Old Telephone = Handy Microphone

Posted on November 24th, 2011

I got the tip from Nordloef that you could easily modify an old telephone in to a microphone by just finding the right cords that went to the microphone and solder them to a 1/4″-jack. We weren’t surprised when we found an old phone at a flea market the same day. He bought it and asked if I would modify it for him. Yes!

The microphone in these old phones is of the oldest category of microphones, carbon microphones. The same kind that german guy used when he spoke to all those ppls in the 1940s..
(His mic is now used in a studio in holland, I think it was. And they claim it’s great for recording drums. And when you think of it.. That guy did kinda sound like a snaredrum.)
wellwell.. anyway! The phones!

It proved to be very hard (ok, not that hard) to get the actual microphone to sound. You needed to make a special circuit and give it some juice in order for it to work. I could probably just have used the phones body with the amp already inside it, but i had chopped off the handle and the cord and just threw the rest away.
I was stuck with nothing!
Or anyway, that was what it seemed.

I then discovered that you could actually hook up the speaker in the earpiece to a 1/4″-plug and drive it with a normal mixer or amplifyer and then use it as a microphone. Just connect the black cord to earth and the yellow to the hot sleeve on the 1/4-plug. (this is true for this unit, but its perhaps not true for all phones out there. this is where a multimeter gets handy.)

It really gives you that telephone sound that you want. I guess since it’s the thing you held to your ear all those times you know the sound that comes out of it. When you use it the other way around, as a microphone, it sounds exactly as you would expect.

I will dig into making use of the “real” microphone. I mean: Who wouldnt want to sound like a snaredrum?

Turns out you can plug the phone to the output jack of a synthesizer or a mixer and listen to the output in the phone. It was to obvious for me to even think about it. This is what it sounds like:

Here are some samples of how the phone sounds when using the earpiece. These sound clips arent edited in any way other than gaining the volume of some of them.

[soundcloud url="http://api.soundcloud.com/playlists/1331091" height="200"]

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2 Responses to “Old Telephone = Handy Microphone”

  1. nitro2k01 Says:

    Attach an XLR jack and use the phantom power for powering. You’ll still need a couple of resistors and maybe a capacitor for good measure, but no battery.

  2. salkinitzor Says:

    Aaah! Thanx nitro! I will try that on my next phone!

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