Piezo considerations

[Asdrael]

So, I managed to score a Schaller Hannes 7 string Piezo for an upcoming build. Happy, it's been out of production for years but there was one (1) of the exact model I wanted still new on a shelf in a EU shop.

 

(Holy molly the piezo wires are thin. Good news tho - they included some heat shrink tube to wrap around the summing board )

 

Now the fun part is figuring out which guitar to build around it. The not so fun part is figuring out which preamp to get in and the wiring. And I suck at this.

My requirements are not too bad: I need to be able to switch between Piezo only, Piezo + Mag, and raw Mag alone. That means, on the last position, the magnetic pickups shouldn't go through the preamp at all.

Schaller does that with the Flagship but they use either a 5 way blade (just... why?) or a rotary switch (just... why?). Both options I am not a fan of.

Ghost has the acousti-phonics which seems like the best option but the diagrams provided either force the mags to go through the preamp even when used alone, or remove the option to mix. Now I suppose someone smarter than me has already figured it out so I'm throwing it out there: I need help

Any ressources or advice? I'll take everything at that point.

[MiKro]

1 hour ago, Asdrael said:

>snip<

Ghost has the acousti-phonics which seems like the best option but the diagrams provided either force the mags to go through the preamp even when used alone, or remove the option to mix. Now I suppose someone smarter than me has already figured it out so I'm throwing it out there: I need help

>snip<

I would go with the ghost setup. You can always put a switch inline with the mag pickup to make it bypass the board.  MK  just my 0.02cents 

[Asdrael]

Thanks. I might channel my old electricity wizard self (I used to build lamps age 6 and never once took a schock so I guess there is something to be said there) and try to make a schematic that I will submit to online gurus.

 

Or just sweet talk my way into Ghost customer support. Getting in touch with Schaller was... very German. And I say that as someone who's been living in Germany for close to 15 years

[henrim]

1 hour ago, Asdrael said:

Getting in touch with Schaller was... very German.

I have gotten friendly and prompt response from them.

[Professor Woozle]

I've got a Shadow P2 which has a Schaller 3D piezo bridge and an active humbucker (Shadow EQ5),  wired separately from the piezo electronics. There's no switch, you mix or cut the two pickups with the volume controls - simple, but it works.

[Asdrael]

Thanks, that would work as a back solution.

I am currently channeling my inner nerd and trying to understand how the preamp works and the provided wiring schemes. It seems they have info on how to do what I want but with 2 switches (one SPDT on/off/on for the selection between piezzo/mix/mag with apparently grounding one shutting it off, one SPDT on/on for rewiring the mag directly to the tip of the jack). I am trying to make it all work with a 4PDT. I think I got it.

This:

 

Ends up being this (fear the drawing skills):

Whatever happens at the quickswitch stage doesn't seem to matter when bypassing the TIP connection as per their wiring. The added passive elements are here to keep the preamp active and not popping in and out when switching, which draws battery (I don't care).

There is probably a more elegant solution to this since I know I will never use a stereo cable, but I guess having the option is not bad.

(I don't have any push pulls to do this as extra left on my controls, and I don't want to add more switches as I am running out of real estate for my plan).

[curtisa]

Arrrghh! Your diagram hurts my brains!

I think the issue with combining the piezo/both/mag switch (QSW) and the mag bypass switch will be that the former needs to be centre-off, whereas the latter needs to be one-or-the-other. To combine the two functions might take something quite esoteric.

You might be able to do it with something like the Dimarzio EP1111 switch. They can be pricey though.

[Asdrael]

My diagram is beautiful, thank you

 

The thing is, since the on/on for the bypass only needs to be on in one condition of the on/off/on, you could use a 4PDT (I think) carefully chosing how you wire it. The on/off/on would use 2 rows, the on/on 1. Which is what I tried on my diagram. I might be missing some grounds somewhere, but I am not sure what grounding both QSW connections would do (will have to ask Graphtec on that one I guess.

I found a guy that did the same mod (except he has mag/piezzo/mix on the switch) after some advanced google-fu and the diagram is basically same as mine. He just grounds everything that is not connected (which I would guess is better for the noise level).

I think simply converting this to the switch positions I want should be good?

[curtisa]

OK, I understand how your diagram works now. Yes - the switch shown in that hand-drawn diagram will be the same type as the Dimarzio one I referenced before, which is the same one you've drawn. I think your scheme will work OK. Not sure if it really matters that the mag portion of the preamp does not get muted (QSW blue) when in 'raw mag' mode, because you're disconnecting the output of the preamp and bypassing it directly to the output jack tip at the same time. Perhaps that's why the hand-drawn diagram exchanged the mix and piezo options?