aion LITHIUM User manual

LITHIUM ANALOG CHORUS 1
PROJECT NAME
LITHIUM
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Electro-Harmonix® Small Clone
An early BBD-based analog chorus most notably used by Kurt Cobain for much of Nevermind.
Chorus 1.0.1 (2022-10-21)
BUILD DIFFICULTY
Intermediate
Actual size is 2.3” x 2.42” (main board) and 1.78” x 0.86” (bypass board).

LITHIUM ANALOG CHORUS 2
TABLE OF CONTENTS
1Project Overview 10 Drill Template
2Introduction & Usage 11 Enclosure Layout
3-5 Parts List 12 Wiring Diagram
6-8 Build Notes 13 Licensing
9Schematic 13 Document Revisions
INTRODUCTION
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 Small Clone 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.
USAGE
The Lithium has three controls:
• Rate sets the speed of the chorus effect.
• Depth sets the intensity of the chorus effect. This was a 2-position slide switch on the original, but
the potentiometer allows for much more flexibility.
• Mix sets the volume level of the wet signal, allowing it to be dialed back for a milder effect. The dry
signal is unaffected and always unity gain.

LITHIUM ANALOG CHORUS 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts—notably potentiometers—so the second tab lists
all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 220k Metal film resistor, 1/4W
R2 1k Metal film resistor, 1/4W
R3 33k Metal film resistor, 1/4W
R4 6k8 Metal film resistor, 1/4W
R5 22k Metal film resistor, 1/4W
R6 10k Metal film resistor, 1/4W
R7 33k Metal film resistor, 1/4W
R8 6k8 Metal film resistor, 1/4W
R9 1k Metal film resistor, 1/4W
R10 100k Metal film resistor, 1/4W
R11 3k3 Metal film resistor, 1/4W
R12 10k Metal film resistor, 1/4W
R13 10k Metal film resistor, 1/4W
R14 12k Metal film resistor, 1/4W
R15 33k Metal film resistor, 1/4W
R16 JUMPER Metal film resistor, 1/4W Use 1k for MN3207 version. See build notes.
R17 OMIT Metal film resistor, 1/4W Use 14k for MN3207 version. See build notes.
R18 39k Metal film resistor, 1/4W
R19 10k Metal film resistor, 1/4W
R20 39k Metal film resistor, 1/4W
R21 39k Metal film resistor, 1/4W
R22 10k Metal film resistor, 1/4W
R23 220k Metal film resistor, 1/4W
R24 20k Metal film resistor, 1/4W
R25 180k Metal film resistor, 1/4W
R26 47k Metal film resistor, 1/4W
R27 120k Metal film resistor, 1/4W
R28 470k Metal film resistor, 1/4W
R29 68k Metal film resistor, 1/4W
R30 82k Metal film resistor, 1/4W
R31 39k Metal film resistor, 1/4W
R32 47R Metal film resistor, 1/4W

LITHIUM ANALOG CHORUS 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
R33 56k Metal film resistor, 1/4W
R34 56k Metal film resistor, 1/4W
R35 47R Metal film resistor, 1/4W
R36 10k Metal film resistor, 1/4W
RPD 2M2 Metal film resistor, 1/4W Input pull-down resistor. Can be as low as 1M.
LEDR 4k7 Metal film resistor, 1/4W LED current-limiting resistor. Adjust value to change LED brightness.
C1 33n Film capacitor, 7.2 x 2.5mm
C2 10n Film capacitor, 7.2 x 2.5mm
C3 10n Film capacitor, 7.2 x 2.5mm
C4 1uF Film capacitor, 7.2 x 3.5mm
C5 1uF Film capacitor, 7.2 x 3.5mm
C6 3n3 Film capacitor, 7.2 x 2.5mm
C7 470pF MLCC capacitor, NP0/C0G
C8 15n Film capacitor, 7.2 x 2.5mm
C9 OMIT Use 4.7uF tantalum for MN3207 version. See build notes.
C10 4n7 Film capacitor, 7.2 x 2.5mm
C11 2n7 Film capacitor, 7.2 x 2.5mm
C12 180pF MLCC capacitor, NP0/C0G
C13 1uF Film capacitor, 7.2 x 3.5mm
C14 2.2uF bipolar Electrolytic capacitor, 5mm See build notes for other options.
C15 47n Film capacitor, 7.2 x 2.5mm
C16 10uF Electrolytic capacitor, 5mm
C17 100pF MLCC capacitor, NP0/C0G
C18 47pF MLCC capacitor, NP0/C0G
C19 220uF Electrolytic capacitor, 6.3mm
C20 47uF Electrolytic capacitor, 5mm
C21 220uF Electrolytic capacitor, 6.3mm
C22 10uF Electrolytic capacitor, 5mm
C23 10uF Electrolytic capacitor, 5mm
C24 100n MLCC capacitor, X7R
D1 1N5817 Schottky diode, DO-41
D2 1N914 Fast-switching diode, DO-35
D3 1N914 Fast-switching diode, DO-35
Q1 2N5087 BJT transistor, PNP, TO-92
Q2 2N5088 BJT transistor, NPN, TO-92
Q3 2N5088 BJT transistor, NPN, TO-92

LITHIUM ANALOG CHORUS 5
PARTS LIST, CONT.
PART VALUE TYPE NOTES
Z1 OMIT Use 1N4739A if building MN3207 version. See build notes.
IC1 RC4558P Operational amplifier, DIP-8
IC1-S DIP-8 socket IC socket, DIP-8
IC2 MN3007 BBD, 1024-stage, DIP-8
IC2-S DIP-8 socket IC socket, DIP-8
IC3 LM358N Operational amplifier, DIP-8
IC3-S DIP-8 socket IC socket, DIP-8
IC4 CD4047BE CMOS multivibrator, DIP-14
IC4-S DIP-14 socket IC socket, DIP-14
SW1 DPDT slide, micro Slide switch, DPDT E-Switch EG1271
BIAS 100k trimmer Trimmer, 10%, 1/4" Bourns 3362P
RATE 1MC 16mm right-angle PCB mount pot
DEPTH 10kB 16mm right-angle PCB mount pot
MIX 250kC 16mm right-angle PCB mount pot
LED 5mm LED, 5mm, red diffused
IN 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

LITHIUM ANALOG CHORUS 6
BUILD NOTES
Setting the bias trimmer
As with other BBD choruses, the bias trimmer can be set by ear with no special equipment. Start in the
center position, and adjust to the left or to the right until you hear a modulated chorus signal. Then,
fine-tune it while listening for distortion or other audible artifacts and adjust the trimmer until these are
eliminated or minimized.
You can also connect an oscilloscope to pin 7 or 8 of the BBD and use the scope reading to adjust for
a symmetrical waveform with equal clipping on the top and bottom. Use a signal generator to send an
8kHz sine wave at 2V p-p as a test signal. This is far higher in amplitude than what the BBD would see in
normal operation, but the heavy clipping allows for optimal adjustment.
MN3007 and MN3207 usage
The original Small Clone uses the MN3007 BBD. This BBD is long out of production, but the Xvive
reissues sound just as good and are highly recommended.
The MN3207 replaced the MN3007 in the late 1980s, optimized for lower voltages down to 5V but with
a maximum voltage of 10V. Today, old-stock 3207s are significantly cheaper than old-stock MN3007s,
and the Coolaudio reissues (v3207) are also significantly cheaper than the Xvive MN3007 reissues, so
it’s an attractive option.
Importantly, though, the 3207 runs on opposite polarity, so in order for the MN3207 to replace the
MN3007, the supply voltage and ground need to be reversed for the chip.
Some choruses such as the Boss CE-2 can be easily converted to using the MN3207 by setting a few
jumpers to invert the polarity, as in our Azure project. We have experimentally included the same
standard MN3007/MN3207 conversion jumpers on the Lithium PCB, although it should be stressed
that we have not tested this and it may be wildly deficient for this circuit. It’s possible that the input
biasing network (bias trimmer through R14) would need additional changes in order to work properly.
Therefore, only attempt a MN3207 conversion if you know what you’re doing. If we hear reports of
success, then we’ll revise the build notes with more confident advice, but for now we are adding a strong
disclaimer to any deviation from the base MN3007 circuit.
Setting the jumpers
Underneath IC2, there are four jumper pads arranged in a square pattern. The MN3007 and MN3207
have their positive and negative supply pins inverted from each other, so the jumpers need to be set to
route the supply voltages to the correct pins.
The underside of the PCB has a legend on the silkscreen showing which way the jumpers should be
soldered. If using a MN3007, both jumpers should be installed horizontally. If using a MN3207 or v3207,
the jumpers should go vertically. If you don’t solder these jumpers, there will be no wet signal at all.
If using a MN3207, make sure to use 1N4739A (9.1V zener) for Z1 to limit the BBD’s supply voltage to
9V. If using a MN3007, this zener can be omitted since the maximum supply voltage is 15V.

LITHIUM ANALOG CHORUS 7
BUILD NOTES, CONT.
VGG voltage
BBDs typically require pin 4 (VGG) to be supplied with a voltage that is 14/15ths of the supply voltage
(VDD) for best performance. This VGG voltage is intended to be supplied by the MN300X series’
companion clock chip, the MN3101.
The Small Clone does not use the MN3101, but instead uses a CD4047 to generate the clock signal.
Electro-Harmonix did not implement an external 14/15 voltage divider, instead connecting the VGG pin
to the VDD supply voltage, and the circuit seems to perform just fine without it.
However, we’ve heard anecdotally that the MN3207 is more sensitive to the 14/15 voltage than the
MN3007, so it may be the case that the MN3207 requires this 14/15 network where the MN3007 does
not. It may also be the case that the performance of the MN3007 in the stock circuit could be improved
with this network, so you could try using it even with the MN3007—though whether it will affect the
character of the effect, we don’t know.
Either way, if you want to use the 14/15 VGG network, use 1k for R16, 14k for R17, and a 4.7uF or 10uF
tantalum capacitor for C9.
To build the stock circuit, omit C9 and R17 (in other words, leave them empty) and jumper R16.
Mix knob
The original Small Clone had a fixed proportion of dry and wet signals mixed in the last op-amp stage.
We’ve added a Mix knob that allows the wet signal to be dialed back.
The vintage Small Clone used a 27k resistor for R24, while the 2002 reissue reduced this to 20k,
resulting in a more prominent wet mix. Due to the addition of the Mix knob, it’s recommended to always
use the modern value of 20k since the mix knob directly adds to this fixed resistance value. Therefore,
to get the “vintage” value of 27k, just turn the mix knob down about 10-15%. With the mix knob at full
rotation, it’s equivalent to the “modern” value of 20k.
Depth knob
The original Small Clone only had a 2-position depth switch to change the intensity of the chorus sound.
We’ve converted this to a potentiometer that allows fine-tuning the depth across the whole range and
beyond, instead of being stuck with two presets.
Vintage/Modern slide switch
The original Small Clone used a 100pF timing capacitor for the clock, while the reissue uses 150pF.
This changes the delay range somewhat, but even adjusting the rate to compensate, the tone is a little
different. We’ve included the vintage 100pf capacitor as the default, as well as a 47pF capacitor that
can be switched in parallel using an on-board slide switch. If you don’t care to have the modern value
available, you can omit C18 and the slide switch (no jumpers needed) and just use C17.
Note that the modern Small Clones also change R8 to 9k1 to add back some of the brightness that is
lost by the capacitor change. This is sort of a hack on EHX’s part since it puts the pre/de-emphasis filters

LITHIUM ANALOG CHORUS 8
BUILD NOTES, CONT.
out of balance, but if you prefer the modern mode and find that it lacks some brightness, you could try
changing out this resistor.
Thanks to Dana for detailed insight into the differences between the vintage and modern versions.
C14 bipolar capacitor
In the original Small Clone, C14 (the LFO timing capacitor) is a polarized 2.2uF tantalum capacitor.
Theoretically, this type of capacitor should be bipolar since the voltages are not reliably higher or lower
on either side, so we’ve specified a bipolar type in the parts list.
If you can’t find one, you can follow EHX’s lead and just use a polarized electrolytic with the positive side
going to the left pad (the same orientation as C22 next to it). There are 40-year-old Small Clones that
are still working just fine, so it can’t be too critical of an issue.
You can also use two 4.7uF electrolytic capacitors wired in series, with the negative legs going to the
pads of C14 and the positive legs tied together. This will give an effective capacitance of 2.35uF, which is
well within tolerance.

SCHEMATIC
LITHIUM ANALOG CHORUS 9
IN
OUT
7
62
58
4
3
1
1N5817
220uF
1MC
10kB
250kC
+9V
100n
GND
2M2
33n
220k
VB
1k
RC4558P
RC4558P
47R
56k
56k
VB
GND
47R
47uF
GND
220uF
GND2
10k
VA
VC
GND2
10uF
VD
33k
VA
GND
6k8
10n
VB
22k 10k
VB
33k
10n
6k8
1k
1uF
100k
GND
1uF
100k
VC
GND2
3k3
3n3
10k
GND2
2N5087
10k
470pF
GND2
GND2
15n
1N914
12k
2N5088
10uF
GND2
VD
OMIT
GND2
33k
GND2
VD
39k
10k
4n7
39k
2n7 180pF
39k 2N5088
10k
1uF
220k
VB
20k
180k
VC
LM358N LM358N
VC
GND2
68k
2.2uF BP
120k
47n
GND2
47k
470k
82k
GND2
GND2
10uF
GND2
39k
1N914
VD
CD4047BE
GND2
GND2
100pF
VD
JUMPER
OMIT
OMIT
GND2
47pF
GND
GND
VA
GND
D1
C19
RATE
1
2
3
DEPTH
1
2
3
MIX
1
2
3
C24
RPD
C1
R1
R2
2
3
1
IC1A
6
5
7
IC1B
84
R32
R33
R34
R35
C20
C21
R36
C22
R3
R4
C2
R5 R6
R7
C3
R8
R9
C4
R10
C5
BIAS
1
2
3
R11
C6
R12 Q1 R13
C7
C8
D2
R14
Q3
C23
Z1
R15 IC2
MN3007
R18
R19
C10
R20
C11 C12
R21 Q2
R22
C13
R23
R24
R25
2
3
1
IC3A
IC3B
6
5
7
84
R29
C14
R27
C15
R26
R28
R30
C16
R31
D3 1
2 3 4 5 6 7 8
9 10 11 12 13 14
IC4
C17
SW1A
2
3
1
SW1B
5
6
4
R16
R17
C9
C18
GND
GND

LITHIUM ANALOG CHORUS 10
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout assumes the use of closed-frame jacks like the Switchcraft 111X. If you’d rather use
open-frame jacks, please refer to the Open-Frame Jack Drill Template for the top side.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
ø3/8” ø1/2”
0.385”
0.625” 0.625”
x: 0, y: -1.775
ø15/32”
x: -0.775, y: -1.775
ø5/16”
ø3/8”
125B
OUT
DEPTH RATE
MIX
FOOTSWITCHLED
DC IN
x: -0.65, y: +1.71 x: 0.65, y: +1.71
ø9/32” ø9/32”
x: 0, y: +0.66
ø9/32”
CENTER (0,0)
0 1 2
CM
0 1
INCH

LITHIUM ANALOG CHORUS 11
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

LITHIUM ANALOG CHORUS 12
WIRING DIAGRAM
125B
IN +VGND GND NC OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT

LITHIUM ANALOG CHORUS 13
LICENSE & USAGE
No direct support is offered for these projects beyond the provided documentation. It’s assumed
that you have at least some experience building pedals before starting one of these. Replacements and
refunds cannotbe offered unless it can be shown that the circuit or documentation are in error.
All of these circuits have been tested in good faith in their base configurations. However, not all the
modifications or variations have necessarily been tested. These are offered only as suggestions based
on the experience and opinions of others.
Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
“goop” the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but
please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!)
DOCUMENT REVISIONS
1.0.1 (2022-10-21)
Changed recommendation for IC3 to LM358 as used in the original. The TL022 is usually an upgrade for
LFOs, but in this circuit it seems to sometimes cause issues with the travel of the Depth pot.
1.0.0 (2022-09-24)
Initial release—and incidentally, the 31st anniversary of the release of Nevermind.