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RATEDEPTHMIX

125B · 3 knobs

Aion FX

LithiumAnalog Chorus

Based on the EHX Small Clone· 1 other board clones it

Category
Vibrato / Chorus· Chorus
Controls
Rate · Depth · Mix
Difficulty
Intermediate
Price
$12.50in stock

From the vendor

An early BBD-based analog chorus most notably used by Kurt Cobain for much of Nevermind.

The Lithium Analog Chorus is an adaptation of the Electro-Harmonix Small Stone chorus pedal, originally released in 1979 and produced up until Electro-Harmonix closed down in 1983. It was a more compact alternative to the Clone Theory, in the same way that the Small Stone was a reduced-footprint successor to the Bad Stone.

The Small Clone was most famously used by Kurt Cobain on “Come As You Are” as well as several other tracks on Nevermind. It has also been used by Jonny Greenwood, The Edge and several others.

The original circuit had two different variants, one using the extremely rare SAD1024 and the other using the MN3007. It’s commonly thought that the SAD1024 version came first and the MN3007 replaced it—and the factory schematic would seem to support this, showing SAD1024 as the default and then including the MN3007 changes as a modification. However, based on date codes of production units, the SAD1024 wasn’t seen until 1981 or possibly late 1980, while the MN3007 was used throughout the whole production run. Whatever the case, the MN3007 variant is far more common.

While it’s often said that Kurt used the SAD1024 version, there is no definitive proof of this that we have seen. It’s statistically much more likely that his was the MN3007 one.

The Small Clone was reissued in the early 2000s, still using the MN3007 BBD but with a few small circuit changes that cause it to sound different. The overall schematic is pretty well identical, though, so the reissues can be easily modified to vintage specs.

The Lithium is an expanded adaptation of the MN3007 Small Clone, with the addition of a Depth control (converted from a switch) and a Mix control. If you want to read more on the changes, the build notes are extensive, so there are plenty of details for the curious.

Note: This project uses a type of capacitor that has been temporarily discontinued by WIMA. Please see our news article about the issue and the substitution spreadsheet for project-specific recommendations. We are stocking a limited supply in the mean time. The build document has not yet been updated to reflect this.

Schematic

The schematic is in the vendor's build document, page 9. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 84 rows

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RefValueNormalizedTypeNotes
Resistors 36
R1220k220kMetal film resistor, 1/4W
R21k1kMetal film resistor, 1/4W
R333k33kMetal film resistor, 1/4W
R46k86.8kMetal film resistor, 1/4W
R522k22kMetal film resistor, 1/4W
R610k10kMetal film resistor, 1/4W
R733k33kMetal film resistor, 1/4W
R86k86.8kMetal film resistor, 1/4W
R91k1kMetal film resistor, 1/4W
R10100k100kMetal film resistor, 1/4W
R113k33.3kMetal film resistor, 1/4W
R1210k10kMetal film resistor, 1/4W
R1310k10kMetal film resistor, 1/4W
R1412k12kMetal film resistor, 1/4W
R1533k33kMetal film resistor, 1/4W
R1839k39kMetal film resistor, 1/4W
R1910k10kMetal film resistor, 1/4W
R2039k39kMetal film resistor, 1/4W
R2139k39kMetal film resistor, 1/4W
R2210k10kMetal film resistor, 1/4W
R23220k220kMetal film resistor, 1/4W
R2420k20kMetal film resistor, 1/4W
R25180k180kMetal film resistor, 1/4W
R2647k47kMetal film resistor, 1/4W
R27120k120kMetal film resistor, 1/4W
R28470k470kMetal film resistor, 1/4W
R2968k68kMetal film resistor, 1/4W
R3082k82kMetal film resistor, 1/4W
R3139k39kMetal film resistor, 1/4W
R3247R47Metal film resistor, 1/4W
R3356k56kMetal film resistor, 1/4W
R3456k56kMetal film resistor, 1/4W
R3547R47Metal film resistor, 1/4W
R3610k10kMetal film resistor, 1/4W
RPD2M22.2MMetal film resistor, 1/4WInput pull-down resistor. Can be as low as 1M.
LEDR4k74.7kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 23
C133n33nFilm capacitor, 7.2 x 2.5mm
C210n10nFilm capacitor, 7.2 x 2.5mm
C310n10nFilm capacitor, 7.2 x 2.5mm
C41uF1uFilm capacitor, 7.2 x 3.5mm
C51uF1uFilm capacitor, 7.2 x 3.5mm
C63n33.3nFilm capacitor, 7.2 x 2.5mm
C7470pF470pMLCC capacitor, NP0/C0G
C815n15nFilm capacitor, 7.2 x 2.5mm
C104n74.7nFilm capacitor, 7.2 x 2.5mm
C112n72.7nFilm capacitor, 7.2 x 2.5mm
C12180pF180pMLCC capacitor, NP0/C0G
C131uF1uFilm capacitor, 7.2 x 3.5mm
C142.2uF2.2uElectrolytic capacitor, 5mmSee build notes for other options.
C1547n47nFilm capacitor, 7.2 x 2.5mm
C1610uF10uElectrolytic capacitor, 5mm
C17100pF100pMLCC capacitor, NP0/C0G
C1847pF47pMLCC capacitor, NP0/C0G
C19220uF220uElectrolytic capacitor, 6.3mm
C2047uF47uElectrolytic capacitor, 5mm
C21220uF220uElectrolytic capacitor, 6.3mm
C2210uF10uElectrolytic capacitor, 5mm
C2310uF10uElectrolytic capacitor, 5mm
C24100n100nMLCC capacitor, X7R
Diodes 3
D11N58171N5817Schottky diode, DO-41
D21N9141N914Fast-switching diode, DO-35
D31N9141N914Fast-switching diode, DO-35
Transistors 3
Q12N50872N5087BJT transistor, PNP, TO-92
Q22N50882N5088BJT transistor, NPN, TO-92
Q32N50882N5088BJT transistor, NPN, TO-92
ICs 4
IC1RC4558PRC4558POperational amplifier, DIP-8
IC2MN3007MN3007BBD, 1024-stage, DIP-8
IC3LM358NLM358NOperational amplifier, DIP-8
IC4CD4047BECD4047BECMOS multivibrator, DIP-14
Potentiometers 3
RATE1MCC1M16mm right-angle PCB mount pot
DEPTH10kBB10k16mm right-angle PCB mount pot
MIX250kCC250k16mm right-angle PCB mount pot
Trimmers 1
BIAS100k100kTrimmer, 10%, 1/4"Bourns 3362P
Switches 2
SW1DPDT slide, microDPDT SLIDE, MICROSlide switch, DPDTE-Switch EG1271
FSW3PDT3PDTStomp switch, 3PDT
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 7
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC2-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC3-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC4-SDIP-14 socketDIP-14 SOCKETIC socket, DIP-14
IN1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountMouser 163-4302-E or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

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