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Quick and dirty XLR out

Discussion in 'Amps, Mics & Pickups [DB]' started by Justin Cauble, Feb 4, 2014.

  1. Justin Cauble

    Justin Cauble

    Feb 4, 2014

    I am an acoustic guitarist and a couple of years ago I was looking into building myself a stompbox (for percussion, not an fx pedal) and knowing absolutely nothing about electronics, I discovered F. Deck's quick and dirty piezo preamp here and used it to make my box. I just stuck the piezo to the top of the wooden box I made and wired it directly into the preamp. The results were incredible, especially if I plugged it into my bass amp. Other performers were asking where they could get one!

    Unfortunately the box was blown away in a tornado shortly after and I never got around to rebuilding it. I want to build a new one now and I was wondering if anyone here would know how to make the output jack an xlr instead of 1/4 in so I can go direct to the PA? Or possibly have both?

    Sorry I know this is not a bass question but since I got the schematic for the original here I thought I'd ask here first.


  2. Francis has schematics for his quick'n'dirty preamp and variations of it for a balanced output on his web pages. (At least he had.) If you don't need the highpass filter, they are easy to make yourself.
    The biggest problem might be the JFET part, since they are hard to get these times. (If you choose a different JFET you need to adjust the resistor values and even then output might be less than before.)
  3. Do you still have the fdeck? If so, just buy a d.I. box. Plug the fdeck into it and there will be an xlr out on the d.I.

    Radial are the nice ones and there are many cheaper alternatives made by whirlwind, art, etc...
  4. Just look at Francis' circuit for the HPF Pre - the section before the phase switch is a balanced output, with the switch selecting the hot or cold side. Remember to put some caps on the outputs to isolate you from 48V phantom power which you could be exposed to (unless you want to phantom power the unit)


  5. Justin Cauble

    Justin Cauble

    Feb 4, 2014
    Hey, thanks for the replies guys. I'll try to look at the different schematics he has posted and see if I can figure it out. I was hoping maybe it was possible to just wire an XLR straight in where the 1/4 out is on the schematic, but I don't know if that would work or be wise.
  6. You can just rewire the 1/4 to XLR, but then you have an unbalanced XLR.
  7. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    Why not just use an adapter? I've been using one in the last week to plug a microphone into a guitar amp - works just fine. Standard XLR on both ends of the cable I own, so an adapter that goes on the amp end - I guess it's female XLR to male 1/4". Unless you need a balanced connection, in which case I second the suggestion of a direct in/out box.