Scruffiestortion - A High Gain 386 Distortion 'Design'

[Scruffie]

Dubbed the Scruffiestortion untill someone else with some form of imagination thinks of a decent name for it  

Not an incredible design by any means, but it gets a nice high gain sound with plenty of bass & treble with a big mids scoop thanks to that tone stack, the whole thing isn't really picky about values and it's really just another 386 distortion. I designed it with the sound of the Dr Boogey & The Size of the EHX Pocket Metal Muff in mind with the ease of build of the tube screamer... whether it gets that... well that's hard to say (especially as my amp is missing its speaker at the moment and tuning a pedal through headphones was trickier than I thought) but I digress, give it a breadboard if you can and any feedback would be appreciated, good or horrible.

Soundclips to follow when I get given my speaker back probably...



Some quick mod ideas... using the positive input rather than negative... added clipping (might try that tommorow) changing the tone stack to suit your tastes (such as a switch to go between scooped and flat mids which will be on mine and I will add the values for later...) lowering the 22uF electrolytic cap to reduce the gain of the circuit and adding a booster infront (e.g. the Fetzer Valve)

[dukie]

Hi Scruffie congrats on your build, looks good. Just have to heard it to really appreciate it, why dont you record it directly to your computer?
I would like to build this but my LM386 is now in a new Burnin Plexis circuit i just build here. Ive been thinking to build a 386 distortion with SRPP/ mu-amp at the front or a cascaded Fetzer Valve to emulate Tube preamp section 
Nice and simple build man!



Cheers!

[soggybag]

Looks like the 386 is set to max gain at all times!

[Scruffie]

Looks like the 386 is set to max gain at all times!

Oh yes... the gain control does have an effect of course but it's nice and high at all times (although it backs up with the volume control nicely) any value much higher than the 22uF electrolytic and it was in oscillation but it has lots of treble on tap without going into oscillation... the tone stack may need adjusting to some tastes, I do have a second one set for flat mids but with the high gain distortion sound... I thought scooped mids were more appropriate.

Hi Scruffie congrats on your build, looks good. Just have to heard it to really appreciate it, why dont you record it directly to your computer?
I would like to build this but my LM386 is now in a new Burnin Plexis circuit i just build here. Ive been thinking to build a 386 distortion with SRPP/ mu-amp at the front or a cascaded Fetzer Valve to emulate Tube preamp section 
Nice and simple build man!

Cheers!

Thanks! That was the idea, to make it nice and simple...

I would record straight into my computer but without any interface inbetween my guitar and sound cards line in I fear it would be an incredibly hissy poor quality sound that doesn't represent the sound at all, I have an MP3 dictaphone that may be more useful though, i've done some recording on it before so if I build up a ruby amp quickly with a smaller speaker I might be able to record that but... to be honest it's so simple that it'd be easier to build it up and perhaps someone else might record a clip.

The 386 is a nice easy chip to get good sounds out of, your idea sounds like it'd be nice, I might try a fetzer infront of this and see what happens, probably should have before but I just stuck with the FET Buffer.

[Transmogrifox]

I would record straight into my computer but without any interface inbetween my guitar and sound cards line in I fear it would be an incredibly hissy poor quality sound that doesn't represent the sound at all,

Just put another one of those FET buffers on the output, too, and it will be a fine preamp for a line in (use output coupling capacitor & 10k to ground of course).  For a microphone input, just put a 2.2k to ground and another 2.2k in series to the output to help with the bias.

This is very similar to Aron Nelson's variations on the 386 amp.   It may be of interest to browse the schematic archives of this forum . Interestingly, the 386 produces a nice crunchy distortion characteristic.  I have a few variations of these circuits laying around.  The one I have built into a box is very nearly identical to yours except it uses the common source amplifier configuration to get a little gain out of the JFET going to the input of the 386 chip. 

[Scruffie]

I would record straight into my computer but without any interface inbetween my guitar and sound cards line in I fear it would be an incredibly hissy poor quality sound that doesn't represent the sound at all,

Just put another one of those FET buffers on the output, too, and it will be a fine preamp for a line in (use output coupling capacitor & 10k to ground of course).  For a microphone input, just put a 2.2k to ground and another 2.2k in series to the output to help with the bias.

This is very similar to Aron Nelson's variations on the 386 amp.   It may be of interest to browse the schematic archives of this forum . Interestingly, the 386 produces a nice crunchy distortion characteristic.  I have a few variations of these circuits laying around.  The one I have built into a box is very nearly identical to yours except it uses the common source amplifier configuration to get a little gain out of the JFET going to the input of the 386 chip. 

Hmm I might give that a go when i've got the chance...

Yes I did say in the title 'design' I did start it from scratch but it did just end up like most of the other designs but I think it is more voiced for a more modern sounding distortion.

As for gain out of the J-Fet that was on my list of things to try, the buffer was good for the moment though but being a high gain device, more gain would be desireable.

[dschwartz]

you can replace the 10K resistor to ground on the "bass" control for a 20k lin pot, and you´ll get a nice mid scoop control.

[Scruffie]

you can replace the 10K resistor to ground on the "bass" control for a 20k lin pot, and you´ll get a nice mid scoop control.

Yeah, i'm going with just the switch, if you replace that value with Fixed 1M & the 100p on the Treble Pot with a 1nF should flatten the mids out.