125B · 3 knobs
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
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 43 | ||||
| R1 | 1k | 1k | Metal film resistor, 1/4W | |
| R2 | 470k | 470k | Metal film resistor, 1/4W | |
| R3 | 10k | 10k | Metal film resistor, 1/4W | |
| R4 | 10k | 10k | Metal film resistor, 1/4W | |
| R5 | 47k | 47k | Metal film resistor, 1/4W | |
| R6 | 10k | 10k | Metal film resistor, 1/4W | |
| R7 | 47k | 47k | Metal film resistor, 1/4W | |
| R8 | 47k | 47k | Metal film resistor, 1/4W | |
| R9 | 47k | 47k | Metal film resistor, 1/4W | |
| R10 | 10k | 10k | Metal film resistor, 1/4W | |
| R11 | 470R | 470 | Metal film resistor, 1/4W | |
| R12 | 100k | 100k | Metal film resistor, 1/4W | |
| R13 | 100k | 100k | Metal film resistor, 1/4W | |
| R14 | 10k | 10k | Metal film resistor, 1/4W | |
| R15 | 10k | 10k | Metal film resistor, 1/4W | |
| R16 | 10k | 10k | Metal film resistor, 1/4W | |
| R17 | 10k | 10k | Metal film resistor, 1/4W | |
| R18 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R19 | 56k | 56k | Metal film resistor, 1/4W | |
| R20 | 330k | 330k | Metal film resistor, 1/4W | |
| R21 | 10k | 10k | Metal film resistor, 1/4W | |
| R22 | 10k | 10k | Metal film resistor, 1/4W | |
| R23 | 10k | 10k | Metal film resistor, 1/4W | |
| R24 | 10k | 10k | Metal film resistor, 1/4W | |
| R25 | 1M | 1M | Metal film resistor, 1/4W | |
| R26 | 47k | 47k | Metal film resistor, 1/4W | |
| R27 | 33k | 33k | Metal film resistor, 1/4W | |
| R28 | 2k7 | 2.7k | Metal film resistor, 1/4W | |
| R29 | 150k | 150k | Metal film resistor, 1/4W | |
| R30 | 47k | 47k | Metal film resistor, 1/4W | |
| R31 | 33k | 33k | Metal film resistor, 1/4W | |
| R32 | 10k | 10k | Metal film resistor, 1/4W | |
| R33 | 1M | 1M | Metal film resistor, 1/4W | |
| R34 | 220k | 220k | Metal film resistor, 1/4W | |
| R35 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R36 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R37 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R38 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R39 | 10k | 10k | Metal film resistor, 1/4W | |
| R40 | 10k | 10k | Metal film resistor, 1/4W | |
| R41 | 33R | 33 | Metal film resistor, 1/4W | |
| RPD | 2M2 | 2.2M | Metal film resistor, 1/4W | Input pulldown resistor. Can be as low as 1M. |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 25 | ||||
| C1 | 47n | 47n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 470n | 470n | Film capacitor, 7.2 x 3mm | |
| C3 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C4 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C5 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C6 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C7 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C8 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C9 | 3n3 | 3.3n | Film capacitor, 7.2 x 2.5mm | |
| C10 | 8n2 | 8.2n | Film capacitor, 7.2 x 2.5mm | |
| C11 | 470pF | 470p | MLCC capacitor, NP0/C0G | |
| C12 | 1uF | 1u | Tantalum capacitor, 044A | |
| C13 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C14 | 3n3 | 3.3n | Film capacitor, 7.2 x 2.5mm | |
| C15 | 8n2 | 8.2n | Film capacitor, 7.2 x 2.5mm | |
| C16 | 470pF | 470p | MLCC capacitor, NP0/C0G | |
| C17 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | CE-2B (bass version) uses 12n here. |
| C18 | 47pF | 47p | MLCC capacitor, NP0/C0G | |
| C19 | 100n | 100n | Film capacitor, 7.2 x 2.5mm | |
| C20 | 10n | 10n | Film capacitor, 7.2 x 2.5mm | |
| C21 | 47uF | 47u | Electrolytic capacitor, 5mm | Reference voltage filter capacitor. |
| C22 | 47uF | 47u | Electrolytic capacitor, 5mm | Reference voltage filter capacitor. |
| C23 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C24 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C25 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 4 | ||||
| Z1 | 1N4739A | 1N4739A | Zener diode, 9.1V, DO-41 | BBD protection diode. Use 1N4743 if using MN3007. |
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D2 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D3 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| Transistors 5 | ||||
| Q1 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses 2SC732TM-GR. |
| Q2 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses 2SC732TM-GR. |
| Q3 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses 2SC732TM-GR. |
| Q4 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses 2SC945P. |
| Q5 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses 2SC945P. |
| ICs 4 | ||||
| IC1 | JRC4558D | JRC4558D | Operational amplifier, DIP8 | |
| IC2 | MN3207 | MN3207 | Bucket-brigade delay, 1024 stages | The Coolaudio version of this chip is called the v3207. |
| IC3 | MN3102 | MN3102 | Clock driver for BBD | The Coolaudio version of this chip is called the v3102. |
| IC4 | TL022 | TL022 | Operational amplifier, DIP8 | |
| Potentiometers 3 | ||||
| RATE | 100kB | B100k | 16mm right-angle PCB mount pot | |
| DEPTH | 100kB | B100k | 16mm right-angle PCB mount pot | |
| MIX | 250kC | C250k | 16mm right-angle PCB mount pot | |
| Trimmers 1 | ||||
| BIAS | 10k | 10k | Trimmer, 10%, 1/4” | Bourns 3362P or similar. |
| Switches 1 | ||||
| FSW | 3PDT | 3PDT | Stomp switch, 3PDT | Available from Aion FX. |
| LEDs 1 | ||||
| LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 7 | ||||
| IC1-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC2-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC3-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC4-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IN | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| OUT | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| DC | 2.1mm | 2.1MM | DC jack, 2.1mm panel mount | Lumberg NEB/J 21 C or equivalent. |
| Hardware 1 | ||||
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |
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