Hands-On Review:Roland AC-100 Acoustic Chorus Guitar Amp

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Faithful Two-Channel Versatility with Astounding Range

Roland's Forte
Two decades ago, in that brief period when the supremacy of tubes was being challenged by upstart solid-state technology, Roland produced a series of solid-state amps that can still be found on stages and in studios around the country. Many players went back to tubes (at least on the front end), but when it came to flawless signal integrity riding a river of pure power, the Roland workhorses just never lost their edge. So, 20 years later, it's no surprise that Roland has produced an acoustic guitar amp with stunning signal clarity and tonal range.

Roland AC-100 Acoustic Chorus AmpAcoustics: a tougher task

Comparatively speaking, the job of an amp dedicated to acoustic guitars is very sophisticated. An electric guitar's signal begins life as an electronic entity, determined primarily by the magnetic interaction between the string and the pickup coil. An acoustics' signal, on the other hand, regardless of the style of pickup or mike, takes on the subtle tones of wood - the bracing and sonic qualities of the soundboard as well as the acoustic properties of the box. To amplify that sound with faithful clarity, without clipping the ends of the frequency range or distorting the signal, requires a very sophisticated piece of equipment. The Roland AC-100 is a very sophisticated unit that goes way beyond just faithful amplification of your guitar's true voice.


Full-range clarity and then some

This amp had me grinning stupidly from the second I pulled it out of the box. Its elegant, handsome cabinet design said high-powered sophistication, while its substantial heft made it clear I was dealing with a heavyweight. But the true jolt came when I plugged it in. It was love at first sound. The room filled with a pure, crisp tone, clean as a spring breeze but not tinny, and grounded by a solid bottom end that wasn't hollow or booming. With chorus and reverb turned off, the tone was exactly that of my guitar unplugged, only louder.


As a test, I whanged a chord and held my flattop inches from the speaker. When it began to howl, I punched the anti-feedback button and spun the knob till I hit the frequency in question. That was that, the noise stopped dead. It was so precise I couldn't even discern the hole left in the tone by the squelched frequency.


Independent amperage

When I looked in the back, the two midrange five-inch speakers set on either side of a punch-packing 12-inch Roland main driver were my first hints that some real genius had gone into the design. Each of the 5-inchers is powered by its own 25-watt amp while the 12-inch speaker has fifty watts of clean power all to itself. This three-way setup is controlled by some serious techno-wizardry - a high-definition DSP chip and a split-frequency space synthesis system. That's where the room-filling presence comes from. It's way high-tech, but makes for a truly cushy chorus and natural-sounding digital reverb.


Choral possibilities

Just as it's a tricky job to amplify an acoustic guitar precisely, adding effects without losing its sweeter timbres requires state-of-the-art engineering and creative design. Clearly, Roland has all the smarts necessary to pull it off. The AC-100 provides three full-bodied stereo chorus settings, each of which adds a distinctively different and eminently usable tonal texture without walking all over the guitar's unique sound. The intelligent tri-amp system sends mids and highs to the left and right speakers, while the lower tones get mixed with the direct signal and sent to the 12-incher. Combined with the three-band EQ controls and three reverb configurations, it offers a really wide palette of possibilities, more than I'd ever need for an acoustic gig.


Each of the digital reverb options is totally natural sounding and generates that grand hall feel, even when the hall you're playing in isn't so grand. With or without the chorus, I had no trouble dialing in the exact reverb sound I was after. Both the chorus and the reverb have footswitch jacks on the back.


Click to EnlargeTwo independent channels you can really use

The AC-100 comes with two independent input channels. For an incredibly fat, expansive tone, you can run your guitar mic'd through the upper channel and your pickup output through the lower "guitar" channel. Then you still have the ability to control EQ and add effects on each signal independently. If your guitar doesn't have a pickup, the upper channel still gives you the full sound-shaping versatility of this amazing unit. You can run a 1/4" or XLR mic jack through the front and delineate mic or aux signal level. The guitar channel is switchable to accommodate guitars with or without pre-amps, including standard electric guitars.


There are also a couple of signal-modifying buttons in line before the EQ controls. The High-Pass Filter (HPF) switch chops out some of the bottom end for a lighter guitar sound. This can be quite useful if the guitar is muddying up your vocals or fighting with the bass or keyboards. (This feature is not available on the Aux mode in the upper channel). The guitar channel also features a Shape switch which generates a more edgy tone (but I preferred the more precise control available from the three-band EQ pots).


If you're a one-person act, the upper channel does a credible job as a PA for your vocal mic, with workable EQ controls and feedback squelch ability (although you can only squelch feedback for one errant frequency at time). There is so much headroom in this amp, and so much independent control, it's actually possible to amp two guitars simultaneously without conflict between tones. Not many acoustic guitar amps can pull off that feat.


Around back

The AC-100 provides everything you expect to keep your instrument in contact with the rest of the world. Stereo XLR and 1/4" jacks connect you to the mixing board for PA or recording. The guitar channel features an effects loop in the pre-amp that can be very useful, and not just for additional effects on your acoustic guitar. If you have effects boxes or pre-amps that generate exactly the kind of electric guitar tone you need, you can loop them in here and use the AC-100 as an ultra-clean, super-powerful electric guitar amp. This works great if you rely primarily on your acoustic but like to go electric for part of your set.


The whole is greater than the sum of the parts

All in all, this is one of the most amazing amps I've ever played through. I was dazzled in the beginning and dazzled in the end. I couldn't think of a thing that I would want from an acoustic amp that the AC-100

doesn't deliver - shockingly clear and accurate tonal reproduction, undistorted power, quick precision EQ control, fantastic fat and versatile chorus, totally natural reverb, multi-channel flexibility, and effortless feedback prevention, all in a gorgeous, rock-solid cabinet. I would be thrilled by this amp at twice the price. If you're an acoustic guitarist playing to an audience of more than two, this is a piece of equipment that could make your life a LOT better.






  • Output: 100W (25W + 25W + 50W)
  • Speakers: 5" x 2; 12" x 1
  • Input
    Mic/Aux Ch.
    -XLR, Phone
    Guitar Ch.
    -Hi/Piezo, Low /Active

  • Control (Front)
    Mic/Aux Ch.
    -Source (Mic/Aux) HPF, Chorus, Reverb (On/Off), Volume, Bass, Middle, Treble
    Guitars Ch.
    -Shape, HPF, Chorus, Reverb (On/Off, Volume, Bass, Middle,Treble, Anti Feedback (On/Off), Frequency

  • Master
    Digital Chorus: Mode (1/2/3), Intensity Digital Reverb:
    Mode (1/2/3), Level Master Volume, Power (On/Off)

  • Rear Jacks
    Line Out: XLR (A, B); Phone (A, B); Pre-EQ/Post-Eff (Select); Effect (Send, Return); Footswitch (Reverb, Chorus)

  • Dimensions: 25-7/16" x 21" x 11-3/4"
  • Weight: 55 Ibs.