Boss AC-2 Acoustic Simulator
A compact stompbox that makes an electric guitar sound a lot like an acoustic. It has four voicings and a dedicated E.G. OUT for players who want to blend both signals.
Overview
The Boss AC-2 is a compact pedal from the company's well-known line of stompboxes. It's built to pull acoustic-style tones out of an electric guitar. It has four mode settings - STANDARD, JUMBO, ENHANCE, and PIEZO - selected with the MODE switch, plus three rotary controls for LEVEL, BODY, and TOP. A pedal switch turns the effect on and off, and a status LED lights when the effect is engaged.
The control layout is simple. LEVEL sets overall output, BODY shapes the low-end warmth, and TOP controls the high-frequency presence. The four modes are voiced to approximate different acoustic guitar characters, so the player gets a handful of starting points instead of one fixed tone. The pedal runs on a standard 9V battery (the S-006P type is listed among the accessories) or an AC adaptor. It uses a standard 1/4" input and output, plus the dedicated E.G. OUT jack.
That E.G. OUT jack is the AC-2's most interesting design choice. The pedal doesn't just process the guitar signal and send it to the output. It splits the signal. When the effect is on, the processed acoustic-style tone appears at the OUTPUT jack, and nothing is sent from the E.G. OUT jack. When the effect is off, the signal passes through E.G. OUT and nothing comes out of OUTPUT. For players running two amps or a split rig, this lets the dry and processed signals coexist in a live setup. The internal signal path is built around four M5218AFP op-amps, with TC4066BF and TC4052BF CMOS ICs handling switching and mode selection. A handful of FETs and small-signal transistors (2SK118Y, 2SK880GR, 2SC3324GE, 2SC4116GR) do the heavy lifting on the audio side.
The circuit is a period-correct analog design. The potentiometers are standard 50kB (LEVEL), 10kB (BODY), and 10kBx2 (TOP) types, and the pedal is powered by a single 9V battery via a battery connector inside the bottom cover. A pedal guide bush, spring, and nylon washer make up the mechanical footswitch assembly. The whole thing sits on a bottom base with a foot base and a bottom cover held on by binding tapping screws. Nothing exotic, but it's the kind of parts list that suggests the pedal is serviceable rather than disposable.
The service-manual portion of the AC-2 documentation carries a 1996 Roland Corporation copyright. That places the documentation in the mid-1990s. Production years for the model itself are not confirmed by the available material, so treat any claimed date range with caution.
Boss's compact pedal line is one of the most widely used in the world, and the AC-2 sits in that lineage as a specialized tone-shaping tool rather than a core effect. It is not a distortion, not a delay, not a modulation box. It is a voicing pedal, and it's useful only if the player wants an acoustic-flavored sound from an electric instrument. The four modes and the split-output design give it more range than the single-knob acoustic simulators that followed.
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