Improvements to Chaos

[Mark Hammer]

Although it is just another meat-and-potatoes diode clipper that sounds good enough for rock and roll, the CHAOS distortion I posted on my site (http://hammer.ampage.org) was received favourably by some and built by a few.  After playing with it for a bit, I found the ouput level a little weak, so I tinkered and can recommend the following changes to improve it.

Instead of a 2+2 1N914 diode arrangement in the second stage, I put in a pair of red LEDs.  Because the LEDs have a higher clipping threshold, I increased the gain of the second clipping stage by putting in a 470k resistor instead of the 100k one in the schematic.  The other thing I did was replace  the 390pf cap in the tone circuit with a 560pf cap for a little more bite in the midrange.

These changes make it a hotter sounding pedal, without removing any of the smoothness at some settings.  I found a little more variation in distortion quality over the last 1/3 of gain rotation, and you don't need to dime the controls any more to get a noticeable volume boost.

Again, as a distortion it doesn't have any advantage over others, but if you've already built it, I think you'll get more of what you like from it with these mods.

[Ansil]

cool idea thanks mark

[syzygy]

I looked on the web site, but couldn't find the Chaos listed.. maybe I just missed it?

I have a schematic from 2003, but I don't know enough to read all of the symbols.  Does anyone have a parts list?  Also, have you experimented with different OpAmps besides the 1458?  Do you recommend all metal film capacitors and resistors?

Sorry for so many questions, I'm trying to figure out all the components I need to buy to do 3 projects.

Thanks,
syzygy

[Torchy]

Try this

[syzygy]

Thanks Torchy, that link worked.  You have just introduced me to veroboard.. I had no idea what I was looking at for a second there.

This will help a lot.  I also noticed that the diode types were not listed.. but looks like from the original schematic they are all 1N914.

What is the difference between the pots 100k-A (volume) and 100k-B (tone)?  Should I get metalized film type resistors and capacitors for best sound?

[Mark Hammer]

...looks like from the original schematic they are all 1N914.

Yes

What is the difference between the pots 100k-A (volume) and 100k-B (tone)?

Volume controls should almost always be log/audio taper, because of how human ears work.  Tone controls are *usually* linear, but it depends on the nature of the tone circuit.

Should I get metalized film type resistors and capacitors for best sound?

Nah.  It's a FUZZBOX, my friend, not a medical diagnostic instrument.

[syzygy]

Well, there is good fuzz and bad fuzz. . but you have much more experience with circuitry than I, so I'm not arguing.   :wink:  Thanks for clearing that up about the 100k pots and the diodes.  You guys respond fast around here!

[syzygy]

To be clear about the clipping section improvements.. Are the 2 LEDs supposed to be wired in parallel, as in symmetric clipping?  and you get rid of the 2 pairs of diodes that were there before?

regards!

[WGTP]

Your correct about the LED's replacing the other diodes.

Not to steal any of Marks thunder, but I sort of like the way the LED's sound when connected to ground at the output.  

Thanks to Mark for the dual op-amp clipping distortion inspiration.

[Mark Hammer]

No thunder to steal, my friend.  Whatever sounds good to your ears is what the circuit OUGHT to be.

[syzygy]

WGTP, what type of music do you play?  When you say you're connecting the LED to ground at the output, are you adding to the original circuit, or also removing some other components in the circuit?

[WGTP]

I would say either way it it a pretty Heavy Rock/Metal sound.

You can do it both ways.  Either leave the diodes/LED's in the Feedback Loop as the original is, and add the LED's to ground, or remove them from the Feedback Loop and just use them to ground.  Definitely try it both ways and see what you like best.  You may find you need a switch if you like all the combinations. :twisted:

As Mark, said whichever you prefer is right.