This is an old revision of the document!
This mod is absolutely essential if you want your x0xb0x to be a bassline machine. It is a really good one to make! Change C21 and C20 from .01uF to .1uF. Some people have found that it gets too boomy if you use your x0xb0x for more of a lead sound, but you can either make it switchable or roll off the bass on your eq.
The DevilFish has a post VCA soft-clip distortion called "The Muffler" that apparently retains bass response.
Soft clip distortion is fairly easy to set up. You get a triple pole switch, and leave one of the poles disconnected, The other pole should lead to a diode going to ground. The other pole should lead to a pair of diodes going to ground, one of them reverse biased. The character of the distortion would change according to the diodes that you choose. You could change this circuit to double up on the diodes
This also might make a passive filter due to C38.
From the Guitar Effects FAQ:
Silicon is reputed to clip abruptly, causing a harsh sound. Germanium clips at about half the voltage of a silicon diode, but is reputed to turn on more slowly in its smaller range. LEDs turn on at about two silicon diode drops, and are also reputed to be slower turn on, with it and germanium giving more "tube like" sounds. Some units with "tube" in the title use LEDs or germanium for clipping.
Oddly enough, the Marshall JCM800 uses a set of two pairs of silicon diodes back to back as clippers. This seems strange in a Marshall, but it is there. When I looked at the schematic, I first thought it was a protective clamp for a tube grid, but the circuit doesn't work that way. They are there for the distortion.
If you perform this mod, please post your experiences with it!
Posted by Guest on the forums:
"while working on adjusting the attack time for the vca envelope i figured i might as well make a full adsr the values could probably use some tweaking and there are some oddities but this seems to work"
|Schematic||Power Supply||Voltage Controlled Oscillator||Voltage Controlled Filter||Envelope Generator||Voltage Controlled Amplifier||Headphone And Mixer||Digital Sequencer||Midi, USB and Sync|
|Fabrication||Building the Ps||Building the Vco||Building the Vcf||Building the Envelope||Building the Vca||Building the Headphone And Mixer||Building the Sequencer||Building the Midi and Sync||Finishing It Off|
|Testing||Testing the Ps||Testing the Vco||Testing the Vcf||Testing the Envelope||Testing the Vca||Testing the Headphone And Mixer||Testing the Sequencer||Testing the Midi and Sync|
|Mods||Ps Mods||Vco Mods||Vcf Mods||Envelope Mods||Vca Mods||Headphone And Mixer Mods||Sequencer Mods||Midi And Sync Mods||Finishing Mods|