Behringer V-Tone Acoustic ADI21

This small box fits the space between the acoustic guitar and the PA system, providing additional controls and, most important, an XLR output. The thick brown plastic body and the heavy metallic base give a sense of solidity; the on/off button may seem brittle, but this device is not supposed to be repeatedly engaged and disengaged while playing!

The tone (three bands, plus middle frequency) and volume knobs are integrated by two cursors for ground lift and -20dB level reduction. A "blend" knob is also present, which is actually a volume control for a simulated microphone in front of the guitar's soundhole. The device can be powered by either 9V battery (lasting about four hours) or adapter: because of the internal pre-amplifier, powering via XLR is impossible.

When disengaged, the device works as a passive DI box. Engaging it will activate the internal pre-amplifier, and this might reduce the sound level, as the volume knob is thought to both decrease and increase the volume; as the blend knob also increases the volume of the unit, some careful soundcheck may be required. In either case, the sound is absolutely convincing: however, the device must always be powered, even in passive mode. Some users reported feedback problems when blending with the microphone simulator: but I never had this issue.

Overall, a good tool at a low price, which will rest in the guitar case's pocket, ready to spring into action.

First of all, this is one great sounding and silent pedal. I bought it to get rid of the piëzo 'quack' of my acoustic electric and found out that 1. it does get rid of it and makes my acoustic electric sound like an acoustic guitar; 2. it is a tone shaper and gives you control over your tone and 3. it adds saturation to your sound if you wish.

It's also quite usable for bass guitars and works as a passive DI.

I bought it for a live acoustic gig. It did very good, This thing has only two flaws:
1. The switch is flimsy plastic and easy to break;
2. While it has an XLR out, it cannot be powered with phantom power but runs on batteries or an external adapter.

I use it in my studio on bass and acoustic guitars. I will never put it on a stage with a band.

This DI/modeling amp was designed for acoustic guitars with piezo (I believe). I am using it with my Blueridge guitar and with a more traditional magnetic pickup, Fishman Neo-D single coil.
I read many reviews and saw videos of people complaining about ADI21 not being good for the job because it distorts too much.
In my opinion that isn't the case. If you set the input gain levels of your mixer, interface or amp right, you won't be having distortion problems. If that is not enough, you can always flick the very useful PAD switch and lower the output gain of the pedal for 20db. So with a bit of knowledge and patience, this pedal can really work great and do the job that it was intended to do; make your amplified acoustic guitar sound richer with the feeling of using a mic and an amp.
The fact that you can choose a mid-range frequency and either cut it or boost it, makes it even more functional since you can not only shape your tone in more detail, but also eliminate possible feedback problems.
The housing is plastic, but it feels more solid than other Behringer pedals. When the pedal is bypassed, it acts as a simple DI.
And it's 21€!!!

A great budget-buy piece of kit. I've bought two and used them both live for over a year in a weekly restaurant gig - the type where you are your own roadie and sound engineer - with a very budget-guitar and Yamaha PA system with floor wedge and two stand speakers. Tone control is great and it let's you beef up the sound of the acoustic guitar (nylon and metal string) when playing live and eradicating the harshness of low-end pickup etc. It's a bit redundant on mid- to high-end guitars. The wires for the battery connector are a bit flimsy and can easily break, so it's best to use a power supply. Other than that it's a very solid piece of kit and can take a few beatings.

This pedal answered my prayers! I was struggling to get a smooth clean tone from my rather harsh electro-acoustic guitar when plugged directly into the band's PA. I tried "Booster" pedals but none gave the range of tones and warmth that this did. The pedal has an admittedly basic 3-band EQ (Bass, Mid, Treble) but this is plenty to allow / compensate for whatever tone is coming from the guitar. The other controls for I've found the optional input via an XLR socket (1/4" input socket also included) particularly beneficial as this makes plugging into the PA a "doddle" and surely improves the signal strength. My one minor gripe would be around battery life as the red LED seems to fade to faint rather quickly though at this price I wouldn't quibble about that. Great value for money