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RATEDEPTHMIX

125B · 3 knobs

Aion FX

AzureAnalog Chorus

Based on the BOSS CE-2 Chorus· 1 other board clones it

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

From the vendor

One of the most revered chorus pedals of all time, it uses analog BBDs to modulate the signal, resulting in the warm, rounded tone characteristic of this era.

The Azure Analog Chorus is based on the BOSS CE-2, first released in 1979 and generally considered to be one of the best chorus pedals ever made. With only two knobs, it’s simple to operate, but it doesn’t take long to understand the wide range of sounds contained inside.

The CE-2B Bass Chorus followed almost a decade later in 1987. It was the same basic circuit as the CE-2, but with one component in the audio path changed to make it better suited for bass, as well as the addition of a Mix knob to blend in the wet signal.

The Azure is based on the original CE-2, but it also incorporates the mix knob from the CE-2B. With the mix knob all the way up, it’s identical to the stock circuit, so this allows the intensity to be dialed back a bit while still preserving the originality. The full bass version can also be built with a single component substitution, covered in the parts list.

While the original CE-2 and CE-2B used the MN3007 BBD, the Azure can run on either the MN3007 or MN3207 (v3207) by setting some on-board jumpers. Since BBD availability is sometimes impacted by international trade disruptions and materials shortages, this flexibility makes it a little easier to find parts that will work.

Note: The PCB-only version of 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. It does not impact the kits.

Schematic

The schematic is in the vendor's build document, page 8. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 95 rows

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RefValueNormalizedTypeNotes
Resistors 43
R11k1kMetal film resistor, 1/4W
R2470k470kMetal film resistor, 1/4W
R310k10kMetal film resistor, 1/4W
R410k10kMetal film resistor, 1/4W
R547k47kMetal film resistor, 1/4W
R610k10kMetal film resistor, 1/4W
R747k47kMetal film resistor, 1/4W
R847k47kMetal film resistor, 1/4W
R947k47kMetal film resistor, 1/4W
R1010k10kMetal film resistor, 1/4W
R11470R470Metal film resistor, 1/4W
R12100k100kMetal film resistor, 1/4W
R13100k100kMetal film resistor, 1/4W
R1410k10kMetal film resistor, 1/4W
R1510k10kMetal film resistor, 1/4W
R1610k10kMetal film resistor, 1/4W
R1710k10kMetal film resistor, 1/4W
R184k74.7kMetal film resistor, 1/4W
R1956k56kMetal film resistor, 1/4W
R20330k330kMetal film resistor, 1/4W
R2110k10kMetal film resistor, 1/4W
R2210k10kMetal film resistor, 1/4W
R2310k10kMetal film resistor, 1/4W
R2410k10kMetal film resistor, 1/4W
R251M1MMetal film resistor, 1/4W
R2647k47kMetal film resistor, 1/4W
R2733k33kMetal film resistor, 1/4W
R282k72.7kMetal film resistor, 1/4W
R29150k150kMetal film resistor, 1/4W
R3047k47kMetal film resistor, 1/4W
R3133k33kMetal film resistor, 1/4W
R3210k10kMetal film resistor, 1/4W
R331M1MMetal film resistor, 1/4W
R34220k220kMetal film resistor, 1/4W
R354k74.7kMetal film resistor, 1/4W
R364k74.7kMetal film resistor, 1/4W
R374k74.7kMetal film resistor, 1/4W
R384k74.7kMetal film resistor, 1/4W
R3910k10kMetal film resistor, 1/4W
R4010k10kMetal film resistor, 1/4W
R4133R33Metal film resistor, 1/4W
RPD2M22.2MMetal film resistor, 1/4WInput pulldown resistor. Can be as low as 1M.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 25
C147n47nFilm capacitor, 7.2 x 2.5mm
C2470n470nFilm capacitor, 7.2 x 3mm
C36n86.8nFilm capacitor, 7.2 x 2.5mm
C4100pF100pMLCC capacitor, NP0/C0G
C5100pF100pMLCC capacitor, NP0/C0G
C66n86.8nFilm capacitor, 7.2 x 2.5mm
C71uF1uFilm capacitor, 7.2 x 3.5mm
C833n33nFilm capacitor, 7.2 x 2.5mm
C93n33.3nFilm capacitor, 7.2 x 2.5mm
C108n28.2nFilm capacitor, 7.2 x 2.5mm
C11470pF470pMLCC capacitor, NP0/C0G
C121uF1uTantalum capacitor, 044A
C1333n33nFilm capacitor, 7.2 x 2.5mm
C143n33.3nFilm capacitor, 7.2 x 2.5mm
C158n28.2nFilm capacitor, 7.2 x 2.5mm
C16470pF470pMLCC capacitor, NP0/C0G
C1733n33nFilm capacitor, 7.2 x 2.5mmCE-2B (bass version) uses 12n here.
C1847pF47pMLCC capacitor, NP0/C0G
C19100n100nFilm capacitor, 7.2 x 2.5mm
C2010n10nFilm capacitor, 7.2 x 2.5mm
C2147uF47uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C2247uF47uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C23220uF220uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C24100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C25100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 4
Z11N4739A1N4739AZener diode, 9.1V, DO-41BBD protection diode. Use 1N4743 if using MN3007.
D11N58171N5817Schottky diode, DO-41
D21N9141N914Fast-switching diode, DO-35
D31N9141N914Fast-switching diode, DO-35
Transistors 5
Q12N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses 2SC732TM-GR.
Q22N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses 2SC732TM-GR.
Q32N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses 2SC732TM-GR.
Q42N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses 2SC945P.
Q52N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses 2SC945P.
ICs 4
IC1JRC4558DJRC4558DOperational amplifier, DIP8
IC2MN3207MN3207Bucket-brigade delay, 1024 stagesThe Coolaudio version of this chip is called the v3207.
IC3MN3102MN3102Clock driver for BBDThe Coolaudio version of this chip is called the v3102.
IC4TL022TL022Operational amplifier, DIP8
Potentiometers 3
RATE100kBB100k16mm right-angle PCB mount pot
DEPTH100kBB100k16mm right-angle PCB mount pot
MIX250kCC250k16mm right-angle PCB mount pot
Trimmers 1
BIAS10k10kTrimmer, 10%, 1/4”Bourns 3362P or similar.
Switches 1
FSW3PDT3PDTStomp switch, 3PDTAvailable from Aion FX.
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-8 socketDIP-8 SOCKETIC socket, DIP-8
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 mountLumberg NEB/J 21 C or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

Other boards based on the BOSS CE-2 Chorus