Another Smash Drive (killer) build report and introduction

[Cthross]

Hello everyone. I've recently become quite enamored with diy stomp box hobby/obsession. I don't think it is really a cheaper alternative to getting a good pedal, but in some cases it definitely can be. As I'm somewhat new to the electronics world I don't quite understand all the theories behind all the schematics. I've bought kits from BYOC and also GGG and had good results, but eventually I felt that it was cheating since it was somewhat of a paint by numbers method of building pedals. In order to grasp the idea of building from schematics I went over to ROG and searched for their simplest builds to begin. I've now completed the sili-face I and II, Tantalus, Grace, Big Daddy, Mosfet Booster, NPN Fuzz Face, and the Smash Drive. I bought a bread board and have been building on that before I decide which pedals I want to box up. So far the Sili-Face I and Tantalus seem very similar. Love the Mosfet Booster. I've also built a few items from freestompboxes.org. I've only really built drive circuits as those are what I like the most. For modulation and delays I think I'd rather buy my effects. Have always loved Fuzz Faces and have enjoyed modifying them on the bread board for sure. Grace and Big Daddy had a high end that I couldn't seem to tame. I loved the idea of a buffer in front of the LM386 and even more having a gain stage to feed the chip, but there was a high end that was just unpleasent. On to the build of my Smash Drive.

I started with the schematic that has the killer version and simple version. First I built the simple version with a volume control. It seemed that I was receiving a giant volume boost with a bit of drive which slammed the input of my plexi and caused distortion, but didn't seem to create to much on its own. Then I tried the ROG Grace and Big Daddy and didn't like those. The high end thing. So I went back to the Smash Drive and built the killer version. Much better. I was getting grind and was able to shape it quite well. The thing I didn't like about the tone stack was how much they affected each other. The interaction bothered me. So I searched and searched on this forum for other options and came upon someone's build of the 'Smashed Pickle'. Only a few component changes and it was completely different. Sounded to me like a modified Big Muff. Sort of. So I now I knew what could be done with this circuit. So I searched some more and linked to AMZ effects and came across Jack Orman's lab notebook. Lots of good stuff there. Many different tone control options. I tried a few of the single tone controls and then tried the Bass and Treble setup. Voila ! ! Perfect. Close anyways. Even with the tacked on tone control there was still plenty of output availiable and the tone was quite shapeable.

From here I began looking at the Saturation and Warp control circuits in the AMZ Lab Notebook. I liked the theory and thought behind these circuit ideas, but it just seemed to detract from the raw nature of the Smash Drive and lost what makes it special. I removed the Saturation and Warp circuits and BAM ! right back to what makes it great. Then I tried just linking pins 1 and 8 for maximum gain possible and it seemed to lose some gain actually. So I put the 100 ohm resistor and 22uf cap in series to ground and it gave the grind and sustain back. So I then moved onto tone stack mods to get the most out of the circuit. I've been changing caps in the tone stack to get different sounds and I have a .02uf on the base side and a 471pf on the treble side. This gives somewhat of a metal tone to the circuit. Very nice pinch harmonics, stays quiet, cleans up fairly well and stays clear and distinctive, doesn't get muddy. I'm currently experimenting with treble cap values to give a nice mid to high mid tone to the circuit. That way I can go from a nice metal tone to a good mid heavy distortion tone.

So now I have a great med gain to almost high gain distortion pedal. From mid heavy to scooped tones featuring Volume, Bass, and Treble controls. The gain is maxed and is controllable from the guitars volume knob.

A couple questions.

1. What would be good way to add a touch more drive to this circuit? Boosting the input? i.e. a gain stage.

2. Is there a way to grab a little bit more high end from the tone circuit configuration?

Thank you to Aron Nelson, Jack Orman, General Guitar Gadgets, BYOC, Freestompboxes.org, and everyone on this forum. Sorry about the long post, but I thought I'd try to make a contribution and give back to this community since these forums have helped me out so much.

Thanks, Chris

[b_rogers]

for fiddling with the tonestack, search for duncan tone stack calculator.......really cool freeware that will allow you to see what you are affecting as you tweak several classic tonestack designs..