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Boss RV70

Digital Stereo Reverb By Derek Johnson
Published January 1995

At a time when the prices of multi‑effects units are, on average, lower than they've ever been, Boss have launched a processor which does... reverb! Derek Johnson looks at the back‑to‑basics RV70.

In the same way that there is a vocal minority who bemoan the loss of "knobs and sliders" from synths, so there are those who look back fondly at the time when reverbs were reverbs and digital delays were digital delays, and they had the knobs to prove it. Roland — the company which begat Boss — may be adamant about never going back to the days of knob‑ridden synths with real (as opposed to sampled) oscillators, and they may never build another TR909, but when it comes to effects processing, they're clearly prepared to go (slightly) 'retro'.

This brings us to the new RV70 Digital Stereo Reverb from Boss. It is simply a reverb, and, yes, editing is undertaken by just four knobs. If you can tweak the knobs and press the 'Write' button, you can work the RV70, and this is as far as you ever need to go if you're a hands‑on, plug‑in‑and‑play type of person. This wouldn't be a Roland/Boss product if you couldn't go deeper, however, and it comes as no surprise that there are indeed hidden — MIDI — depths to the RV70. To be more specific, there are certain features of the RV70 that can only be accessed over MIDI and which make the RV70 a more sophisticated beast than it might at first appear to be — see the 'MIDI Matters' box elsewhere in this article for details.

Physical World

As you can no doubt see from the accompanying photo, the RV70 comes housed in a 1U rack and features a slightly jazzier colour scheme than the usual black. Apart from the four editing knobs, there are the expected input and output level controls, a Direct button (which selects either the effects‑only output or a mix of effects and input signal) and a central display which features a three‑character, seven‑segment LED display, peak LED and a trio of indicator LEDs which show you what effect type is currently selected. A pair of up/down buttons to the right of the display select Programs and parameters, and the MIDI and Write buttons are self‑explanatory. At the rear, there are stereo input and output jacks, +4/‑10dB level switch, MIDI sockets, a remote socket for remotely turning effects on or off, and the captive mains lead — no external power supply!


Inside this deceptively simple package is a 16‑bit DSP (44.1kHz sampling frequency) that utilises what Boss call AF — Adaptive Focus — to "significantly reduce quantisation noise by combining multiple samples to optimumly match signal levels through analog to digital conversion." That's a quote from the manual, but it does mean in practice that the RV70 is one of Boss' quietest units.

My mention of the three 'effect type' LEDs above might indicate a fairly simple machine internally; in fact, while there are three types of effect possible from the RV70, these broad definitions hide a total of 11 different algorithms. The three groups of effect types are:

  • Reverb, a sophisticated, dedicated effect.
  • Non‑linear, a filtered, delay‑based digital algorithm that can produce wicked, metallic sounds.
  • Reverb + Delay, which offers a choice of two parallel and serial reverb/delay combinations.

Without any recourse to MIDI, editing is simply a matter of selecting a program that features an algorithm you want to use or has a sound close to what you want, then twiddling the four knobs and, by pressing the Write button, saving the result when you're happy. The four knobs have different functions, depending upon which Preset and which algorithm you're editing. The parameters they control for each group of effect types are as follows:

  • Reverb: reverb time, pre‑delay, HF damping and density.
  • Non‑linear: non‑linear time, pre‑delay, filter and density.
  • Reverb + Delay: reverb time, pre‑delay, delay time and feedback.

Note that when you twiddle a knob, the number in the display starts to change; when you've finished, the display reverts to the current program number. The parameter values shown nearly always range from 0‑100, and don't necessarily bear any relationship to real‑world values, such as delay or decay times — you simply work by ear. Even if you want to produce timed delays, this is easy enough to do.


The sound quality of the RV70 is excellent, and having hands‑on access to your parameters makes coming up with sophisticated‑sounding treatments a doddle. Your average multi‑effects processor may offer more options, but they're not nearly as much fun, nor necessarily as immediate as the RV70.

I found that even when simply using the front‑panel knobs it was possible to come up with outrageous and interesting treatments. For example, when using a Reverb effect, setting the reverb time to 0, a high value on the pre‑delay, and a high density value produced a really fat pseudo‑delay effect. The HF damp knob is also remarkable: small adjustments really make dramatic differences, going from ultra‑sheen sparkly digital reverb right down to an absolutely dead room. And let's not forget the Non‑Linear algorithm: the clangorous, metallic treatments available here are worthy of processors with much higher price tags.

It's always a shame to have to dig up negative comments regarding a piece of hardware that I'm genuinely enthusiastic about — I felt the same way about Digitech's TSR12 a couple of issues ago — but some users may find the lack of a naming facility for patches a bit of a drag: that's one of the advantages of the LCD approach to operating systems. It's back to pencils and paper, I'm afraid. I could also bemoan the lack of a front‑panel effects bypass switch, but I won't.

I will mention the price, though. At £375, some may comment that the RV70 retails for the same as some multi‑effects processors. That's true, but even so, I find myself rushing to Boss's defence — this unit really does sound good and is so much fun to use. And I suppose musicians of restricted bank balances might appreciate being able to buy one high‑quality effect at a time, when finances allow, rather than having to stump up all the cash for an all‑in‑one unit. The move to specialised processors is, as far as I'm concerned, a good one — I still have a small collection of Boss micro‑rack units, which have an immediacy and a character I often find lacking in more up to date, better‑specified products. There's no doubt that all‑purpose multi‑effects units have a place, and are great value, but the prospect of being able to choose a reverb from one company, a flanger from another and a delay from yet another, based on each company's strong points, is an attractive one. The complete freedom to patch individual processors in any configuration is also highly desirable.

It would be nice to see more companies follow Boss down the specialisation path; financial considerations aside, I hope this is the start of a musician‑friendly trend.


  • 16‑bit linear, 128X oversampling ADC
  • 16‑bit linear, 8X oversampling DAC
  • 44.1kHz sampling frequency
  • 199 program memories
  • 11 algorithms
  • +4/‑10dB input level
  • Dynamic range: >90dB effect (120dB direct)

RV70 Algorithms

  • REVERB: Room 1‑3, Hall 1 & 2, Garage
  • REVERB + DELAY: Hall‑parallel, Room‑parallel, Room‑series, Hall‑series

MIDI Matters

The RV70 is a simple to use, good sounding little processor. But what if you enjoy playing with MIDI? The RV70 won't disappoint you. Underneath the foolproof exterior is a sophisticated MIDI‑equipped centre, with plenty of parameters to play with in real time. The relevant MIDI information is provided in a separate MIDI specification document — not provided with the review machine — and should allow the user to come up with profiles for use with the MIDI mixer page of the typical high‑end sequencing software package. The manual itself goes into some depth on how to use the RV70 with the new Roland MCR8 MIDI controller — see exclusive review elsewhere in this issue.

Being able to access certain parameters only over MIDI may be seen as a negative point, but it needn't be a problem: look at the MIDI access as something of a bonus to a very straightforward processor, a bonus which makes the RV70 attractive to a wider range of people. Just to give you a taster, here's a list of the parameters available over MIDI, which you can modify using the usual range of MIDI continuous controllers.

  • Algorithm selection (1‑11).
  • 3‑band EQ, with peaking or shelving low and high bands, and peak mid.
  • Parameters relating to the Reverb and Reverb+Delay‑based algorithms, as follows: room size, reverb time, density, pre‑delay, HF damp frequency and gain, LF damp frequency and gain, release density, early reflection level, reverb level, delay time and level (left, right and centre), delay feedback level, delay time scale.
  • Additional parameters for the Reverb+Delay algorithms: reverb level, delay time and level (left, right and centre), delay feedback level, and delay time scale.
  • High‑cut filter frequency.
  • Output level.
  • Parameters for the Non‑linear algorithm: Density, pre‑delay, four‑way envelope with time and level for each point, non‑linear filter, non‑linear filter type, delay feedback level, non‑linear time, high‑cut filter frequency, output level, non‑linear filter type and resonance.

This provides an impressive degree of editability by anyone's standards, and certainly extends the appeal of the RV70 towards the more demanding sound designer.


  • Very easy and immediate to use.
  • Powerful (if hidden) MIDI implementation.
  • Great sound.


  • Limited display.
  • No bypass switch on front panel.


The hands‑on approach, coupled with a sparkly, noise‑free sound, equals another winner from the Boss/Roland family of processors.