Akashic Guitar effects circuit lookup
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Enclosure not stated · 5 knobs

Dirtbox Layouts

Fuzzhead Fx Harmonic GyrolatorVerified

Based on the Fuzzhead Fx Harmonic Gyrolator

Category
Fuzz
Controls
Gain · Texture · High · Low · Level
Build
Vero· 19×18· 26 cuts, 13 links
Layout
Verified · Dirtbox Layouts marks it as built and working
Tags
Fuzz, Fuzzhead Fx, Overdrive

From the post

Harmonic Percolator is one the coolest vintage dirtboxes out there with its simple yet unique design, its odd even order harmonics texture, odd mojo parts and it is also a very good overdrive with the gain control rolled back. But using mostly humbucker equipped guitars nowadays it tend to be overly compressed and a bit muddy and dull. Started to tinker with it tso it would suit hot humbuckers but no dice. As it is an unique circuit like no other, the usual mods didn't work out very well like reducing input cap or add a resistor in line with the input signal. But I stumpled upon Dead End Fx Splinter project whcih offers a sollution for this namely reducing the coupling cap value between the transistors and adding a cap across the base of Q1 and ground. Later on I added a "Texture" control which techically is a resostat which alters the resistanse to ground for one of the clipping diodes. Most stock HP's has 4,7k resistor here for some assymetric clipping. I used a 10k pot so stock setting is at noon, turn it up and you get a more open and wide distortion, roll it back for some glithy compreesed sounds with sub octaves jumping around. And I added a two band gyrator tonestack at the end with values not to far away from Boss HM2. The result is a quite lo-fi, fat, industrial and grim fuzz.

Schematic

This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Dirtbox Layouts. No KiCad fragment has been drawn for this circuit yet.

Parts list 38 rows

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Check before you build · 2 values the reader of this layout was not sure of
  • 91K at column 15, rows C-F: printed clearly, unusual value
  • D1-D3: legend says only 'Germanium', no part number
RefValueNormalizedTypeNotes
Resistors 14
×110Ω10read from the layout by eye
×1330Ω330read from the layout by eye
×1470Ω470read from the layout by eye
×13.3K3.3kread from the layout by eye
×210K10kread from the layout by eye
×218K18kread from the layout by eye
×247K47kread from the layout by eye
×151K51kread from the layout by eye
×191K91kread from the layout by eye
×1100K100kread from the layout by eye
×1220K220kread from the layout by eye
×11M1Mread from the layout by eye
×11.2M1.2Mread from the layout by eye
×1??LED resistor, value not given; read from the layout by eye
Capacitors 13
×1100pF100pread from the layout by eye
×1470pF470pread from the layout by eye
×15.6nF5.6nread from the layout by eye
×218nF18nlegend: increase to 47nF for single coils; read from the layout by eye
×147nF47nread from the layout by eye
×168nF68nread from the layout by eye
×2100nF100nread from the layout by eye
×1120nF120nread from the layout by eye
×11uF1ufilm; read from the layout by eye
×11uF1uelectrolytic; read from the layout by eye
×24.7uF4.7uelectrolytic; read from the layout by eye
×147uF47utantalum; read from the layout by eye
×2100uF100uelectrolytic; read from the layout by eye
Diodes 2
×3GermaniumGERMANIUMD1-D3, part number not given; read from the layout by eye
D41N58171N5817read from the layout by eye
Transistors 2
Q1MP20AMP20AMP20A or other PNP Ge w. low leakage, Hfe 50-70; read from the layout by eye
Q2BC108BBC108BBC108B/C; read from the layout by eye
ICs 1
IC1TLC274TLC274read from the layout by eye
Potentiometers 5
GainA100KA100kPotentiometerread from the layout by eye
TextureB10KB10kPotentiometerread from the layout by eye
HighB5KB5kPotentiometerread from the layout by eye
LowB5KB5kPotentiometerread from the layout by eye
LevelA50KA50kPotentiometerread from the layout by eye
Trimmers 1
×1100K100kread from the layout by eye