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Phantom-powered piezoelectric contact microphone and preamplifier

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Below are audio recordings of my piezoelectric transducer on various instruments, with and without the preamplifier.
Unless otherwise indicated, the piezoelectric disc itself was placed on the top face of each instrument, as close as possible to the center of the bridge.

More instruments will be added as I get the chance to record them.
Technical note: The sound files are unedited. In a recording or performance scenario, EQ would be used to cut frequencies between 2kHz-10kHz for a more natural sound.

Use headphones / good speakers to hear the difference clearly!
Without preamplifier
(raw piezoelectric signal)
With preamplifier

Download
Charango
(fingerpicking)

Download

Download
Charango
(strumming)

Download

Download
Guitar (acoustic)
(steel strings)

Download

Download
Guitar (classical)
(nylon strings)

Download

Download
Guitalele (modified)
(nylon strings)

C2 G2 D3 A3 E4

Download
^^ The guitalele was re-strung to emulate a 5-string mandocello. ^^

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Kalimba
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^^ This was recorded close to the sound hole. ^^
Placing the pickup near the bridge of the kalimba picked up a lot of finger noise.

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Mandolin
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Viola
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Violin
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Instruments I have tested on, but not recorded:
- cello - double bass - santoor** -

** hammered dulcimer from India

Notes about this pickup/preamp:

  • The preamplifier will not work with a standard mono guitar cable. It comes with a custom TRS->XLR cable; after which a standard XLR microphone cable can be used to connect it to an input.
  • The piezoelectric transducer will work with any other commercially available preamplifier; however, this preamplifier cannot be used with other transducers as it has been engineered to work specifically with the one presented here.
  • Phantom power is required for the preamplifier to operate.
Advantages Disadvantages
  • The contact microphone can be attached to nearly any instrument or surface to pick up sound.
    It could even be used to record sounds underwater, with suitable waterproofing.
  • No batteries needed for the preamplifier, as it is powered by phantom power (available on most common audio interfaces).
    If phantom power is not available, the piezoelectric mic can still be used without the preamp, and it will sound like a generic piezo microphone (with the usual disadvantages).
  • Because the microphone outputs a balanced signal, it is highly resistant to electromagnetic interference such as the 'hum' from mains electricity (provided that the equipment it is connected to is properly set up).
  • By design, there is no gain/volume/EQ control on the microphone or preamp; all adjustment (if any) must be done at the mixer.
  • Since the microphone is in direct contact with the body, a small change in location could potentially have a noticeable effect on the timbre; and it will inevitably pick up more handling noise than a conventional microphone.
    With that in mind, the microphone will pick up sound from anything that it is attached to, but may pick up an unwanted amount of mechanical noise from heavily percussive instruments, and will work poorly on most wind instruments.
Please consider buying me a coffee to help me develop this microphone further.
© Anand Lobo