The Sili-Face II Chronicles

[bwanasonic]

As mentioned in another post, I've recently discovered the joys of breadboarding. I started with the runoffgroove sili-face II* as a core, and used it as a springboard for some basic experiments I'd been meaning to try. Along the way the way I learned a few things about cap types as well.

After twiddling with most of the values in the ciruit, I came to the conclusion that the *stock* values were pretty well thought out, and with the exception of the input cap, I went with pretty much stock values for the *core* of the circuit. I have a lot of those tiny little *box* mkt caps, and used those for input, output, and feedback bypass initially. The only 4.7uf I had was a tant, so I started with that for the 1k bypass. I liked this first incarnation, but it had a strange, *peaky* and sharp Q. It seemed a bit *ringy* when I turned down my guitar volume. I started replacing cap types, and found *greenies* on the input/output helped a lot. Still a bit too sharp of a Q in the overall freq. response, so I replaced the 4.7 tant with two 10uf electros in series, + to +. Ahh, much better! Finally replaced the feedback resistor bypass with a dipped 1% film from smallbear. I had started with 2N3904s for trannies. I tried 5089s, but the gains on the ones I had at hand were too high and caused squealing oscillations. Just in time, my shipment of BC109s came in from Olaf at banzaieffects. These sounded great, and now I started fooling with diode pair clipping on the output, and Joe D's *Vulcan* diode arrangement on Q1. So far, the plan is to use a 3PDT stomp to switch the clipping diodes, that also switches a volume compensating 100k trimpot in parallel with the volume pot, and a bi-color LED. You could setup the trimpot so that switching in the diodes gives you a little solo boost. Then, two toggles will be used. One to switch between *Fat & skinny* input capacitance, and one to switch the *vulcan* diode arrangement. Briefly experimented early on with a Rangemaster in front, and this seems like a promising config. Now to box it up, and test it "in the field"...



Kerry M

[B Tremblay]

Whoa!  You've certainly spent some significant time with the SF2!  All your mods look well-considered and very interesting.  Thanks for sharing with us.

[petemoore]

Great Work !!!
 Way to draw that extra volume control and switch in there.