125B · 3 knobs
AmethystAnalog Delay
Based on the BOSS DM-2 Delay
- Category
- Delay
- Controls
- Delay · Feedback · Level
- Difficulty
- Advanced
- Price
- $12.50in stock
From the vendor
One of the earliest analog delay effects to use a bucket brigade chip, and still widely considered among the best ever.
The Amethyst Analog Delay is based on the BOSS DM-2, which was originally released in 1981 and is still widely considered to be one of the best delay pedals ever made.
The DM-2 circuit uses the MN3005 bucket-brigade delay (BBD) chip, which has 4,096 stages and makes the unit capable of around 300ms of delay time when properly calibrated. It also uses a compander to significantly improve noise performance for the delay line.
In 1982, Boss updated the circuit to use the MN3205, which has better audio specifications at the expense of lower maximum voltage and headroom. This is called the “Second Edition” or DM-2 V2. There are no actual changes to the audio portion of the circuit, but the BBD and clock run on inverted power so the PCB had to be modified slightly to accommodate either version.
For many years, the DM-2 V1 was out of reach for most DIYers due to the scarcity of the MN3005 and MN3101. However, with the Xvive reissue of the MN3005 released in 2015 and Cabintech’s CT3101 clock released in 2023, the classic circuit is once again convenient (if not cheap) to build.
The Amethyst PCB has jumper pads so you can choose either the MN3005/MN3101 or the MN3205/MN3102 chipset depending on availability. Otherwise, it is a direct adaptation of the original DM-2 with no modifications or substitutions.
The PCB also includes space for a few extra components so that you can build the Way Huge Aqua Puss, which is a slightly modified clone of the DM-2 from the mid-1990s. See the build notes section in the documentation for more information.
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. This does not impact the kits.
Schematic
The schematic is in the vendor's build document, page 10. Open the build document. No KiCad fragment has been drawn for this circuit yet.
Parts list 101 rows
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 38 | ||||
| R1 | 10k | 10k | Metal film resistor, 1/4W | |
| R2 | 470k | 470k | Metal film resistor, 1/4W | 475k for Aqua Puss. |
| R3 | 10k | 10k | Metal film resistor, 1/4W | |
| R4 | 10k | 10k | Metal film resistor, 1/4W | |
| R5 | 47k | 47k | Metal film resistor, 1/4W | 47.5k for Aqua Puss. |
| R6 | 47k | 47k | Metal film resistor, 1/4W | 47.5k for Aqua Puss. |
| R7 | 10k | 10k | Metal film resistor, 1/4W | |
| R8 | 10k | 10k | Metal film resistor, 1/4W | |
| R9 | 10k | 10k | Metal film resistor, 1/4W | |
| R10 | 10k | 10k | Metal film resistor, 1/4W | |
| R11 | 10k | 10k | Metal film resistor, 1/4W | |
| R12 | 10k | 10k | Metal film resistor, 1/4W | |
| R13 | 10k | 10k | Metal film resistor, 1/4W | |
| R14 | 100k | 100k | Metal film resistor, 1/4W | |
| R15 | 10k | 10k | Metal film resistor, 1/4W | 100k for Aqua Puss. |
| R16 | 18k | 18k | Metal film resistor, 1/4W | |
| R17 | 22k | 22k | Metal film resistor, 1/4W | |
| R18 | 100k | 100k | Metal film resistor, 1/4W | |
| R19 | 100k | 100k | Metal film resistor, 1/4W | |
| R20 | 10k | 10k | 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 | 10k | 10k | Metal film resistor, 1/4W | |
| R26 | 10k | 10k | Metal film resistor, 1/4W | |
| R27 | 22k | 22k | Metal film resistor, 1/4W | |
| R28 | 47k | 47k | Metal film resistor, 1/4W | 47.5k for Aqua Puss. |
| R29 | 47k | 47k | Metal film resistor, 1/4W | 47.5k for Aqua Puss. |
| R30 | 10k | 10k | Metal film resistor, 1/4W | |
| R31 | 47k | 47k | Metal film resistor, 1/4W | 47.5k for Aqua Puss. |
| R32 | 470R | 470 | Metal film resistor, 1/4W | 150R for Aqua Puss. |
| R33 | 100k | 100k | Metal film resistor, 1/4W | |
| R34 | 10k | 10k | Metal film resistor, 1/4W | |
| R35 | 10k | 10k | Metal film resistor, 1/4W | |
| R36 | 22R | 22 | Metal film resistor, 1/4W | BBD power supply filter resistor. |
| RPD | 1M | 1M | Metal film resistor, 1/4W | Input pull-down resistor. |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 35 | ||||
| C2 | 47n | 47n | Film capacitor, 7.2 x 2.5mm | |
| C3 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | 10uF electrolytic for Aqua Puss. |
| C4 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C5 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C6 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C7 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C8 | 100n | 100n | MLCC capacitor, X7R | |
| C9 | 220n | 220n | Film capacitor, 7.2 x 3mm | |
| C10 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C11 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C12 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C13 | 82n | 82n | Film capacitor, 7.2 x 2.5mm | 100n for Aqua Puss. |
| C14 | 330pF | 330p | MLCC capacitor, NP0/C0G | |
| C15 | 1uF | 1u | Electrolytic capacitor, 4mm | |
| C16 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C17 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C18 | 1uF | 1u | Electrolytic capacitor, 4mm | |
| C19 | 2n2 | 2.2n | Film capacitor, 7.2 x 2.5mm | |
| C20 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C21 | 1n | 1n | Film capacitor, 7.2 x 2.5mm | |
| C22 | 39n | 39n | Film capacitor, 7.2 x 2.5mm | |
| C23 | 330pF | 330p | MLCC capacitor, NP0/C0G | |
| C24 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C25 | 220n | 220n | Film capacitor, 7.2 x 3mm | |
| C26 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C27 | 1uF | 1u | Electrolytic capacitor, 4mm | 10uF electrolytic for Aqua Puss. |
| C28 | 100n | 100n | Film capacitor, 7.2 x 2.5mm | 220n for Aqua Puss. |
| C29 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | 10uF electrolytic for Aqua Puss. |
| C30 | 100pF | 100p | MLCC capacitor, NP0/C0G | |
| C31 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C32 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | 10uF electrolytic for Aqua Puss. |
| C34 | 47uF | 47u | Electrolytic capacitor, 5mm | Power supply filter capacitor. |
| C35 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C36 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C37 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 4 | ||||
| Z1 | (omit) | (OMIT) | Zener diode, 500mW, 8.2V | Use 1N5237B (8.2V zener) for MN3205 version. |
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D2 | 1N914 | 1N914 | Fast-switching diode, DO-35 | Jumper for MN3205 version. |
| D3 | (jumper) | (JUMPER) | Fast-switching diode, DO-35 | 1N914 for MN3205 version. |
| Transistors 4 | ||||
| Q1 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | MPSA18 for Aqua Puss. |
| Q2 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | MPSA18 for Aqua Puss. |
| Q3 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | MPSA18 for Aqua Puss. |
| Q4 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | MPSA18 for Aqua Puss. |
| ICs 4 | ||||
| IC1 | JRC4558D | JRC4558D | Operational amplifier, dual, DIP8 | LF353N for Aqua Puss. |
| IC2 | NE571 | NE571 | IC socket, DIP-8 | Coolaudio v571 is a current substitute. |
| IC3 | MN3005 | MN3005 | Bucket-brigade delay, 4096 stages | Can also use MN3205 or v3205. See build notes. |
| IC4 | MN3101 | MN3101 | Clock driver for bucket-brigade delay | See build notes for sourcing. |
| Potentiometers 3 | ||||
| DELAY | 1MB | B1M | 16mm right-angle PCB mount pot | Called "Repeat Rate" on the original DM-2. |
| FEEDBACK | 50kA | A50k | 16mm right-angle PCB mount pot | Called "Intensity" on the original DM-2. |
| VOLUME | 50kB | B50k | 16mm right-angle PCB mount pot | Called "Echo" on the original DM-2. |
| Trimmers 3 | ||||
| BIAS | 22k | 22k | Trimmer, 10%, 1/4", Bourns 3326P | Can substitute 20k or 25k. |
| CANCEL | 10k | 10k | Trimmer, 10%, 1/4”, Bourns 3326P | |
| CLOCK | 1M | 1M | Trimmer, 10%, 1/4”, Bourns 3326P | |
| 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-SOCKET | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC2-SOCKET | DIP-16 socket | DIP-16 SOCKET | IC socket, DIP-16 | |
| IC3-SOCKET | DIP-14 socket | DIP-14 SOCKET | IC socket, DIP-8 | |
| IC4-SOCKET | 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. |