pMic

A printable A-B-Stereo Microphone

DSC03949

I wanted to have a mic which I cought use for general purpose recording in conjunction with my old iriver h120 (with rockbox installed). I didn’t found a suitable mic without a build in recorder:)

So after a little bit googleing I found this article about a low-cost homebrew solution and decided to get a bunch of these panasonic wm61-capsules described in the article to start experimenting with them – here is the result.

A special feature of this microphone is it’s variable stereo width (by time-of-arrival stereophony).

The button near the audio jack is the on/off-swiitch, the second one a gain boost. By swapping two resistors in the circuit, the gain boost could be easily converted to a gain damp. The preamp circuit isn’t necessary at all, if your recorders preamp has phantom power. But the 9v battery increases the headroom for louder signals and powers the 4 capsules more convenient. The distance between capsules and preamp shoud be as short as possible.

I’m quite happy with the sound. Here are some audio examples: https://github.com/Piesi/pMic/tree/master/docs/audio_examples

You can download it here:
http://www.thingiverse.com/thing:186913
or here
https://github.com/Piesi/pMic

DSC03977

closed wide

medium

open

DSC03967

DSC03972

16 thoughts on “pMic”

  1. Would you sell me one of these? I dont have access to a 3d printer and I dont trust myself assembling electronics. I blew up my 606 drum machine trying to modify it 🙁

    1. Hi Zak,
      yes, why not. I don’t know what to charge for this yet. So, I’ll write a bill of materials on the weekend to calculate what the production costs and then call you back…:)

      1. Awesome! Thanks Piesi.
        If you would like to include the shipping in your bill I live in Adelaide, Australia, SA, Postcode 5000.
        Look forward to hearing from you 🙂

    2. Hi, I’ve just added a BOM to the git-repository. I decided to go with four price options you can choose from:

      pMic Basic (without preamp):
      diy kit: 25€ + shipping (to australia 15€) = 40€
      assembled: 40€ + shipping (to australia 15€) = 55€

      pMic Preamp:
      diy kit: 35€ + shipping (to australia 15€) = 50€
      assembled: 70€ + shipping (to australia 15€) = 90€

      The assembly of the preamp is the most complex and thus
      expensive part, since I have no machinery to make the pcb.
      But as I mentioned, the preamp is not necessary. I’ll make
      a non preamp version (but with 9v phantom power)and add
      audio examples for that, so you can hear if there is a difference.

      1. This is probably a pretty stupid question but I’ll ask anyway. I noticed that you use a 3.5mm Jack. Does that even work with phantom power? (I am under the impression that phantom power requires an XLR connector). I’m talking about the basic, no preamp version.

    1. Hi Jesse,
      the capsule case is only 1.5 cm thick, while
      a sonic wave at 20kH has a wavelength of about
      1.7 cm. So from what I’ve learned about propagation of sound, the wave should lean around the sides of the case. I made a quick and dirty test and didn’t notice any change of volume as I turned the mic around…

Leave a Reply

Your email address will not be published. Required fields are marked *