Programmable Digital Reverb
...While Simon Trask gets to grips with a more expensive model from America, with more parameters, a remote-control unit, and various other goodies; is it worth the extra?
"Performance MIDI" is what ART call their system of real-time control of reverb characteristics. It's good, but there's a lot of competition.
NOT SO VERY long ago, there was a clear dividing line between the outboard gear used by professional studios, and what you were likely to find in the average home studio. But the past year has seen the arrival of microprocessor-based digital reverb and multi-effects units whose relatively low price belies their professional quality, and which have consequently found their way into both types of studio.
Americans Applied Research and Technology (ART) are no strangers to signal processing, having started life as the renowned MXR company. The DR1 is ART's top-line digital reverb, and as such appears to be subject to ongoing software updates which are intended to make it one of the best-specified reverbs on offer. For instance, the latest update (version 1.2) introduces what ART call "Performance MIDI" - essentially a means of controlling reverb parameters in real-time via MIDI.
THE DR1 HAS a frequency response of 35kHz dry and 14kHz reverb, with a 16-bit linear DAC and a dynamic range in excess of 90dB in all modes. A bass rolloff switch located inside the unit (time to get the screwdriver out) allows you to tailor the low-end frequency response of the DR1 - low-frequency filtering is applied to the incoming signal before it's sent to the reverb processing circuitry. The switch selects between two rolloff frequencies: 50 and 150Hz (50Hz is the default setting, and should prove adequate for most requirements). One slightly alarming aspect of the DR1 is that it "runs warm" (to use ART's phrase) and exhibits a degree of hum (presumably from the transformer), but as long as you leave adequate ventilation space, this doesn't appear to cause any operational problems.
The unit comes with 40 ROM preset and 100 user-programmable memories onboard. The presets provide a healthy selection of reverb and other effects, based on 21 different "room" algorithms: five plate, five room, five hall, two effect, one reverse, one gated, one DDL and one flanger/chorus. However, unlike the SPX90s and DEP5/3s of this world, the DR1 doesn't allow you link different effects - either in series or in parallel.
The DR1's presets can of course be used as the basis for creating your own effects, which can then be stored in any of the user-programmable memories. A particularly handy feature is the ability to lock any of the latter individually, which guards against accidental overwriting of some effects while allowing others to be created and stored.
The rear panel of the DR1 sports quarter-inch jack stereo inputs and outputs, MIDI In and Thru (the latter software-switchable to Out), a footswitch input for controlling the "kill/inf" function (more on this later), telephone-style input for a remote control unit (which comes with the DR1), a button for selecting a choice of two input levels, and a further button for switching the dry signal in and out of the signal path.
The front panel divides into three sections: Preset (governing memory selection), Value (governing parameter setting), and Level (where you set the amount of reverb for left and right channels separately, and view the overall input level on a ladder LED); two two-digit LED windows indicate memory number and parameter value respectively.
THERE ARE SEVEN effect parameters directly accessible from either the front panel or the accompanying hand-held remote control. These are: room, pre-delay, decay, high-frequency damping, position, diffusion and minimum decay. While front-panel access is straightforward enough, selecting and editing parameters is made a lot easier by the remote control (which comes attached to a lengthy stretch of cable, and therefore allows you to program the DR1 on a flat surface far removed from your effects rack - invaluable in the studio, of course). Let's take a closer look at those programmable parameters.
Pre-delay is adjustable from 0-200mSecs in millisecond intervals. This governs the time interval between the source signal and the first reflections, allowing the former to sound uncluttered and more distinct.
Decay is variable from 0.1-25 seconds, with a greater resolution of values provided for shorter times. "Decay time" is defined here as the time required for the reverberant sound to decay to one millionth (-60dB) of its original energy.
"Minimum decay" on the DR1 is a useful feature which essentially brings a shorter decay time into play when the signal level builds up - useful for avoiding boominess in a reverb simulation with a long decay.
Diffusion refers to reverb density, which is a function of the number and spacing of reflective surfaces in the environment. On the DR1, a setting of zero creates the illusion of sound bouncing off a lot of surfaces, with a resultant "choppy" effect - especially in the case of percussive sounds. Increasing the parameter value results in a progressively smoother effect, which creates a more natural-sounding reverb.
Another characteristic of reverberation is that higher frequencies are absorbed more quickly than other frequency components, with the rate of absorption depending on the nature of the reflective surfaces that define the environment. On the DR1, damping is variable over a relative range of 0-19. A value of zero actually results in a sound which is brighter than what you'd find in the real world, while values above 9 result in treatments which are unnatural at the other end of the scale. All in all, this turns out to be one of the most effective features in determining the character of a DR1 reverb effect.
Position allows you to change your apparent position in the environment being simulated. This is achieved by varying the mix of initial sound and subsequent reverberation. In real life, if you move away from a sound source, you hear less of the initial sound and more of the reverberation. On the DR1, a Position parameter value of zero means you are at the front of the room, 5 puts you in the middle of the room, and 9 puts you somewhere near the back.
The above parameters apply to the "normal" rooms in the DR1's housing estate-full of acoustic treatments. In the case of special effects, they take on new functions. For instance, with the flanger/chorus "room", the controls assume such functions as left and right sweep width, sweep speed and regeneration, while for the multi-tapped DDL, decay and min decay become left-channel and right-channel delay times respectively (a tenth-of-a-second to a second in 1OmSec increments for each channel).
On the subject of non-reverb effects, the DR1's ROM presets include such effects as step flange, reverse slap, reverse swell, drone, ping-pong, echorec, downward percussive flange and chorus - all of which are useful treatments, though as the DR1 can only utilise a single effect at a time their use may be constrained by your need to use reverb effects. If outboard gear is at a premium and you're involved in multitrack recording, you can always record with one treatment and mix with another.
Subjectively speaking, the quality of the DR1s effects is (almost) everything that you would expect from a pro-quality digital reverb unit nowadays. However, the DR1 exhibits more colouration on its reverb effects than you will find on some other reverbs; to these ears the Ibanez SDR 1000, for instance, has a more transparent and smoother quality. The plates in particular are quite "ringy", and the gated and reverse effects may not be to everyone's taste, either, as they lack bite. Otherwise, full marks.
Now, about that "kill/inf" button. This can be assigned to have one of three effects: kill the entire reverb signal, kill the decay (early reflections continue), or infinite hold, which far from killing anything, actually sustains the reverb effect. Useful and usable, "kill/inf" can also be selected by a footswitch plugged into the DR1's rear panel.
The DR1 provides another murderous feature: a "kill" preset memory. This has the effect of killing any reverberant signal, which effectively means that you can deactivate the DR1 via a MIDI program change - a handy feature.
In their quest to pack the DR1 with as many features as possible, ART have included a Factory Demo mode. This auto-steps through the unit's factory presets, displaying each parameter value in sequence; the speed at which this happens can be set on a scale of 1-10. Thus, when trying out the DR1, you can concentrate on playing and listening while the DR1 does all the fiddly selection work for you.
Yet another feature, this time potentially useful in performance, is the Increment Preset mode. This allows you to select a sequence of chosen memories that can be stepped through from the front panel or a footswitch.
I'VE MADE BRIEF mention of the DR1's newly found "Performance MIDI" features without going into them in any detail. Before I do that, I'd better mention that MIDI on the DR1 doesn't confine itself to such involved functions; there are some perfectly standard facets to the implementation, too. To begin with, the reverb's programs can be called up remotely from a MIDI instrument using MIDI program-change commands. You can assign an onboard memory to each incoming program-change number (1-128) so that, for instance, MIDI program 67 could call up DR1 memory 24. This feature (now fairly common on MIDI-compatible effects processors) allows you to assign the same effect to a number of synth patches without having to duplicate effects in memory. Program-change reception can be allocated to any single MIDI channel (1-16).
And so to Performance MIDI, which allows the DR1 to have two of its current values simultaneously altered via various MIDI messages: note-on and note-off velocities, note-on and note-off key numbers, poly and channel aftertouch, pitch-bend, continuous controllers 1-11, and switch controllers 64-67. For each DR1 memory, you can choose two groups of four values: the front-panel parameter affected, the MIDI message used to affect it, the scaling, and the starting/centre value. The greater the scaling value (the range is -128 to +128), the greater the DR1 will change in response to MIDI messages (the negative scalings allow inverse responses). Now this is what I call flexibility - or, more specifically, performance responsiveness, which is what this aspect of the MIDI standard is all about.
The possibilities offered by Performance MIDI are too many to consider here, but a few examples are: note-on/off velocity controlling decay, so that the harder you play, the longer the reverb effect continues to decay; note-on/off key number controlling position, so that depending on where you play up and down the keyboard, the apparent position of the listener in relation to the reverberant field changes; volume controlling high-frequency damping; sustain pedal controlling Kill/inf on/off; and sostenuto pedal controlling high-frequency damping.
It's significant that ART have called this feature Performance MIDI, because there's no doubt that used in conjunction with a MIDI keyboard - I used the DX7IID, which currently has pride of place in the MT office - or with something like Yamaha's MCS2 MIDI Control Station, this aspect of the DR1 hugely enhances the unit's effectiveness as a creative performance tool.
The DR1's MIDI section also caters for System Exclusive communication, allowing its memories to be sent to another DR1 or to a remote storage device. While the onboard memory provision is plentiful, there's no denying the value of this ability - particularly for studio engineers who want to store groups of settings used on particular sessions. The DR1 allows you to dump the current memory settings, or all the memories plus the MIDI program table.
It's also possible for the DR1 to transmit and receive SysEx messages for individual parameter value changes in real-time, which makes for interesting possibilities both for slaving a second DR1, and for recording and playing back effect parameter changes using a MIDI sequencer.
The manual gives full details on the DR1's SysEx implementation, so no-one should be left in the dark about what can and can't be done. Finally, a word of praise for the DR1 manual in general. It's thorough, easy-to-read, and educational - throwing in a sensible discussion of the nature of reverb alongside explanations of how to use the DR1. Also included is a (very) handy quick reference card.
AS WELL AS being a high-quality reverb with a great deal of flexibility when it comes to creating effects (which can be natural simulations or "unnatural" creations) the DR1 comes packed with useful features.
Still, it's worth bearing in mind that there are other high-quality digital reverbs on the market (the Ibanez SDR 1000 and the new Korg reverbs, for instance) which are significantly cheaper than the DR1, and some of which also manage to offer sophisticated MIDI control. Listening to space has never been this crucial.
Price £1006 including VAT
More from Bandive, Brent View Road, London NW9 7EL. 01-2024155
Review by Simon Trask
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