Trouble with mic circuit need advice ?

[curry87]

Hi im having the following troubles with this circuit:

Im getting alot of hiss and clicking though the earphones its not very clear.

Things to add also im using a 10 meter shielded audio cable between the preamp and the electret mic its away from any wall sockets that could pick up a hum.

I apologize if the spice pic is not very clear,Ive just started using spice.What improvements should i make to clean up the sound as much as possible ?

 

[canadaelk]

Your sim drawing is really hard on the eyes!
If your mic is 10m away from the amp you are bound to get hum as the shielded cable would not be a balanced line.
Try this: Use a foil shielded wire instead of braid shielded, it has better shielding capacity than braid. Or move U1 to the mic. This way you have a low impedance feeding the shielded cable. E

 

[audioguru]

Of course your circuit produces hiss, its voltage gain is 20,200! Are you trying to hear people talking on the other side of the world?
It amplifies the thermal noise in the input resistor R6. It also amplifies a lot the small amount of hiss from the electret mic.

Reduce the total gain to 100 or 200. Then the hiss will be 100 times or 200 times less.
The shield on the input cable will stop hum and has nothing to do with hiss. Does it have hum? If it has messy wiring on a breadboard then the wires are antennas for picking up hum.

The level from the mic will be higher if you replace R6 with 10k.

A more expensive audio opamp and power amp will reduce the hiss and use metal film resistors.