An extremely low quality microphone

 

In sound recording and soundscaping work, we are generally after the utmost quality in our selection of microphones. However, there are circumstances when we want a recording to sound really 'old'. Of course one can attempt to use all sorts of filters on an originally good quality recording but the authentic sound quality of a real old recording will be very difficult to obtain. There is more to it then simply being LoFi. This is mainly due to the extreme and non-linear jumps in the frequency characteristics of really old microphones. Their very narrow bandwidth contributes also greatly to the sound. To make the realisation of such old sound easily possible, we designed a microphone using a carbon element taken from a pre world war 2 telephone, but otherwize completely compatible with modern audio equipment. This microphone is phantom powered and has a balanced output.

We give two circuits: the left circuit blocks the DC component and has a relatively low output signal, whereas the right one is of an even greater simplicity, since the DC through the transformer is not blocked. Signal level is a lot higher, but the circuit draws more current from the phantom power than allowed by the specs for professional audio equipment. Remind you that a carbon microphone is inherently a sound-pressure dependent resistor and thus must have a current flowing through it in order to get a signal. The circuits are extremely simple and do not use any active components. We used a housing from a broken Beyer ribbon microphone, to give this ELQ-mike a really professional look and feel...

 

Godfried-Willem Raes

Ghent, april 1th 2010

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