Ok, so let me start by saying that I’m still relatively green with my comprehension of circuits, so forgive any ignorance… I picked up a SD Tweak Fuzz about 6 months ago in trade. I haven’t totally fallen in love with it, plus GC did their whole “let’s sell them all for $40” deal that pretty much devalued the pedal for me for any future trades, so why not have some fun with it…
analogguru posted a schematic here a while ago:viewtopic.php?f=1&t=12#p17
First, my issues with the pedal:
Stock volume was lacking. I have addressed this with SD’s mod, but I have questions about that (see below).
Pedal tends to sound a little nasally in “tweak” positions 2-5, is too bassy in position 6 for guitar but needs a little more for bass, and position 1 is worthless (IMO).
Fuzz is a little raspy/harsh. I know it’s a fuzz, but I’d like to smooth things out a bit.
SD had a mod posted on their site to increase the volume of the pedal by removing/jumpering R5 and replacing R4 with the 8k2 resistor from R5 (or one of similar value). I’ve found that the “Roger Mayer” mods for this actually replace the 470 ohm R4 with a 1k resistor, and replacing the 8k2 R5 with 18k. Can someone tell me the point of these two resistors, and what the differences in the mods would be?
C1 on the main circuit is a cap across the base/collector of Q1. My understanding of this is to “soften” the clipping and give the Si transistor more of a Ge feel. Is that correct? (note: the Alex Saraceno Afro Fuzz version that this was based on uses a Ge tranny for Q1.) Could this be having the side-effect of making the pedal sound nasally, though?
Next, I was thinking of shifting around the caps on the rotary switch, removing #1 and making #2 - #6 the new #1 - #5, respectively, then adding an even bigger cap to use with a bass. For better response with a bass, would it be worth adding a larger output cap on a mini toggle to switch to? Also, looking at the rotary board, there is a 100k resistor grounded before the cap for each selection. What’s the point of these? I don’t see them on the “classic” FF circuits…
Also, I was thinking of doing one of the “Fuller” mods (I guess what Mike Fuller does on his Fulltone ’69 pedal) wherein he adds a pot in series with the input of the circuit, before the input cap. I’ve seen both recommendations for 50k and 100k. Has anyone tried this, and if so, what are your thoughts?
Finally the magic question… I want to stick with NPN Si transistors. Any thoughts for ones to try?