The DOD FX40B is a vintage seven-band graphic EQ pedal, made in the USA and sold throughout the 1990s until it was discontinued in 1999. A graphic EQ gives you a row of sliders, one per frequency band, so you can shape the tone of your guitar or bass by eye: push a band up to boost it, pull it down to cut it. On the FX40B, each band can be boosted or cut by up to 12 dB, and a separate output level slider lets you raise the overall volume for a clean boost without changing the tone.1
The seven bands and the controls
The FX40B features seven octave-band sliders for precise tone adjustment. Each slider covers a band an octave apart from its neighbors, spanning the core of a guitar's range from the low end up to the upper treble1:
| Band | Center frequency |
|---|---|
| 1 | 100 Hz |
| 2 | 200 Hz |
| 3 | 400 Hz |
| 4 | 800 Hz |
| 5 | 1.6 kHz |
| 6 | 3.2 kHz |
| 7 | 6.4 kHz |
Each frequency band can be boosted or cut by up to 12 dB using its respective slider. In practice, that means you can dip a troublesome frequency, say a boxy 400 Hz, or lift a band that is missing, such as top-end sparkle at 6.4 kHz, and hear the change band by band.1
Alongside the seven tone sliders, a separate slider controls the overall output level. DOD notes that this allows for a clean volume boost, which makes the pedal useful as a straight level lift into an amp or another pedal, with the tone bands left flat. For more on where an EQ sits among tone-shaping pedals, see Equalization Pedals.1
FX40B compared with the FX40
The FX40B is the successor to the earlier DOD FX40 equalizer, which was released in 1983. DOD notes that the FX40B is often noted for being quieter, having a greater boost/cut range, and delivering a cleaner sound compared to other EQ pedals.1
| DOD FX40 | DOD FX40B | |
|---|---|---|
| Released | 1983 | Successor to the FX40, sold through the 1990s |
| Reputation | Original DOD EQ pedal | Quieter, greater boost/cut range, cleaner sound1 |
Versions and looks
The FX40B went through several enclosure looks over its long run, which is worth knowing if you are buying secondhand1:
- Early models: light gray casing with red graphics1
- Mid-80s versions: metallic brown-and-light gray color scheme1
- Later 90s versions: white silkscreen1
The FX40B was discontinued in 1999, so any unit on the used market today is a vintage pedal. The three enclosure styles above can help date a particular unit.1
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Questions
What frequencies does the DOD FX40B cover?
The FX40B's seven sliders cover octave-spaced bands at 100 Hz, 200 Hz, 400 Hz, 800 Hz, 1.6 kHz, 3.2 kHz, and 6.4 kHz. Each band can be boosted or cut by up to 12 dB with its slider, and a separate eighth slider sets the overall output level.
Can the DOD FX40B be used as a clean boost?
Yes. Alongside the seven frequency sliders, the FX40B has a separate slider that controls the overall output level. DOD's own product page notes that this output level control allows for a clean volume boost, so the pedal can be used to push a signal louder without touching the tone bands.
When was the DOD FX40B discontinued?
The FX40B was sold throughout the 1990s and was discontinued in 1999, according to DigiTech's vintage product spotlight on the pedal. It succeeded the earlier DOD FX40 equalizer, which was released in 1983.
How is the DOD FX40B different from the DOD FX40?
The FX40B is the successor to the earlier DOD FX40 equalizer, which was released in 1983. DOD notes that the FX40B is often described as quieter, with a greater boost and cut range, and delivering a cleaner sound compared to other EQ pedals.
Was the DOD FX40B made in the USA?
Yes. DOD's product page states plainly that the FX40B was made in the USA. The pedal was sold throughout the 1990s before being discontinued in 1999.
How much can each slider boost or cut on the DOD FX40B?
Each of the seven frequency sliders can boost or cut its band by up to 12 dB. The bands are spaced an octave apart, from 100 Hz up to 6.4 kHz, and a separate output level slider adjusts the overall volume independently of the tone bands.
Sources (1)
- Vintage Product Spotlight: DOD FX40B EQ Pedal, DigiTech, 2025-09-24