two pickup with independent tone

[jhaneyzz]

I am building a literal "stomp box" as in a wooden box with two piezo pickups in it.

I get all the basics of how to do this and have everything working, however, I want the pickup under my toe to produce a low "thump" and the pickup under my heel to produce a high "tap".

Ideally, I would prefer to do this with only passive electronics.

I know how to build simple High and Low Pass circuits with combinations of Resistors and Capacitors.

My problem come with the fact that it if simply wire a low pass filter to one pickup, and a high pass filter to the other, since they share a common ground, the effects basically cancel each other out. (I know that is not exactly what is happening, but suffice it to say that it doesn't do what I would like to do.)

SO. looking for someone with more experience than me to tell me how I might make this work, even if I have to build some sort of active mixer circuit.

Ideally what I would like, is a volume pot and "tone" pot for each pickup. But by "tone" I don't mean standard guitar pickup tone. I would like to employ a Low Pass circuit for the "thump" and a Hi Pass circuit for the "tap". for each, using a potentiometer to vary the pass frequency.

I might want a Master volume pot as well.

I know... it's kinda overkill for a freaking stomp box, but I'm an overkill kinda guy.

James

[MaxPower]

http://www.geofex.com/article_folders/eqs/paramet.htm

Parametric EQ might be a good option. Else you might check out synthesizer filters for some ideas.

[robthequiet]

Could you provide a diagram for the circuit as you have it for now? Maybe a photo?

[stallik]

In my experience, piezo's in a box can be coaxed to give a low thump by tapping with your foot but that's because the box had been hit with a dull thump and the piezo is picking it up.
Hitting the same box with another dull thump and expecting it to transform into a bright 'tish' just isn't going to happen.
On the other hand, if you were to hit the box with a thin bit of metal or a stick, the sound would be brighter so you'd stand a chance.
I've seen stompboxes fitted with a thin plate of metal supported above the Stompbox which you whack with your foot to generate the initial, brighter sound. This is usually at the toe end as it's easier to generate the short tap and ring.

[bluebunny]

I've seen stompboxes fitted with a thin plate of metal supported above the Stompbox which you whack with your foot to generate the initial, brighter sound. This is usually at the toe end as it's easier to generate the short tap and ring.

I was thinking along these lines too: a sprung, hinged wooden flap with bottle tops or fat brass thumb tacks nailed on each side.  If you want a "tap" noise, I guess the place to start is something that "taps" acoustically?  (YMMV, of course.  I've never tried this and I've only had two coffees so far this morning...)

[idy]

One idea to isolate two passive circuits is to keep them separate: two 1/4" jacks out, use an external mixer.