SHS Strat with three push-push volumes

[Yogi B]

As I've mentioned in the past, I've got a new plan for my SHS Strat -- my original plan, now some four years ago, was an exercise in maximising what could be achieved with a 4PDT ON/Z/ON switch and an 8PDT double-megaswitch. Also, as I've previously said that design was never realised: I was never really happy with it, never got as far as ordering the 8P5T, instead filling the hole in my pickguard with a humbucker sized P90 and calling it a day.

So, obviously, I'm now revisiting the idea of putting a humbucker in its place, but before I detail the new plan, I shall discuss what I view as shortcomings of the old design:

Although I'm quite fond of the idea of using blade switches in a more auxiliary role, in this case as the mode switch, that unfortunately relegates the main bridge/middle/neck selection to a 4PDT toggle which don't have the nicest feeling to operate.

Additionally this meant that the fifteen different possible selections were positioned along the 5-way switch in an arbitrary way. Sure, the switches are conceptually easy to understand: a 3-way bridge/middle/neck toggle and a 5-way mode selector. However, the mode switch is too powerful for its own good, despite attempting sort the selections into logical groups and ordering, I doubt that there's enough reasoning relating the adjacent modes in order to intuitively steer my mind to my sought selection. Returning the 5-way switch to a more traditional function would greatly help in this regard, as would reducing the total number of selections.

Following on from that, I have a couple of guitars with a 5-way switch a a two-position 4PDT, giving a total of ten selections. These work well as they are quite easy to comprehend as two sets of five: 'normal' and 'alternate' modes. However, because the mode toggle acts globally and is paired with a master volume and a master tone control, this style of wiring offers no ability to preset a pickup selection and/or volume level accessible through the manipulation of only one switch.

So we arrive at my new proposal which strips the available number of pickup combinations to ten, but delegates the choice between 'normal' and 'alternate' settings between three push/push volume pots.

The ideas is to have only ever one volume pot active, controlled via the 5-way switch: bridge volume in position 1; middle volume in positions 2, 3 & 4; and neck volume in position 5.

The push-push portion of each volume control then separately toggles between the modes: bridge p/p in positions 1 & 2; middle p/p in position 3 only; and neck p/p in positions 4 & 5.

The disparity between those two assignments (e.g. middle volume controls pos. 2, 3 & 4, but middle p/p controls only pos. 3) is intentional, as it makes sense to me based on what the actual selections are. Should I later decide that I'd rather have the middle volume control only position 3, then it is a relatively simple change (needing only a few wires to be moved).

The requirement for the 5-way selector switch is six poles. Hopefully this will be achievable by jury rigging two super-switches together, reducing the spacing between the wafers such that I can fit three in the space where two were previously (leaving me with a 6P5T and a spare DP5T), though I will need some appropriate nuts & bolts to replace the rivets that hold a stock super-switch together.

In order from bridge to neck we have: bridge SC (north), middle HB South (screw) coil, middle HB North (slug) coil, and neck SC (south), and the intended switching scheme is as follows:

1. • Bridge volume control active
   • Bridge volume push-push down: B × M_S
   • Bridge volume push-push up: B × (M_S + -M_N)
   
   
2. • Middle volume control active
   • Bridge volume push-push down: B × -M_N
   • Bridge volume push-push up: B + M_S
   
   
3. • Middle volume control active
   • Middle volume push-push down: M_S × M_N
   • Middle volume push-push up: B + N
   
   
4. • Middle volume control active
   • Neck volume push-push down: N × -M_S
   • Neck volume push-push up: N + M_N
   
   
5. • Neck volume control active
   • Neck volume push-push down: N × M_N
   • Neck volume push-push up: N × (M_N + -M_S)
   
   

(Those are all nominally hum-cancelling selections.)



You'll see that five of the six poles are tied up with the main switching, leaving only one pole to switch the volumes -- not enough properly disconnect the unused volumes, so in all positions all three volumes load the signal in parallel. Though the result isn't so bad: 500k / 3 = 166.6k, a nice middle value between two 500k pots (250k) and two 250k pots (125k) -- in fact, more precisely, it is the harmonic mean: 2 / (1/250k + 1/125k) = 166.6k -- alternatively it could be thought of as a 500k volume paired with a 250k tone.

This along with the main switching could be done better with the two extra poles of a 8P5T, and it might still ultimately come to that, but for now I'm sticking with the 6P5T plan.

[newey]

Rather than modifying 2 4-Pole switches, why not just buy the 8P5T from EYB and save yourself the need to mod the 2 switches into one?

[frets]

Yogi,
I think it’s awesome. 🤗

[Yogi B]

Sept 29, 2020 15:47:29 GMT -5 newey said:

Rather than modifying 2 4-Pole switches, why not just buy the 8P5T from EYB and save yourself the need to mod the 2 switches into one?

I suppose that boils down to three things:

• Bragging rights -- "Eight Poles? Who needs a whole eight poles? I can get basically the same functionality with only six -- that's TWO fewer!"
• Curiosity -- I want to know how viable a DIY 6P5T actually is, this idea requiring one is therefore a good opportunity to put it to the test.
• Cost -- Not just for the Eyb switch, but doing it properly (with an 8P5T) would only be encouragement to also upgrade the push-pushes to a triplet of S1 switches, at roughly fourfold the cost.

[newey]

Oct 4, 2020 22:18:02 GMT -5 Yogi B said:

but doing it properly (with an 8P5T) would only be encouragement to also upgrade the push-pushes to a triplet of S1 switches, at roughly fourfold the cost.

OK, so that's the Nutz™ reason . . .