For most musicians, the name "Boss" will forever be associated with guitar pedals—and for good reason. Artists such as Kurt Cobain and Prince were well-known for their use of the legendary stompboxes, and they were considered to be so rugged and dependable that the old joke goes that in the event of a nuclear apocalypse, all that will be left once the smoke clears will be cockroaches, and (functioning) Boss pedals.

As foolhardy teenagers in a terrible punk band many moons ago, my friend and I decided to test out this theory by seeing just how much abuse an HM-2 pedal could take before it stopped working. This involved various crimes, including throwing it out of a third-storey window, running it over with a car, and crushing it underneath a 4x10 speaker cab. It survived the entire ordeal. I wish I knew where it had gone actually, because they are apparently worth a fair bit of cash now.

It might surprise you to discover that indestructible pedals aside, Boss has also been responsible for a number of other devices over the decades that have developed cult followings in their own right. For example, the SP-404 Mk2—well-loved and revered by modern lofi beatmakers—is just the latest in a series that began with the Boss SP-202. Similarly, the Boss DR-55 drum machine—whilst incredibly limited by today’s standards—has achieved iconic status, partly thanks to being used by artists such as the Cure and Soft Cell.

But did you know that, in the 1980s, Boss also offered a line of budget-friendly studio effect processors? Let's talk about the Boss Micro Rack series.

The Micro Rack Series

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One of the more intriguing offerings from Boss came in the form of a series of Micro Rack units. Released in the mid-'80s, these appeared at a time when home recording was becoming more of an accessible reality, but which still required the use of relatively bulky and expensive equipment. The Boss units were a line of audio processors designed to provide an alternative to the pricey rack-mount studio effects of the time from manufacturers like Lexicon and Eventide—and were not just more affordable, but also much more compact. They retained the standard 1U height for 19” rack compatibility, but were about half the width, providing much more flexibility for mobile rigs and DIY recording.

While perhaps best suited for home studio use, these units are also built like mini tanks—robust enough to take a beating as part of a live setup. One would expect nothing less from Boss, after all. In many ways, that reputation for reliability arguably contributes to their enduring popularity—as plenty of them are still going strong today with minimal maintenance—some forty-plus years since their release!

In keeping with their pedal-based heritage, all of the units are powered via individual "Boss style" 9V DC connections on the rear, though they handily can also be daisy-chained to reduce the number of individual wall sockets—and to keep things even tidier, there was also a dedicated multi-output power supply available in the same micro-rack-form as well, called the RPW-7. There are various ways to adapt and mount these units in standard rack cases, but Boss also produced a dedicated housing called the BMR-5, which is especially useful for desktop use, and also increasingly difficult to find.

The Units

The Micro Rack series was unfortunately relatively short-lived, but included a wide variety of different effects such as EQ, delay, reverb, and pitch-shifting—each with their individual idiosyncrasies. There is something especially appealing about dedicated devices focused on doing one job and doing it well, and the Boss units provided that in spades. With straightforward controls and a familiar interface, they provided an intuitive entry point to studio effects in comparison to the more complicated, menu-driven digital offerings that were gaining popularity at the time in the professional environment.

Some of the models available include:

• RCL-10 Compressor/Limiter: A stereo compressor, limiter, and expander with mic, line, and instrument inputs on the rear. You get dedicated controls on the front-panel over output level, threshold, ratio, attack and release - as well as a noise gate with controls for the threshold and decay.
• RCE-10 Chorus Ensemble: Classic Boss-style stereo chorus with controls over the modulation depth and rate as well as pre-delay time. In addition, there is a basic built in EQ, and a master effect level.
• RPH-10 Phaser: Who doesn’t love a phaser? Well, maybe quite a lot of folks, but in the 80s it was a must-have effect. This one comes with three separate modes, a feedback control, and a modulation section with three parameters (manual, rate, and depth) which lets you dial in everything from subtle movement to all-out psychedelic phase-shifting.
• RGE-10 Graphic Equalizer: Stereo 10-band EQ with 12dB boost/cut per band. For alternative equalization duties, there is also the RPQ-10 Preamp/Parametric EQ, with adjustable frequency, gain, and bandwidth controls.
• RRV-10 Reverb: A decidedly 80s style digital reverb with 9 different reverb types including plate, room, hall, and even a reversed multi-tap style delay. There is a built-in pre-EQ tone control, and two knobs to control the output level of the dry and effected signals.

While many of these units have been "discovered" and gone on to gain popularity with modern producers, two in particular have developed something of a cult status due to their unique features and capabilities. Specifically: the RPS-10 Digital Pitch Shifter and Delay, as well as the RSD-10 Digital Sampler and Delay. These allow for especially interesting and unusual sonic manipulation—something that I’ll come on to talk about a bit more shortly…

The Magic

The Boss Micro Rack units are sometimes described as effects pedals in rack form—and in some ways that is true. They featured many of the sonic characteristics that people expected from the company, and also included a "remote" input to allow you to toggle the effect on or off with an external footswitch. However, to solely consider them in this vein would be a mistake—for these wee beasties have a secret; one which for some time has been shared between producers in whispered tones—particularly those who partake in the endless pursuit of "character."

Many years before Eurorack’s dream of endless modulation was brought into being by Doepfer and went on to take over the world (as well as our wallets), some of these teeny Boss bad-boys had implemented several features to let you interface more widely with different bits of gear.

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• Modulation bus: Both the RPH-10 Phaser and the RBF-10 Flanger had dedicated modulation inputs on the rear—complete with a polarity switch to invert the sweep. This was intended to allow you to synchronise the modulation of two separate units together for stereo operation. This feature was also found on the RDD-10 Digital Delay.
• Keyboard input: As I noted earlier, the RPS-10 and RSD-10 are especially noteworthy. This is largely because of the inclusion of a dedicated "keyboard input" on the rear of the units. The purpose of this was to allow you to manually control elements such as the pitch-shifting effect by the use of an external keyboard. This doesn't use MIDI—it pitch-tracks audio input in order to determine the pitch shift amount or delay time, respectively.
• Hold input: The Boss RPS-10 has a dedicated "hold" input on the rear. This allows you to "freeze" or sustain the effect at any given time.

These features were useful on their own, but folks have to come to discover that the real magic comes from using them in non-standard ways—usually involving feeding in more complex signals into the modulation or keyboard inputs. For example, rather than simply playing a continuous, single note to control the pitch shifting of the RPS-10, you could apply a pitch bend to the signal, or…send in an arpeggiation. Combined with the feedback knob set to "high," this can very quickly get into weird and wonderful territories. Think of it kind of like an EarthQuaker Devices Rainbow Machine on steroids.

[Above: an incredible video demonstrating the positively unhinged possibilities of the RPS-10.]

One of my personal favorite techniques is to use the RPS-10 with keyboard input to glitch up drums. You start by running a drum loop into the unit, then apply a non-continuous or broken tone to the keyboard input. This results in a warped, sort-of-stretched rhythm which shifts and lurches about in a manner that even the Twin would be proud of.

The Boss manuals recommend using basic waveforms for the most predictable results, but there is nothing stopping you from feeding all sorts of audio into these ports. What happens if you play a drum loop into the keyboard input? Or apply an audio rate signal into the RPH-10 modulation synch input? You are only really limited by your imagination. Creative combinations of the keyboard and hold input through the use of sequences and gates are especially fun to play around with.

It’s hard to say whether the flexibility of these modulation ports was intentional on the part of Boss or not, but either way, the possibilities for sonic exploration and experimentation are vast, and rival some of the most obscure and expensive bits of modular gear that I have in my studio. Of course…you don’t need to keep these separate, as you can always combine these rack units with your other esoteric gear for even more rabbit holes to fall down. Why not feed in the output of a modulated complex oscillator from your Eurorack system into the keyboard input? Even just writing this makes me want to go and dig out the RPS-10 to see what kind of textures I can come up with. Whilst some kind of sonic madness is inevitable in this arena, it isn’t all chaos, and it is perhaps surprisingly very easy to get eminently musical results.

Conclusion

While the half-rack concept never really caught on in terms of mainstream popularity, the original Boss Micro Rack units themselves have increasingly garnered interest from home producers that are looking for the kind of hands-on experience that only hardware processors can provide, as well as their creative modulation possibilities.

The dependability and versatility associated by the "Boss" name provides some assurance about longevity given their vintage, though let’s be honest here…they also just look cool. The colourful knobs offset against the sleek grey and blue in that compact form factor is almost enough on its own to warrant a purchase…I personally have both an RPS-10 and an RSD-10, and they are two bits of gear that I will never sell. Their unpredictability provides endless opportunities to sample and chop up for use in tracks, and they are a lot of fun to use. So much fun in fact, that I was wary of even writing this article, lest I contribute to the steady rise in price of these beauties on the secondhand market.

However…the secret has unfortunately by now firmly gotten out, so if you find yourselves intrigued by these micro-boxes, it might be a smart idea to get ahold of one sooner rather than later.