Author Topic: Si Tonebender Differences  (Read 881 times)

fuzz guy

Si Tonebender Differences
« on: August 08, 2019, 09:44:46 AM »
I've got a Fuzz Dog Pitbull kit on order, which is a silicon Tonebender. I've always been interested in the Scarab Deluxe, although I can't really afford one, and I know both these pedals are similar, apparently both based on a circuit called the Hot Silicon. I was interested to see how the two circuits differ, and I was wondering if someone could explain some of the differences to me. I'm trying to build an understanding of how all this stuff works.

Here's an image of the Pitbull schematic and BOM, which can also be found here, http://pedalparts.co.uk/docs/Pitbull.pdf




and here's a schematic of the SD I found, drawn by someone on another forum,




On both schematics C1 is part of the Girth/Fat knob circuit which changes the input capacitance, the value for the Pitbull is 1u and for the SD it's 10u. What would the difference in sound be?

What is the purpose of the 100p caps between B and C of Q2 and Q3 on the Pitbull?

The Fuzz Pot on the Pitbull is 1KC and on the SD it's 1KB. I assume the anti-log would get fuzzier faster?

C7 on both schematics seems to be part of the Tone circuit. On the Pitbull it is 5n6, but 8n2 on the SD, what would be the difference to the Tone control?

Thanks
« Last Edit: August 08, 2019, 09:48:04 AM by fuzz guy »


idy

Re: Si Tonebender Differences
« Reply #2 on: August 08, 2019, 03:46:29 PM »
C1: bigger=more bass coming into circuit.
100p caps introduce negative feedback for super highs, smoothing off high end.
C7: that extreme of the tone knob has a high cut, but very high. The other travel, with th4 bigger cap, cuts "all the highs." Make C7 bigger and the brightest setting is darker.

fuzz guy

Re: Si Tonebender Differences
« Reply #3 on: August 08, 2019, 06:25:48 PM »
Thanks guys, that's really helpful. Gus are you the one who helped to develop that original circuit?

Summing up, the Fat control on the SD will allow you to dial in more low end than the Girth control on the Pitbull and the Tone control on the Pitbull will have more high end than the SD when turned all the way up. The Pitbull will also lose some high end with those smoothing caps on Q2 and 3.

So the overall effect of these differences means that the Pitbull circuit will be capable of brighter tones than the SD?

What about the effect of the Fuzz pot being linear on the SD and anti-log on the Pitbull?

nocentelli

Re: Si Tonebender Differences
« Reply #4 on: August 09, 2019, 10:16:23 AM »
What about the effect of the Fuzz pot being linear on the SD and anti-log on the Pitbull?

Most of effect of the fuzz pot happens in the last few hundred ohms of resistance in the pot. An anti-log pot spreads this small range of resistance over a larger portion of the pot travel than a linear pot, making finer control easier at the higher fuzz settings.
Quote from: kaycee
squeeze on the back and never open it up again

fuzz guy

Re: Si Tonebender Differences
« Reply #5 on: August 09, 2019, 06:20:42 PM »

Most of effect of the fuzz pot happens in the last few hundred ohms of resistance in the pot. An anti-log pot spreads this small range of resistance over a larger portion of the pot travel than a linear pot, making finer control easier at the higher fuzz settings.

Thanks, that's what I figured but wasn't sure. I'm planning on modding a Fuzz Face I made which currently has a log pot for the fuzz control, changing it to anti-log to spread out the usable range.

I'm going to build the Pitbull as is and see how I like it first. It's good to know what little tweaks I might be able to try though if I want.

Thanks for the education.

BetterOffShred

Re: Si Tonebender Differences
« Reply #6 on: August 09, 2019, 11:39:18 PM »
I put a C1k on every fuzz face style circuit I build.  B1k is trash by comparison.  Just saying

fuzz guy

Re: Si Tonebender Differences
« Reply #7 on: September 03, 2019, 08:32:38 AM »
I built the kit as it was, the only difference was that they sent a B1K Fuzz pot instead of the C1K. It's a great fuzz, very versatile, and has immediately become my favourite.