CLASSIC FM?

It looks like a groovebox, but inside it's a powerful FM synth, fully editable via bundled software. Derek Johnson & Debbie Poyser modulate those frequencies...

Even when you thought FM synthesis had gone away, it hadn't. There were several years during the '80s when you couldn't turn on the radio without hearing the distinctive clangy bells, upfront basses and unrealistic yet somehow appealing brass sounds that digital Frequency Modulation is so good at. But eventually sample‑based synthesis overtook FM in the mainstream, and analogue began its return to pre‑eminence via the dancefloor. FM synths, like the analogue 'dinosaurs' of a few years before, littered the free ads, becoming the cheap instruments of synthdom.

And we all know what happens then. When synths become old and cheap, impoverished musicians pick them up and turn them to their own ends, and eventually they're rehabilitated as a source of trendy 'new' sounds. It happened with analogue, and to a lesser extent (perhaps because of FM's legendary resistance to programming), it happened with FM too. FM basses, in particular, became a staple of certain dance music styles. Yamaha's investment in Frequency Modulation technology continued to look safe.

It's still looking safe, with the launch of the first stand‑alone FM synth in almost 10 years, the DX200. (We disregard 1998's FS1R, which was marketed as an eight‑operator formant synth.) Not that you'd immediately identify the 200 as FM, despite the small 'FM Synthesis' screened next to the name of this knob‑laden groovebox. The sound‑generating powers of FM (in this case derived from the engine on one of Yamaha's PLG150FM plug‑in boards, which lies at the heart of the DX200) have been married to a tricksy four‑track analogue‑style sequencer, simple effects and sample‑based rhythm sounds, to produce a very cool‑looking box in Yamaha's 'Loop Factory' series. It's partnered in the same range by the SU200 groove sampler (reviewed November 2000) and the similar AN200 physical modelling sequencer workstation, reviewed in last month's SOS. The DX, though, can be used simply as a fully editable polyphonic sound module, or in groovebox mode with three rhythm parts and a monophonic synth part.

What FM synths lacked in the '80s were real‑time editing knobs, and these the DX200 has aplenty. They're the key to how the DX200 makes FM approachable, allowing fundamental parameters to be edited with simple knob tweaks. Sonically, too, this is FM with a difference, because Yamaha have added a modelled emulation of a voltage‑controlled filter (VCF) that lets you shape an FM sound as though it was an analogue one. And the more ambitious can still access the full depths of FM sound creation, because inside the DX200 is a six‑operator FM engine, editable via the bundled Mac/PC editing software. In DX‑style FM synthesis, operators are the equivalents of oscillators, are either designated Carriers or Modulators, and are arranged in an Algorithm — for more on all this, see the 'Bluffer's Guide To FM' box at the end of this review.

Overview

Pattern tracks can be muted/unmuted during playback for instant creation of arrangements on the fly.

Yamaha manage to cram a lot into the DX200's foolscap‑sized front panel, yet the impression isn't of a cramped control layout. The main display is a fourcharacter LED, with a matrix of nine labels, such as Song, Pattern and Beat, to its right. The currently lit label indicates what the display relates to at any one time. Below the LED panel is a group of related buttons, plus a data knob that edits the values in the display. The panel's main section (Voice) hosts all sound editing knobs and buttons, including an LFO section, a set of envelope generator (EG) controls (routable to either the filter or the separate amplitude EG), a VCF section, an Effects section, and a set of FM‑specific editing knobs. Below all this is the Keyboard section, 16 numbered keys which can be played like black and white notes on a real keyboard. These keys also allow sequencer steps to be entered, as well as acting as shifted Song, Pattern, MIDI and Utility controls. Finally, there's the Control section at the bottom left, which hosts sequencer controls, including transport buttons.

The simple back panel features MIDI I/O (no separate Thru), a headphone jack, stereo jack audio output, external PSU input and a power switch.

The Synth

Tweaking the cutoff parameter of the DX200's resonant filter.

As already mentioned, when used with its built‑in sequencer facilities the DX200 is a monophonic synth with three additional monophonic rhythm parts, although when accessed via MIDI, it's capable of generating 16 simultaneous notes of synth voices, plus up to 32 simultaneous rhythm sounds.

Synth voices are saved with sequence data as Patterns, and the DX200 comes with 256 of these preset (see 'Bring The Noise' box opposite for comments on these), plus 128 user slots. To create an original voice, you select a user Pattern, then commence building the sound, first choosing an FM algorithm on which to base it (once again, refer to the 'Bluffer's Guide' box if you're lost). Different algorithms create sounds with different characters, and some are better for making certain sounds than others. Just like the venerable DX7, the 200 offers 32 algorithms to choose from, but making the choice is down to experience; noticing which algorithms are used by the Yamaha presets you like (or are closest to the sound you want to make) is a good start.

The following facilities can then be set up for your sound:

• LOW FREQUENCY OSCILLATOR

There's a choice of six LFO waveforms (triangle, up/down sawtooth, square, sine, sample & hold) and a routing parameter to assign the LFO to modulate pitch, amplitude and/or filter. Speed control is via a dedicated knob.

• ENVELOPE GENERATORS

There are two of these, of the standard ADSR (Attack, Decay, Sustain, Release) type, to determine how the sound's amplitude and filter contours change over time. Each stage has a dedicated knob, but there is only one set of ADSR controls for both envelopes. The Filter and Amplitude EGs can be selected simultaneously, for quick tweaking if the sound doesn't need separate filter and amplitude contours.

• VCF

The filter is a resonant device with cutoff frequency and resonance knobs, plus a Filter EG depth control with both positive and negative movement, so that inverse envelopes can be applied to the filter (these make the filter close over time instead of opening). Six filter characteristics are available: 24, 18 and 12dB low‑pass, band‑pass, high‑pass or band‑eliminate — typical of an analogue synth, but unusual and most welcome on an FM instrument!

• PORTAMENTO

For creating glide effects. This is editable via a dedicated knob.

• KEY ASSIGN

This mode selector button allows you to determine whether you play the DX200 monophonically or polyphonically. This might seem odd on an instrument that's essentially monophonic when used with the built‑in step sequencer, but polyphonic voices behave differently to monophonic ones (the decay of one note will still sustain when another is played, if required), and of course the mono/poly options are valid when playing the DX200 over MIDI; in this situation the mono option lets you play bass and lead sounds as if they were being generated by an old monosynth. A Unison option for both modes stacks up and detunes four voices of polyphony for a fatter sound, albeit with only four‑voice polyphony in Poly Unison mode.

• FM MODULATOR CONTROLS

So far, we've come across little, other than the presence of 'algorithms', to indicate that this is an FM synth, but the FM Modulator knobs change all that, accessing a range of FM‑specific parameters (of course, since these are still accessed by knobs, there's no need to tangle with FM theory if you don't want to — you can just tweak until the desired result is obtained). Basically, when used from its front panel, the DX200 offers the user less control over the Carriers and Modulators in the FM algorithm than in classic old‑style FM: there's some choice of Modulators, but then the influence those Modulators have over the Carriers is governed by just three knobs, labelled Harmonic, FM Depth and FM Decay. Decay is a simple envelope, controlling how quickly or slowly the modulator's level (and its effect) fades out. Harmonic controls the frequency of the preset selection of modulators, and FM Depth their level. In concert, the three knobs determine how subtle or obvious the frequency modulation effect is. If it's more obvious, the sound will be clangorous and metallic, but in general, careful use of these controls helps add movement and depth.

• NOISE OSCILLATOR

This adds one of 16 types of noise to a sound. Yamaha suggest that this is good for 'dirtying up' a waveform, but it's a fairly basic facility that can't be used as a modulation source. It can, however, add a noise attack to a sound, as in wind instrument or percussion simulations.

• EFFECTS

A simple, single processor is on offer, featuring a handful of delays, flangers, phasers, overdrive/amp effects, plus a chorus and a reverb. There's little editability — just a send control to the effect, and one additional parameter, such as delay time for the delays. The effects sound OK, but you find yourself wishing for more.

In addition to the main effects, there's a switchable Distortion effect, available solely to the synth voice; the only control over this is how much is applied, from a fairly subtle dirty edge to a singing, compressed, guitar‑like sustaining grunge.

Your edited sounds, as mentioned above, have to be saved with their respective Pattern. Avoid the Scene knob if you've not yet saved your voice, as an inadvertent tweak can completely blitz your edits. This knob, along with its two associated buttons, hides a neat facility: to store two versions of a sound and either switch between them with the buttons, or morph between them by turning the knob. The Scene facility was also offered by Yamaha's recent CS‑series synths, but the morphing ability is new, and great fun to use. It also expands the user memory, in effect, as two versions of all 128 user sounds can be stored if you use it.

The Sequencer

The DX200's step sequencer offers four tracks of eight, 12 or 16 steps each, with each step able to generate either three or four events: the ones that can be applied to the Synth voice are Pitch (MIDI note number), Gate Time (note length) and Velocity. The three Rhythm voices have a additional option: Instrument Select, for assigning one of 121 drum, percussion, bass and sound effect samples to a step. Since each step in a Rhythm voice can still be assigned a Pitch, you can use Rhythm voices to create melodic material — bass lines, for example — alongside the Synth voice and whatever Rhythm parts you've created, expanding the DX200's versatility. Each Pattern track can also have its own Level and Pan value, set in friendly fashion by knobs.

Accessing these many parameters involves a certain amount of mode switching, so various controls have multiple functions. For example, the eight knobs immediately above the keyboard tweak synth parameters during synth editing, but during sequence creation they become step parameter value knobs. Because there are only eight, they're switched in two banks, so that the user can alter parameters for all 16 steps, and further switching allows the knobs to alter the three or four parameters available to each step. You soon get the hang of it. A handy shortcut makes it possible to quickly change one parameter on multiple steps, useful for moving a parameter's value into the right ballpark, or setting all steps in a Rhythm Track to the same Instrument.

A real‑time Pattern‑record option is also available, complete with metronome, count‑in and looping overdub (plus the option to shift the DX's keyboard over the full MIDI range). The only real frustration with this option is the 16‑step limit. Sequence or voice data can be copied from one Pattern to another, but not, sadly, between individual tracks.

Play It Again

The main Voice Editor window, showing the many parameters that can be edited in depth, particularly the FM algorithm operator parameters on the bottom third of the screen.

Some great playback facilities can be applied to Patterns once they've been recorded. At the press of a button, a Pattern can be reversed, which is most enjoyable. You can also double or halve a Pattern's tempo, apply a variable Swing for a triplet feel, give an entire Pattern a +/‑ 24‑semitone pitch offset (this affects the Synt h track and the Rhythm track bass sounds), mute/unmute Pattern tracks, and shorten or lengthen all notes on all tracks in a Pattern with a gate‑time offset. Retrigger and roll effects, made popular by some dance idioms, are also available: the former continuously restarts the Pattern, and the latter creates a quarter‑, eighth‑ or 16th‑note roll on the synth voice while the Rhythm parts carry on playing. Patterns can also be rotated forward or backward, so that they start on a different note; this can't be done during playback, however.

The 'Beat' facility allows you to designate a new number of steps for a Pattern after it's been recorded. For instance, chopping four or eight steps off a 16‑step Pattern causes the remaining steps to stretch to fit the same time scale — so a 12‑step Pattern plays four beats of eighth‑note triplets, and an eight‑step Pattern plays a bar's worth of eighth notes rather than 16ths. This facility won't suit every Pattern, but it can create a good effect.

Finally, Patterns can be assigned to 12 of the individual keyboard buttons and triggered live in any order. Shifting the keyboard over a three‑octave range allows up to 36 Patterns to be triggered.

These Pattern manipulation options are essentially meant for live performance, but in Song mode some of the same effects can be programmed by selecting the desired events to occur on any of a Song's Pattern steps. A Song is a chain of up to 256 steps, with each step able to contain a Pattern and various playback settings: these comprise pitch offset, reverse, beat mode, swing, gate time, track mute, and a tempo value. The last facility means songs can jump from very slow to hyper‑fast (the tempo range is 20‑300bpm). There's memory space for 10 Songs.

And there's more: it's possible to record the movements of up to four synth voice parameters into a Pattern, using the DX200's 'Free EG' (great feature, odd name!). Once a synth track has been recorded, you can go into Free EG mode, select a length (up to eight repetitions of the current Pattern), choose a Parameter and then record knob‑driven changes to that parameter. Free EG playback length can be changed after recording, so tweaks recorded over a bar could be stretched to the full eight bars.

The DX200's MIDI spec is quite advanced, and most of its knobs and buttons transmit MIDI data which can be recorded into an external sequencer — these knob movements are transmitted whether you use the DX200 as a groovebox or a sound module (also, all the 'knobbed' parameters, and the many hidden parameters normally accessible only via the editor, can be altered over MIDI, from a MIDI mixer map or hardware controller). The DX200 lacks a Local Off mode, though, so be careful how you set up the target sequencer, to avoid recording the wrong data or tweaking the wrong tracks. Also be aware that there are two modes for transmitting and receiving MIDI data, one of which bizarrely disables a number of knobs. Of course, the DX200 can be a MIDI sync master or slave.

MIDI data that's not transmitted, sadly, includes the real‑time Pattern‑manipulation options discussed above. Incidentally, the DX200 can dump its memory contents over MIDI, so if you don't have a PC or Mac you can save to a MIDI data filer, or use a generic SysEx librarian if you work on another computer platform.

Conclusions

We wouldn't feel the need to change that much about the DX200, though it would be great if Pattern playback features could be recorded into the onboard sequencer on the fly, or if they transmitted MIDI data for recording into an external sequencer. An arpeggiator would also be good, as would more Pattern steps (though the sequencer wouldn't then be a classic 16‑step device), and the effects feel rather undeveloped.

As a sequencing workstation, the DX is fun and very hands‑on. Yamaha have implemented some nice operational tricks to help make the most of multi‑function controls and limited display; for example, you can easily check the current value of a knob, or its original value before editing, and obtain fine control over parameters by switching from dedicated knobs to the stepped data‑entry knob. Honourable mention should also go to the manual, which isn't perfect but adopts an accessible and largely useful 'Tip' format.

Yamaha have done a fine job of making FM tweakable in friendly analogue fashion, yet the DX200 retains the distinctive FM sound character that sets it apart from other new synths on the market. The addition of a resonant filter just makes it more versatile, allowing the creation of a wider range of timbres. The DX200's sonic precision suits it very well to highly rhythmic music, and although some of its preset sounds are quite aggressive and/or strange, they certainly have a place in today's market, particularly among harder‑edged styles. However, because the synth's sound engine is so programmable, especially with the help of the excellent bundled editing software, this instrument won't be restricted to just those styles. It's good value for money, too.

Overall, the DX200 is a great instrument which will certainly appeal to a wide range of people, from relative novices (who will love the tactile ease of the workstation) to more experienced synthesists (who will be able to explore its sonic corners in greater detail with the bundled editing software). Many musicians — us included — would be very happy to own one.