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FUZZTONEVOLUME

125B · 3 knobs

Naegele Audio

Modded Tone Bender Mk. III

Based on the Sola Sound Tone Bender Mk. III· 10 other boards clone it

Want a PCB? Naegele Audio laid out a PCB for this circuit and sells boards, as well as relay bypass and I/O boards: message PedalBuilder on the PedalPCB forum.

Category
Fuzz
Controls
Fuzz · Tone · Volume
Price
see vendor
Tags
PedalPCB forum, PCB by message
Read the post at Naegele Audio

From the vendor

After building a Dizzy Tone and a Buzzaround, I set my eyes on their close cousin, the Tone Bender Mk. III. Like most early fuzz pedals, the component values of the Tone Bender Mk. III and its variants changed frequently during their relatively short production period. Some values remained constant, but others (the RefDes values in this schematic) changed from one version to another. <a href="https://forum.pedalpcb.com/attachments/tone-bender-mkiii-schematic-template-png.76999/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='1804' height='758' viewBox%3D'0 0 1804 758'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/77/77018-61fcfe064493fcc106cf562463f8e668.jpg?hash=Yfz-BkST_M" class="bbImage lazyload" style="" alt="Tone Bender MKIII schematic template.png" title="Tone Bender MKIII schematic template.png" width="357" height="150" /> <img src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/77/77018-61fcfe064493fcc106cf562463f8e668.jpg?hash=Yfz-BkST_M" class="bbImage " style="" alt="Tone Bender MKIII schematic template.png" title="Tone Bender MKIII schematic template.png" width="357" height="150" /> I highly recommend looking at Andrew's write-up on the different Mk. III versions at Vero-P2P, which includes a handy table for seeing how component values differed from one version to another. As you can see, there are quite a few options to choose from! I started off by breadboarding the standard circuit using the Sola Sound Tone Bender values. Off the bat, I really liked the texture of the distortion, but found the overall sound thinner and quieter than I would like, even with the volume control maximized. I recalled hearing that the DAM Fuzz Sound versions had been designed to address these issues, so I pulled their values from the table, increasing C4 to 220nF and C5 to 4.7nF, and decreasing R4 to 10k. Those changes did a lot to thicken up the tone, perhaps too much, as it was now slightly boomy. I tried reducing C4 to 180nF, which thinned out the tone more than I wanted, while doing nothing about the unwanted boominess. I ended up reducing C3 to 4.7µF, while keeping the 220nF, which removed the boominess while keeping the tone nice and thick. Unfortunately, the maximum volume was still slightly below unity gain. To increase the output level, I split the 18k resistor in R3 into two resistors (8.2k and 10k). This reduced the attenuation on the bass side of the tone circuit, while keeping the Q3 bias unchanged. As you can see in the simulation below, the output level of the modification is significantly louder than the original. Original (18k) <a href="https://forum.pedalpcb.com/attachments/original-png.77000/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='1298' height='770' viewBox%3D'0 0 1298 770'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digi

Schematic

The schematic is in the post. Open it at Naegele Audio. No KiCad fragment has been drawn for this circuit yet.

Parts list 32 rows

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Check before you build · 1 value the reader of this schematic was not sure of
  • R101: LED resistor drawn as 'CLR' with no value
RefValueNormalizedTypeNotes
Resistors 13
RPD1M1Minput pulldown; read from the schematic by eye
R1220k220kread from the schematic by eye
R247k47kread from the schematic by eye
R310k10kread from the schematic by eye
R410k10kread from the schematic by eye
R53k33.3kread from the schematic by eye
R610k10kread from the schematic by eye
R710k10kread from the schematic by eye
R810k10kwith R9, the split 18k Q3 collector resistor; read from the schematic by eye
R98k28.2kwith R8, the split 18k Q3 collector resistor; read from the schematic by eye
R1010k10kread from the schematic by eye
R1110k10kread from the schematic by eye
R101??LED current limiting resistor, drawn as CLR; read from the schematic by eye
Capacitors 10
C1100n100nread from the schematic by eye
C2220p220pread from the schematic by eye
C3220n220nread from the schematic by eye
C44u74.7uread from the schematic by eye
C5220n220nread from the schematic by eye
C64n74.7nread from the schematic by eye
C101100u100usupply filter; read from the schematic by eye
C10210u10uLT1054 charge pump; read from the schematic by eye
C103100u100uLT1054 output filter; read from the schematic by eye
C104100n100nsupply filter; read from the schematic by eye
Diodes 1
D1D18D18germanium, sets Q3 bias with Q3's leakage; read from the schematic by eye
Transistors 3
Q1EFT83EFT83germanium, hFE 59, leakage 67µA (from the post); read from the schematic by eye
Q2EFT83EFT83germanium, hFE 52, leakage 70µA (from the post); read from the schematic by eye
Q3ASY33ASY33as drawn; the post says an ACY33, hFE 204, leakage 279µA; read from the schematic by eye
ICs 1
IC1LT1054CPLT1054CPvoltage inverter; read from the schematic by eye
Potentiometers 3
FuzzB100kB100kPotentiometerread from the schematic by eye
ToneB100kB100kPotentiometerread from the schematic by eye
VolumeA100kA100kPotentiometerread from the schematic by eye
LEDs 1
D101LEDLEDstatus LED; read from the schematic by eye

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