TALKING SLEEVE Official Distortion - sharing so that you can all have a go!

[anchovie]

My musical alter-ego Talking Sleeve decided to boost his ego by having a signature model. It does from crunchy to full-on distortion, and takes a different approach to the common op-amps-and-diodes.

Schematic:


Vero:



HOW IT WORKS

As many of you probably know, the CD4007 contains three pairs of N/P MOSFETS. In this circuit, each pair is used in a different way.

The first stage uses just the N of the pair to boost the input signal and provide high input impedance. The output of this goes via a gain control and a high-pass filter into a maxed-out LM386 to seriously overdrive things. From there, we go back to the CD4007 into an unpowered FET pair, with each FET tied to its respective rail to act as a passive asymmetrical clipper. Then it's on to the final pair, set up as an inverter and exploited as an amplifier in the traditional CMOS manner in order to whack some symmetrical clipping on top of everything, power amp-style.

I'm very pleased with the results as it doesn't get mushy on full six-string chords and provides pleasant useable sounds across the whole travel of the gain pot. Decay is very smooth - none of the splutter that you might get with a 386 in the circuit.

Here's a quick demo recorded on a phone camera; apologies for the string rattle - the kids are asleep so I couldn't crank the amp. Unfortunately, I didn't have the camera rolling when I tested it a high volume in the afternoon and some stuff fell off a shelf as a result!

MOD POTENTIAL

Increase C7 to let more low end into the distortion section.
C1 controls how much treble is rolled off at the asymmetrical clipping stage.
C3 controls how much treble is rolled off at the symmetrical clipping stage.
Add the ability to switch between two gain pots.
Tweak the tonestack to taste (it's just the Big Muff topology, I've made it more of a tilt control because that works best with my amp settings) or replace with your preferred tonestack.
10uF coupling caps don't have to be as high as 10uF (I just have a big bag of them that I got cheap).
Polarity protection diode doesn't have to be 1N4002 (ditto).


Enjoy!

[pakrat]

Thanks for sharing anchovie, that sounds nice.

[aron]

Sounds BIG!

[anchovie]

Thanks pakrat and aron!

I'll get a louder demo done as soon as an opportunity becomes available. I've also been sent an Eagle file to check so there should be a PCB layout for this in the near future.

Just noticed that the schematic has an extra 1K resistor after the 100n input cap. It didn't make a difference when I took it off the breadboard which is why it didn't make it to the layout.

[digi2t]

James, you killed the vid too quick. I was just about to fall into that sustain trance at the end, and you ruined it. 

Really smashing sound, even at low volume. This one is definately going into my library for the future. Thanks dude.

Cheers,
Dino

[G.Neyrey]

Sounds great, anchovie. Thanks for sharing. It can knock things off the shelf during a test run? Count me in for a build!

[~arph]

Sounds very good! I'll throw it on the breadboard!