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.

I have used this product for several years as a solo performer, especially in bars and pubs.

It's well made, cans tan up to a few knocks and offers a range of useful audio features. If your acoustic doesn't have a built-in preamp, this is really useful for shaping your sound without having to fuss with the sound board or PA. For home recording it offers a good buffer for acoustic sound, especially if you're going DI.

There are a couple of caveats, however. This is obviously subjective, but in my use as a performer I find it awkward to set up and use. Unless you're going to set it on a pedalboard, with an independent power supply, getting it situated in your performance space is a pain without having cables all over the place and it doesn't do all that much to boost your passive pickups thorugh a PA (which is what I bought it for). Changing batteries is a bit inconvenient also.

I'm sure there are plenty of good applications for this, and plenty of people who would love it, but for my needs it just doesn't quite fit the bill.

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€!!!

Let me start by saying that this is definitely not a Baggs PADI. Let me also say that it costs about 1/10 of the PADI's price. Generally speaking it will tame the "quack" associated with USTs (under-saddle transducers). The sweepable mids are a great feature especially considering the price and besides EQing that control can also be used to kill any feedback that you might be getting. The blend knob should be used with caution as a little goes a long way and you can easily get valve-like distortion out of it (useful for electric guitar though). Overall a nice product for the price, make sure you invest in an AC adapter as it can't be powered by phantom power and it can eat through batteries relatively easy. A plus is that it can double as an active DI box.