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RSP Intelliverb VIrtual Room Processor

By putting quality before quantity, Rocktron have come up with a professional-quality digital reverb at a mid-market price.

You can't always take your recording setup to a concert hall - but maybe you can bring the concert hall to your setup. Derek Johnson reviews a reverb processor from RSP that lets you design your own acoustic environment.

When it comes to multi-effects units these days, a little money goes a long way — but no matter how impressive the effects sound in combination, there are still many occasions when what you need is a basic, but very high-quality reverb unit. This is particularly true when mixing vocals, which is why professional studios have dedicated reverb processors from the likes of Lexicon and Klark Teknik sitting alongside their multi-effects processors.

A couple of years ago, Sony recognised the need for a sensibly priced, dedicated reverb unit and produced the DPS-R7 which, although seemingly costly when compared to a typical multi-effects unit, is very competitive when viewed alongside the industry standard Lexicon units. RSP Technologies, a part of the Rocktron empire, have taken a similar approach with their Intelliverb. Being an American company, we might also expect the unit to have more of an American sound — technically competent though the Japanese undoubtedly are, even their most sophisticated digital reverb units have failed to fire the imagination in the same way as, say, the USA-built Lexicon.

Brief Specification

Nominal Input Range: +4 to -16dBu
Input Impedance 100Kohms
Dynamic Range 105dB (HUSH In) Peak signal A weighted noise floor, direct level = +6dB
THD + Noise .006% (1 kHz, -5dB input level)
Frequency Response 20Hz to 20kHz +0.1, -0.7dB

Like the Sony unit, the Intelliverb under review sports several multi-effects capabilities selected to complement the reverberation effects it can create. It can generate up to three effects at once, and though this might not seem like a lot when compared to a true multi-effects processor, it does stretch the capability of the unit far beyond that of conventional reverb.

Like many of today's digital processors and consumer CD players, the Intelliverb uses 16-bit, Delta-Sigma conversion technology with 64X oversampling. Three individual convertors are employed, while the internal processing is 24-bit, yielding a theoretical dynamic range of over 100dB. The audio bandwidth is 20Hz-20kHz, and though it can be argued that a lesser bandwidth is perfectly adequate for natural reverb simulations, a wide bandwidth undoubtedly helps create more transparent chorus and delay effects.

The main claim to fame of this unit is the Virtual Room (TM) algorithm which, as its name implies, allows you to enter the physical parameters of a real room and the unit will then simulate the acoustic environment for you. Room simulators have been around for a while, but this must be the first time one has been implemented so effectively in this price range. Running this algorithm requires a lot of fast memory chips which, apparently, partly accounts for the higher than average cost.

Aside from the Virtual Room, the effects algorithms can also handle pitch shifting, chorus, delay, ducking and a digital version of Hush Systems (another subdivision of Rocktron) single-ended noise reduction. This latter process treats the input to the Intelliverb, which means it has no adverse effect on the reverb decay characteristics, but helps clean up noise present on the console's auxiliary send mix buss. This is particularly important with larger consoles, as the amount of mix buss noise is directly related to the number of mixer channels. There have been many occasions when effects units have been blamed for being noisy when in fact the aux mix buss was the culprit all along.


Question: What's black, 19" wide, has large black knobs and a 16-character LED display? Answer: Just about every effects unit in the universe, including the Intelliverb.

If you hate buttons, then you'll like the Intelliverb: all editing is done through four of RSP's nifty knobs. These have a positive click for each movement you make, which is very reassuring. Actually, there are a few buttons, but they each have only one job to do. To the left of the 16-character LED display is the Preset knob used, surprisingly enough, for the selection of Presets; a Recall button to the left needs to be pushed to confirm a Preset selection, and the display flashes "Press Recall For" to remind you of this. The other button in this vicinity is labelled Config, and when this is pressed (and its attendant LED lit up), the display shows the current effects configuration (a list of effects and the order in which they appear) rather than the Preset name.

To the other side of the display are three more knobs, used for editing your own Presets: Parameter Adjust, Parameter Select and Function Select. There are also three more buttons, labelled Compare, for comparing an edited Preset with the original upon which it is based; Store, for storing a freshly edited Preset; and Bypass, for muting all effects. The remaining knobs are simple, smaller, input and output level controls (the input control has a range of -11dB to +10dB), with a five-LED input level meter, mix clip LED and output clip LED inputs and outputs are in stereo, with a mono option, and connections are on unbalanced mono jacks; the output can be switched, on the front panel, between -10dB and +4dB. There are two MIDI sockets — an In and an Out/Thru. The last connection is a four-pin power socket; the power comes externally, which is rather irritating, since that leaves you with a rather large, ungainly plastic box sitting in the middle of your floor.

As mentioned earlier in the review, Intelliverb contains six basic algorithms — called Configurations, according to the manual — which incorporate the effects chosen for the present Preset and the order in which they appear in the signal path. Each Configuration starts with a variety of Mixer parameters, which allow you to control most signal levels within the current Configuration, and stores them as part of the Preset. Next is the Hush noise reduction, followed by a number of effects. Since the Virtual Room effect is very complicated, it appears in a Configuration on its own, with various mixer, Hush, gate and ducker parameters. A simpler reverb is also available in some multi-effect Configurations; simplified reverb types include Plate, Room, Hall, Dual (a nifty effect that allows the left and right channels to be processed independently), and Stadium. (See the sidebar for a list of Configurations.) Note that, unlike a true multieffects unit, you can't create your own combinations of effects in the Intelliverb.

The delay section works differently for different Configurations; with the Hush, Delay, Ducker Configuration, the delay can be of three types — stereo, ping pong or two tap. The two tap delay has a maximum delay of 2500ms; ping pong and stereo have two parallel delays of 1250ms each. The rest of the delays on the unit have a maximum 740ms delay time. The Configurations featuring chorus/delay or pitch shift/delay pairings can be thought of as straight delays, since setting the LFO or pitch shift parameters to 0 means no chorus or pitch change, and up to eight separate delays of 740ms each.

A Ducker appears on all but two Configurations, and in its simplest use is to attenuate the level of the current effect while the source signal is present, returning it to its full level when the source signal has finished playing. This can result in a much less cluttered sound, and can be used in quite subtle or non-subtle ways, according to the user.

Pitch shifting is available in two configurations and can be used to add harmonies up to one octave higher and/or two octaves lower than the input signal; depending on the Configuration, two or four shifts at a time are possible, meaning that interesting harmonies can be added to the input signal if you like. Fine tuning parameters also allow these Configurations to be used for subtle detuning effects.


There are 256 Presets on board, and while all are overwriteable, Presets 128 to 254 are duplicates of the first 127. Good news on the MIDI front is that these 254 Presets can be easily mapped against the 128 program changes. Other MIDI capabilities, apart from System Exclusive dumping of the Intelliverb's memory, include being able to assign up to eight controllers to various parameters within Presets. This comprehensive facility allows, for example, any controller between 0 and 120 to be assigned to control reverb decay time, or various room size parameters. The assignment procedure is simple; just remember to hit Store when you're finished. One place the manual appears to let the user down is in not actually listing which parameters are available for MIDI control; that's because they're virtually all available, but only eight at a time.


Editing is simply a matter of turning the Function Select knob to the right until you see the overall function you'd like to edit; then you turn the Parameter select knob to find the parameter you'd like to alter, and finally, use the Parameter Adjust to change the value of that parameter. As soon as a value is altered from the current Preset, the red LED above the Store button goes on, which reminds that you have in fact changed a value; pressing Compare toggles between the previous Preset values and your edit. You can exit editing at any time by simply choosing a new Preset with the Preset knob, and, of course, hitting Recall.

An edited Preset can be given a name, although this is the least attractive part of using the knobs; it is necessary to scroll through the available character set, although this only includes capital letters, numbers and a few odd characters — no Japanese character set here!

Note that altering some parameters (particularly Virtual Room size and position parameters) while the Intelliverb is in use produces some rather unpleasant side-effects. The lesson is don't play any sustained chords while editing.

Whether RSP's method of editing suits you or not is down to your own prejudices; I find it quite friendly and fast. It doesn't feel as obtuse as some strictly knob-free parameter access I have known, and the knobs have a pleasingly positive feel about them. While it may seem irksome that the knobs have to be turned a lot to get to the high Preset numbers or big parameter values, in practice a quick turn or two can change values by large amounts, with a few clicks fine-tuning your desired result. The manual is quite helpful, although some explanations seem to be a little cryptic.

Sonic Seasoning

About half of the factory presets are made up out of the Hush-Virtual Room configuration; these include various plates, rooms, chambers, halls, arenas and stadia, with six or more varieties of each, numbered A0-A5. Preset titles named as such (Plate A0, Chamber A5 and so on) utilise the same room size specifications for each group, with A0 having minimal amounts of reverb decay, early level and reverb level. These parameters are gradually increased through the group. Presets ending with B3 or B4 and B5 utilise a different room specification than A0-A5, but the numbers 3, 4 and 5 indicate that the reverb decay, early level and reverb level parameters are the same as corresponding presets numbered A3, A4, and A5.

A particular favourite was Preset 57, Hall B5, which was superb for a heavily orchestrated piece I was working on: strings came to life, and a pizzicato bassline gained added depth rather than being swamped or boinging off into the distance; good sense of depth and space benefited the entire 'ensemble'. It would be difficult to pick out other Virtual Room Presets for comment, since all actually sound very good, but in different ways.

Sonically, it's hard to fault the Intelliverb; quite apart from the excellent Virtual Room, there are some good chorusing (eight-voice is very lush) and clean delay effects on board, and the Hush technology definitely keeps input noise at bay. I have to praise the pitch-shifting capabilities as well. There are sometimes noticeable delays, and extreme shifts are not always useful, but generally the effect is musically valid; some of the harmony type Presets (93 Minor 6, 106 +Min3-Min6, for example) are excellent and useful, with not so much of the 'lumpiness' of less expensive units. Downward shifts maintain good quality and, while not totally natural, add a warmth and character that is far from unpleasant. The pitch shift, in conjunction with large delays, results in some very odd Presets — 14 Escher, for example — that provide a lot of movement. The same is true of 13 Circles, which uses the eight-voice chorus to similar effect, without pitch shifting, doppler-type effects.

The Virtual Room itself is excellent: it is possible to design a room of any dimension up to 35m long by 25m wide by 20m high, with various reflective properties, and place your sound source reasonably accurately in that room. With the Reverb/EQ parameters ahead of the 'room', it is possible to simulate a huge tiled edifice or a carpeted, one metre square box, and listen to the results. It's a very flexible system indeed. The result on vocals especially is very natural; no matter what parameters are programmed in, the result is a real-sounding ambience that doesn't compromise the input signal in any way. Similarly, a finished track (instruments and vocals) can be treated with just one effect, again without compromise. The trick here, however, is finding the right room for the job.

Using the MIDI controllers with Virtual Room parameters opens up some interesting applications; if you were working with speech or sound effects, it would be possible to give the impression of someone walking, and talking, through the 'room', although in no way does the Intelliverb provide 3D or wraparound effects.


The only real disappointment build-wise, for me, was RSP's decision not to use an internal power supply. I realise that this may have made the package less compact, but what difference does this make once the unit is racked up? RSP do justify their move: an external PSU means less chance of hum and interference problems internally, although the PSU with my unit did have a problem or two on the dodgy wire front, occasionally resulting in rather a lot of ripple and crackling on the old monitors, not to mention failure to power up. As for the rest, I have always liked RSP/Rocktron's positively clicking knobs — they make for instinctive editing — although some may find that they protrude a little far from the front panel.

The Intelliverb is a sophisticated piece of hardware, and placing it in the market is a little tricky. RSP have gone down a similarly specialised route to Sony and rather than provide more and more simultaneous effects for less cash, have honed a handful of quality effects. Excellent multi-effects are possible, but it is the quality of the Virtual Room reverb algorithm which will sell the Intelliverb; indeed, can't help wondering whether RSP should even have detracted from the 'purity' of the idea of a reverb-only device by adding those extra effects — after all, if what you want is a multi-effects unit, you're unlikely to want the Intelliverb. In fact, using the Intelliverb as a multi-effects unit deprives the user of the Virtual Room, since its sheer processor and memory-hungry operation makes it unavailable in those Configurations. But for the studio user who needs something special in the reverb department, something with a bit of real programmability and a natural sound, the Intelliverb certainly fits the bill. The asking price may put some people off, but for others, reverb you can believe in is an often unobtainable goal, a goal which has just come a little closer.

RSP Intelliverb

  • Realistic, natural reverb, courtesy of Virtual Room algorithm.
  • Friendly operating system.

  • Weighty price.
  • External power supply.


Transatlantic exchange rates on electronic hardware have never been on the consumer's side, and this is a problem here; the result is that the Intelliverb is pretty pricey: at around £1175, it costs more than the quality Sony DPS-R7 reverb — though the Sony doesn't offer room simulation — and about the same as one of the best (for my money, anyway) multi-effects units on the market, Ensoniq's DP/4. Consequently, the Intelliverb is a bit of an oddball. In its favour are the implementation of the very good Hush noise reduction system, its high-quality sound, and the Virtual Room algorithm. If you want the Virtual Room algorithm (and there isn't really anywhere else you can get it at this price), coupled with classy, expensive-sounding and realistic reverb, then you need this unit. On the other hand, if your music isn't shouting out for a Virtual Room, then there are many worthy contenders for your money out there, and only personal sonic preference should make your buying decision.

Intelliverb Configurations

- A Hush; Virtual Room (Mixer, Hush, pre/early, reverb/EQ, room, position, gate, ducker).

- B Hush; 4-voice Chorus; Delay; Reverb (Mixer, Hush, voice/delay 1-4, ducker, reverb).

- C Hush; Delay; Ducker (Mixer, Hush, delay, ducker)

- D Hush; 8 Voice Chorus; Delay (Mixer, Hush, voice/delay 1-8).

- E Hush; 4-voice Pitch Shift; Delay (Mixer, Hush, Voice 1-4).

- F Hush; 2-voice Pitch Shift; Delay; Reverb (Mixer, Hush, voice/delay 1 & 2, delay 3, ducker, reverb).

Virtual Room Parameters

Predelay 0-370ms
Diffusion 0-9
Early reflection level up to 0dB
Reverb delay 0-200ms

Reverb level up to 0dB
Reverb decay 0-99
HF damp 1 0-99
HF damp 2 level LP to 0dB
HF damp 2 frequency 63Hz to 18kHz
HF roll off level LP to 0dB
HF roll-off frequency 63Hz to 18kHz
LF damp level HP to 0dB
LF damp frequency 63Hz to 18kHz
LF roll-off level HP to +6dB
LF roll-off frequency 63Hz to 18kHz

Length 1-35 metres
Width 1-25 metres
Height 1-20 metres
Front offset -10 to +10
Back offset -10 to +10
Left offset -10 to +10
Right offset -10 to +10
Ceiling offset -10 to +10
Front reflections 0 to 99
Back reflections 0 to 99
Left reflections 0 to 99
Right reflections 0 to 99
Ceiling reflections 0 to 99

Source F/B front 17m to back 17m
Source L/R left 12m to right 12m
Listen F/B front 17m to back 17m
Listen L/R left 12m to right 12m
Separation 0 to 25m

Further Information
RSP Intelliverb £1173.83 including VAT.

Washburn UK, (Contact Details).

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Soft Options

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Licensed To Thrill

Recording Musician - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Recording Musician - Nov 1992

Donated by: Mike Gorman, Colin Potter

Scanned by: Mike Gorman


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Studio FX > RSP Technologies > Intelliverb

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Digital FX

Review by Derek Johnson

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