the idea in one of Craig Anderton's books on guitar wiring (which I actually have somewhere). Knowing a little info enables one to search the USPTO patent and application database.

The left-most "Rhodes" schematic in my post
guitarnuts2.proboards45.com/index.cgi?board=schem&action=display&thread=1145315219
is the original design. The other two schematics are my extrapolations for tone variations from using the same cap to effect high-freq tone cut and coil shunting (this ain't splitting), and using two separate caps to effect same. No values were stipulated as I would likely run some pSpice simulations first for a particular overall wiring design anyway.


The first schematic in the post is a design that I came up with some years ago to effect a variable selection of series/single/parallel mode for a two-coil pickup. It lingered until I found blending pots that were truly full-on in the center detent position (Fender bass blend pots which are linear, or the StewMac blend pots which are inferred as being full-on and audio taper).

The blend pot is often OVERLOOKED for its other (unpublished but) significant usage. A blend pot is BOTH a normal taper/volume/tone control AND a REVERSED taper/volume/tone control.

If your single element blend pot design seems to act like a switch, you really need a "left-hand" pot (reverse taper). If your left-handed and can't find the proper handed taper for your controls, you're often out of luck.

In any of these cases, USE A BLEND POT and choose the appropriate taper.


The third schematic is just the use of a DPDT series/parallel switch and a blend pot to effect series and parallel blending of two coils. It, of course, could be used on a two-coil humbucker as well as on two separate pickups.

One can do some things with blend pots, many different ways.
Think of them as analog versions of the 6 Terminal ON-ON-ON switch!