October 1, 2003

by Andy Ellis

These days, most acoustic guitarists accept amplification as a practical necessity. Some—like wildman Monte Montgomery— embrace technology, while others use it grudgingly, but virtually everyone recognizes the need for sound reinforcement when performing in spaces larger than a living room. Still, it’s not an easy adjustment. While electric guitarists are used to hearing their sound emerge from an amp located some distance away, many acoustic pickers find being estranged from their music profoundly disconcerting.

To address this problem, Motion Sound—a company known for its Leslie-like rotary speaker cabs and combos—has developed an acoustic guitar amp with a spinning speaker chute. The AG-110H AcousticField ($659 street) is designed to disperse the sound of an amplified acoustic in four directions, thus sounding more animated and dimensional than a conventional combo amp. Motion Sound bills the AG-110H as a spatial enhancer, but in addition to its ventriloquist tricks, the unit is capable of organic chorusing effects reminiscent of a vintage Fender Vibratone (think of George Harrison’s warbly fingerpicking on Cream’s “Badge”).

Covered with tough, attractively textured “truck bed liner” paint, the AG-110H’s compact cabinet houses a 150-watt 10" Eminence speaker and a 3.5" ferro-cooled horn, both driven by an 80-watt solid-state power amp (a crossover shunts frequencies above 3kHz to the horn). Hidden inside and mounted over the speaker, a rotating chute spins sound through the front of the amp, as well as ports on the top and sides. Using the Slow and Fast knobs, you can preset two speeds and toggle between them with the supplied footswitch. An Acceleration control lets you set the speed transition time—nice. The footswitch also sports a Stop button, which freezes the rotating chute, and a pair of status LEDs.

The AG-110H’s integrated preamp offers two inputs: One is a guitar-friendly, high-impedance q" jack, the other is an unbalanced q" line input for a drum machine, CD player, or keyboard. Using a handy front-panel trim pot, you can adjust the guitar jack’s input gain to accommodate signals ranging from a passive piezo-saddle pickup to an active onboard preamp. A single volume knob adjusts the signal from both inputs.

The unit’s EQ consists of Bass, Middle, and Treble knobs, plus a Contour control. Bass and treble frequencies are fixed at 150Hz and 3kHz, respectively, and the Contour knob emphasizes midrange frequencies above or below 800Hz. Though simple, the tone controls are voiced well for acoustic guitar. Using the Contour and Middle knobs, for example, I was able to target and attenuate the boxy mids of my Fender Telecoustic without causing it to sound muffled. The Bass knob let me fill out my sound at low
volumes, yet it also proved effective for cutting low-end feedback when the amp was blasting. There were times, however, when I missed the feedback-busting muscle of a notch filter. The AG-110H also lacks a speaker phase switch—an anti-feedback tool offered by most other acoustic guitar amps.

The amp’s Accutronics spring reverb is noteworthy. In addition to a reverb level knob, it has a tone control that’s useful for dialing in subtle ambience without calling attention to the reverb itself. The AG-110H provides a large spectrum of reverb tones, ranging from bold and sproingy to soft and sweet.

With its industrial finish, burly rubber feet, and resilient grillecloth, the AG-110H is built like a tank. However, because the plastic potentiometer shafts aren’t secured after they emerge through the front panel, the knobs wiggle slightly. Players used to the rigid feel of typical amp knobs may find this unsettling.

Sonic Swirl
The device’s raison d’ˆtre is its spinning chute. At it slowest speed, the AG-110H’s rotor enhances chords and lines with almost imperceptible animation. Astute listeners will hear a subtle phasing, but the essential impression is one of warm, radiated timbres. As you increase rotor speed, the AG-110H moves from a gentle chorus to a Doppler-rich swirl. Cranked to full speed, the rotor spews sound that pulses at about 170 bpm—fast enough to produce a watery effect, but not gurgling organ tones or manic vibrato.

While all the electronic Leslie and Uni-Vibe simulators I’ve tried can generate faster, more intense effects than the AG-110H, none match its spatial magic. Because the AG-110H sends sound bouncing off nearby surfaces in ever-changing patterns, the amp creates a lush, enveloping presence—it’s like sitting inside a sonic lava lamp. In comparison tests, my stompboxes delivered more extreme tones, yet sounded oddly static. And unlike electronic rotary simulators, the AG-110H doesn’t smear or obscure the fine, high-frequency details—such as the noise of fingers on strings—that are essential to righteous acoustic tone.

Volume is always an issue with acoustic amps, and the AG-110H is no exception. At 80 watts, it’s certainly loud enough to use onstage with other amplified stringed instruments—at a songwriter’s showcase, for instance—but the AG-110H doesn’t have the horsepower to compete with a moderately loud drummer and electric bassist. Fortunately, that’s not a deal-breaker. Anticipating a need for sound reinforcement, Motion Sound equipped the AG-110H with an internal mic and a pair of XLR outs. One handles the mic signal (which picks up the acoustic sound of the swirling chute), and the other carries the direct amp output (including your volume, EQ, and reverb settings). By routing these two outs to a mixer, you have the ability to dial up any mix of dry and rotary sound, and slam it through the house P.A.

These XLR outs also let the AG-110H shine in the studio. With the amp connected to a mixer, I was able to lay down parallel tracks— one direct, the other rotary—and pan them slightly apart for a robust, yet euphonious tone. Putting a room mic on my flat-top and running it in tandem with the AG-110H’s internal mic yielded spectacular rhythm parts with sharp attack and shimmering sustain. Mechanically, the spinning chute is silent—no squeaks or bearing noises intrude on intricate passages—and even the direct signal has
extremely low quiescent noise.

Bottom Line
Light and small enough to haul almost anywhere, the AG-110H makes a satisfying alternative to typical acoustic combos. The internal mic greatly simplifies onstage setup, and, in the studio, the AG-110H is a viable alternative to chorus pedals and rackmount Leslie speaker simulators. Because it moves air, the AG-110H is an acoustic instrument in its own right, and therefore has the potential to satisfy your esthetics while helping you be heard.


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