More questions on an analog bit crusher...

[chris_d]

Hallo. Specifically talking about the Experimentalists Anonymous op amp/jfet-based one. I built it last night and after reading some posts here was able to get it working by swapping R7 for a 47k and R4 for a 500k.



I have a couple questions.

It seems to require a very loud audio source? If i feed a guitar or similar signal into it, the high pitched overtone is much louder than the "bit crushed" signal. If i run a loud signal(i.e. guitar into noisy cricket into bitcrusher) the input signal can do a reasonable job of drowning out the high pitched tone.

What can i do to allow a guitar to go straight in with less of the high pitched signal? Is this a layout issue? Someone mentioned supplying the two ICs with separate Vref sources? Does that mean i would need two batteries, or simply one more 100k from the existing 9v to a different location in addition to the current one? Does someone have a schematic of what this should look like?

Otherwise this is a pretty cool circuit. Seems to work most effectively in its current state with drums and drum machines, but some interesting effects with keyboards too. If i can get it sorted out better i will post the vero layout i did. Right now it is a mess, and i would like to fix that high pitched sound problem if i can first.

Thanks for any thoughts!

-chris

[The Tone God]

Sorry if this is late but you can check out Crazy Larry and pick what bits you need from that. You can hear the sounds samples to know if it will do what you want.

Andrew

[chris_d]

Sorry if this is late but you can check out Crazy Larry and pick what bits you need from that. You can hear the sounds samples to know if it will do what you want.

Andrew

Cool. I will check that one out, as well. Thanks!

-chris

[dthurstan]

Im planning on building 1 of these and I was thinking coukd the buffer X1 be changed to a booster (like http://www.muzique.com/lab/boost.htm)? But get rid of the 100K Pot and adjust a 14K trim to booster the signal above "the high pitched overtone". I was going to have a big muff style output stage (tone and volume controls).

Any thoughts?

Cheers

Dave

[brett]

Hi
First, check the pinout on your J201.

Can you test the output level from the first op-amp?

Try another JFET.  I'd try a 2N5485 or 2N5486 (or even a MPF102).
Also, I'd add a voltage "bleed" to the gate.  A 1M resistor from gate to ground should do the trick, as the JFET capacitance isn't too high.

I agree that you probably want a boost at the front end.  But don't go more than 10x or you'll risk clipping.  3x should be good.
cheers