Two acoustic guitars plugged into the same desk can sound like two different instruments, and often the guitars are not the reason. The pickup is. Each type senses one physical thing at one point on the instrument, and what it senses decides what arrives at the DI.
The three common types are the under-saddle piezo, the soundhole magnetic and the internal microphone. Each leaves a different part of the guitar out. This post walks through why, then how Woody, a DI acoustic guitar enhancer, brings any of them to the same starting point with its PICKUP switch.
What each pickup actually senses
The under-saddle piezo is a strip of piezoelectric material sitting in the bridge slot, under the saddle. A piezo element produces a voltage when it is squeezed. Every time a string vibrates, it presses down on the saddle and the strip turns that changing pressure into signal. It is measuring force at the bridge, which is where the string's energy is most concentrated and most immediate. The result is fast, detailed attack and plenty of upper harmonics, but very little of the top, back and air cavity, because those respond after the string has already pushed on the saddle. The store's own description is the honest summary: an under-saddle piezo arrives bright and thin. It is the "quack" people mean when they say a DI acoustic sounds like a DI.
The soundhole magnetic works like an electric guitar pickup: a magnet and a coil, clamped across the soundhole. A steel string moving through the magnetic field induces a current in the coil. It hears string motion at one point along the string's length and nothing else. The wooden top is not magnetic, so the body is invisible to it, and the sensing point near the neck end of the soundhole favours the fundamental and lower harmonics over the bright edge a piezo catches. That is why a soundhole magnetic arrives mid-heavy: round, warm in the sense of having more low mids, and closer to an electric guitar than to a miked acoustic.
The internal microphone is the one type that does hear air, but from the wrong place. It sits inside the body, a few centimetres from the top, the back and the bracing. The inside of a guitar is a small enclosed cavity with hard walls close on every side, so its own resonances and reflections dominate what the capsule picks up. A studio microphone a foot in front of the guitar hears the cavity's resonance radiating out of the soundhole and mixing with the top's movement in open air. The internal mic hears the inside of the box. Its sound is boxy.
None of these is broken. Each is a sensible trade-off for a live stage, where an open microphone would feed back and bleed. But for recording, each captures a narrow slice of the instrument, and a different slice from the next, so two parts tracked through different pickups will not sit the same way in a mix even with identical processing after them.
Bringing them to the same starting point
Woody is built on the opposite idea: a pickup signal goes in, and the guitar as a pair of studio microphones would hear it comes out. Its BODY control holds sixteen voicings (Studio 1–4, Dreadnought 1–8 and Jumbo 1–4), and each is a guitar body heard by two microphones, one at the neck and one at the body, spread left and right.
That only works if what goes in is predictable. A voicing designed around a balanced pickup would sound one way fed by a bright, thin piezo and quite another fed by a mid-heavy magnetic. That is the job of PICKUP. With PICKUP on, Woody listens for a few seconds and brings any of the three to the shape the body was built on, so the voicings sound the same whatever the guitar is wearing. With it off, the pickup is left as it is.
In practice that removes the corrective-EQ step that usually comes first on a DI acoustic, and leaves the choices that matter:
- BODY chooses the instrument. The quickstart advice is to loop four bars and try all sixteen with the band playing; Woody crossfades between voicings without a click, so this works while the track runs. The voicing that sounds smallest on its own often sits best.
- WOOD sets how much the body sings, from TIGHT, where the resonances settle into a controlled, even response, to DEEP, where they stand out and ring longer.
- SPACE adds the air around the instrument: a short, diffuse tail either side. Not a reverb; the room a microphone hears.
- MIX blends the pickup's own signal back in, time-aligned, for the attack and directness that help a part cut through.
MIX is where the pickup's character comes back on purpose. A piezo's bright attack is a liability as the whole sound and an asset as a small part of it. The quickstart setting for a full band, a Studio voicing with WOOD toward TIGHT and MIX back to about 80%, uses exactly that: most of the sound is the miked body, and the remainder is the pickup's edge, lined up to the sample so the two do not smear.
If the pickup's own sound is one you want to keep, leave PICKUP off and the voicings work on top of it unchanged.
Two setup details matter whichever pickup is in play. Set INPUT first: play the loudest part and turn INPUT until the IN meter peaks in the amber, -12 to -3 dBFS. Presets never change INPUT or POWER. And load Woody on a mono track in a mono-in, stereo-out slot; a guitar with two outputs arriving as a stereo input is summed to mono. With four samples of latency, the same chain works while tracking, so the player hears a miked guitar in the headphones instead of the pickup.
What to try
If you have more than one acoustic, or one with a different pickup from a friend's, record the same four bars through each pickup. Start a 14-day free trial of the full version, put Woody on each track with INPUT in the amber and every other control at rest, and listen with PICKUP off: three different guitars. Turn PICKUP on for each, give it a few seconds, and listen again on the same BODY voicing. Then bring MIX back to about 80% on the piezo track and hear how much of its bright attack you actually want.