Spin-a-Split with a tone cap

[frets]

Guys,
I’m blurry on this one but I’m hoping some of the veterans can help me out here. I think I remember seeing a Spin-A-Split mod that had a tone capacitor attached to the switch. It was by ChrisK or 4Real...maybe? It was from one of the Gods. Can anyone help me find that one? I’ve looked and looked. As always, thanks!!

[Yogi B]

This? (From the MODULES thread.)

Apr 20, 2006 22:56:37 GMT -5 ChrisK said:

Red Rhodes (Peavey) Tone_Coil Split Pot

I thought we had a thread specifically about the Peavey T-60 which was a model that employed this (the leftmost of the above) wiring as stock, but the only mention of a T-60 I can find is by D2o discussing fretwire.

[newey]

Yogi B:

I think frets means the "spin-a-split" mod, whereby a pot is used to variably split a coil from full HB to full split, with variation in between- sort of like a blender to control the percentage of coil splitting.

I have the Red Rhodes mod on my LPJ and it works fine, but it's "all or nothing" at 8-9 on the knob, there's no variation.

I'm not sure on the "with a tone cap" part of frets' request. A search herein for "Spin-a-split" by post mentions generated 5 pages of results; limiting the search to thread titles still gave like 8 results. In many of these threads, diagrams have gone missing, so not sure on the tone cap part- and I'm not exactly sure of what frets meant by that anyway.

I think this may be the thread that originally discussed the "spin-a-split" idea, but as I said, there are others. In looking through the threads, there are references to it originating from a diagram off of the SD website.

guitarnuts2.proboards.com/thread/3981/push-pull-switch-spin-split

[Yogi B]

Jun 12, 2021 6:02:16 GMT -5 newey said:

I think frets means the "spin-a-split" mod, whereby a pot is used to variably split a coil from full HB to full split, with variation in between- sort of like a blender to control the percentage of coil splitting.

I have the Red Rhodes mod on my LPJ and it works fine, but it's "all or nothing" at 8-9 on the knob, there's no variation.

Well that's entirely down to the taper, ChrisK should've drawn the resistance zigzags concentrated in the centre of the pot, to illustrate resistance that follows an S-curve (i.e. W, G, or 4B taper — depending on the manufacturers nomenclature) as that is what I believe the Peaveys originally used. (An S-curve giving the neutral position at 50% and equally distributing the tone roll off and spin-a-split functions between the two halves of rotation.)

But for most people who are just co-opting their original logarithmic tone pot it works more as a 'free coil split switch', giving very little control over the split amount, just as you describe.

I'm not sure on the "with a tone cap" part of frets' request.

Continuing that quote "with a tone capacitor attached to the switch" — well, ChrisK's above schemes certainly don't use a switch, so maybe frets is thinking of a push-pull that alternates between a regular tone control & spin-a-split when pushed/pulled. I don't know if I've seen that before, but it's definitely a possibility.

[frets]

Happy Saturday Guys😻,

After thinking hard about this, I remembered I had the diagram for it in my files.  Here is what I was referring to.

[JohnH]

i like this idea and i have it on my LP. Its based on ChrisK's diagram that Yogi posted. His left one goes to full coil cut at 10 and I like that on the neck PU, with 500k pots and a 0.022uF tone cap . The bridge PU uses the righthand version, where at 10 one coil is bypassed by the other cap instead of being fully shunted, to keep some weight in the split tone. i like a 0.047uF cap for this.

But as noted above, you dont really get any partial split tones by finessing the pot. Its either the full effect at 10, or turn it down a smidge and you are audibly at full humbucker tone, which then rolls down treble as you turn tone lower.

Ive had this system for a long time. I use the split tones and it gets me them without push-pull switches (which I dislike) and lets me use good full-size pots.

Threads:

a basic one:

guitarnuts2.proboards.com/thread/3167/simple-les-paul-mod-parts

more happening:

guitarnuts2.proboards.com/thread/4571/humbuckers-lp-modular-wiring-design

[Yogi B]

Jun 12, 2021 16:30:25 GMT -5 frets said:

After thinking hard about this, I remembered I had the diagram for it in my files. Here is what I was referring to.

4real's original post featuring that image can be found here: HSS strat, MR + phase + 3xHB variable control

It is a bit of an odd one:

• with the pot pushed in: it's a regular spin-a-split that shunts the upper coil as drawn
• with the pot pulled out: the lower coil gets the cap in parallel, so the humbucker is already partially split. This lower coil is further removed via rolling down the control, however it's wired like a 'reverse' (independent) volume control -- only shunting the lower coil, not the cap. Therefore when fully split the result is the upper coil in series with both the cap and pot in parallel, thus giving a mild bass cut

In that thread there's also a version 2 which is electrically equivalent when pulled, the difference is that when pushed uses voltage divider wiring for the spin-a-split. Unfortunately, this isn't ideally suited to a logarithmic taper, and so results in most of the change between HB & single confined within the upper range of rotation.

I assume 4real was counting Cenulab's original as version 1. Posted both here and on the Seymour Duncan forums. The images are gone, and even back in 2010 4real didn't find a diagram:

Dec 19, 2010 1:49:37 GMT -5 4real said:

Couldn't find the actual diagram...but was described thus..."I see the red and white (coil junction) wires are on two separate lugs instead of together on the middle lug, plus a .001 mf cap across the two non-ground lugs."

That description sounds an awful lot like a voltage divider with a treble-bleed cap, and this follow-up post (on the SD forum) from ArtieToo pretty much confirms it (again images now dead, and emphasis mine):

When rotating from full HB toward split, for the first third of the rotation you can hear the the "girth" of the HB start to decrease; you start to lose some of the lows and low mids. As you turn a little further, you hear a sort of "swell" of the treble/high mids (an increase, that is), but it's not at all harsh or brittle sounding; it's extremely warm and "buttery", for lack of a better term. This effect peaks at about the halfway point in the pot's travel, and as you progress down from there the treble decreases again and you move sonically into more traditional Stratty SC sound (more or less) and finally end up at full split . . .

As I analyzed this a bit more, this makes perfect sense. With the pot at full clockwise and counter-clockwise rotation, you have this:



CCW bypasses the cap and gives you full humbucker mode. The resistor is there, but of such a high value as to be negligible. CW gives you full "split" mode. The cap and the adjustable coil are bypassed.

Midway on the pot gets interesting. It would look like this:



But that's a little hard to decipher, so lets redraw it as this:



Its the exact same thing, just drawn differently. As we can see, we have the parallel combination of R1 and C1 in series with the adjustable coil. That RLC network is in parallel with R2, and that whole mess is in series with the stud coil. So . . . we have the adjustable coil attenuated by R1, but the highs bypass that attenuation via C1, giving us a "portion" of its highs. Those highs are mixed, in series, with the slightly attenuated signal from the stud coil.

As you rotate the pot, R1 increases while R2 decreases . . . and vice-versa.

Therefore, I think we can say that 4real was shooting for a spin-a-split switchable between each coil and simultaneously arrangements A & C of JohnH's Bending coils in series, got 3/4 of the way there, but ended up with something quite different from arrangement C.

[frets]

Yogi,

I can’t get your pics to come up in any browser. Do you mind reposting?😺

[newey]

frets:

Yogi is quoting 4real's prior thread, the images froim which have disappeared. Since Pete (4real) is deceased, he can't repost them himself . . .

[frets]

Thanks Newey and thank you Yogi,

Too bad they’re gone, it’s such an interesting topic.

[Yogi B]

Jun 14, 2021 15:34:19 GMT -5 newey said:

Yogi is quoting 4real's prior thread, the images from which have disappeared.

Actually those images are from ArtieToo's post of the SD forum. I thought about stripping all but the part to which I added emphasis, but decided to post the whole thing verbatim, including the dead images — in case someone with better google-fu happens across the originals.

---

I know this thread is about spin-a-splits, but...

Edit: separated into a new thread