Good Buffer/Preamp circuit for electret mic

Caleb Chia · 4th May 2011, 08:46 AM

Hi,
I need to mic up some fiddles but I dont want to spend heaps on real instrument mics. I would like to build some mics using cheap electret inserts. I have tested the quality and it seems pretty good, but I read somewhere that they need a preamp for longer cables to reduce the impedance or something to prevent noise.
Does anyone know of a good discrete circuit to use that uses very few transistors? There's one that looks good on the net but uses heaps of transistors. What if I just put a simple class A amp like this?

I might use phantom power, and don't need a balanced output.

RogerGustavsson · 4th May 2011, 10:44 AM

Hi Caleb,

That circuit is not suitable. If you intend to use a phantom power supply, you must have a balanced/differential output. Cheap electret inserts use to have a built-in impedance converting JFET. This circuit could work with a Panasonic WM-61 and phantom power (9-48 V).

Roger

4th May 2011, 08:46 AM	#1
Caleb Chia diyAudio Member Join Date: May 2008	Good Buffer/Preamp circuit for electret mic Hi, I need to mic up some fiddles but I dont want to spend heaps on real instrument mics. I would like to build some mics using cheap electret inserts. I have tested the quality and it seems pretty good, but I read somewhere that they need a preamp for longer cables to reduce the impedance or something to prevent noise. Does anyone know of a good discrete circuit to use that uses very few transistors? There's one that looks good on the net but uses heaps of transistors. What if I just put a simple class A amp like this? I might use phantom power, and don't need a balanced output. __________________ Flux fixes everything

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4th May 2011, 10:44 AM	#2
RogerGustavsson diyAudio Member Join Date: Aug 2004 Location: Huskvarna	Hi Caleb, That circuit is not suitable. If you intend to use a phantom power supply, you must have a balanced/differential output. Cheap electret inserts use to have a built-in impedance converting JFET. This circuit could work with a Panasonic WM-61 and phantom power (9-48 V). Roger