Anyone with experience with midi guitars?

[David King]

I have a bass I'm struggling to get finished up and one of my hangups is deciding what midi controls are needed and how best to integrate them with the traditional magnetic and piezo controls.
The bass has a dual P pickups which will be controlled via a switch to go between the rear set, both sets in parallel and the front set.
There will be a stacked passive magnetic volume/ tone pot. That output will go to a dedicated jack.
It will also feed the MAG pad on an RMC polydrive I B.
The Polydrive I B has six "Bass Excellence" piezo saddles that each get buffered and sent via pins 1-6 to the rackmount Axon 100
Pin 7 should be a summed piezo output along with whatever mag input is fed in i.e. guitar output.
pin 8 is synth volume
pin 9 has no connection
pin 10 is switch 1
Pin 11 is switch 2
Pin 12 is +7VDC
Pin 13 is -7VDC
The shell is ground/drain.

The RMC wiring diagrams show the following controls:
Program Up/Down switch
Synth Volume pot - 250K-B (linear)
Guitar/Mix/Synth switch
Mag/Piezo blend pot - 5K-Bcd (linear w center detent)
Master tone control - 10k-B (linear)
Instrument volume - 50K-B (linear)

I was really hoping to do away with some of these controls by stacking the pots but unfortunately they are all different values which is going to make that difficult if not impossible.
I'll probably try stacking the synth and instrument volumes since a 100kB dual concentric pot would probably work OK for both of those.

I'm guessing that the 5k and 10k pots could also both either be 5k or 10ks in a stack (if I knew where to find such a thing). I doubt that the blend will care if it has a center detent or not.
SO that's 3 stacked pots and 3 switches and 3 jacks
Can anyone comment on this plan?
Where would you locate the various switches? Would you group the synth switches and pots in one area and the mag stuff in another? Put all the switches off in a corner?
Could I eliminate some of these controls completely? (I've never played midi instrument and it's been at least 10 years since the last one I built.)

[David King]

I heard back from Richard McClish last night that the synth pot value can't be fudged, it has to be a 250k-B pot as the system is expecting precise voltages to work correctly.
I think my best bet is to try to gang up the mag volume with one of the other volumes and the mag tone with the master tone pot though that will limit some of the functionality.

[David King]

I've found a dual concentric B250k/A250k pot available that would allow me to stack the synth volume with the mag pickup volume.
It would make more sense probably to stack the "Instrument volume" with the synth volume. This might be possible by mixing and matching layers of Alpha brand white concentrics from various sources. It would be nice if I were getting paid for this BS.

[David King]

To set the guitar/synth mix it might not work so well to have those two in a stack if they are in fact independent controls.
Why is it so hard to drill a bunch of holes in a $9000 instrument?

[Jason Rodgers]

Nothing I can add or offer, of course, but I'm watching with interest and hope you post pictures. I'm confident that you will find a thoroughly practical, though utterly unrepeatable, solution.

[David King]

Thanks for the moral support Jason!. I drilled 4 holes yesterday and mounted the 4 existing pots that came with the Polydrive. I'll make some very short knobs that won't get in the way and locate the switches as best I can. Rather than stacked concentric pots I may just do ganged pots whereby the same knob affects both the piezo and magnetic volume or tone simultaneously since I doubt those controls will ever need to be independent. It still means ordering and modifying pots which is tricky but doable.