Electret mic, can i extend the cable

Thread Starter

ErnieH

Joined Feb 17, 2017
11
This Circuit from afrotechmods YouTube channel, on op amps, made this circuit and it works a treat.

Can I extend the cable on the microphone if so how far please.

Ernie.
 

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ronsimpson

Joined Oct 7, 2019
676
Yes you can extend. The longer the wires the more noise. Mic cables are usually shielded and the two wires are often twisted to help with noise.
 

Audioguru again

Joined Oct 21, 2019
1,473
The wires in your mic are already unshielded and pickup interference. Afrotech Mods shows a short piece of shielded audio cable that you did not use. Also the messy wires all over the place on your solderless breadboard are antennas that pickup interference.

A microphone must use a shielded audio cable but it has capacitance. If the cable is long then the capacitance and the fairly high impedance of an electret mic cut high audio frequencies.

Did you use the same lousy old LM324 quad opamp as Afrotech Mods? It produces hiss, has a poor high frequency response, produces crossover distortion and does not have enough output current to properly drive 32 ohm earphones. You should use an audio opamp like an OPA134.
 

Thread Starter

ErnieH

Joined Feb 17, 2017
11
Hi audioguru thank you for your comments, I used an LM358, as that's the only one I had, I tied off the unused other op amp inside.

To check a circuit I usually build up the breadboard / bird's nest version first to see if I've got the circuit right and that it works, & was surprised how well this Circuit worked as is.

When I decide I am going to build up and use a project I use the demo prototype board with only copper pads on the back from Jaycar and shrink everything down regards length of unnecessary wires.
I will note that chip you suggested in that project folder thank you.

Ernie H
 

Audioguru again

Joined Oct 21, 2019
1,473
I know about Jaycar. G'day mate, is it hot enough for ya, down under? Here in Canada it is -1 degree C.
The lousy old LM358 uses two of the same "horrible for audio" opamps in it as the LM324.
You know how smooth is a sinewave? Crossover distortion sounds like buzzing on signals. Here it is at the output of an LM358 or LM324:
 

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