Analog Bit Crusher

[gez]

When the square output is at ground potential the FET is off (providing pinch-off threshold is reached), but when it's at V+ potential the gate-source junction is forward biased. 

That should have read gate-drain junction in this case (though that cap does provide a path to ground for the source).

[slacker]

just breadboarded this and it sounds really good, goes from nice ringmod type sounds to complete sonic mush 
I had to change R7 to 220K to get any output from the oscilator and I had to lower R4 to about 500k to get the J201 to switch, but I've only tried one J201 so it might be a case of trying some more to get one that will work with a bigger resistor.
The bleedthrough is pretty low, there's a bit coming from the oscilator but most of it comes from the jfet switching.
I tried the inverting opamp idea with pre boost/post cut and using a gain of +-20 lowered the bleedthrough a lot.
I also wonder whether it might be worth decoupling the jfet like in RG's stutter pedal, because at the moment the second opamp is getting its Vb voltage from the output of the first one. I think this means that when the jfet is off the opamp's momentarily unbiased which might be adding to the noise. Decoupling would also let you try the jfet as a shunt to ground switch instead which is sometimes less noisy.
Cool circuit though, definately worth playing with.

[puretube]

b*mp coz I missed this thread
due to my 50th birthdayparty
in Turkey, the day before...

[John Lyons]

Anyone built from this layout, or have a working one?


Thanks

John