Small amps have been around for a long time: Roland, Fender, Crate, Electro-Harmonix, and Vox among others, have made guitar amplifiers that were scaled down and extremely portable. Such amps tend to have no more than an 8-inch speaker and usually max out at about 15 Watts. They serve musicians well, whether for practice, recording specialized parts, or just noodling; rarely would they be considered usable on a full gig with drums, bass, and the whole shebang—until now.

A few years ago a small company out of Northern California began offering an amp about the size of a lunchbox, sporting a 6.5-inch speaker, that could compete with the big boys when it came to raw power. The ZT Amplifiers Lunchbox professed 200 Watts of peak power packed into a package no bigger than a desktop monitor speaker.

Whether the amp, in fact, puts out more wattage than a Marshall JCM800 is moot. I reviewed the electric version over a year ago and have been happily using it on full-band gigs ever since, packing it into a suitcase that fits in an airplane’s overhead bin, with 2/3 of the case left over for pedals, wires, etc.—and I am not alone. The electric version of the Lunchbox has proved a smash hit, especially with traditional jazz players who require tons of clean headroom and are tired of hauling heavy amps to low-paying restaurant gigs.

However, flattop pickers are even more demanding of clean headroom than archtop wielders. Emboldened by the success of the electric version, ZT Amplifiers has released the Lunchbox Acoustic ($399 street) for acoustic-guitar players. But can it compete with the big boys as nimbly as its electric brother?

“Unplugged”
Ever since MTV’s Unplugged debuted, the interest in acoustic playing has skyrocketed. Of course, we all know that unplugged is implicitly enclosed in parenthesis, as, in order to be heard live, acoustic guitarists are more often than not plugged in somewhere.

FIG. 1: From the top panel, you can access the two independent channels—guitar and microphone—as well as select one of three levels of feedback cut.

While the folkies of the Fifties and Sixties may have been content to stand or sit steadily in front of a microphone, modern players want to be free to move about the stage when and if they are not singing (and sometimes, with the aid of headset mics, even while they are singing). Plugging the acoustic pickup into the PA is an option, but it can create feedback issues when the instrument is monitored through a speaker pointing right at its soundhole. Then there are those small coffeehouse gigs, where no PA is available.

Enter the acoustic amplifier.

To adequately suit the needs of your average player, an acoustic amp must supply enough clean power so that it will never distort regardless of how hard the picker plays. Unlike electric amps that are voiced in a midrange that warms up solid body guitars and favors distortion, acoustic amps must provide the full frequency range of a PA system. Many also serve as mini-PAs, with inputs for vocal microphones and phantom power.

The ZT Lunchbox Acoustic comes with all the features that the modern flattop fondler requires. It has two channels—one for a standard acoustic pickup and one for a vocal mic, or a pickup system with a microphone option.

On the amp’s top, each channel has its own Gain, Bass, Treble, and Reverb controls (see Fig. 1). A 1/4-inch guitar input and the Anti-Feedback Control are found here, as well. A phantom-power switch for the microphone channel is on the back, along with XLR and 1/4-inch mic inputs, a 1/8-inch stereo aux-input jack, an external speaker output, a variable headphone/DI output, an effects loop with active send for multi-amp setups, and a 115v/230v voltage switch (see Fig. 2).

FIG. 2: For a portable acoustic amp, the rear-panel packs a lot of features, including stereo line-level input and output, an effects loop, and two types of mic inputs.

The speaker switch allows you to defeat the internal speaker for headphone practice or when sending the signal to an auxiliary speaker. However, you can leave the internal speaker functioning while you use the DI output, allowing the amp to function as a monitor while you run the direct-output signal to the house PA. At 7.5" x 9.8" x 7.7", and weighing 12 lbs., the Lunchbox Acoustic is small enough that a mic stand input on the bottom would be a welcome addition when using the amp as a personal monitor.

Tiny Titan
As we mentioned, acoustic amps require abundant headroom—rarely do Dreadnought players want their instruments to distort. The Lunchbox Acoustic’s 200W power claim aside, it contains more than enough headroom to keep the hardest attack clean at enough volume to fill a small club. As an added precaution against unwanted grit, the ZT includes anti-clipping circuitry.

How do they pack so much pristine power into such a puny package? As with most modern miniaturization, the answer is “digital.” After the analog input stage, which includes the gain control, the signal is converted into a 24-bit, 44.1 KHz digital signal. Dynamics and EQ processing are implemented in the digital domain, where the tone control models a vintage amp. After the plate-style reverb emulation, the signal is converted back to analog and routed to the power amplifier. The amp is based around two Class A/B output stages, running fully bridged across the speaker load to deliver high levels of RMS power and peak dynamics.

Torture Test
I ran a Loar acoustic guitar fitted with an LR Baggs M1 passive pickup in the sound hole into the Lunchbox Acoustic. In order to send enough signal to drive the input, I put a simple, transparent preamp pedal between axe and amp.

Though lacking any horn-type drivers, the Lunchbox’s 6.5-inch speaker offered plenty of highs and, even more astounding, an abundance of low end. According to ZT, the custom-made speakers vibrate further back and forth than almost any 10- or 12-inch speakers, delivering a towering sound that belies its size. Regardless of these claims, the Lunchbox Acoustic’s speaker has the same dimensions as the electric Lunchbox speaker, yet it offers a full-range tone without any mid-range bump. This amp brought out the character in the woody honk of the Loar, rather than turning it into a generic “acoustic” sound.

Sitting with the amp directly facing the soundhole of the instrument, I turned up the volume and adjusted the Anti-Feedback control. “Control” is the operative word as it doesn’t eliminate feedback entirely—you will still have to be careful about taking your hands off of the strings—but I can see it being a big help in a live situation.

Because I rarely gig on acoustic guitar, I had the singer/guitarist I have been playing with check it out in rehearsal. He plugged in his Martin D-35 guitar, equipped with an old Frap pickup under the bridge and a contact mic on the body. The two pickups are summed through a stereo cable and run into a Fishman system that includes a volume pedal/preamp.

He had been playing through the PA, having already rejected an available larger acoustic amp by a major manufacturer. But he was immediately blown away by the sound coming out of this little powerhouse. He faced the Lunchbox Acoustic directly at himself with no feedback issues and we ran a line from the DI out to the PA so the rest of us could hear him. Placing it behind him for performances in larger spaces will help deal with the feedback problems that can appear at louder volumes.

As I learned when using the electric model, the Lunchbox Acoustic offers an amazingly wide sonic spread for an amp of its size. This will allow all of us to hear his guitar on stage without having to send it through the vocal monitors. At one point we checked out the vocal mic through the second channel and found the resulting sound to be the equal of many small PAs.

". . . a welcome addition to the growing line of ZT products, all of which exceed the limitations of their size."

Loud, Clean, Portable
The solidly built, intelligently designed ZT Lunchbox Acoustic guitar amplifier is a welcome addition to the growing line of ZT products, all of which exceed the limitations of their size. Other amps have more bells and whistles but the ZT doesn’t seem to be missing anything essential. Why include digital effects when most serious players would prefer to use their own? And who needs a graphic EQ when many guitar pickup systems feature one and an EQ pedal is dirt-cheap?

It is hard to beat the ZT Lunchbox Acoustic, especially when used as a mini PA for house concerts or small clubs. And it’s ideal as a personal monitor for the stage. What’s not to like about a full-featured, full-range amp that you can carry to the gig in the basket of your bike?

Pros: Big, high quality sound in a small package. All the essential features. Reasonable price.
Cons: No standmount on the underside.

Michael Ross in a New York City-based guitarist/producer/music journalist. He contributes articles to Guitar Player, Premier Guitar, Guitar Edge, EQ, Sound On Sound,Getting Great Guitar Sounds and All About Effects.