When dedicated acoustic guitar amps were introduced about a decade
ago, pickup-equipped acoustic guitars were finally able to sound natural
on stage without the use of an entire PA. Today, almost every major
manufacturer of guitar amps offers an acoustic model, and a few companies,
such as Ultrasound (2875 R Ave., Adel, IA 50003; [888] 308-1557; www.ultrasoundamps.com),
specialize in the genre exclusively. Growing out of UJC Electronics,
a company with a long history of electronic assembly work, Ultrasound
was founded with the sole purpose of producing an affordable, high-quality
amplifier for acoustic instruments. After entering the scene with
the original AG-50 in 1999, the new company quickly created a buzz
on the Internet and through a handful of professional players, including
country picker Thom Bresh. For this review, I focused on the second-generation
AG-50DST ($667, models without reverb starting at $438) and the matching
AG-50E powered extension cabinets ($327) as well as the input-expanding
PAMM minimixer ($249).
Featuring two coaxial eight-inch speakers with cone-mounted tweeters,
the AG-50DST’s portable cabinet measures 13 x 18 x 10.5 inches. It
weighs only 23.7 pounds, so it’s possible to carry the amp in one
hand and a guitar in the other. The durable unit is covered in brown
tolex and is equipped with metal corner protectors. Removing the chassis
from the cabinet reveals clean wiring and good workmanship all around.
The amp’s user-friendly control panel features just six knobs to rein
in its 50 watts of power. Master volume, bass, and treble make up
the heart of the controls, assisted by a notch filter (sweepable from
100 to 350 Hz and activated by a separate switch) and level and mode
controls for the built-in digital effects. The Alesis-supplied effects,
similar to the company’s Nanoverb, include 16 combinations of reverbs,
choruses, and delays. A single quarter-inch input connects the guitar
to the amp, effect-send and -return jacks allow external effects to
be patched in, and a balanced output (with a switch to select a pre-
or post-effects signal) eliminates the need for a separate DI box.
The controls also include a "shape" switch (which cuts mids and boosts
highs and lows to create a "smile-curve" EQ setting) and a lighted
power switch. The closed back of the amp is home to three quarter-inch
jacks (for mono line out, stereo line out, and headphones) and an
AC power receptacle, which also holds the externally accessible main
fuse.
Equipped with only a single volume control and a power switch, the
AG-50E extension speaker’s front panel is a minimalist’s dream come
true. Featuring the same dimensions and speakers as the full-blown
amp, the extension is driven by an identical 50-watt power section,
but its lack of an internal preamp means that it requires a line-level
input signal to function. Although it’s designed to work in tandem
with the amp (using its line-out signal) or mixer, these powered cabinets
can also be driven by other preamps or line-level signals, and several
units can be daisy-chained together for additional power.
The final link in the complete Ultrasound chain is the company’s
PAMM (Pre-Amp-Mini-Mixer). The PAMM, which was designed to expand
the amp’s available inputs, includes two microphone channels (with
12-volt phantom-power–equipped XLR inputs, quarter-inch inputs, three-band
EQ, and input and output level controls), two guitar channels (with
quarter-inch inputs and level controls), and two RCA jacks for adding
a tape or CD player to the mix. The only output option is a single
quarter-inch mono jack, and the unit is powered by an external "wall-wart"
power supply. Housed in a sturdy sheet-metal case, the unit appears
indestructible.
Because the various components of the Ultrasound rig allow for a
number of different applications, I checked them out in a few different
setups. Besides plugging straight into the amp (using a Taylor 712C
with an L.R. Baggs Dual Source system and a RainSong WS1000 with a
Fishman Prefix Onboard Blender), I tried the amp with one extension
in mono, two extensions in stereo, and with the PAMM. I also used
a Rane AP-13 preamp to drive a pair of the extensions alone.
With the amp’s tone controls set flat, I was able to get a very transparent
representation of the guitars’ sounds without a lot of fussing around,
and the addition of a subtle reverb gave the pleasant tone some room
to breathe. With the active pickup systems installed in the test guitars,
I was able to turn the volume up to about six before the amp began
breaking up. At this point, the volume was at a level that would be
sufficient for a solo gig at a restaurant or a party, but using it
in a loud band might require additional power. Thanks to Ultrasound’s
modular concept, however, a more powerful system is only an extension
speaker away. Running the amp with one extension speaker drastically
increased its punch and overall volume. Using two extensions with
a stereo Y-cable allowed the use of the effects’ stereo capability
and created a spacious sound (unfortunately, a single amp and extension
can’t be set up for stereo sound). I was still able to reach the system’s
limits when I strummed hard and turned up the volume, but by then
I had also reached the volume level of a small PA. (Ultrasound also
offers a 100-watt version of both the amp and the extensions, featuring
four speakers each, which should satisfy those with even greater volume
needs.)
I would suspect that separate gain and master volume controls would
increase the amp’s headroom with some pickups, as it would allow a
better match with the input signal. The amp’s sparse EQ section was
able to effectively fine-tune the overall sound, but it’s limited
to two bands and won’t be able to perform miracles if the input signal
isn’t reasonably satisfactory to begin with. The notch filter worked
like a charm, effectively battling feedback without excessively altering
the tone. My Rane preamp (with an Alesis Nanoverb in its effects loop)
connected to two extensions proved to be an excellent combination.
With this setup, those who already own preamps and effects would only
need a couple of extension speakers to provide enough power for a
small venue.
After these positive impressions, I found the PAMM to be disappointing.
While the amps featured quiet circuitry, the mixer was on the noisy
side. There is nothing inherently wrong with the unit’s basic design,
but I would have liked to see more features designed specifically
for acoustic guitar. High on this wish list is a TRS stereo input
with phantom power for electret mics, which would allow the unit to
be used as a true "blender" for multiple-source pickup systems. It
would also be handy to have stereo outputs and an effects loop so
it could be used with only one pair of the extension speakers. If
mixer flexibility is important to your rig, you should probably shop
around for alternatives, some of which are available at similar prices
from other manufacturers (Ultrasound has also announced that it plans
to introduce an upgraded stereo mixer later this year).
The bottom line is that the heart of the Ultrasound system offers
great value and flexibility. With its basic, well-conceived features,
the AG-50DST is bound to become a good friend to many acoustic guitarists.
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