Flexible distortion

[PBE6]

Just wanted to share a schematic for a flexible distortion I've been working on:


The first stage is a bass roll off to prevent excessive fizz in the distorted signal. The second stage is the gain stage, switchable between soft and hard clipping. The third stage is a bass boost, lifted straight from ROG's "Thor", to compensate for the pre-distortion bass loss. The fourth stage is a guitar tone knob-style treble roll off. The last stage is an amplifier that provides a little bit of makeup gain.

I should add that I'm not 100% sure about the impedance on the input stage, I might just use a quad opamp and add a buffer before the bass roll off.

Any comments welcome, I will hopefully get around to building it next weekend.

[anchovie]

That pre-cut control will cause problems - you'll need a cap between it and the 470k opamp bias resistor otherwise you've got a point referenced to both ground and half-supply. The low total resistance of the filter will bring the input impedance right down so you'll need that buffer like you suspected.

[slacker]

You might be interested in this little snippet, it gives you a gain stage where a pot controls the gain but also pans between hard and soft clipping.
http://www.diystompboxes.com/smfforum/index.php?topic=72404.0

[PBE6]

Good catch! Thanks.

[Gus]

Have you seen this site?
http://www.gmarts.org/index.php?go=217