For every string player who has ever been ready to leave a dysfunctional band, but wondered what he’d need to make it on his own, there’s another who just wants to know where she’s supposed to turn when she can’t find anybody to jam with. Thanks to the wonders of modern technology, there’s one answer for both questions: a digital phrase sampling unit, also known as a looper special-effects pedal.

A looper is an electronic device that enables the performer—the loopist, if you will—to record one or more short musical phrases and to play back the recording while playing live along with it. In effect, it allows solo players to accompany themselves. It’s an often groove-oriented layering process, like adding audio tracks in a studio, except that this action can be done onstage.

Looping has a long history: musique concrète pioneer Pierre Henry, Edgar Varèse, and Karl Stockhausen experimented with the technique as far back as the early 1940s. The Beatles pioneered the use of looping in the recording studio with 1966’s “Tomorrow Never Knows,” from the Revolver album. But live looping is a relatively recent phenomenon. Increasingly, the equipment’s possibilities are being explored by a surprising musical population: string players. “Cellists [especially] tend to gravitate towards loopers!” says electric cellist Matthew Schoening, one of a growing legion of cello loopists who are expanding their instrument’s role onstage.

Others include cellist Sam Bass of the duo Loop!Station, Alex Kelly, and Zoë Keating (formerly of Rasputina).

Typical Loop Station Features

Loopers are manufactured with an often bewildering gamut of features. But the first things a prospective loopist should consider when selecting a looper are:

• length of time available for recording a single phrase
• monophonic or stereophonic capabilities
• capacity to create and store multiple loops
• ability to “undo” and “redo” a recorded loop
• ability to “quantize” the loop to make it seamless
• ability to change loop tempo without changing pitch
• battery power and/or availability of an AC adaptor
• ease of use in a performance environment

Any model will stack loops, allowing the loopist to layer recorded sections (similar to overdubbing tracks in the recording studio), but smaller pedals require more effort to stack loops and access features. Even the most inexpensive loop stations offer “Undo/Redo” functions, permitting the looper to delete or add a loop to the stack. Note: you can only delete loops in the order that they were recorded, so if you don’t like that middle loop, you’ll have to delete the first one as well.

One other consideration, some loopers deliver high-def 24-bit/96 kHz sound, but do you really need that level of audio quality onstage? After all, it will add to the cost.

The best advice: buy a looper based solely on what you want it to contribute to your live performance.

A Few Looper Units

The Boss RC-2 Loop Station ($170–$190) is the rock-bottom, entry-level option. Its features are compressed into an eye- wateringly tiny single-pedal configuration. Like most loopers, it includes drum-machine patterns as well as a quantizing feature and boasts up to 16 minutes of mono recording, which is nice for those who love a dense forest of licks.

The Boss RC-20XL ($215–$260) is a two-pedal unit that can handle 16 minutes of mono recording of up to 11 loops with a quantizing feature that corrects tempo inconsistencies, and can save up to ten loops.

The DigiTech JamMan ($235–$300) looks similar, but it’s also computer- friendly. It has 24 minutes of recording time with the included memory card (you can install a larger memory card) and a USB port. There’s a “Center Cancel” function for karaoke-style vocal-part removal and a “Full Range Sim” that bolsters the mono sound when it’s going through a puny guitar amp. It can store and recall 11 phrases.

The Electro-Harmonix 2880 Super Multi-Track Looper ($410) looks like a little toy recording studio. This four-track recorder with a stereo mix-down track gets several minutes of recording time per track using the memory card provided, but for live stuff, the optional foot controller (another $112) is a must.

The BackLine Engineering RiffBox ($420) allows the loopist to switch between layers with “intelligent looping” technology that automatically turns on when it senses repeated patterns. There also are simple delays and doubling effects, but no drum machine. It can output a headphone feed to a drummer, signal-process a solo backward in real-time as well as “vari-speed” tunings harmonically related to the original loop, all with up to 40 seconds of pristine stereo recording.

Cellist Matthew Schoening runs his NS Design cello through a Boss RC-50 ($500). The seven-footswitch unit provides up to 24 minutes of stereo recording (or 49 minutes mono) with USB transfers and the ability to pan and fade three stereo phrases simultaneously for balance and clarity. You can also stack three phrases for a complex layering effect. It locks to MIDI for effects switching and offers an array of quantization and synchronization options.

The Boomerang Rang Plus ($599) offers two independent loops (up to four minutes each), but also a dozen sampling options that allow a string player to create a live reverse passage, similar to the backward lead guitar sounds used by Jimi Hendrix and the Beatles, among others.

“I really like the idea of creating stuff live,” say Schoening, whose virtual orchestra of loops has shared the stage with the Northwest Symphony in Washington.

Indeed, the ability to use this technology and remain musical is the key challenge. With all the equipment Schoening has tried, his mantra remains “Less is more.”

“I try to make it as interesting as possible,” he says, “and not make it sound like loops.”

The Sound of One Foot Looping

If you head to your local music store, you might start with a Boss RC-20XL—Matthew Schoening started with its predecessor, the Boss RC-20. Beware of small amps: layers of looping can blend into a sonic mishmash. To build a loop (1) turn up the Level, Mic, and Inst. knobs, (2) tap the left-foot pedal exactly when you begin the phrase you want to play, and (3) tap it again precisely when you want it to end. Does it take practice? You bet. (4) Tap the left again to overdub another layer. (5) When you’ve had enough, tap the right pedal to stop the recorded sound. Tapping the left pedal again kicks in the recorded loop again, right where you left off. —G.W.