Speaker As A Microphone

[Nathan] sent in his speaker microphone project. Speakers and microphones are physically similar – usually mics are much smaller to allow decent high frequency response. In this case, [Nathan] wanted something to pick up kick drums or bass guitars, without the cost of a commercial version like the subkick. It’s built around a dual coil 6.5 inch subwoofer. The passive circuit design allows the coils in the speaker to be configured for differing impedance, phase and isolation.

24 thoughts on “Speaker As A Microphone

  1. i once saw a guy from Shure re-wire an sm58 as a tiny speaker as a demonstration of this very concept.

    I especially like that he’s wired it up to be more than just a mic.

    Doing cool shit with junk is awesome.

  2. of interest to any people with ipod earbuds:

    stick them in your mic input on your computer, and you can use the left earbud as a microphone. very handy in a pinch, and it also sounds fine through line in

  3. Hmmm, not so sure about using headphones as a PC mic, The PC provides a DC voltage to the right bud, I guess that others here might know if that DC voltage was enough to overheat the bud over time.

  4. I was using speakers as microphones back in 1980. I accidentally discovered it playing with my brand new state of the art cassette recorder. I actually got better sound of the speaker than I ever did any mic that I could hook up to it AND it was significantly more sensitive. I used it to record my parents talking with my uncle 2 rooms away and I couldn’t physically hear them at all with my ears but I could hear them loud and clear through the recorder. Since then I’ve used speakers as microphones several times, even recently.

  5. this has been a common dj trick since the late 70s… if you dont have a mic at your mixer, just plug your headphones into the mic jack, make your announcement, and plug em back into the cue jack.

  6. This is a classic ‘hack’.

    Since I have virtually no cash, I use a car speaker (found in trash, of course) as my main mic. It sounds terrible, but alright for rough demos. From a 4 track tape recorder.

  7. Wow, I mean just wow. In other news, water can be used for drinking AND bathing!
    Seriously, folks. Take apart an old microphone from the 50’s; it’s a speaker!
    Remember in grade school how the PA system speaker was also a microphone?
    This goes waaaay back to when they actually were the same thing; I even have an ancient bakelite telephone where instead of the mouthpiece having a carbon mike, it’…just another speaker!

    So as to not just gripe and groan;

    Other uses for speakers and/or microphones:
    -Poor man’s laser show:
    lay raw speaker on back.
    lay a mirror on it so that one end is supported by the speaker.
    Aim laser pointer at mirror onto ceiling. play music.

    -Poor man’s actuator:
    -strip most of the cone off or make holes so that air movement is reduced.
    use to move parts of halloween display, such as eyelids or lips.
    recorded speech makes a good signal source.

    -passive (resonance) amplifier / frequency selective microphone:
    -take Aluminum tubes about 1/4 inch in dia, cut to various lengths. Bundle together.
    attach speaker to end of bundle (air tight, please).
    Each tube if cut carefully will amplify a single frequency only, picked up by the speaker.

    1. I totally made the poor man’s laser show when I was in High School!!! What a trip back to memory lane. I remember the best way I made it was to stretch a balloon (like heavy duty one) over the speaker and glue the mirror to it. . . Made some really cool light show effects.

  8. “Hmmm, not so sure about using headphones as a PC mic, The PC provides a DC voltage to the right bud, I guess that others here might know if that DC voltage was enough to overheat the bud over time.”

    Shouldn’t be a problem. Typically it’s only a 5V bias designed to drive the electret microphone pre-amp at ca. 1 mA. I would be surprised to find a commercial device that does not have some kind of current limiting in case of a short circuit.

  9. after looking at the circuit, i wonder about impedance of this device since the transformer is a 1:1 and the coils are 4 ohm each. does it react favorably with preamps, and how would it compare with commercially manufactured mics?

Leave a Reply to lonas Cancel reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.