After the long wait, H&SR finally gets its collective hands on Yamaha's hottest new property. Could this be the most sophisticated affordable digital reverb yet?

Yamaha certainly seem keen to maintain a high profile in the music world, and with products like this and their range of FM synths, they can't fail but to do just that. The REV7 really goes for the jugular of any competition, and only Roland have brought out a comparable product in the same price range. Both have their particular strengths and weaknesses so I won't presume to tell you which one is the better of the two as in the final analysis; it relies very much on personal taste and the use to which the product will be put.

The REV7 is, as you may already realise, equipped with MIDI control and sports 30 preset effects as well as giving you the option of creating and storing another 60 of your own effects in its non-volatile memory. As if this weren't enough, a remote control unit is included in the price and, if you don't want a conventional reverb effect at any time, the REV7 doubles as a stereo digital delay which can generate up to one second of delay per channel at full bandwidth (around 12 kHz). On board modulation facilities mean that you can also produce flange, chorus and vibrato effects, again all in stereo, and there are programs for non-linear and gated reverb effects. There are too many facilities and details to cover in a brief introduction so on with the nitty gritty.

Appearances

We are told that even the most practically minded studio engineers appreciate good cosmetic design when they see it and clients certainly do, so with this in mind, the REV7 is off to a good start. A slim 2U deep, the packaging exudes style with its all black and gold livery and LCD display, and the key-pad controls have that reassuring expensive feel that instantly inspires confidence. You can see from the photograph what it looks like so I'll save the description of the controls until we come to use them. The rear panel offers a choice of stereo balanced inputs and outputs on stereo jacks or XLRs and these operate at the professional standard level of +4dBm. Additionally there are MIDI In and Thu DIN connectors, and an 8-pin DIN socket for the remote control about which we'll hear more later. The mains lead is captive.

Equalisation

The spectral content of the reverb sound can be modified to a large extent by virtue of the fact that it's possible to alter the high and low frequency decay times independently, and these parameters are programmable. Further control however, is made possible by the inclusion of a 3-band sweep equaliser, but the settings of this cannot be stored in memory. The only other controls which cannot be programmed are the input gain control and the effect balance control, but as the input gain only needs to be set up once at the start of a mix, this is no problem. The lack of a programmable balance control may however be an inconvenience in a live, MIDI controlled situation. Monitoring of the input level is performed by an eight section LED ladder meter which handles the task more than adequately.

Recipe For Success

Before going further, it's interesting to look at the ingredients which go to make up a reverb sound and to examine the degree of control that may be exercised over them in the REV7.

Reverberation is generally characterised by its decay time, which is the time taken for the reverb to die away to a level 60dB below that at which it started (though for all practical purposes, it may be considered as the time taken for the reverb to decay to the point where it can no longer be heard). In the case of the REV7, this may be varied up to a maximum of ten seconds and, though this is shorter than the figures offered by Roland, it is still more than long enough for any normal application.

Regular H&SR readers will know about the importance of Pre-Delay in creating more natural effects, and the range offered here is from 0.1 to 100mS, again a sensible choice. In addition to the Pre-Delay, there is an Initial Reflection parameter and this is included because in large halls, it's not uncommon for a single repeat to occur just before the onset of the main body of reverberation. On the REV7, this takes the form of a single repeat positioned dead centre in the stereo image, and this is variable in amplitude and timing, the delay range being the same as for the Pre-Delay: at maximum, the first reflection may be made the same level as the original sound. The key controlling this parameter is a dual function type and subsequent operations switch between the Amplitude and Delay Time setting modes.

Previously mentioned was the fact that the high and low frequency decay times can be set independently and this is done by multiplying the mid-band decay time by a number, 0.1 to 2.0 for the Hi, and 0.1 to 2.4 for the Lo frequency range. This is a very necessary facility, as it simulates the way in which the walls of a real acoustic environment absorb different parts of the audio spectrum with different degrees of efficiency.

This brings us neatly onto Diffusion which concerns the way in which the shape of a room and the fittings within it affect the rate at which the sound reflection density builds up. Generally the diffusion will be less in a parallel sided room than in an irregularly shaped one. Diffusion may be varied through the range 0 to 10 where 0 represents the least diffuse sound.

Reflections

Impressive though this list of variables may be, there's still a lot more to simulating a given environment than shuffling these figures, and one of the most significant periods in the development of a reverberant decay is the very beginning when the brain can still pick out and analyse individual reflections before their density builds up. The REV7 contains in its internal operating program, six different patterns of initial reflections which characterise rooms, halls, plates and springs. Additionally there is a random pattern which is not intended to simulate any known natural environment and a reverse effect where the reflections actually increase in amplitude after their initiation. So far so good, but there's even more to come.

In a real room, the rate at which the initial reflections die away is determined by the way in which the walls absorb or reflect sound and this is simulated by using the Liveness function, variable from 0 to 10. The spacing between these early reflections is determined largely by the room size: in a large room the reflections will be more widely spaced than in a small one. To simulate that effect we have the Room Size control which may be varied from 0.1 to 10, roughly corresponding to effects ranging from from the inside of a catfood tin to an empty space shuttle fuel tank.

All these parameters may be accessed, modified and stored from the key-pad and you may be glad to know that that's about all there is in the way of reverb parameters - however, we've still got the delay effects to check out.

Delay

In this mode you've effectively got the first reflection plus a further single delay to play with, but none of the reverb parameters, and you can set up a different delay time for each of the two channels if you so wish. The maximum delay time is 900mS but if you cascade this with the 100mS delay available for the first reflection, you can just squeeze a second out of it. The level of the delayed signal is variable but this is the same for both channels.

If you want to create echoes rather than just straight delays, there is a Feedback function, common to both channels variable from 0 to 99%, the maximum setting giving a very stable, almost indefinite repeat. With DDLs we've become used to very bright clean echoes and these can occasionally be a disadvantage as they can be distracting. Don't worry, Yamaha have fitted a High Dump control which offers varying degrees of top cut in the range 0 to 10 for the delayed signal without affecting the quality of the direct signal.

Modulation

By incorporating an LFO with depth and rate parameters, all the usual flange, chorus and vibrato effects are easy to set up and as a bonus, you can still use the Initial Delay to add up to 100mS of delay to whatever effect you set up. Unlike most other units, you can produce flange and reverb effects at the same time, and in the Reverb Flange mode, the Feedback gain is replaced by a Reverb Time parameter and a fixed feedback ratio of 30% is applied. In this mode there's also an amplitude modulation parameter where the LFO can be made to control the output level if required. The modulation frequency range is 0.1 to 20Hz. All these frequency modulation effects work in true stereo, ie. the frequency of one channel increases as the other decreases, giving an effect which is both rich and mono-compatible.

Stereo Phasing is also an option on the REV7 as are Tremolo (in fact vibrato) and Symphonic which is a kind of ADT/chorus effect.

Presets

There are some 30 preset effects loaded up and ready to go as soon as you power up the unit, and though I don't intend to list them all, there's a good selection of hall, room, plate and spring simulations as well as a host of special effect settings. These include gated reverb and non-linear effects as well as the more conventional flange, chorus and so on, and there are also special treatments for strings, electric bass and brass to name but a few. I'll be looking at some of these in more detail in the 'Listening Test' section.

MIDI

Like the Roland unit, the REV7 will accept MIDI information on any one of 16 channels and the purpose of this is to enable switching between the effects in memory using Synth type patch change information. This is very handy if you use a synth and want to program a different effect to complement each sound patch. To accomplish this, the REV7 allows you to allocate its 90 memories to a maximum of 128 MIDI voice numbers which will then change automatically when you (or your sequencer) select a new sound patch.

The MIDI facility is likely to be less used in studios unless they specialise in sequencer driven music, but the reverb patches may be accessed from the front panel or from the remote control unit.

Remote Control

This tiny plastic controller is attached to the REV7 via a thin multi-way cable terminating in a DIN plug and in effect duplicates the main front panel keys REV1 to 4, E/R1. This gives the user access to all the preset effects and to the first seven of the user programmable effects. If you are using the remote control to do a mix, it makes sense to store the effects that you need in positions 31 to 37, otherwise you will have to resort to tedious stepping through.

When the remote is plugged in, the front panel controls on the REV7 are still active so you can leave the remote connected permanently if you wish which is just as well, as in a rack mounting situation, it could be awkward crawling round the back looking for a single DIN plug in the depths of spaghetti land. Connecting up the MIDI could be a little fiddly as these sockets too are located on the rear panel, but as there is no practical alternative, I can't complain.

Operation

There are three ways that you can recall your programs; Direct, via the Numeric keys or using the +/- keys. The first mode, Direct recall, allows single button selection of the first six programs in the preset bank, and by pressing the button labelled User Program, the same six keys give access to the the first six user settings. Other programs may be reached by stepping through with the Others key.

Alternatively you could use the Numeric keys; simply press Memory, the memory number of your choice followed by Recall, and there it is. As with all delay line devices, the output is corrupted during program changes and so is momentarily muted to prevent the output of garbage.

The last and possibly least elegant method of access is to use the increment/decrement keys, but if you store your patches in the order in which you intend to select them, it does provide you with a single key method of memory selection.

Saving effect patches into memory is similar to the Numeric keys method of memory access, and in this case, the Numeric keys are used in conjunction with the Memory and Store keys which results in a very simple and logical operation.

When it comes to actually setting up a sound, this is done by selecting and modifying one parameter at a time and this is a simple three stage operation. Firstly the appropriate parameter is selected by using the Parameter Select key (logical so far) and then its value altered by using either the Numeric keys or the +/- keys. When you are satisfied that you have arrived at the right value, this is locked in using the Enter button. When you are changing the decay time, the effect of the new setting can be heard before you press the Enter key which is good news. It goes without saying that all the memories are retained when the unit is powered down.

One restriction soon becomes evident when you are creating effects, and that is that you can only vary seven parameters for any given memory so you are really editing presets rather than building up sounds from scratch. For example; if you are working on the Large Hall preset, you can vary the decay time and the initial delay and also the level and delay of the first reflection. You can also vary the Diffusion, and both the high and low frequency damping but you can't experiment with different patterns of initial reflections or alter their Liveness or Room Size. This I feel is a bit of an imposition as you can't just sit down and build up a unique reverb treatment from scratch - though you might be able to get close to what you want once you've found the right preset from which to start. Of course you have to accept some compromise if the price is to be kept reasonable and there's no doubt that the price of the REV7 is indeed most reasonable.

The handbook for the REV7 is clearly written and presents all the necessary information in an easy to digest form and there is a table detailing the parameter types and values for each preset. This is a great help when it comes to deciding which ones to use as the basis for your own settings.

Listening Test

As usual, out came the digital drum machine and we commenced the test by checking out the presets. The most conventional of these were the Halls and Plates so here we were looking for a smooth natural sound. As expected the sounds were first rate and very smooth, though when I came to vary the Diffusion, the perceived difference was minimal in spite of the fact that I thought that I knew what I was listening out for. I would go as far as to say that in the context of a real mix, this control would be of little real value and certainly any setting between the two extremes would be un-noticeable.

The Early Reflections modes provide only early reflections without the main body of reverb and this is useful for simulating ambience or giving a mono sound sound source some kind of stereo depth. You can vary both the Liveness and the Room Size which gives a lot of flexibility to this treatment and that makes it all the more difficult to understand why this facility is omitted from the more commonly used reverb treatments. The way things are structured at the moment, all your hall simulations have to be built up using the same set of initial reflections and there is no way to change their spacing or decay profile.

There are other reverberant treatments in the preset section tailored to enhance specific instruments which work well in their own right, but these also make a good starting point for effects of your own. After years of trying to get rid of spring reverbs, there is even a preset dedicated to simulating this very beast (but without the twangs), and the Echo Room setting is a very good general purpose reverb setting for virtually any type of sound source.

Special Effects

In addition to the ambience and reverb effects, there are also presets for gated reverb and reverse reverb, both of which are very convincing. The gated reverb effect is now fairly well established where a burst of reverb follows the sound being treated, usually a drum, but the reverse setting takes a little bit more explaining. This effect does not produce a reverb before the initial sound, an effect easily achieved by turning the tape over and recording in reverse, (For real time reverse reverb, see the Zlatna Panega review in E&MM, April 85) but generates a reverse envelope to the reverb. This is done by producing a set of initial reflections which actually increase in amplitude and then decay rapidly giving the effect of a reverse reverb following the 'right way round' sound. Though this effect is normally best suited to use with drums, it can also be very effective when used on slow guitar parts and vocals.

Digital Delay

Most digital reverbs are dedicated devices, rather like the staff of H&SR, but Yamaha have given the REV7 the capacity to act as a true stereo digital delay when it is off duty. As a basic delay, the system produces clean, quiet results and its 12kHz bandwidth means that sounds remain bright throughout the one second delay range. The first reflection can be programmed as a separate echo with up to 100mS delay and this may be followed by up to 900mS of delay, independently settable for each channel. If feedback is applied, this is the same value for both channels, and you have the option of using the REV7 as a stereo in, stereo out device or for mono in stereo out operation. All the other standard delay effects such as chorus, flange, phase and vibrato are catered for, the flanging being refreshingly deep, but there is also a preset for flanged reverb.

Flanged reverb is ideal for those over the top ELP type drum solos and is very expensive sounding. Used with imagination, this preset could be modified to give some quite tasteful effects.

A final word about the equaliser section and that is that you can create most of the sounds you need without it. If you consider it as an extension of the EQ on yor mixing desk, you won't worry about the fact that it's not programmable. If your desk has a somewhat limited EQ section or if you are using an unequalised effects return, this extra EQ is very welcome.

Used on sound sources other than drums, the REV7 presented no problems at all and all the reverb sounds could be made to sound very natural if you want that kind of sound. If on the other hand you want a special effect you can get that as well so it really is suited to all kinds of production work.

Conclusions

I could go on for hours talking about this product, but at the end of the day, you're going to have to listen to it to find out how impressive it really is. There are one or two gripes about the fact that you can't actually alter all the parameters to build your effect but this is more than balanced by the good basic sounds and the selling price.

Another area that could be improved is in the area of identifying your own programmed effects. As things stand, these carry the same title indicated by the LCD display as the preset from which they were derived, but it would be so much better if you could enter your own title as is possible on the DX7.

MIDI control is not as important in the studio as it is if you're a synth player but it's nice to be given the option, and the fact that you can also generate high quality digital delay effects has got to be a big attraction.

The signal to noise ratio on paper is an uninspiring 60dB and there is no information to say what level this is referred to or what the weighting is but in practice, the unit is very quiet. Even with the input stage badly underdriven, there was no significant noise so don't believe everything that the specs appear to tell you, use your ears.

So there it is; a state of the art digital reverb including all the DDL effects with a remote control unit thrown in. Definitely a milestone in the history of affordable outboard gear - now we'll have to wait until next year to find what else they've got in store for us.

Further information is available from: Yamaha-Kemble, (Contact Details).