Hi Guys, I need some guide on audio =)

hello guys,

thank you so much for viewing on my post. Ok i just having a simple question. i found this blog and it is very very http://interface.khm.de/index.php/lab/experiments/arduino-realtime-audio-processing/ to begin with custom guitar pedal. i am trying to make a tweak on the circuit. to be usefull in guitar amplifier, however i still remain failed to do it and i want to keep trying.=) i'm using "LM324" and trying to search a good circuit for it. but i still failed to do it and know i am in "LM386" the problem on it have a very noisy sounds. i know that i have a limitation on circuit but i willing to learn and spend time working on it. =)

can anyone suggest me a circuit for guitar pedal that works on amp or speaker with the use of any of this LM324 or LM386? =)

Thank you so so much and very very much for any answer!=)


If you want to use the circuit in the link as a pedal, you shouldn’t need an LM324 or LM386. The circuit should work as-is, but the input impedance is on the low side for a guitar and that will knock-down your signal a bit. I haven’t bothered to look at the software, but the hardware looks OK.

Have you tried running a line-level signal through that Arduino circuit to confirm it’s working?

To increase the input-impedance, change the 100k resistors to something like 2Meg and the increase the 10K pot to 100K. You can probably eliminate the 4.7nF capacitor.

The LM324 is a quad op-amp that can be used for all kinds of things. The LM386 is a small audio power amplifer that can drive a speaker. The LM324 or Arduino can’t drive a speaker.

…but i still failed to do it and know i am in “LM386” the problem on it have a very noisy sounds.

What??? Noise from that Arduino circuit might be “normal”… But I really don’t know… The Arduino’s ADC is only 10-bits, and it doesn’t have a true DAC at all… just PWM. And, it’s a relatively slow processor with limited memory. For high quality audio, you’d need an external ADC & DAC, and I’m not sure how much audio processing you can do before you run out of processing power.

A good multi-effects guitar pedal isn’t going to be cheap or easy to build… Something simple, like an analog distortion box could be made with an op-amp.

Hi DVDdoug,

I try what you suggested, changing the 100 to 2meg and also changing the 10k pot to 100k pot. but it does’nt output any guitar sound on 8ohm speaker, anyway is it working on 8ohm speaker?

thanks in advance! :slight_smile: