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Piezo's. Both running them over distance and pre amps

Discussion in 'Audio' started by darren adcock, Nov 5, 2018.

  1. darren adcock

    darren adcock

    457
    33
    Sep 26, 2016
    Hey all.

    Today I was trying to help an artist with an installation. They want to amplify water dripping on metal objects, I tested today attaching piezo discs on to them (water proofed) with simply putting a 100nf capacitor across it's contacts then running them around 15 meters each to a mixing desk then into speakers.

    The results were ok, but not exactly great quality.
    -Firstly we had to push the mixer to it's max as the signals were too quite. Is building pre-amps the right way to solve this?
    -Secondly there was a typical ground hum that was audible. Is this from the length of the leads? A combination of the length of leads and having to turn the mixer all the way up? My immediate thought was to have the initial piezo disc and lead run short to a pre-amp then run a longer cable from there to the mixer.
    -Thirdly we managed to tune into a local radio station! :-D

    Any thoughts on what might be best here? We could use shotgun mic's but the discreetness of piezo discs is a preferred aesthetic.

    Thanks in advance

    Darren
     
  2. Alec_t

    Alec_t

    2,611
    687
    Jul 7, 2015
    Twisted pair cable, or screened cable, would keep noise/hum pickup to a minimum. Any capacitor would likely be more effective at the mixer end of the cable. Pre-amplification is clearly needed if you're having to crank the mixer to maximum gain.
     
  3. darren adcock

    darren adcock

    457
    33
    Sep 26, 2016
    Thanks Alec, off to look at Piezo Pre Amp circuits now and the cables you suggest.

    Dunno why I didn't think about screened cable, doh!!!!! just used whatever I had lying around at the length needed today.
     
  4. darren adcock

    darren adcock

    457
    33
    Sep 26, 2016
    Ok so spent sometime looking at circuits and reading what i think is required. I found the below circuit from Elliott Sound Products....Fig 10 in this link. http://sound.whsites.net/articles/high-z.html

    Is this a suitable circuit?

    [​IMG]
     
  5. Alec_t

    Alec_t

    2,611
    687
    Jul 7, 2015
    Looks good.
     
  6. darren adcock

    darren adcock

    457
    33
    Sep 26, 2016
    Thanks Alec. I'll order the components I need and report back if any problems.
     
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