EUB - piezo setup advice needed

[Jack.Straw]

Hello. I've built a garage-style full-scale upright and need advice on amplifying it. I plan to experiment with piezo placement in the body, but need to figure out my parts list and wiring plan first. Here is what i'm looking at so far:

Pickup: 15mm Piezo Element
Tone: 2meg Audio Taper Pot
Volume: 2meg Audio Taper Pot

Does that look about right for an electric upright? Do i need resisters?

Thanks in advance for any advice you can offer!
-Jack

[fdeck]

I suggest that you need a preamp between the pickup and any subsequent circuitry. My website documents some extremely simple DIY preamps. And once you have the preamp in there, then you can use lower impedance volume / tone circuit such as the typical controls in an electric bass.

[Jack.Straw]

Fancis, thanks, that sounds perfect! I've been looking around the net trying to find a simple pre-amp circuit i could build. I'm thinking about the first one in your "Quick & Dirty Piezo Pre-amps" pdf.

So, assuming i build that pre-amp to your specs: Would i wire the piezo to the input of the pre-amp, then run the output of the pre-amp to the tone/volume controls, and then to the jack? With the pre-amp installed before the pots, would you recommend 250k or 500k pots?

Thanks again! I strung up the bass for the very first time last night.. i'm so pumped!

[ToneRanger]

Here's the piezo I've been using: www.fittell.id.au/piezo
Under the bridge on my solid-body, it gives a big fat sound. A shim of cork helped seat it better - before that, the bridge angle was very touchy.
Initially I ran it direct to my amp (which worked fine into my Eden but not into my old tube head). Then I built one of fdeck's little buffer circuits so I could add volume & tone controls. For tone, I bought one of every value capacitor going up from .05 and did trial/error until I found the value I liked (sorry, can't remember what I ended up with). I soldered a 2-pin socket onto the tone pot so I could just plug in the caps I was trialling.

Got any pics of your bass?

[Jack.Straw]

Great link, TR, thanks! I don't have pictures yet, but i'll take some and post them laster tonight.

fdeck, i've added all the components for your q&d pre-amp to my shopping cart over at mouser.com. I have substituted JFET 610-2N5486 per your update. I have a question though; since im using this as an internal pre-amp wired in before the pots, should i leave out the phone jacks and just wire straight in with shielded wire from the piezo tab and then out to the pots?

Edit- pics: