The Behringer BDI21 V-Tone Bass Driver is an analog bass preamp, overdrive and DI box in a single pedal. Behringer bills it as a "Bass Amp Modeler/Direct Recording Preamp/DI Box" and says it delivers "vintage tube tones for funked-up slap, gonzo overdrive and everything in-between." It combines the features of an active DI (direct injection) box with the company's proprietary tube emulation circuitry, so it can shape your bass tone going into an amp and also feed a mixing desk or audio interface directly.1
What it does
The BDI21 sits between your bass and the rest of your rig and does two jobs at once. As a preamp and overdrive, it applies tube-style emulation to your signal, with the amount of that character under your control. As a DI box, it provides a direct recording output. Behringer describes the two modes plainly: you can use it as a recording output DI with tube emulation, or as a standard active DI box when running in bypass mode. In bypass, step on the switch and the pedal passes your instrument's straight, pure tone while still working as an active DI.1
Because the circuit is analog, the tube character comes from emulation circuitry rather than digital modeling, and there are no tubes in the box.2
The controls: five dials and a blend
The pedal keeps its front panel simple: five dedicated dials plus a blend control1.
| Control | What it does |
|---|---|
| Drive | Sets the amount of drive1 |
| Treble | Treble adjustment1 |
| Bass | Bass adjustment1 |
| Level | Output level1 |
| Presence | Presence adjustment1 |
| Blend | Mixes the amount of tube emulation with the direct bass signal2 |
The Blend control is the one that defines the pedal's character in use: it lets you mix how much tube emulation you want against your direct bass signal, so you can run anything from a touch of grit under a clean fundamental to a fully driven tone.2
Power
The BDI21 runs on a 9V battery or a 9V DC center negative power supply. Behringer specifies its own PSU-SB DC power supply, which is not included with the pedal. RockBoard lists the current draw at 25mA.12
The PSU-SB power supply is not included, so plan for a battery or a supply that meets the 9V DC center negative requirement.1
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Questions
Is the Behringer BDI21 analog or digital?
The BDI21 is an analog circuit. Behringer describes it as combining the features of an active DI box with proprietary tube emulation circuitry, and RockBoard's PedalPedia lists its circuit type as analog. That means the tube-style character comes from analog emulation circuitry rather than digital modeling, and there are no tubes inside the pedal itself.
Does the BDI21 work as a DI box when bypassed?
Yes. Behringer says you can use the BDI21 as a recording output DI with tube emulation, or as a standard active DI box when running in bypass mode. Step on the switch and the pedal passes your instrument's straight, pure tone while still feeding the DI output, so it can sit on a board purely as a DI.
What power supply does the BDI21 need?
The BDI21 runs on a 9V battery or a 9V DC center negative power supply. Behringer specifies its own PSU-SB DC power supply, which is not included with the pedal. RockBoard lists the current draw as 25mA, which is modest enough for most pedalboard power supplies.
Does the BDI21 use real tubes?
No. The BDI21 uses Behringer's proprietary tube emulation circuitry, not actual vacuum tubes. The tube-style character is produced in the analog circuit and can be mixed with your direct bass signal using the Blend control.
Where can I find the BDI21 manual?
The manual is available as a PDF from Behringer's documentation, covering English, German, French, Dutch, Italian, Japanese, Chinese, Danish and Greek. RockBoard's PedalPedia page for the BDI21 links directly to it.
Sources (2)
- BDI21 | Behringer, Behringer
- BDI21 V-Tone Bass Driver by Behringer, RockBoard (rockboard.de PedalPedia), 2026
