ZT Acoustic Lunchbox Amp Review

AG 225 September 2011

Posted by Gino Robair

The ZT Amplifiers Lunchbox has gained considerable recognition as a high-output electric-guitar amp with remarkably good tone in an attractive and lightweight design. Since ZT began in 2008, the Berkeley, California–based company has achieved this by using digital signal processing (DSP) to create a convincing guitar sound at all volume levels. As a result, the parts that normally add size and weight to an amplifier, such as the tube components and transformer, have been removed, allowing ZT to create an electric guitar amp that resembles a school lunch pail and weighs less than ten pounds.

The Lunchbox Acoustic offers this design to acoustic players who want the full frequency response and extra headroom that an acoustic amp provides, with features that working musicians appreciate: a dedicated mic channel, an effects loop, and a stereo line-level input. The result is a miniature PA system that is perfect for rehearsals, gigs at small venues, and recording.

Full Menu

Like other ZT amps, the Lunchbox Acoustic’s tone is shaped using DSP. After the gain control, the guitar and mic signals are digitized at 24 bits/44.1 kHz. DSP technology is then used for tone shaping, dynamics processing, and reverb before the signals are converted back to analog. The Lunchbox Acoustic’s DSP is voiced specifically for amplified acoustic instruments, so its overall frequency response is flatter than that of the Lunchbox, with a slight low-end boost. The DSP’s limiter reduces clipping when the input gets too loud, and you’ll hear it kick in when the input gain level is high and you play aggressively.

At 12 pounds, the Lunchbox Acoustic is much lighter than your average acoustic amp, but still includes a discrete mic channel with independent input gain, tone, and reverb controls, as well as two inputs—XLR and 1/4-inch—supporting professional and consumer-grade microphones. The channel offers +12 V phantom power, allowing you to use most condenser mics. The Lunchbox Acoustic also has a 1⁄8-inch stereo line input that can be used to add backing tracks onstage or for practicing. After the mic and guitar signals are converted back to analog, they are summed with the line input and sent to the effects loop, which has separate send and return jacks. The volume knob controls the final output level. You can use the send output as a DI to run everything through a powered system, such as a PA. However, an eight-ohm output is also included if you want to use a passive, external speaker (which must be rated at 100 watts or more) rather than the internal speaker. The amp’s digital reverb is modeled on a plate reverb design, and the knob controls the wet/dry mix. The effect sounds very good, but a little goes a long way, and I really appreciated having independent control over the reverb for each channel.

The Lunchbox Acoustic includes Feedback Cut, a three-setting EQ circuit that does a great job of notching out feedback on both channels. It effectively eliminated the high squeal of my mic and the midrange roar of my acoustic guitar. Because of the steep dips it imposes over the frequency spectrum, Feedback Cut alters the timbre of the input signals, though that isn’t necessarily a bad thing. Having three preset EQs is useful for some instruments. Setting two, for example, did a good job of rounding out the tone of my mandolin.

Healthy Portions

Although it is rated at 200 watts, the Lunchbox Acoustic doesn’t sound nearly as loud as, say, a tube-based electric guitar amp at that rating. And it doesn’t provide enough output on its own to compete onstage with a moderately loud drummer. The Lunchbox Acoustic was designed to offer greater fidelity than a guitar amp, with enough headroom to simultaneously handle an acoustic-electric instrument, a mic, and a line input. And it does this remarkably well. It’s loud enough to easily cover house concerts and café shows, and the Send/DI output allows you to conveniently patch into a larger venue’s PA system.

Despite having only treble and bass knobs for each channel, you can get a wide range of useful tones. Not surprisingly, the most realistic guitar sound I got came from a Taylor 314ce acoustic-electric, which is outfitted with the Taylor Expression System. Between the guitar’s onboard tone controls and those on the amp, I was able to dial in a sound that was remarkably natural at high volume. But even with my ancient no-name guitar with its home-built piezo pickup, the onboard EQ helped me lessen the “quack” you often get from transducers.

ZT says that the Lunchbox Acoustic can be used with a variety of instruments, from electrified accordion and harmonica to organs and synths. I was very impressed by the sound quality of my Washburn M-1 mandolin, which has a built-in bridge pickup, through the amp. My lap steel and analog synth sounded fantastic through the Lunchbox Acoustic, particularly when soaked in reverb. However, I wasn’t pleased with the tone from any of the solid-body electric guitars I plugged into this amp.

Light Lunch

If ZT had included only the guitar channel in the Lunchbox Acoustic, with its pro-level tone and headroom, it would still be a worthwhile purchase. But the fact that it can be used as a miniature PA, while remaining small enough to fit under an airplane seat, makes the Lunchbox Acoustic a no-brainer for anyone wanting to amplify an acoustic-electric instrument.

SPECS: 200-watt power amp. Two channels. XLR and 1/4-inch mic inputs. Bass, treble, and reverb controls for each channel. 6.5-inch speaker. 1/4-inch headphone output with volume control. Aux input on 1/8-inch stereo jack. Eight-ohm external speaker output. Effects loop. Internal/external speaker switch. 12 lb. Made in China.

PRICE: $529 list/$399 street.

MAKER: ZT Amplifiers: (510) 704-1868; ztamplifiers.com.

Excerpted from Acoustic Guitar September 2011

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