Monday, January 09, 2006

Microphone+Preamp development

Microphone development from up-left, clockwise:

- Piezo-element used in cheap sound-buzzers. Piezoelectric material is layered on a thin copper substrate. We used the 'inverse' effect of the buzzer, hence mechanical vibtrations are converted to weak electrical signals.
- Small electret-type microphone.
- Acoustic guitar pick-up (Shadow SH711). The piezoelectric element is of higher quality and better shielded against noise.
- Piezo-electric film which offers several advantages, e.g. flexibility

Because of high-impendance and low signal of acoustic pickups, we tried using different pre-amp circuits in order for better recordings. Most of these circuits were taken out of cheap commercial electronics. By trying different configurations of we found out the right choise of pre-amp is crucial to get a clear signal as possible, especially if it is combined with filtering capabilties (EQ).

Microphone-preamp combinations.

During recording, it was evident that external noise was an issue. One factor which infunced that was cables and exposed circuits. We replaced excisting wires with special shielded audio cable.


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