Roll Music RMS755

Super Stereo Compressor

Roll Music RMS755 Super Stereo Compressor

Review by George Shilling

Minneapolis-based Roll Music… (which is a different company from Rolls Corp in Utah, here ‘Roll’ is derived from the difference between ‘Rock’ and ‘Rock and Roll’ music) …claim that the RMS755 is designed to squeeze life into your mix, not out of it.

The design takes a straightforward approach; it’s a fairly compact unit with a modest feature set, the emphasis being centred on audio quality, allowing a lower retail price compared with other specialist ‘boutique’ analogue units; commendably the UK price is a lower number of pounds than the US dollar price. The brains behind the design belong to recording studio tinkerer Justin Ulysses Morse, a name that conjures an imaginary figure, but it seems he is a real person!

My first impression of the unit’s styling is that it is something of a mixture of old and new, and that also neatly sums up the philosophy. The front panel is etched with smart labelling and legending, (though not always legible, depending on ambient lighting; at least it won’t rub off). The stylish matt grey knobs look like Manley refugees, whilst the sideways curved-front meter certainly harks back to the 60s. Build seems solid, the side-vented steel case is small and shallow – only about 13.5cm or 5½ inches deep, but the unit still feels quite weighty. Around the back, things are conventional; IEC mains socket with fuseholder (voltage selection requiring lid removal), and Neutrik XLR sockets for inputs and outputs, with clear printed legending - easier to read than the front panel etching. On the front, the power switch is different from the website illustration, where it appears green neon; the review model’s is a conventional black with white I - 0 legended rocker, but in compensation… [Reviewer adopts Prince-style vocals…] “Wow!” The gorgeous retro-style meter glows purple from its backlight! Gorgeous! Hang on a minute, wasn’t that little purple genius fellah also from Minneapolis? Must be something in the water…

The Super Stereo is designed primarily as a mix buss compressor – Morse set to work on it when the original commissioning customer of the (now well established) Folcrom summing mixer requested a mix compressor design. When so many mix engineers are summing ‘outside the box’, slapping on an analogue mix compressor is an opportunity not to be missed. It seems the customer wanted something of the SSL buss mixer cohesion, without the clichéd gluey sound of that particular design, and upon closer inspection, the controls are broadly similar, and the unit apparently uses the same VCA.

Threshold, Attack and Release are switched knobs, whilst Threshold and make-up Gain are continuous pots, these both feel loose and undamped; there’s a little play, but nothing to worry about.

The Ratio selector features four settings: 1.5:1, 2:1, 4:1 and 10:1, and these adequately cover all eventualities. Interestingly, changing this setting automatically changes the Threshold, so comparing Ratios is more meaningful as the total gain reduction remains roughly similar. Hence the uncalibrated Threshold knob. The Gain make-up has an indicated zero position, and ranges usefully from -14dB to +20dB. Attack features 10 positions from a super-fast 0.05mS to a leisurely 50mS, this allows for a wide tonal variation, and this is where the unit demonstrates its flexibility. Release similarly features 10 settings from 0.1 to 2Sec, fast settings sound really exciting, whilst the slower settings can hide the effects of compression to some degree. In addition to the fixed Release times, there is a slightly misleadingly-named mode with a pushbutton. The legend says “Dual”, and I assumed this meant dual channel as opposed to stereo-linked, but that is not the case. It means dual-release, and is similar in some respects to the workings of an LA-2A. It’s a kind of auto-release mode, where fast transients release more quickly than sustained high level compression. But here, the mode is not entirely independent of the Release setting, so a great degree of variance is possible; Morse implies that he didn’t want to insult audio professionals with a completely automatic setting, and the resulting control therefore results in 20 different possible Release settings.

One particularly notable feature is the sidechain high-pass filter. Pre-set at 150Hz, this siphons off the low frequencies from the compression control circuitry, preventing pumping of the overall mix level due to prominent bass drums and suchlike. I love this feature, it allows greater overall compression without things making things sound daft. A similar function appears on the more expensive and sophisticated API 2500, and even forgotten cheapie the MindPrint T-Comp – but on all these devices this feature is a winner. It sounds absolutely cooking on the Roll.

Although the design is loosely based on the SSL, with all the additional work that Morse has put into designing the side-chain circuitry, this sounds nothing like other SSL derivatives, which seem rather unsubtle in comparison. The refined yet powerful Roll has a more open sound, it’s a little richer, less rubbery and certainly more exciting. Think Drawmer 1968 (Mercenary) or even API 2500. The top and middle jumps out, and - particularly in Dual mode - the low-end is solid. The claimed figures boast terrific sonic performance, with a fantastic frequency response of 2Hz to 150kHz, this due to the short signal path, which Morse describes as ‘benign’. But that suggests ‘unexciting’, so let’s say ‘neutral’ instead. In a short-term review situation, one tends to transplant the RMS755 across existing mixes, and this yields excellent results – the flexibility of settings means you’ll easily make it work. But the real joy is building a mix into the compressor, tweaking it as the mix takes shape.

The Super Stereo can be refined or exciting, or both. But with the Filter and Dual buttons pressed, it becomes truly Super-Duper, adding a refreshing glow to any mix. The balance of features vs. price is spot-on, and the RMS755 gives the professional mixer everything one needs in a great mix buss compressor.


Meaty, juicy compression; Sidechain high-pass filter; Adjustable program-dependent Release time mode; Hard-wire bypass; Fabulous meter backlight!



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Reproduced with kind permission from George Shilling. Copyright George Shilling.