ET Phone Home – New/Old Mic Techniques

Phone_Harp_PlayingI just did a festival gig over the weekend where I recognized a very old microphone technique that I haven’t seen in 45+ years. This was a blues act with a harmonica player. But instead of using a standard microphone for his “harp”, he had an old telephone receiver from a vintage rotary phone wired up to a little 5-watt tube amp. And he played into the earpiece, not the actual carbon button mic.

It sounded fantastic foPhone_Harp_Mic_CloseUpr dirty blues harp, so I’ve ordered a vintage telephone receiver circa 1962 or so, and will build my own “phone mic” for harmonica. But I’ve got a twist on the concept. I know how to properly bias the old carbon button mic and install a selector switch and boost knob in the receiver handle so the player can select between sorta clean and really dirty/overdrive. Going to get interesting, so watch for a DIY article here along with a live performance video from one of my harp playing buddies.

Phone_Receiver_Parts

UPDATE: I just received my 1960’s phone receiver from FleaBay and it looks good. The earpiece is on the right side, which is basically a little speaker. Since it has a coil and a magnet just like a microphone, it can be used as-is to mic a harmonica. The left side is what really interests me since it’s a carbon button microphone with a lot of mid-range frequency response (basically 300 to 3,000 Hz). However, just like a condenser mic it needs a bias voltage to operate and a load resistor to sink the current. It should also be possible to add a potentiometer to change the mic sensitivity/gain, sort of like a boost switch. Now, am I smart enough to fit it all inside the handle? We shall see…

 

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