Author Topic: LM386 Bridged Distortion Pedal?  (Read 5114 times)

Alan410

LM386 Bridged Distortion Pedal?
« on: April 19, 2014, 05:51:32 AM »
Hiya!

I followed a schematic : http://www.runoffgroove.com/littlegemMK2.png

And ended up with a near satisfactory amplifier.

I brdiged the 10uf capacitors and replaced it with a 10k pot that adds distortion.

The problem is that when I connect my guitar, I get no audio at all. If I connect it to my computer I get sound.

Also there is alot of background noise.

I removed the JFET that was supposed to be there because I didn't have one, it still works without it, not sure what it was for in the first place.

My distortion is also a bit messed up, having the my pot off (lowest) and then turning it up lowers the sound, but then builds up to the highest volume.

So problems I have are:

No sound from guitar.
Bad/strange distortion
Bad quality sound

bluebunny

Re: LM386 Bridged Distortion Pedal?
« Reply #1 on: April 19, 2014, 01:42:25 PM »
Hiya!

Hiya!  Welcome...   :)

Quote
I removed the JFET that was supposed to be there because I didn't have one, it still works without it, not sure what it was for in the first place.

If you removed the JFET (it was a buffer), at what point do you introduce your signal?  Did you also lose the 1M5 resistor to ground?
Ohm's Law - much like Coles Law, but with less cabbage...

Jdansti

Re: LM386 Bridged Distortion Pedal?
« Reply #2 on: April 19, 2014, 01:58:13 PM »
The JFET is your preamp. I'm guessing that the signal from the guitar is too small for the rest of the circuit to work without it. Your computer's output is already amplified.

BTW-Welcome to the forum!
« Last Edit: April 19, 2014, 02:00:42 PM by Jdansti »
R.G. Keene: EXPECT there to be errors, and defeat them...

diydave

Re: LM386 Bridged Distortion Pedal?
« Reply #3 on: April 20, 2014, 05:07:16 AM »
Change the fet-buffer to a fet-boost.
Really good distortion.