SSS design using 3 way and rotaries - second opinion?

[jhng]

Hello again. It looks like I am going to need to rewire my Strat in due course. Since I am redoing it anyway, I considered making some changes to improve the usability. I would be enormously grateful for a second pair of eyes on the schematic I have come up with.

By way of background, I currently have a volume pot with a push/pull and a five-way selector. No tone controls. I am getting increasing fed up with needing to both change the selector switch and use the push/pull to jump between my most used sounds (particularly N, MxB, NxB). I also find that I quite often knock the selector switch from 4 to 5, for example.

I was therefore planning to swap the 5-way for a 3-way blade switch, get rid of the push/pull and use my two spare tone holes for rotary switches to manage wiring selections. The concept is as follows:

The Three Way Blade switch selects:

1. N
2. Rotary 2
3. Rotary 1

Rotary 1 controls the Bridge and Middle pick-ups and gives the following six combinations:

1. B
2. M
3. B+M (parallel)
4. BxM (series)
5. -B+M (Parallel Out of Phase)
6. -BxM (Series Out of Phase)

Rotary 2, which was the tricky one to work out, gives the following combinations:

1. N+B
2. NxB
3. N + Rotary 1 (parallel)
4. N x Rotary 1 (series)
5. -N + Rotary 1 (parallel out of phase)
6. -N x Rotary 1 (series out of phase)

In theory, the set up should then allow for positions 2 and 3 to be preset by means of the rotary switches, meaning that 'in flight' changes can generally be done on the three-way.  E.g. setting it for N, NxB, MxB, which would cover 90% of my playing already.

In position 2, the combination of the two Rotaries when Rotary 2 is in positions 3 to 6 also means that the total potential combinations is very large. So if I do want an occasional special effect, e.g. an out of phase sound, there is room for exploration. By my count the total number of combinations, discounting two intended duplicates, is twenty-five and includes all the possible parallel and series options (in and out of phase) together with a reasonable selection of hybrid parallel/series options (although I've never really found those much use).

The schematic below uses a 4 pole / 3 way blade switch (available from Goeldo in Germany apparently) and two 4 pole / 6 way rotary switches. For the 3 way and the rotaries, the selection numbering is always 1 at the top of the page and 3 or 6 at the bottom. If anyone has time to give it a thumbs up, I would be hugely appreciative. Also happy to leave the schematic on the site if it is helpful for other people.

[newey]

jhng-

I am debating whether this should be moved from "Schematics" to the general wiring area, as you are requesting someone vet the schematic, rather than posting a schematic or diagram which has already been verified. But, since it may be OK as is, I'll leave it here for now. If it needs correction, revision, or generates extraneous discussion, I'll move it to Wiring.

I'm at work and don't have the time to look at it presently, but it's an interesting idea, provided you can in fact secure the 4P3T lever switch. Seems like getting that rare bird in hand should be Job One . . .

Also, I don't know if you have used rotaries before in a build, but I haven't seen rotary switches with the knurled shafts to take a regular Strat knob, you will probably need to source knobs with a set screw fastener for the rotaries. Rotaries often need a bit of leverage to get them to rotate to the next position, so a smooth-sided knob like the Gibson "speed knobs" often doesn't work well with a rotary, you need to be able to grip the knob better, so a machined surface like a Tele knob works better. Or a chicken-head style knob will also give a bit more leverage.

[Deleted]

hmm i did make a Rotatary Switch that does like your Rotary

m, M, M+B, m+B, B, MxB, mxB .. i guess last one i did was N/A
but i think could tie two back to back
so then it would phase the last lot

N
N + (m, M, M+B, m+B, B, MxB, mxB)
N + (M, m, m+b, M+b, b, mxb, Mxb)
N x (m, M, M+B, m+B, B, MxB, mxB)
N x (M, m, m+b, M+b, b, mxb, Mxb)
(m, M, M+B, m+B, B, MxB, mxB)
(M, m, m+b, M+b, b, mxb, Mxb)


I think if was you, use colour cables to keep track of them

[jhng]

Newey, thank you for your message. I wasn't sure whether to post on the schematics board.  I figured since it was complete that was appropriate, but happy to move it elsewhere if that is better. In terms of parts, I think I've sorted that already:

4P3T blade switch: shop.rall-online.net/epages/61511639.sf/sec8021fa2b13/?ObjectPath=/Shops/61511639/Products/17080029
4P6T rotary switches: www.stewmac.com/electronics/components-and-parts/switches/rotary-switches/

On the rotary switches, those knurled shafts look like they will probably cope with Strat knobs. I have had a rotary switch before that needed a different style screwed knob, as you say.  Looks a bit weird on a Strat so I'll try to avoid that.

Angellahash, Interesting to hear that you've already tried something similar and I agree that coloured wiring will be essential once I get to the soldering stage. Otherwise, I'll end up in a total muddle.

[newey]

OK, I hadn't seen those rotaries with the knurled shafts, so you're good to go there (although there are 2 different types of knurled shafts and correcpondingly different knobs).

[Deleted]

sadly mine are just working proto-types

Maybe i need someone skilled like FRETS to build a harness for it and wire it up as her soldering is far better than mine.

just need to work more on my lever switch, worked when i had the PCB taped on but solder on so it wouldnt move the BLEEPER gave wrong readings

[newey]

Not all the way through with this, but so far it checks out. However, this may not be a wiring issue but more of a nomenclature issue- at Position 4 on Rotary 2 (which is the position shown selected on the schematic), your table indicates N x Rotary 1; this implies the neck pickup will be in series with whatever is selected via Rotary 1. With Rotary 2 as shown in position 4, Positions 1 and 2 on Rotary 1 check out OK, but your table implies that position 3 should be N x (B + M); I'm seeing (N x M) + B.

Also, with 3-way at position 3, which disconnects rotary 2, your table lists -B + M; I'm seeing -M + B. These two will of course sound the same, so just a nomenclature issue. But then, with Rotary 2 at position 4 (again, N in series with Rotary 1), instead of N x (-B + M), it's really N x (-M + B) This would also be a distinction without a difference if all three coils are esssentially identical, but might be different if the coils are dissimilar. Same thing at Position 5 of Rotary 1, you have -B x M, I'm seeing B x (- M), and with adding the neck pickup at position 4 of Rotary 2, N x (-M x B).

So, all these positions work, just not exactly as you have listed, and the differences may not sound any different.

BTW, it is very helpful, when dealing with more than 2 pole switches, to number or letter the poles so we can more easily refer to them.

[jhng]

Hi Newey, Thank you so much for taking the time to have a look at this. Regarding nomenclature, you are quite right that it is 'just' naming. I should have been more precise and indicated exactly which pup was flipped in the OOP combinations rather than just putting a - in front of the pair.

Regarding the combo which occurs with Rotary 2 in position 4 and Rotary 1 in position 3, I have double checked this and I think it does seem to work as Nx(M+B). See the below image which highlights the signal path. However, I note that I am also not super bothered about the hybrid combos in any event, so it wouldn't bother me too much if it turned out slightly different.

[newey]

jhng

Regarding the combo which occurs with Rotary 2 in position 4 and Rotary 1 in position 3, I have double checked this and I think it does seem to work as Nx(M+B)

You are right, now that I follow your red line. Too much switching going on here!

Anyway, the rest of the diagram looks OK to me, but this is pretty complex, we should probably get a third set of eyes on it.

[jhng]

Hello Newey,

Thank you so much for looking over this. I'm glad to hear that it checks out. I was quite confident, but a second pair of eyes is really helpful.

You are right about it being a lot of switching. I have parts coming in a few weeks, so in the interim I will have to meditate carefully on the wisdom of it all before I commit and dust off the soldering iron...

jhng