IN PROGRESS Keeley Fuzz Bender…
- Thread starter Coda
- Start date
2nd resurrection for this thread!!
Lol.
I just got through building the Truth Bender from Effects Layouts, it's a clone of the Fuzz Bender... I also have an original Fuzz Bender and took them both up to a friend of mine that plays guitar well. Both pedals are basically the same sounding but one had a little more gain than the other. The discrepancies between the two can be compensated with small twists of the knobs, so basically they are the same...
They key is getting the transistors correct (gains and leakage for the Ge transistor).
First I tried 2 Si transistors with gains of around 50-60 each... These didn't do it for the right sound. I ended up using a hfe of 125 for transistor #1 and a hfe of 150 for transistor #2.
The Ge transistor is the biggie. I first used a low leakage transistor with a gain of 60 like the yellow hybrid Tone Bender then another with a hfe of 80 and the pedal didn't sound right... So I carefully desoldered the Ge transistor from my original Fuzz Bender to measure it. The hfe was 117 and the leakage was 1.08ma!! CRAZY leakage on that transistor is needed for the bias and fuzz control to work correctly, especially the bias control. With this transistor, the fuzz is full and smooth with the bias knob fully CCW and very spitty and gated the more you turn the bias knob CW. So in my EL board I ended up using a Japanese NPN Ge transistor with a hfe of 107 and leakage of 950ua, just under 1ma... I also tried a russian gt404 with a hfe of 103 and leakage of 483ua. Both worked well with good variance on the bias knob, the Japanese very high leakage transistor worked better out of the two.
What I would recommend to builders is to buy a NTE103A transistor for the Ge transistor... These 103A transistors leak like crazy, basically they SUCK! Lol, but in this application it's what's needed for correct functioning of this pedal.
Lol.
I just got through building the Truth Bender from Effects Layouts, it's a clone of the Fuzz Bender... I also have an original Fuzz Bender and took them both up to a friend of mine that plays guitar well. Both pedals are basically the same sounding but one had a little more gain than the other. The discrepancies between the two can be compensated with small twists of the knobs, so basically they are the same...
They key is getting the transistors correct (gains and leakage for the Ge transistor).
First I tried 2 Si transistors with gains of around 50-60 each... These didn't do it for the right sound. I ended up using a hfe of 125 for transistor #1 and a hfe of 150 for transistor #2.
The Ge transistor is the biggie. I first used a low leakage transistor with a gain of 60 like the yellow hybrid Tone Bender then another with a hfe of 80 and the pedal didn't sound right... So I carefully desoldered the Ge transistor from my original Fuzz Bender to measure it. The hfe was 117 and the leakage was 1.08ma!! CRAZY leakage on that transistor is needed for the bias and fuzz control to work correctly, especially the bias control. With this transistor, the fuzz is full and smooth with the bias knob fully CCW and very spitty and gated the more you turn the bias knob CW. So in my EL board I ended up using a Japanese NPN Ge transistor with a hfe of 107 and leakage of 950ua, just under 1ma... I also tried a russian gt404 with a hfe of 103 and leakage of 483ua. Both worked well with good variance on the bias knob, the Japanese very high leakage transistor worked better out of the two.
What I would recommend to builders is to buy a NTE103A transistor for the Ge transistor... These 103A transistors leak like crazy, basically they SUCK! Lol, but in this application it's what's needed for correct functioning of this pedal.
Fama
Well-known member
Thank you for the values! I just built mine a bit earlier and it works fine, but the Bias control was a bit of a letdown. Now I can try to see if I have a transistor with high enough leakage to make it work better.
I think my silicon transistors are also in the 250 range for HFE, so I'll try some lower ones.
Fama
Well-known member
FWIW I built mine on the EffectsLayouts PCB, and it worked fine. Just pointing that out if you don't want to wait.
Matopotato
Active member
I think I used this schematic. The 1044 got very hot, so I let the two X be disconnected.I always forget about this one. Seems the Fuzz Factory is more popular as a 5-knob fuzz. Not sure how accurate this schematic is, though…
Had some glitches and stripboard did bridge at one place, bit now it works nicely. I was fortunate to find an old vintage Ge transistor from some old radio or tv of the 70s sonthe bias gives me many options. Wants to be early in the chain. I used a layout for stripboard, but it matched the schematic well enough if my memory serves me right.
