The Tech 21 SansAmp Acoustic DI is a direct box and preamp for acoustic instruments, built around the company's SansAmp tube and microphone emulation circuitry. Tech 21 describes its purpose as giving an acoustic a natural warmth and presence, "as if you were miking it through a tube pre-amp"1. It is aimed at players who want to plug an acoustic pickup straight into a PA or recording rig and get a sound closer to a miked acoustic than a bare piezo or under-saddle pickup usually delivers.
The pedal also carries sweepable, semi-parametric EQ controls that Tech 21 says remove unwanted feedback, which is one of the recurring problems of amplifying an acoustic instrument1. It was released in 1997, and the later Tech 21 Para Driver DI evolved from it2.
The controls
The Acoustic DI keeps its control set focused on shaping an acoustic pickup signal and killing feedback1:
| Control | What it does |
|---|---|
| BLEND | Mixes the direct instrument signal with the SansAmp Tube/Microphone Emulation circuitry |
| BASS, MID, TREBLE | Active EQ controls, cut or boost +/- 12dB |
| MID SHIFT | Parametric EQ control that selects the center frequency of the Mid control; sweep range 170 Hz to 3.0 kHz, for notching out frequencies causing feedback |
| LEVEL | Regulates the XLR and 1/4" output levels |
All control details from the Tech 21 product page1.
The BLEND control is the heart of the unit: at one end you hear the untouched pickup signal, and as you turn it you bring in the tube and microphone emulation, so you can dial in how much of the SansAmp character sits on top of your acoustic's own voice1.
The MID SHIFT sweep is what makes the EQ genuinely useful against feedback. Rather than a fixed midrange knob, it lets you move the center frequency of the Mid control anywhere from 170 Hz to 3.0 kHz, find the exact frequency that is ringing, and cut it there1.
Power and connections
The Acoustic DI is flexible about power. It runs on phantom power, an optional 9V DC power supply (Tech 21 Model # DC2), or a 9V battery, though no battery is included with the unit1. Phantom power is the practical option for gigging players: if the console at the venue supplies it, the pedal needs nothing else.
The 9V battery is not included, so if you intend to run on battery power you will need to supply one yourself1.
On the input side, the instrument-level 1/4" input has a very high impedance of 4.7 megohms, which Tech 21 says provides maximum output and dynamics, a specification aimed at getting the most from passive acoustic pickups1.
There are two outputs: a balanced low Z XLR that is switchable between 0 and -20dB, and an unbalanced low Z 1/4"1. The XLR pad makes it straightforward to match the level to a mixing console, and the LEVEL control regulates both outputs together1.
Where it came from
The SansAmp Acoustic DI was released in 19972. It later served as the starting point for the Tech 21 Para Driver DI: as Bass Musician Magazine reported when marking that unit's 20th anniversary, "The SansAmp Para Driver DI evolved from the SansAmp Acoustic DI, which was released in 1997"21. The Acoustic DI sits within Tech 21's wider SansAmp family of preamps, which also includes units like the SansAmp Classic and the SansAmp RPM.
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Questions
Does the SansAmp Acoustic DI need a battery?
No. It can run on phantom power, an optional 9V DC power supply (Tech 21 Model # DC2), or a 9V battery, which is not included. If you plan to use a battery, you will need to supply your own.
Can the SansAmp Acoustic DI use phantom power?
Yes. Tech 21 states the unit is phantom power operable, so when it is connected to a mixing console or interface that supplies phantom power over the XLR output, it can run without a battery or separate power supply.
What does the Mid Shift control do on the SansAmp Acoustic DI?
Mid Shift is a parametric EQ control that selects the center frequency of the Mid control. Its sweep ranges from 170 Hz to 3.0 kHz, which lets you notch out the specific frequencies causing feedback on an acoustic instrument.
What outputs does the SansAmp Acoustic DI have?
It has two outputs: a balanced low-impedance XLR output that is switchable between 0 and -20dB, and an unbalanced low-impedance 1/4-inch output. The Level control regulates both output levels.
What is the input impedance of the SansAmp Acoustic DI?
The instrument-level 1/4-inch input has a very high impedance of 4.7 megohms, which Tech 21 says provides maximum output and dynamics from the pickup.
Sources (2)
- Acoustic DI, Tech 21 NYC, 2019-06-24
- Gear News: Tech 21’s SansAmp Para Driver DI Celebrates 20th Anniversary, Bass Musician Magazine, 2025-09-02
Geddy Lee
