Why buy a drum machine with a built-in sequencer if you're happy with the sequencer you're using? No reason at all, say Kawai, as they unveil their new percussion synthesiser module.

WITH COMPUTER SEQUENCERS reaching a stage of development where their facilities far exceed those of the average drum machine, there's a definite need for percussion expanders. After all, why pay for the sequencer side of a drum machine if you're never going to use it? Admittedly some up-market models, like Roland's R8, have performance functions aimed at the realistic reproduction of a drummer's feel, but Roland have been able to offer even the R8 as a module. However, manufacturers in general seem to be coming round to the idea of a beat box with less emphasis on sequencing and more on sound capabilities.

Kawai have often been innovative in their approach to synthesis, and the XD5 is continuing along this path. The unit is based on the K4, but uses a higher sampling rate for better quality - we're not dealing with a run-of-the-mill drum sample player but a dedicated drum synthesiser. It's an interesting idea...

OVERVIEW

THE XD5 OFFERS a selection of 215, 16-bit, 44.1kHz PCM samples, and 41 synthesised waveforms. A maximum of four sources can be combined together to create a Tone, and total polyphony is 32 sources. The internal structure is similar to previous members of the Kawai "K" family in that 64 Single patches - a Tone and its programmed parameters - can be stored internally along with 16 Kit patches. A Kit may have up to 88 tones assigned along a keyboard. The XD5 also incorporates Output patches for assigning Tones to its eight audio outputs.

While many manufacturers incorporate a small number of pushbuttons with multiple uses, the XD5 has a total of 31 dedicated function buttons on its futuristic front panel - made possible by its 2U-high rackmount format. The only duplication is with the letters and numbers for accessing patches. Two vertical sliders handle volume and value input while the central display is a backlit 2 x 16-character LCD. A pushbutton for power, a card slot and headphone socket complete the front panel lineup.

The rear panel sports eight outputs (L, R, 1-6), MIDI In, Out and Thru sockets and an input for a 12v DC supply. I say this each time, but it's encouraging to see a manufacturer using a separate PSU - no internal heat or hum.

HEARING THINGS

THE XD5'S SINGLE button offers you the instant gratification of hearing the 64 single Tones by selecting a letter and a number - four banks lettered A-D and 16 tones per bank. To hear this current Tone you can either connect a keyboard or, even easier, press the Play key and use a pair of headphones. This means you can work on patches without a MIDI keyboard or sound system. The preset Tones are pretty good although the cymbal Tones are looped and a little too short in some cases. More of that later.

EDITING

IF THE VALUE of a parameter has to be altered on any of the edit screens, this can be achieved by either using the Value slider or the +Yes/-No keys. I tended to use the slider to get near the value and then finish off the job with the keys. Another important button is labelled Previous, this returns you to the parameter before the current one. This is useful because the parameters are scrolled through by repeatedly pressing the relevant edit button - and you can't move backwards. Compare allows you to toggle between the original version and edit. Needless to say, you have to save an edit before changing to a different mode.

As previously mentioned, the XD5 isn't a preset sample player. Pressing a key on a keyboard plays a note into a Digitally Controlled Oscillator (DCO) which selects the relevant note for the current Tone. There are two choices of waveform; Digital Cyclic (DC) or Pulse Code Modulated (PCM) samples. DC waveforms are basically digitally synthesised sounds which can be used in the creation of a Tone. They are clean, high in harmonic content and are useful for adding specific characteristics to a sample of a "natural". For instance, it's often difficult to bring out the ring from a snare drum rimshot but by combining the relevant harmonics with a snare sample, the task is made that much easier.

Of course, DC waveforms are only going to be useful if you have a good sample to work with in the first place. The XD5 has 215 high quality, PCM drum samples, and the structure of a Tone is such that you can combine together up to four elements. You are effectively creating a drum tone by using up to four building blocks.

After selecting a Single Tone, pressing the Edit button takes you into edit mode. There are nine screens for modifying a Tone; each of these shows which of the four elements are in use, what type they are (P = PCM, C = DC waveform) and a line underneath one of the elements shows which one is being currently edited. The front panel has four buttons each for Source Select and Source Mute - you can choose which element you're editing and ensure that you are also listening to that element as well.

Edit screens are accessed by pressing appropriately-labelled buttons; continued pressing of a button scrolls through the editing possibilities. Edit takes you into the most basic of these screens from which you can alter volume, output patch and submix (see later), and patch name.

Common sets up the mode for a Tone. Apart from the four available sound sources, there are two digital filters - Source mode lets you decide which configuration is going to be used. Normal uses two sources and one filter, Twin uses two such groups while Double mixes all four sources before passing them through the two filters in series. Bearing in mind that the number of sources selected will affect the XDs polyphony, this first step has to be thought through. Further selections for ring modulation follow, but the other important programming feature here is the polyphony setting, which affects how a Tone reacts when played repeatedly. The two Poly modes let you choose whether Tones overlap or not when accessed from the same key - a hi-hat might require consecutive notes to mute previous ones, while a snare drum roll might require Tones to overlap. There is also a third option, called Solo, in which a second note anywhere on the keyboard cuts off the previous one. You might use this with tuned percussion or bass.

"The XD5's DC waveforms are mainly used for combining with the PCM samples - what's surprising is that electric pianos, basses and organs also exist within that list."

Hitting an acoustic tom hard causes its pitch to rise as the skin stretches. The XD5's Auto Bend function imitates and recreates this, giving you control over the Time and Depth of the bend. Velocity Depth changes the degree of pitchbend according to the velocity of the hit.

Source Common sets the delay between the MIDI input and the attack phase beginning and then gives a selection of eight velocity curves. The main purpose of these is to cater for different velocity responses from attached MIDI devices.

DCO gives you the selection of waveforms by number. Their names - even shortened versions - would have been of great help here, because the choice of 256 means continuous reference to a table. Tuning (coarse, fine and fixed) is the other important aspect editable here. The DCA edits control the envelope of a Tone. Level sets the initial level of the attack while Attack, Decay, Sustain and Release carry out their normal duties.

DCA Modulation adjusts the envelope response to the velocity of the MIDI note input. It affects the initial and sustain levels, effectively acting as a compressor or expander depending on whether a positive or negative value is set. Decay Modulation carries out a similar job for the decay stage of the envelope - the note velocity will appear to change the overall envelope length of the Tone. Both these edits offer more - or less - natural drum sounds.

The timbral quality of the Tone is edited from the DCF parameters. Filter Cutoff frequency filters out the harmonics within a sound above the value set. This is used in conjunction with Velocity Depth for creating the timbral "shape" of a Tone - again giving potentially more natural sounds. The Resonance parameter is another welcome inclusion - congratulations, Kawai.

DCF Modulation gives you control over the envelope of the filter including Attack, Decay, Sustain and Release and Envelope Depth for actively altering the cutoff frequency according to note velocity. Progressively hitting a snare harder could be duplicated by the relevant setting of this parameter.

But why go to all this trouble? Why not simply use a sample of the real thing? The reason is that a sample only accurately represents an acoustic event at a particular velocity (amongst other things). Had the sample been taken when the drum was hit slightly harder or softer, the sound would have contained a different set of harmonics. By adding synthesis to the basic sample, the illusion of real percussion sounds is more readily created.

KITTED UP

AN XD5 KIT is a selection of Single patches, or Tones, assigned to individual keys. The screen entered by pressing Edit gives you options of a similar nature to those of the Single mode: volume, output patch and name. Edit key selects the current MIDI key, from A1 through to C7. Scrolling through these shows which Tones are assigned to each note (some keys may show the same tone to create a group of keys with a common Tone; this will either change in tune as you move along the keys or present you with a block of notes with the same tuning if Fixed tune has been selected). Single lets you scroll through the available Tones and so select the relevant one for that note.

There are two other edits available here: the first is for the Pitch of a tone, the second concerns output assignment. Pitch is important with tuned percussion sounds - a cowbell, for example. Audio output edits cover for Level and sub-mix channel. These provide a degree of mixing between the various Tones.

PATCHING OUT

OUTPUT PATCHES ARE quite a clever idea on Kawai's part. Each Output patch is the equivalent of an 8 x 8 mixer with the inputs to the mixer being called Submixes (A-H) and the outputs from the mixer leading to either a panned position using the L/R outputs or one of the individual outputs (1-6). Each Tone can be assigned to one of the inputs and will then follow the routing for that patch.

"The XD5 really comes into its own when you start layering together waveforms and individually adjusting their envelopes and velocity sensitivities."

Consider how this might work in practice. Take a typical drum kit of bass drum, snare drum, hi-hat, three toms and a crash cymbal. The toms would go to the left and right outputs, suitably panned, while the rest would go to individual outputs. The only restriction is that there are only eight inputs to the mixer so you could have all eight going to panned positions across the stereo outputs, or have some routed to individual outputs and the remainder to positions across the stereo outs. This is not as flexible as, say, Roland's configuration where any tone can be positioned in any position in the stereo spectrum. However, the 16 output patches can be set up for general, rather than specific, purposes. For instance, you could use one patch for a standard drum kit and impose it on any of the kits you create in that style. Also, you can set up the effects routing for the individual outputs and then change single patches which are still being routed through the same output patch. Most manufacturers would have you resetting the output assign each time you change the source Tone. This idea is clever but I'm not certain whether the restriction of eight mixer channels will appeal to everyone.

SOUNDS

THE FIRST 41 of the XD5's sounds are DC waveforms - these are mainly used for combining with the PCM samples, but what's surprising is that various electric pianos, basses and organs also exist within the list. Amongst the PCM samples is the usual selection of bass drums, snares, toms and hi-hats along with latin percussion, various industrial sounds and the obligatory brass hit. All samples are available reversed, and many of them as looped samples. Finally, there are four groups where 11 samples are layered across the keyboard as a kind of preset kit.

On soloing any DC waveform, there appears to be a loud click at the beginning. Taking the attack above 25 gets rid of this and it may be intentional - it certainly adds attack to percussive sounds. But the same click also occurs on many of the PCM samples which may be down to a fault on this particular XD5. The actual quality of the samples is very good, with practically no noise in either the samples or outputs.

The loops on some of the cymbal samples are very short, especially the rides. The only way around this is to set the decay level low so that the sample is fading away as the loop becomes apparent. Unfortunately this can lead to unnaturally short sounds.

The XD5 really comes into its own when you start layering together waveforms and then individually adjusting their envelopes and velocity sensitivities. It requires effort, but the results are worthwhile especially when you know what particular aspect of a drum sound you want to bring out. A low-level DC waveform underneath a PCM sample can work wonders. One useful facility here copies features set up for one source to the others within a Tone, hence duplicating envelopes.

FEELIN' MIDI

BEARING IN MIND that the XD5 is a drum synthesiser, the MIDI implementation is quite sparse. It will recognise MIDI Volume (controller #7), Patch changes and can have the master fine tune set via Registered Parameter Number 1 but that's about it. As there is no LFO, the absence of MIDI modulation and aftertouch is no surprise, but recognition of pitchbend could have given some interesting percussion sounds and effects. Kawai have also been slow to take up the idea of using MIDI controllers to internally address functions.

There are a variety of System Exclusive dumps available, however, including one patch and all patches for single, kit or output and you can also save all internal data. Similar dumps are available for the external card.

VERDICT

THE IDEA OF allowing you to mould your own drum sounds is an interesting one and there's little doubt that, with a modicum of effort, you can get good results. Using the DC waveforms lets you fatten up percussion instruments or make them sound like something completely different. The likely problem the XD5 must face is that many people will want to turn on a drum machine and have an instant array of brilliant sounds.

The XD5's cost places it in the same market position as Roland's R8M which already has access to an impressive library of sound cards. Admittedly, XD5 owners can expect to have new patches become available - Kawai tend to put these out on Q80 disks - but these will have to be programmed using the existing 256 internal waves, where the R8M can use fresh samples. What's perhaps more relevant to the XD5's market position is the fact that the Alesis SR16 is retailing at £299 with 233 drum sounds on board. With these two factors in mind, Kawai may have difficulties convincing the public of the viability of what is otherwise a ground-breaking approach to MIDI percussion sounds.

Price £599 including VAT. Price may be subject to change due to the recent increase in VAT.

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