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Boss RC-505 MkII

Desktop Loop Processor By Paul Nagle
Published June 2022

Boss RC-505 MkII

Boss’s best‑in‑class looper just got even better.

It’s almost a decade since Boss gave us the RC‑505: a fresh take on looping based around five stereo tracks, effects, plenty of memory and reliable MIDI synchronisation. Most eye‑catchingly, its large buttons and tabletop format marked a clean break from pedals with small metal buttons and guitar fixations. After several years in service, it received a free update increasing the memory even further and boosting the effects and remote control abilities. A lot of people were very happy indeed.

It was therefore a pleasant surprise to hear there would be a new chapter in 2022. Reassuringly called the RC‑505 MkII, this model features updated hardware and extra dollops of pretty much everything. We can surely forgive original owners a certain amount of anticipatory drooling, but this could also be an opportune moment for others to discover what all the fuss is about...

The New

As you excitedly unbox, it’s plain the RC‑505 MkII is going to grab a significant acreage (420 x 234mm) of desk space, although it weighs less than 2kg. If your live or studio rig has been gradually shrinking over the years, now could be a timely reminder that large doesn’t necessarily mean bad — it might translate to a more direct, welcoming interface. Of particular note are the sliders: at almost double the length of the earlier model’s, they are fully capable of meaningful, responsive mixing. This is just as well, because this model can bounce down and consolidate tracks, and print effects, a feature that was probably high on many users’ wishlists. Speaking of effects, there are a total of 49 choices for the input stage and 53 to transform track playback, with four of each type available simultaneously. Further bonuses include storable effect combinations and step sequencers.

Each track has gained an ‘FX’ button that serves as a top‑level toggle for effect status, and while this, too, has increased the footprint, it’s so darn convenient it never feels unwarranted. Dedicated buttons are offered for key functions, such as starting/stopping the entire machine or the rhythm section — a built‑in ‘super metronome’.

The LCD is a simple monochrome affair of 128 x 64 pixels and beneath it are four black encoders that, along with some of the buttons, blend mysteriously into the black background, a design trend only Douglas Adams could have predicted. Many menu pages feature text along the display’s bottom row, relating to encoder function. While text and encoders don’t exactly line up, I was more concerned about the viewing angle: unless you look more or less directly downwards, the bottom row isn’t always readable. Neck aches aside, it’s so much faster adjusting four parameters at once, and the new Edit buttons mean that tweaking before effect activation is actually quite slick now.

The front panel is partly composed of shiny black plastic, of a type best suited to those who never sweat. Backlit buttons and intelligent use of colour ensure you can always tell what’s going on. I’ve long been a fan of the large round pads used for recording, playback and overdub; they make perfect sense at almost any level of intoxication.

While the first model featured two ‘proper knobs’ for microphone and instrument levels, these functions are now found in menus and under encoder control. It’s not an ideal swap but is understandable, given there are now a total of six inputs — two for XLR microphones (with phantom power), plus two pairs of inputs for synths, mixer sends, and so on. On stage these might even eliminate the need for a mixer. In general, the I/O really delivers — joining the main stereo and phones outputs are two assignable stereo subs. EQ is provided for inputs and outputs, with a compressor available to each microphone. If that isn’t enough, an optional final glue in the form of a master reverb and compressor can be assigned to the main or either sub output.

Internally, the recording capacity has been jacked up to a staggering 13 hours of total audio, with up to 1.5 hours on each track! These 32‑bit recordings are sharp and clean, and if you don’t already have a conversion app (say, to import them into a DAW), Boss Tone Studio is a free download. Suffice it to say the RC‑505 MkII should appeal across the board, whether you like to prepare loops in advance or simply wish to grab the moment, without worrying if it turns into an indulgent, unhurried jam. A total of 100 patch memories are provided, each ready to hold loops, effect setups and functions you’ve assigned for remote control.

The packed rear panel sports two assignable pedal inputs, plus standard MIDI In and Out sockets, the latter optionally a soft Thru. The USB port has similar MIDI functionality but can serve for backup and restore purposes when required. And, in common with many recent Roland/Boss products, the RC‑505 MkII can serve as a USB audio interface, which can be jolly useful.

The back panel is busy, but should cater for all your needs, with a healthy selection of audio I/O, expression pedal inputs and everybody’s favourite size of MIDI ports.The back panel is busy, but should cater for all your needs, with a healthy selection of audio I/O, expression pedal inputs and everybody’s favourite size of MIDI ports.

Loop Guru

Performers are offered a number of ways to begin, either by jamming or singing along with the built‑in rhythms, or by tapping out a suitable tempo on the button and going with that. If you prefer to slot into a larger system, synchronisation with MIDI clock is as solid and reliable as before.

After an initial exploration, you soon realise the value of storing a few empty patches as templates. For example, it’s so handy having your favourite effects primed in advance, or specifying the type of overdubbing, whether tracks loop or play just once, and whether each track operates in single or multi mode. Single mode is useful for verse/chorus type structures or when you have several takes but need only one to play at once. In multi mode, all tracks play freely.

Other time‑savers to set up for convenience might include tying tracks to specific inputs or to certain sub outs, or setting up unusual loop lengths. All that done, recording is initiated by hitting one of the large pads then playing or singing (or both). Hit the pad again and, depending on your preferences, the track will switch to overdub or playback. Whenever a track is playing, hitting that same pad invokes overdub again, and if you make a mistake, it’s easy to undo or wipe the whole track ready to go again.

Recording is always one track at a time and, unlike delay‑based loopers, the audio cycles around perfectly, with no option to age or degrade. The MkII has introduced an extra overdub replace mode, though: now you can choose whether or not to hear the previous pass during recording.

I mentioned unusual loop lengths just now but I should clarify that polymetric recording is not as straightforward as the manual suggests. This is how it works: all recordings whose lengths are set to Auto will be exactly the same length as the first. If you choose different loop lengths, either by specifying a number of bars in advance, or picking Free (you can choose as you go), your choices won’t necessarily be honoured. Confusingly, there’s a hidden rule: even supposedly free recordings must be multiples of the first’s length. The best workaround is to record one dummy bar initially, after which the ‘multiples of’ rule means you can, indeed, enjoy true polymeters. You can even return later, delete the dummy recording and reuse the track. However, it’s not ideal and if, like me, you often work in large bar counts, you’ll probably agree that a visible bar counter is sorely missing. Users who stick to regular loop lengths, probably in multiples of four bars, will experience no hardships whatsoever.

Having recorded several tracks, you can consolidate them by bouncing down. I’m happy to report that the destination track can be much longer than the source(s), incorporating mixing and effect tweaking on the fly.

Each Track button opens a series of playback‑related pages. Getting around involves either repeatedly pressing Track or using the tiny left/right buttons. It’s a decent enough system, made puzzling only when you try an option that won’t change until you stop all playback. Assuming you didn’t specify a length in advance, these are the pages where you discover how long your loop actually was, along with deciding its optimum level, panning and play modes. As before, reverse is an option and this is joined by double‑ or half‑speed modes, with the option to transpose the pitch tape‑style. Such delights are new in the MkII and not yet bomb‑proof — I experienced my only crash when experimenting in this area. Incidentally, the time‑stretch algorithm seems an improvement, although I admit to being rather fond of the shaky original. As is often the case, it’s still best not to stray too far from the recorded tempo, unless you enjoy the resulting warbles.

The Loop menu contains some items that apply globally, like the fade‑in and fade‑out times applicable when you start or stop a track. However, you must still return to the Track menu to enable this on a per‑track basis. Additionally, you need to hit Exit to leave some menus before others will open, which feels kinda clunky.

Having recorded several tracks, you can consolidate them by bouncing down. I’m happy to report that the destination track can be much longer than the source(s), incorporating mixing and effect tweaking on the fly. It’s ideal for capturing effected output and for freeing up tracks in general. You can save to a different patch location during playback and therefore build fairly complex structures as you go. Tracks playing when you switch patches will be activated when the newly selected memory kicks in.

Perhaps the neatest looping aid is the improved undo. Known as Mark Back, it can store a desired return point for every track. The idea is you develop a track until you’re happy, set a Mark Back point, add further overdubs and then toggle between the marked state or overdubbed state. Alternatively, you can return to the pre‑record state and head off in new directions. The practical results are to dramatically increase what each track is capable of. Mark Back could be a worthy candidate for foot pedal assignment, leaving both hands free for other things.

A total of 16 user Assignments are offered. The sources include the panel buttons, plus pedals or incoming MIDI CCs. Assignments can be a bit daunting to set up (and to remember), but the workflow rewards are worth the effort. Some user configuration is possible for the encoders, too: for instance, you can allocate duties such as memory selection, switching display modes, controlling the rhythm variation and level, and so on.

The RC‑505 MkII measures 420 x 234 x 67mm and weighs in at 1.8kg.The RC‑505 MkII measures 420 x 234 x 67mm and weighs in at 1.8kg.

RC Effects

Up to four effects can be applied to your inputs, and the results are recordable. A separate set of four effects may be applied to any (or all) of the tracks during playback, and you can store four banks of these (A‑D) for both input and track use. To switch between banks, hold down the Edit button, wait until it turns blue, then select an alternative using the (now also blue) FX buttons. I can’t stress how powerful this is, whilst simultaneously wishing the switching process was slightly faster and there was a bank copy facility.

Although there’s just one big knob for tweaking a pre‑selected parameter (usually effect amount), a ‘pass thru’ mode is offered, in which the knob only makes audible changes after passing the current value. Editing on the fly is pretty slick given there are four parameters on each page and, making use of the Assignment options, you can allocate any favourite parameter for remote control. Pushing and turning an encoder increases the amount of adjustment but, for some parameters (such as delay times that go up to 2000ms), it can still take quite a while to reach the value you want. When you’re pushing and turning a great deal, you realise the encoders have unpleasantly hard, sharp edges.

The list of effects is long and, as you’d expect from Roland/Boss, impressive and diverse. The 10‑second reverb is far more tailorable than before and the beat‑sync’ed delays are as sweet as ever. Familiar processors include filters, octave effects, slicers, phaser, flanger and chorus, but the real magic is in the more exotic entries, with names such as Twist, Rise, Electric and Robot. Electric performs bizarre shifting and formant operations, applying voice characteristics to any source, while Rise invokes a rising or falling resonant cascade, hinting at runaway delay feedback. They’re all so playable it feels unfair to single out just a few, although I’m rather partial to the preamps that supply everything from a subtle extra presence to full on gritty dirt.

Since the RC‑505 MkII is so well suited to vocal use, I should mention that its vocoder can respond to incoming MIDI notes and allows you to modulate existing tracks with your voice. There’s a harmony effect which can also follow MIDI notes or be locked to a specific key; and while I didn’t always find it predictable, it’s fair to say that neither are my own vocal skills.

Tucked away in the background is a step sequencer designed to automate a range of effect parameters. It’s a basic enough affair of up to 16 steps with no smoothing between them, but is nevertheless a useful tool for introducing movement and unexpected twists.

The effects act as inserts for all — or selected — tracks and some offer direct and effect levels as separate controls. So it’s entirely possible to create a chain in which activating one element kills the sound entirely, or which feeds only the effected sound onwards for further processing. Performing with the effects is a major part of the 505’s appeal.

I loved the original model and the RC‑505 MkII is larger, more powerful and addresses almost every shortcoming.


The RC‑505 MkII is even more of a pleasure to use than its predecessor. There are a raft of significant improvements but, for me, the longer sliders and track FX buttons proved an instant hit for live performance. The enhanced undo system makes each track go further than ever, and while I’d grown to accept the sound of the older machine, there’s no denying the MkII is cleaner. The effects are excellent, and with four banks ready to store favourite combinations, plus bounce‑down capability, there’s no excuse for producing shabby results direct from the hardware, although you can export to a DAW for further processing if you wish.

Not everything is ideal, though. For example, the handling of polymetric patterns is ripe for improvement and, at the very least, a bar counter should be added. And in a machine designed for real‑time performance, it’s odd that some functions need a stop/start to engage. Personally, I’d be tempted to replace those encoder caps with rounder ones, but, as you can probably tell, I’ve reached the nit‑picking stage.

Ultimately, I loved the original model and the RC‑505 MkII is larger, more powerful and addresses almost every shortcoming. With a humungous recording capacity, extended I/O and generous array of cool effects, the RC‑505 MkII raises the expectations of what a looper should be.  

MkII Will Tango

I must admit I never use the rhythm section of my RC‑505, but it’s undeniably convenient if you don’t have a drum machine around, or to the performer who values simplicity. You can route the rhythm’s output to headphones or one of the sub outputs, if necessary.

The factory drum patterns cover a fairly decent range, from foxtrot to punk, world to electro, pop to metal. Of the 200 available, I found the Guide grooves the most worthwhile. This is partly because they are the least complicated of all, but mostly because they feature non‑common time signatures, such as 6/8, 5/4 and 7/8 right through to 15/8, which caters for all but the wildest prog rock challenges.

There are 16 kits to choose from, including acoustic kits and Roland classic beatboxes. And if you aren’t satisfied with the factory content, you can import your own MIDI grooves via Boss’ Rhythm Converter software.


Neither the original RC‑505 or the MkII are typical loopers, so their feature sets are difficult to match exactly. However, another Boss product, the RC‑600, could be worth considering if you prefer a more traditional format. It’s basically the same engine but offers six stereo loops and a foot‑oriented workflow.


  • Large, friendly interface.
  • Comprehensive I/O, decent‑length sliders, cleaner sound and 13‑hour recording capacity.
  • Five stereo tracks with bounce‑down capability.
  • More and better effects, plus improved routing.


  • Polymetric recording could be better handled.
  • Lacks a bar counter.
  • Some options require a stop/start to activate.


The RC‑505 MkII is a superb companion for vocalists, synth players and tabletop performers of every persuasion. The original was no slouch but in this model, the sound is cleaner, the I/O more extensive, the sliders longer and the effects better. Your only difficulty might be filling that elephantine memory.


£549 including VAT.