Author Topic: Hook the IC-based overdrive to a speaker, what do I need?  (Read 5580 times)

ericohman

Hook the IC-based overdrive to a speaker, what do I need?
« on: April 26, 2010, 04:25:35 PM »
Hi everyone! Nice project.

I breadboarded the little gem amplifier a few days ago and used it with a speaker I didn't use that was sitting in a solid state combo amp. Yesterday I breadboarded this IC-based overdrive. I like the sound of it.

What do I need to make a speaker move from this circuit? I tried connecting it but nothing happens, I know the LM386 (as in litte gem) is an audio amplifier, where as this IC-based overdrive uses LM741. But I'm curious about how to make this overdrive stompbox into a tiny amplifier...

Any ideas?
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Eric // Skellefteċ, Sweden.

CynicalMan

Re: Hook the IC-based overdrive to a speaker, what do I need?
« Reply #1 on: April 26, 2010, 08:00:06 PM »
You'd need a power amplifier like the little gem to drive a speaker, because anything with an output impedance of over a few ohms would be very quiet to silent. The IC OD has an output impedance of 10k to 110k, so would fall under silent. The LM386 is made to drive speakers and has a very low output impedance.

Load3r

Re: Hook the IC-based overdrive to a speaker, what do I need?
« Reply #2 on: May 05, 2010, 11:19:25 PM »
My very uninformed thought would be to just mash the two together? Maybe a little arcane.  :icon_mrgreen:

If that works, a few components might be able to be eliminated. Maybe the volume pot on the OD250 and the drive pot on the Little Gem with resistors of your preferred value. Or maybe leaving them in gives you the option of pushing the whole unit into heavier distortion via 386 clipping.

And would the input cap (0.01uf) on the Gem be necessary? It's power filter cap (100uf) should be good to nix, seeing as you would hook Va from the OD250's power supply section to pin 6 on the 386.

Would this all be futile without a buffer such as Little Gem Mk.II or Ruby? I see that input cap disappears from the schematics once such a stage is added.

Hmmmmmmmmmm, if my theory can be somewhat confirmed, I would be willing to cobble together a schematic and breadboard version.  :icon_cool: