I'm thinking of converting a spare Strat into an acoustic/electric gigging guitar. I have a Lace Sensor Gold in the neck and am thinking about buying one of those piezo bridges (Fishman, Baggs etc). I would like this guitar to have one knob only, which would be a blender control. Is this possible? I think Baggs et al. sell blender units, although some of them seem to be outboard jobbies, and I'd obviously prefer something small that fits under the scratchplate...
This is doable, but the issue that arises is that the piezo system needs a preamp, and is thus an active signal. The passive pickup(s) won't play well with the active output (think: impedance mismatch).
JohnH has experimented with this type of arrangement, and he has designed an active buffer circuit that buffers both the signals so they can be mixed via a blend control. And, I'll link you to his design as soon as I can find it . . .
Ideally, you would have another of those modules just after the magnetic/normal pickups and there controls, so you are blending two active outputs. So you would have normal Strat wiring to module 1. Fishman piezo to its own preamp, then active module 2 blends the two outputs and gives you an active output that you can pan from magnetic to piezo.