Two-Rock Amplification became part
of Premier Builders Guild, a collective
of high-end guitar and amp brands
in November of 2010, and the partnership
has since freed designer Bill Krinard
to build more of the tools that have
facilitated some of the best blues and
rock tones of the last decade. If you need
proof, just listen to recent work from
John Mayer, John Scofield, Eric Gales,
Joe Bonamassa, and Matt Schofield.
Two-Rock’s mission has always been,
in significant part, dedicated to tone
transparency—making amps that capture
the individual voice of a guitar
down to the last detail. With the new
EXO-15, the company focused on capturing
that accuracy and transparency in a small,
A Modern Tone-Aged Family
Two-Rock’s pint-sized, point-to-point-wired
powerhouse is built with a lot of the same
design considerations as the rest of the
company’s products, though a crafty bit of
redesigning went into making the EXO-15
the compact creature it is. Krinard and fellow
Two-Rock designer Chad Mangrum
discovered that cutting the middle of the
powder-coated aluminum chassis and moving
the components to the top and bottom
of the head saved enough room to fit it all
in a tiny enclosure that weighs in at just over
As you might guess from its name, the
EXO-15 has a maximum output of 15 watts.
The signal begins its trip through an all-tube
preamp driven by two 12AX7 tubes that
feed a class AB power amp built around two
6V6 power tubes. There’s a single 5AR4 in
the rectifier section. I think it’s pretty neat
that Two-Rock decided to go with a tube
rectifier in their mini amp, which is pretty
uncommon. (These days, most low-watt
amps use solid-state rectifiers.) In this regard,
the EXO-15 is similar to the tube practice
amps of the ’50s and ’60s, when Supro,
Silvertone, Fender, and Gibson dominated
the small-amp landscape.
Feature-wise, the EXO-15 is rather
Spartan. A trio of EQ controls—bass,
mid, and treble—grace the front panel,
along with gain and volume knobs.
There’s also a contour control to shift the
overall frequency shape, and a passive effects
loop on the back panel of the amp. The
EXO-15 is a single-channel amp, so there’s
no variable gain boost available. So it’s up to
you to use your guitar’s controls, the amp’s
tone controls, pedals, and your fingers to
dramatically alter your sound once you’ve
set the amp.
The EXO-15 absolutely hits the mark in
terms of delivering Two-Rock’s luscious
cleans and pinpoint response. For a lowwatt
amp, it sounds and feels much bigger
than you’d expect—serving up plenty of
volume for small, intimate gigs.
I tested the EXO-15 with Two-Rock’s
Standard 1x12 cabinet, loaded with a custom
WGS12-65B from Warehouse Guitar
Speakers. The cab was a semi-open back,
which helps emphasize the powerful clean
tones that are among the amp’s biggest
strengths. Using a 2011 Fender American
Stratocaster, I gleefully dug into the EXO-
15 with everything set at noon, save for
the gain knob, which I left at around 10
o’clock. The resulting tone was powerful
and full, with robust mids and round-butrich
highs. There was ample low end on
tap, but not in excess or in quantities that
upset the amp’s excellent balance.
The lows work well to provide a foundation
for the mids and highs, and the high
and high-mid frequencies bloom beautifully
with this low-end support. The sum of this
frequency recipe carries beautifully thanks
to the semi-open back design.
The EXO-15 is nothing if not versatile.
Each control has an impressive range
and effect on the tone, particularly the
midrange knob. Most of the time, I left
the treble and bass controls at or around
noon, and moved the mids in and out to
conjure the balance I wanted to hear. And
with that bit of tone tweaking alone, I got
a copious quantity of great tones—from
funky rhythms to full, expansive chording
to raunchy early ’70s single-note work—
with minimal knob twisting.
Even more tone variation is available via
amp’s contour control. It’s subtler than any
of the three proper EQ controls, but as I
moved the contour control down, the mids
seemed to decrease and the bass took on a
darker voice. Interestingly, the highs stayed
intact, but the sparkle diminishes perceptibly
the more I turned the control down.
There’s also a shift in the guitar’s sensitivity
to pick dynamics. And hitting the strings
harder yielded more sting and bite in the
highs, along with a tighter low end.
Two-Rock’s overdrive flavors, while not
quite the source of renowned as the company’s
clean sounds, are outstanding. In the
case of the EXO-15, the company’s quintessential,
full-bodied overdrive takes on a
dirtier voice, mostly thanks to the lower
wattage and rectifier. With a 2010 Gibson
Les Paul Standard at the front of the signal
chain, the fully cranked EXO-15 soared
with super-detailed mids that evoked more
than a little Texas sabor. I also got a flat-out
killer low end that was tight, audible, and
organic—an ideal backdrop to the overdrive’s
perfectly voiced highs and mids.
Switching to a Strat again, dropping the
gain down to around 11 o’clock, and cranking
the volume yielded an absolutely gorgeous,
velvety drive on the bridge pickup.
Adding more treble gave the top end bite
and sustain that prompted mental comparisons
to a vintage cranked Fender Deluxe. It
was a beautiful tone that made it really hard
for me to put the guitar down—and indeed,
a lovely reflection of the guitar’s voice.
For players who spend most of their time
in the studio, the Two-Rock EXO-15 is a
must-try, especially if they work in multiple
musical genres. It’s not a metal or super
heavy-rockin’ amp by any means—at least
without a powerful distortion pedal in the
chain—but it doesn’t try nor have to be.
The EXO-15’s ability to enable the player
to effortlessly dial in great jazz, blues, and
classic rock tones is truly remarkable for an
amp with such little wattage. The perceived
volume levels might be a bit much for players
who are in the market for small tube
amps because of noise constraints in their
apartments or houses. This head just doesn’t
sound that quiet. But the EXO-15 is a spectacular
performer by any other standard.
And in a cluttered world of low-watt tube
amps, it stands out loud and proud.
you prefer vintage and classic
tone, but want a little extra
modern kick in the voicing.
you need molten gain
for heavier playing.
$1,295 (head) $549 (standard 1x12 cabinet) - Two-Rock