Hello Tronics Gods, thanks for your help to build my op amp experiment, i was wanting 2 know how long i could extend both mic & speaker leads while still retaining good sound quality, i can get approx 4m on the mic end & 15m+ on the speaker end, with the circuit in the middle. I'm wanting 2 know can i get more lead on the mic end? as the circuit / mic simply didn't work if the mic lead was longer than around 4m, the circuit was dead / no noise in the speaker.
This circuit was based on Afrotecmods circuit help & Dodgydave's preamp circuits.


Thanks
ErnieH

 

I'm wanting 2 know can i get more lead on the mic end?

Maximum length is going to depend on the cable you choose. Shielding and impedance will matter.

as the circuit / mic simply didn't work if the mic lead was longer than around 4m, the circuit was dead / no noise in the speaker.

That sounds more like a problem with the cable. You should get something, even if it's just hum.

 

the circuit was dead / no noise in the speaker.

The LM358 is an op-amp, not a power amp. Unless your 'speaker' has an inbuilt amplifier the speaker will act like a short-circuit on the LM358 output.
Your mic cable looks like an ordinary 2-core one. Screened cable is needed instead.

 

To my eyes it looks like shielded (screened) cable, so indeed I would look elswhere. I have run some fairly long high impedance microphone cables and the first complaint is a loss of the higher frequencies. If it "suddenly went dead then the problem is something else, most likely s single strand short circuit at one end or the other. And while theLM324 is an OK audio amplifier if used at low gain, it is certainly not able to deliver much power. If you are driving that set of ear-buds that I see in the photo I would also suspect a problem with the leads to the earphones.