The BOSS AD-2 Acoustic Preamp is a stompbox for acoustic/electric guitars that's designed to make up for the often-lackluster quality of undersaddle, piezo pickups. The AD-2's Acoustic Resonance feature analyzes the input signal as you're playing and applies processing to recreate the woodier sound of your acoustic instrument. Twisting the knob associated with this effect adjusts multiple interlocking controls within the pedal itself, allowing you to tailor the resulting song for specific timbres or purposes—i.e., for fingerpicking or strumming—quickly and effectively.
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\r\nAlso on hand—or rather, under foot—is an ambiance effect which adds some reverb to the signal. This reverb is EQ'd and processed to work with your acoustic guitar in a more complementary way when compared to other, comparable reverbs. As with the ambiance control, one-knob adjustment of this reverb will affect many interlocking parameters.
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\r\nThe AD-2 offers one input for your acoustic guitar, though you do have your choice of two outputs. A standard output jack can feed an acoustic guitar amp or a monitor, while the DI jack’s TRS connection sends a balanced signal to a PA mixer. If you choose, you can turn off the ambiance effect on the DI'd channel, thus giving your FOH mixer the ability to apply reverb in accordance with their own predilections.
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\r\nShould you encounter any feedback, a one-knob notch filter will help you mitigate it immediately. This pedal has a buffered bypass path, which helps bolster tone over longer cable runs. If you'd like to mute your signal while changing guitars or tuning with an external tuner, simply press and hold the footswitch for two seconds.