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Boss RC20XL

Loop Recorder Stomp Box By Paul White
Published September 2005

Boss RC20XLPhoto: Mark Ewing

Record loops and overdub in real time for lightning-quick track creation live or in the studio.

You might reasonably ask what a review of a stomp-style guitar pedal is doing in Sound On Sound, so let's get that out of the way right now. Firstly, the RC20XL builds on the concept of the now discontinued Lexicon Jam Man (and the looping functions of the more recent Line 6 Delay Modeller) insomuch as you can record loops (called Phrases in Roland-speak) and then overdub onto them live. The Jam Man elicited a lot of interest from our readers, especially when Lexicon stopped building it — it seems that you always want most that which you can't have! The second reason I find this product interesting is from a technology standpoint, as to my knowledge it is the first looper to use flash memory, which means segments of audio can be retained in memory indefinitely for live performance use. Better still, as memory is now much cheaper than it was, the recording time is measured in minutes rather than seconds. In fact a maximum of 16 minutes of memory is available, split between the various loops you wish to record. Clearly this pedal is ideal for admirers of Robert Fripp's guitar wizardry who want to play semi-experimental music live, but it can also be a creative studio tool, as you can build up loops in a very intuitive manner before recording them into your sequencer for future use as the basis for a new song.

Loop Recorder Stomp Box

The pedal itself follows a familiar Boss format with two footswitches controlling most of the live action. Two further footswitches (one of which can be a dual up/down pedal) can be connected via rear-panel jacks to control Phrase Shift, which I'll talk about a little later, and Reverse, which does just what it says — plays the recorded loop backwards. Although this unit is designed for use mainly with guitar, there's also an unbalanced jack mic input, though I wouldn't recommend this for serious recording work. However, it is useful for those high-street busking sessions with a digeridoo (or whatever) and you can even use the mic and instrument inputs at the same time if need be. The output of the unit is strictly mono and power can come from an optional PSU or from six AA batteries. Digital units like this tend to be fairly hungry on batteries, so the mains adaptor is a good idea — unless you're busking in the high street using a battery amplifier!

Working with loops can be a problem, because if you get an overdub wrong, you generally have to go back to square one. However, that's no problem here, as there's a very welcome Undo/Redo button. To help timing, there's also a useful metronome and a facility for having the loop recording end precisely on a beat rather than exactly where you hit the pedal. This is really helpful in creating tight-sounding loops. Once a loop has been recorded, its tempo can be changed without altering its pitch, though as with most time/pitch manipulation there's only so far you can go before the processing artefacts start to show.

Other live performance niceties include the ability to store multiple Phrases, then decide whether each should play back as a 'one shot' performance or loop continuously. Because this pedal can store multiple Phrases, and store them after power down, you could load up a few backing tracks into it (from CD, your computer or any other suitable audio source) ready to perform. There's no way to back up loops other than to record the audio output, though, and from my own perspective the ability to dump and load audio files via USB would have made a lot of sense.


There are relatively few controls on the front panel, but it's worth going through them as their functions are not always as straightforward as they might seem. The Level control sets the playback volume, but from its position on the left-hand side it would be easy to mistake it as some kind of input-gain adjustment, which it isn't. A second level control, labelled Guide, adjusts the level of the guide rhythm part, which is best thought of as a cross between a click track and a simple drum machine. The controls that actually adjust the line and mic levels are located on the far right of the machine, the logic being that this is the side your input jack goes in (to suit right-handed players). Below this is a Tap Tempo button for setting the click tempo in the usual way, but by pressing and holding it you enter a mode where you can step through a number of alternative time signatures, so you don't have to do everything as 'four to the floor'. Furthermore, if the Tap Tempo button is used in conjunction with the shift button, you can select different guide patterns to play along to.

The Phrase Select knob is a rotary switch with 11 numbered positions, each relating to the Phrase you're saving or playing back. A Loop Phrase indicator LED lights if a loop Phrase has been saved in the currently selected location and if this flashes rapidly when you're trying to overdub or save, it means you have insufficient memory left. It also blinks during Phrase playback. Once a Phrase has been recorded, it needs to be stored into internal memory using the Write button, otherwise it will be lost when the unit is powered down. Using Write and Shift together deletes the currently selected Phrase. A second LED does a similar job for a one-shot Phrase being recorded or played back.

Auto Start is a neat feature and allows recording to be triggered by the first note of the performance, rather like the automatic triggering function on samplers. Also, when this button is pressed and held along with the Shift button, it toggles between loop playback and one-shot playback. The final button that needs some explanation is Mode, which allows the user to select the recording method. Also, when held down along with Shift, it enables the user to decide how playback will stop: there's a choice of Normal (right pedal stops playback immediately), Fade Out, or finish at the end of the current loop cycle.

You may have noticed the alternative wording next to the Mode LEDs, one of which says Flat Amp Simulate. This is designed to produce an approximately flat-sounding response when the pedal is being used through a typical guitar amplifier, which will make pre-recorded backing loops sound less coloured. There's also a centre-cancellation feature for attenuating the vocals in material being recorded via the stereo Aux mini-jack on the rear panel, though how well this works depends on how the original material was mixed. This feature also reduces the level of guitar solos or anything else in the mid-range that's centrally panned in the mix, which tends to leave the rest of the mix sounding a touch 'treated'. This is all starting to smack a bit of Karaoke and I don't really want to go there!

Boss RC20XL rear connections.Boss RC20XL rear connections.Photo: Mark Ewing

Using The RC20XL

Before using the RC20XL, you need to be aware that the internal memory is divided into two sections, the first acting as a temporary record buffer and the second allowing up to 11 different Phrases to be saved. Recordings must be saved using the Write button if you want them to survive a power-down, in much the same way as you have to save edited synth patches. The rotary switch selects which of the 11 possible Phrases you are saving into, and once you put something important in memory, you can protect it from overwriting to avoid it getting wiped accidentally. When recording loops that need precise timing, the Loop Quantise mode is actually very useful, as it effectively quantises your pressing of the Stop button to the nearest beat (before or after the press), although you have to be working to the timing click (which also provides a count-in) for this to apply. There's also a button-press combination that lets you record a new Phrase at the same tempo as the last one you recorded, which is handy if you've forgotten what that tempo was! When tempo-change processing is being applied, this only relates to tracks that have been saved into memory, and once you've got the tempo right, you have to re-save to make the edit permanent.

For live use, it is worth buying a dual pedal to use in the Phrase Shift socket, as this will allow you to switch between the Phrases you have recorded by shifting up or down by the desired number of increments. Ideally you use the pedal well before the end of the Phrase so that you don't run out of time to select the next Phrase. To move up three loop numbers, you simply press the pedal three times. If you select a one-shot Phrase, this stops at the end, so it's a good way to set up song endings if you're using the looper for more traditional songs, though to me this isn't the most creative or practical way to use it.

When you overdub onto an existing Phrase, the result is held in the temporary area of memory until it is saved or erased. Until then you can Undo and Redo the overdubs as necessary without changing the original loop. Multiple overdubs are also possible, though the sound quality deteriorates slightly every time you add a new layer. Nevertheless, you can build up quite complex layers when playing live without the sound quality suffering to an unacceptable degree, and you can still undo the last layer if it didn't sound right.

I found that most of the time I used the RC20XL to provide a very basic chordal backing over which I could improvise (and the guide tempo sounds are interesting enough to use as part of the music), or I'd start with a clean slate and layer up several improvisational parts to create a live performance that built in complexity as the song progressed. This is a great way of working if you like jam-based composing and performance, and often you'll find that something magical happens during one of your meanderings that warrants being captured for further development after being copied over to your sequencer.

The ability to reverse playback is no longer new, but it still sounds good on more ambient material, though I would have also liked to see a dedicated switch for halving or doubling the tempo in real time, as there is on the Line 6 box. Using the RC20XL at a basic level doesn't take too much getting used to, but you do need to spend an hour or two playing with it before you take it out to a gig. Some of the more advanced features are a bit cryptic, so it pays to keep the handbook where you can find it, but on the whole the RC20XL is a lot of fun and very immediate in the results it can produce. The quality of the recording is also perfectly clean and clear enough for most guitar-related applications.

Loopy Tunes

At the time of its launch, the RC20XL was the most advanced pedal looper around. However, technology moves on and there are already announcements from competitors that they will be building similar devices using flash memory cards, enabling the user to take the total recording time up to hours rather than minutes. Whether you need this extra recording time or not depends on how you work. If you work to backing tracks, then I don't think the RC20XL is the best way to go, as it has limited memory and is mono only — an iPod will do the job much more easily. However, if you like to improvise over grooves or loops that you've created earlier, then overdub onto these during live performance, the RC20XL has a lot going for it and it probably has enough memory for you to do a whole set of music based on repeating loops. The fact that you can pre-load it with loops and then write-protect them is excellent, as is the ability to undo overdubs. Maybe there could have been more dedicated switches and fewer hidden functions, but on the whole the RC20XL doesn't take too much getting into and the brief manual is actually pretty clear and straightforward. I have to admit that the concept of the RC20XL really appeals to me, and when it comes to balancing features with cost and ease of use, Boss are not too far off the mark at all.


  • Flash memory allows long-term storage of your material.
  • Practical pedal format.
  • 16 minutes of loop memory.


  • Memory can't be expanded.
  • Extra pedals needed for full operational flexibility.
  • Mono playback only.
  • No memory back-up option other than recording the audio out.


The RC20XL is a good compromise between a technological monster and a no-brainer guitar stomp box. It allows the experimental player to perform magical things live, it has a memory not reliant on being left powered up, yet it is affordable and not over-complicated.


£249 including VAT.

Roland UK +44 (0)1792 515020.

+44 (0)1792 799644.