SD-1 Modifications Complete!

[phillip]

I finished modifying my brand new SD-1 a few hours ago and it sounds great!  More distortion and crunch!  I did the Keeley ****5-Star Ge mods, except I didn't add the 47pF across the clipping diodes (it sounds great without it!), and I used a regular Ge. diode instead of Ge. transistor soldered in to function as a diode.  The original IC in this one was a JRC4558DD, which sounded good enough, but I removed it and installed a socket in its place.  Right now I'm running a Burr Brown OPA2604 and it sounds fantastic!  I'm also going to compare the BB with the original 4558DD and a Texas Instruments RC4558P.  

I've drawn up a correct schematic for the SD-1, traced out from my new one, including the JFET switching section:

http://axiseffects.home.att.net/misc/SD1.gif

And here's the schematic that shows the modified parts:

http://axiseffects.home.att.net/misc/SD1_Modified.gif

Phillip

[Ansil]

so you would recomend the burr brown

[phillip]

I would definitely recommend the Burr Brown IC, even though it costs $3.50 for one...well worth the investment.  I woud also recommend getting ahold of all the other 4558-type ICs that can be used so that a lot of experimenting can be done

Phillip