Is there room in the market for yet another digital reverb? MARK BADGER checks out Yamaha's upmarket version of the REV7...

The latest reverb device from Yamaha, the REV5, lies squarely on the converging paths of economy and sophistication, the previous stations on Yamaha's road being the REV1 (the 'pro' model), the REV7 (the 'home studio' model), and that little usurper, the SPX90 MkI and MkII (the 4-track/multi-effects 'wonder' which ate up the REV7 market). This year, we also have the REX50. At the heart of these machines lie a few custom DSP chips (digital signal processors) which have been developed over many years' product releases, a process which started with that still useful machine, the R1000. All these units (except the R1000) share the same sort of programming approach and can be denominated in price by the bandwidth of the unit, the sophistication of its user interface, and the year of release! The onward rush of musical microprocessing has meant that with each successive year, the standards by which we judge these machines are met more easily, and must therefore be subsequently revised.

We must have now neared the apex of this development, for the REV5 has 16-bit ADCs and DACs which sample at 44.1 kHz (CD quality), providing an effect bandwidth of up to 20kHz and a dynamic range on the effects channels of between 78 and 84dB (this is perhaps the most crucial of these specifications, as it tells you where the noise floor lies). These specifications, and the clarity of the sound quality achieved, make the REV5 something of a 'thru box'. It can be difficult to tell whether a given effect is actually happening, the noise by which I traditionally recognise that an effect is working being entirely absent, making the reverberation all the more believable.

As you'd expect for a machine costing more than £1000, the REV5 has a stereo signal path, at least in terms of the direct 'through' signal. However, the effects channel uses a 'mono' analogue-to-digital convertor (ADC), deriving the signal from the sum of the stereo inputs, and then outputs the results of its machinations via two separate processors into a stereo output. This means that, unlike certain other effects boxes on the market, it cannot treat the two stereo channels independently, with a reverb program on one and a delay on the other, say.

However, the REV5 is capable of producing two effects simultaneously, as we shall see.

FEATURES

The REV5 has 39 ROM (preset) memories, each of which configure the internal DSP chip to provide a different type of effect. These range from standard reverberation (large and small halls, for instance), to acoustic manipulations which defy description, taking in delay, echo, flanging, chorusing, pitch-shifting, phasing, tremolo, and others (!) on the way. 60 'user memories' then provide space where you can store, and name, your modified versions of the presets. In addition to an average of about 20 parameters per effect, each memory location also controls an excellent 3-band, fully parametric, EQ which acts on the sound in the digital domain, and which supplements the analogue, 3-band, semi-parametric, EQ on the input (placed before the ADC in terms of signal path).

All this takes the physical form of a black, 2U high, rack-mount box which looks almost identical to the REV7. The only minor differences are the colour of the 2 x 16 character LCD (now backlit in yellow) and the names, and colours, of some of the 39 buttons which provide the 'human interface'. Though the two units share the same box, and at first sight many of the same programs and parameters, when they are set side-by-side the differences are quickly apparent (at least if you look inside the box).

Connections are made via electronically balanced XLR or stereo jack plugs on the back panel. Here, there are switches to adjust the input sensitivity and output level of these connections to +4dBv or -20dBm, enabling you to easily interface it with both 'pro' and 'home' recording equipment.

The multitude of buttons has meant that Yamaha have been able to dedicate groups of them to particular tasks. Thus there are eight buttons dedicated to calling up particular memories, (seven ROM and seven RAM), six buttons dedicated to manipulating the parameters of those memories, and a full numeric keypad for entering parameter values directly, which still leaves ten buttons for utility tasks. These controls are all grouped on the right-hand side of the fascia.

The controls for the analogue EQ, type and level of input (mono or stereo), and power are lined up below the display.

The large variety of dedicated buttons, their easily associated LEDs, the backlit display, and the large LED memory location display, contrive to make the REV5 a very easy device to manipulate.

HALLS OF RESIDENCE

As I briefly mentioned, the REV5 comes with two standard room emulations: a Large Hall and a Small Hall. In addition to these reverb types there are also programs which provide emulations of two different plate reverbs (Vocal and Percussion), a spring reverb, a natural echo chamber, and then two types of reverb which Yamaha have labelled as 'Strings' and 'Snare'. All these programs share the same parameters, yet seem to use different algorithms of those parameters. For instance, you don't get quite the same sound effect if you adjust all 22 parameters of a Small Hall and a Vocal Plate similarly. The Vocal Plate has a particular way of modulating the upper harmonics of the sound as the reverberation fades, whereas the Small Hall seems to generate less modulation while sustaining a lower harmonic.

Whatever the subtle differences between the preset 'source' programs (the ROM contents you use as the basis for your own programs), it is the adjustment of the various parameters which has the greatest effect (!). Some of these are adjustable for any of the programs, others only appear in conjunction with particular types of effect. The common parameters are the setting of the programmable EQ, the time before the onset of the effect, and those parameters which control the appearance of the sound reflections in the stereo field (with separate controls for left/centre/right levels and delays). You can also programme the mix between effect and direct channels (this is in addition to a small dial on the fascia which does this job in the analogue domain), programme the output level of the effects channel, and invert the phase of the right channel with respect to the left (good for enhancing flange effects). These are all 'acoustic utilities', that is they are extremely useful for getting the most out of a given effect but don't really change the nature of the final product, and are distinct from the utilities which Yamaha have devoted a front panel button to (and which I'll discuss later).

The appropriately labelled 'Parameter' button and the more cryptically labelled 'Int Param' button, change their nature according to the preset program you've chosen. Repeatedly pressing these buttons calls up a variety of parameters on the LCD, depending on the type of program you are using. So, for the reverb-type programs, the Parameter button will reveal: the Reverb Time, controlling the duration of the effect (0.3-99.0 seconds); the High Frequency Ratio and the Low Frequency Ratio, which control the harmonic content of the reverberation (High 0.1-1.0, Low 0.1-2.4); and the Diffusion, which affects the 'brightness' of the effect (0-10).

Pressing the 'Int Param' button scrolls you through parameters which control the balance of reverb and reflection, the density of those reflections, a low pass filter, the (are you ready for this! ?) Space Modulation Control (which Yamaha declare controls the interference between reflections, and which I think must win the 'Best Parameter of '87 Award' if only because of its title), and a gate level control which adjusts the threshold setting of the REV5's internal noise gate.

In addition to this already extensive list of parameters, you will also discover a hitherto unmentioned facility of the REV5 - it produces two reverberations at once! The second is produced as a function of the first, that is the parameters are ratios of the primary reverb parameters. You can adjust the duration of the secondary reverb to be anywhere between one tenth and ten times the length of the primary (enabling reverb times in excess of 15 minutes!), and its level to be up to 100% of the primary. The delay which occurs before this secondary reverberation is produced is controlled separately and can be up to 500 milliseconds.

There is one other reverb program - Reverb & Gate. On this setting, the parameters are extended to include controls for the level, delay, hold, and release functions of the REV5's internal noise gate. I used this program to create the most monstrous snare sound this part of Britain has ever witnessed. I can only suggest that you arrange a demo in conjunction with an S900, TR909, TR626 (reviewed elsewhere in this issue), a pair of UREI4511 monitors powered by two Rauch DVT50s, virtually any nice mixing desk, and a Yamaha REV5 of course! I liken the effect to the sound you must hear standing at the wrong end of the firing squad when the time finally comes - something infinitely piercing with a terminally abrupt finish!

Somewhere amidst the REV5's range of parameters lie all the rooms you've ever entered, and many you will never see (only hear!). This is the result of two factors, one being the really excellent sound quality, and the other being the fact that many of the parameters stretch beyond the limits of emulating real spaces. You will never find a space which offers 15 minutes of natural reverberation for instance, unless perhaps you are climbing mountains (even then the clamping factor of such environments imposes distinct restrictions on the nature of such reverberations and the sounds required to invoke them; thunderclaps, earthquakes, landslides, bombs, etc).

The flip-side to this coin is that you will never fit a full 'concert/all the trappings of a great endorsement deal' drum kit into a box 50x50x50mm. The magic of the REV5 lies in the way 15 minutes of reverb becomes a virtually infinite hold on any sound you play into it. These are environments which could not really be reached on the earlier REV7, because such settings introduced too much tell-tale quantisation noise (plus the fact that the maximum reverb time of the REV7 was 10 seconds). This greater ease at extremes has benefits at more reasonable settings too, in that the REV5's reverberation is very rich and thick, much better than the somewhat 'dry' REV7. It's a bit like the difference between a good tea-bag and the real thing: if you are in a hurry you probably wouldn't notice, but if you stop and partake you soon become aware of the enhanced flavour of a superior brew.

BEYOND REVERB

The REV5's programs include many other effects, some only vaguely related to the creation of ambience. Perhaps they are the ingredients which Yamaha have found are needed to create their impression of spatial synthesis. Given the quality of the reverb, these other options present you with an expensive dilemma - can you afford two REV5's?! While some of these other programs require only a brief mention, as their effects will be familiar to virtually anyone who has listened to a record in the past ten years, others produce effects which require a new language, new definitions appropriate to the sort of 'digital distortions' which can be attained.

The 'common' presets are those which produce a delay (up to 2.9 seconds with independently programmable left/right channels and feedback levels), a stereo echo (with delay times of up to 1.4 seconds, again with independently programmable left/right for time and feedback level), and the various modulation-type programs. These are mostly excellent imitations of classic guitar and keyboard effects and include two types of Chorus, Stereo and Reverb Flange, Stereo Phasing, Tremolo, and finally a type of modulation effect which Yamaha have resorted to labelling 'Symphonic' (for examples of any of these effects have a listen to their greatest exponent, Jimi Hendrix, on the milestone Are You Experienced album).

Of all these programs it is the Reverb Flange which I find myself most enjoying, especially when used in conjunction with a distortion pedal - but they are all of excellent, transparent quality. It is only when the parameter settings are taken to extremes that the effects become obvious and intrusive, on milder settings each program would enhance virtually any recording, sweetening the bitterest mix.

All these modulation-type programs share virtually identical parameters: modulation frequency, depth, delay and feedback gain (for the flanging programs), low pass filter frequency, and internal noise gate threshold. These are all accessed via the 'Parameter' and 'Int Param' buttons, which become reconfigured according to the preset you are examining.

In addition to these 'classic' effects, there are three types of Pitch Shift program with similar parameters, all of which configure the REV5 to act as a sort of real-time sampler, transposing pitches as they occur. The differences lie in the way in which two of the programs produce two distinct shifts in pitch (one works in mono, the other in stereo) and thus have a second set of the appropriate parameters. These include: degree of pitch transposition (a value which can be input from any MIDI keyboard), fine tuning, delay time, low pass filter frequency, and noise gate level. With shifts of up to an octave in either direction and delays of up to 400 milliseconds available, these programs can provide an excellent shortcut to some really nice harmonies.

The last of what I must resort to calling the 'normal' programs is Pan, which, as you might expect, sweeps a sound across the stereo field. The controlling parameters here include: speed (0.1-40Hz), direction (left-right, right-left, or middle-out), depth (0-100%), low pass filter frequency, and noise gate level. Once again the quality of the effect and its potential applications merely serve to spur a desire for a second REV5 to perform this new task, but luckily this is one of the jobs which can be performed in conjunction with a reverb-type program.

COMBINED EFFECTS

In all, there are nine 'dual function' preset programs on the REV5 which simultaneously combine the actions of two effects in conjunction with the internal noise gate. The effects are produced in differing orders on each program and usually include one reverb setting. The parameters of these programs include all those to be found in their constituent parts as well as those which control the actions of the gate, the parameters for which I've already mentioned. However, there is an extra gate parameter available for the combined programs - a MIDI note-event trigger which invokes the gate whenever the REV5 receives a Note On command (more about MIDI later). There is, unfortunately, no parameter controlling which note(s) the gate will respond to.

The actual combinations (in strict order of appearance) are: Echo-Reverb-Gate, Chorus-Reverb-Gate, Symphonic-Reverb-Gate, Pitch Shift-Reverb-Gate, Reverb-Symphonic-Gate, Reverb-Pan-Gate, Reverb-Pitch Shift-Gate, Early Reflection with Reverb-Gate, Plate with Hall-Gate. These programs provide an extremely sophisticated 'springboard' to the wilder, untamed, spaces within the REV5. In fact, during one experimental session, I managed to create some sort of intense digital oscillation, which rose up into my stereo field with a roar like a thousand massed Orcs - I was in an overload situation caused by setting one parameter fully positive and another fully negative, then adjusting the reverb time. I was forced to abort my exploration by switching the whole unit off, drastically cutting levels, and then cautiously examining which parameters I'd altered to create such a monster. This caution aside, these programs provide the greatest degree of ambience alteration available on the unit, the only criticism I can offer about these presets is that they are just that, preset. You cannot change the types of effect that they combine, though you can, of course, alter any of the existing programs' parameters and then store your customised version in one of the 60 user memories.

Those of you who are still awake and reading carefully will have noticed that one of the combined programs uses an, as yet, unmentioned preset - an Early Reflection program, of which there are eight. I've left my description of these until last because they present the least documented of the effects available on the REV5, in terms of historical precedence. They are, to my mind, the most interesting of the available programs, on a purely acoustic level, and are also extremely useful for imitating the sound of a miked-up speaker when recording with direct-injected instruments.

Once again, all the parameters for these presets are similar, it is the algorithms that the parameters control which are different for each program type. These are labelled as: Early Reflections 1, Early Reflections 2, Electric Bass 1, Electric Bass 2, Kick, Reverse Gate, Rehearsal Room, and Live Reference. These effects produce signals which contain only the direct, 'dry' reflections of a sound, not the 'wet' reverberation between them. This option being yet another benefit of the REV5's programmable DSP chips. The sound itself is a little tricky to describe, something like an echo set to extremely short delay times with time-variable regeneration levels.

The actual patterns to which these reflections conform relate to the type of preset effect which uses them. Thus the Mode parameters are labelled: Small Hall, Large Hall, Random, Reverse, Plate, Spring, Pan-A and Pan-B. Adjusting this parameter accordingly causes the reflections algorithm to produce effects which mimic the way in which sound waves behave after their first 'bounce'. These formats are also controlled by a group of other parameters: Liveness (the way the reflections fade overtime); Room Size (the time between individual reflections); Diffusion (which alters the 'clarity' of the reflections); Number Of Reflections (1-34); Density (providing two rates for the time between reflections for four of the programs); Space Modulation (putting in a brief appearance on the same four programs); Feedback Delay, Gain, and High Frequency Ratio (acting on the regeneration rate of the reflections themselves); a Low Pass Filter (to control the otherwise intrusive high frequency content when using regeneration effects); and finally a Noise Gate.

As you might imagine from the sheer number of parameters, these programs are capable of generating some extremely interesting acoustic effects, the Electric Bass presets transforming pretty average DI'd basses into mighty rhythm sticks played on pukka bass amplification, for instance. On the outer edges of the various parameter settings you encounter types of effect as yet unused, ripe for the pick of your imagination. Like ordinary sound synthesis, the results obtained are directly related to the creativity applied.

It's nice to be able to turn to a 'Utilities' section on a reverb unit, usually an area of programming reserved for samplers and synthesizers. Yamaha have addressed many of the criticisms levelled at the REV7 here, in that you can now name your own programs, set up four tables to map the REV5 program numbers to MIDI program changes, send bulk data dumps via MIDI on a specified channel (entire memory, single memory, program change table), and set the range of the footswitch memory 're-caller' (a handy feature for performance work). There's also a remote control device, but this doesn't allow you to change parameters, only recall memories. Pretty limited for today's market.

This has been a lengthy review, full of praise for what I think is basically an excellent machine. That said, I feel that outlining a couple of disappointments I felt when looking at what the REV5 has to offer will serve to balance all my superlatives. I've only got a few gripes: the lack of MIDI control for real-time parameter manipulation; the way in which the effects change when a new memory is called up; and the fact that there is no facility for copying all the parameters which are static from one memory to another in the Utilities section.

Considering it was Yamaha who earlier this year introduced the world's first digital mixing desk to offer total automation via MIDI, I would have thought that on the REV5 there would be at least two parameters which could be assigned to follow MIDI controller values (the DMP7 mixer has 2081). The problem with changing memories and effects is the momentary lack of them as the REV5 internally re-configures itself to produce the new effect. This creates a sudden rush into the foreground of all the sounds which are being played through the unit and can be very unsettling.

VERDICT

These minor quibbles aside, the Yamaha REV5 is certainly capable of giving some powerful effects, with very few limitations in how these effects are applied. When considering the quality of such devices we arrive at an interesting paradox inherent with any effects machine. They are all signal 'distorters' - they accept a sound at their input and then distort it according to a variety of parameters. The paradox lies in the way in which we find this distortion acceptable, or not, and the fact that as the quality of the effect and its distortion improve, we find it harder and harder to recognise its existence at all.

I found that the REV5 is not only acceptable, it's downright attractive. I suggest you look it over, if possible in the privacy of your own studio as there are too many variations of ambience to cover them adequately in your average half-hour demo at your busy local audio dealer (I always hire an example of a unit and try it at home before parting with any cash). I cut my teeth on guitar heroism and still feel there is no substitute for the gnashing jaws of screaming valves, yet for virtually any other effect I'd be very happy to find that I had a REV5 to work with. It is a tool which is very worthy of your consideration.

Price £1179 inc VAT.

Contact Yamaha-Kemble, (Contact Details).