Programmable Polyphonic FM Synthesizer
An overview of this flagship of the DX range of FM-based synthesisers
E&MM takes a first look at the latest prototype from the Yamaha factory
The DX1 is a 6-octave 73-note programmable instrument, with touch sensitive weighted action keyboard like the Yamaha GS1 or an acoustic piano. In terms of memories and voice, it's like the CS80, with two channels where you can select one instrument voice from each channel. In Single mode you choose one voice; in Dual mode one voice will go to the left output and the other to the right; in Split mode you select one voice for upper and lower parts of the keyboard, depending where you set the split point.
There are a total of 64 voice memories on board, but in practice, when you select a voice you are really choosing a 'Performance Program' memory which is a combination of two voices in whatever mode you've preprogrammed.
The voice instrument memory system and the way in which voices are produced are identical to the DX7. So you could easily go from the DX7 to a DX1 — in fact, it would be a good deal simpler because you've got a large display panel across the instrument indicating what is going on, as well as the central liquid crystal display (LCD) that is larger (40 characters x 2 rows) than the DX7. The Performance Program memory directly under the LCD is very important — for example, if you're in Dual mode, you're not just choosing two voices, you're also bringing in things like programmed vibrato speed for each voice, output levels, individual touch response on each of the keys, whether one voice is monophonic and possibly the other polyphonic, whether one's got portamento or not — these extra performance characteristics are all coming up in the 'Performance Program' (PM) section. So all 64 PMs could be set for totally different response in performance from the way the instrument is played. Even the Pitch Bend wheel can have its range programmed.
Each PM is called up by pressing one of the 8 momentary switches in an upper 'Bank' row and one of the switches in a parallel lower row labelled 'Performance & Voices'. All the switch buttons in these 2 rows just above the keyboard, including the 'Voice Memory' group to the left and the 'Key Assign Mode' to the right, have built-in LED 'on' indication. The PM group also acts as Function select buttons for defining the performance parameters.
Some examples might be: take Bank 1, Performance memory 1 — the LCD shows a long title "ROCK PIANO WITH BREATH CONTROLLED BRASS"; or Bank 1, PM 5 with "CHOIR, MAINLY CHAPS GOING AHH!" A "ROCK PIANO" could be with 'TOUCH BRASS', the latter coming on with extra pressure. "ROCK ORGAN WITH OLD LESLIE" contains all the wheezes and thumps like the real thing! Putting together a string orchestra sound with different vibrato and timbres on each voice was particularly impressive and hardly needed the usual chorus effect in addition.
The 'Voice Memory' section is divided into two channels called Voice A (upper row switches) and Voice B (lower row). Using a similar means of selection as the Program Memory section, 4 Bank and 8 Voice switches call up anyone of 32 stored sounds in Voice A and also for Voice B. Each of the stored voices can be your own created sounds or a set of 32 loaded into the appropriate voice via Cartridges A or B. These are inserted in the slots on the right of the control panel. A ROM cartridge contains 64 factory preset sounds in 2 groups of 32 that are selected by a small switch on the cartridge case. A flap on the slot closes the hole and nicely stops dust getting inside, while the cartridge is labelled so that it's obvious which way round to insert it. A RAM cartridge is used to store your own sounds - either in Voice or Program Performance form. All the voice-type cartridges you prepare are usable on the DX7.
When the Bank button in use is pressed again, the LCD reads a voice's chief features such as Internal Voice A1-8, B1-7, both polyphonic, etc. As well as stereo left and right outputs on the DX1, there is a third mono output for routing through effects.
Since two voices can be used to make the final sounds, one of these is examined at a time by simply pressing an A or B Voice button plus Function in the Key Assign Mode group to assign it to the LCD. Then the two rows of Performance Program buttons under the LCD become Function buttons.
First, the LFO can be set with pitch modulation depth, amplitude depth, sensor (ie. velocity, pressure or breath) on pressing Bank button 1. Moving along the row, button 2 calls up LFO Speed, Delay Time, Waveform Select, Key Synchronizers on or off; No. 3 looks at Performance Controls - Poly or Mono, Source Select (0 = internal, 1-15 = external MIDI channels allowing specific communication between chosen MIDI instruments and/or home computers). Also Pitch Bend Range, Step: Modulation Wheel Sensitivity, Assign to Amplitude and/or Pitch Modulation Depth or EG Bias; Foot Controller Sensitivity, Assign (as Pitch Bend); the same for After Touch sensitivity, and Breath Controller.
Key Individual After Touch sensitivity buttons follow - that means you can have pressure 'bringing out' the note or notes you press harder, with adjustable decay rate and overall key pressure. It is then assigned as 'Response' to one or more of the 6 'Operators'. (The DX Operators are the main building blocks for an FM Algorithm. The latter simply means a specific routing arrangement of the 6 operators that will construct a particular range of sounds).
Extreme effects can be called up by increasing the output of a particular operator — say it's the lowest part of an algorithm routing (this is similar to the VCA in an analogue synth), then it could turn a 'timpani' into a 'side drum roll' and so on. This After Touch control is not on the DX7.
The lower row of buttons in the PM section allow examination and modification of Portamento, Glissando, Sustain, Portamento Pedal control on or off, and Time; 'Miscellaneous' is an audio output level attenuator to match up levels of each voice in a Performance Program; Oscillator Key Synchronize as on the DX7 makes all the 'oscillators' start from the same place in the waveform. Since this instrument is 16-note polyphonic, with sync off a smooth transition is made back to the first note. Otherwise a noticeable click would be heard, especially with sustain on. But there are advantages for using sync on with certain sounds and effects.
Continuing, there is Program Output (the third mono output) on or off; Sustain Pedal on or off — that's useful for example, in Split mode, where you might be using a bass on the left and piano on the right, with the latter only requiring sustain.
Next comes the voice Name button, which pressed once allows naming of each Voice using the upper buttons on the panel, and then a further press allows naming of the Performance Programs; Voice 'K Point' for Key Transpose, Split Point select, Performance Key Shift — this leaves the Voice Memory intact but lets the PM have a transposed setting of it.
Several 'Utilities' are then provided on the remaining buttons in the lower row for copying Envelope data from one operator to another, pushing Operator data into the memory, initialising a Voice Memory, scratching (deleting) all Voice Memories, Master Tune, Internal Memory Protect, Change Battery indication, and Recall Previous Edit data.
If you use the Save utility, it has a first option to 'Save all voices from Internal memory A into External RAM cartridge A'. If you punch in the 'No' Data Entry button, it tries again with 'B' into External B', then 'Performance Memories into External A', and finally 'Performance Memories into External B'.
A 'Load' utility has the same options in reverse. The cartridge can be formatted for receiving data and given an ID number. There are also a few extra assignments that are only explained in the only currently existing manual for the DX1 in Japanese!
Each button actually has 3 or 4 of the functions accessed on further presses. A cursor moves along the LCD display to indicate the function selected.
These are the controls located at the left end of the keyboard for Volume, Balance between Voices A & B, and an improvement over the DX7 is that Portamento is readily available with long to short adjustment rather than fixed on or off within the voice memory. Here, too, are the Data Entry controls: on/off, yes/no, or count up/down 1 step buttons, plus a slider that gives variable change over the whole numeric range of 0-99 quickly as well as up/down setting for on/off, yes/no.
Two wheels are provided for Pitch Bend +/-12 semitones range and adjustable pitch step (spring-loaded return-to-centre), and Modulation Amount (free movement).
You can also change any of the Key Assign modes at any time to Single, Dual or Split and you can select one of the voices directly from an external RAM cartridge, so a total of 128 voices are always available from the two cartridges.
The weighted action of the keys is, of course, a major performance characteristic of the DX1. Total weight of the instrument is not quoted, but anyone who has moved around a CS80 or GS1 will know there's a lot of kilograms involved to test the most athletic roadie!
The lower right group of control buttons called 'Key Assign Mode' set keyboard modes, allow storing of sounds, selection of cartridges A or B, and two main operations: 'Edit/Compare' and 'Function'.
The Edit/Compare button lets you edit or create a sound, then a further press will recall the original sound you worked on for comparing and checking. Creating a sound in this mode shows another big difference between this and the DX7 — across the panel is a large plastic panel with screened writing within blocks that illuminate appropriately to show, from left to right: Operator make-up (this is actually a 'static' drawing for reference only), Algorithm indication (1-32) — square blocks show Operator numbers in the selected format linked by illuminated lines, plus Feedback setting (operators with feedback have a dot by their number), then Oscillator, Envelope Generator, Keyboard Scaling and Sensitivity settings.
Beneath the display panel are the relevant control buttons for changing these settings — here's the next big difference from the DX7, in that one button is provided for each parameter. Changes are therefore very easily made and do not require to be 'dialled up' on the LCD display. In fact, on this instrument, the LCD plays no part in the construction of a voice, and it's much more like working with a standard synth control panel. Only the Operator Select buttons have built-in LED indication because the other Edit buttons have settings shown on the main display.
Data entry buttons need not be used to change settings. For example, holding the 'Feedback' button down will show its value changing continuously from minimum to maximum in a cycling action. Each operator will have its own set of values as if it's a complete synthesizer in itself (although that is not really true in the analogue sense), and the whole display shows these values.
So the Envelope Generator display gives information on either the Pitch Envelope or the Amplitude Envelope. Rates 1-4 and Levels 1-4 are shown as numbers (0-99) and the peaks of the envelopes as illuminated vertical lines between. Pitch is scaled by horizontal lines over +/- 4000 cents (100 cents = 1 semitone), and Amplitude is from -96.0 to 0dB.
The point here is that parameters which are not shared, ie. are specific to a particular operator, are all shown; whereas parameters which are shared are in the Performance Program section already described.
The Oscillator section of the display shows the following: Frequency Ratio mode — a red dot here means that the pitch is related to keyboard pitch. Otherwise it will be a Fixed Frequency in 1, 10, 100 or 1,000 Hertz ranges that turns an Operator into a sort of LFO element.
Oscillator pitch is set by Coarse and Fine buttons and displayed as a decimal, with a Detune button for displacing pitch 7 steps up or down from the basic frequency.
This section has another unique display — it's a 'Level' graph with linear and exponential +/- curves drawn on it. A single LED then lights on the selected curves for left and right parts of the keyboard. The 'Breakpoint' between left and right is also assign able as a keyboard note number. Value can be 0-99 for all 3 settings (even though the keyboard has only 73 notes!). Left and right curves are given as a Depth value to indicate the amount of change you want the keyboard to make (linearly or exponentially) as you play up and down its range.
This is an important function as it 'tightens' up the envelope. It increases the Rate values (from 0-7), thus decreasing the time between the envelope peaks, always towards the top of the keyboard (as on a traditional piano).
Overall key sensitivity is adjustable (0-7). Incidentally, the highest number here is not necessarily the biggest key velocity effect, so you really have to work aurally to find the required control — unlike analogue synthesis, which is much more predictable.
Amplitude Modulation sensitivity (0-3) can also be set. At maximum on all operators, the sound will only come on when one or more of the assigned modulation sources are activated - the breath controller, foot control, modulation wheel and after touch.
Finally, the Operator/Output Level (0-99) is defined and also shown as a vertical LED display from -96.0 to 0dB.
The full display across the board is rarely used in performance — its prime use is for constructing a sound precisely with full visual confirmation by numbers and LED 'pointers'. The only exception would be when you had pre-planned some specific change in a Voice.
Most of the time in editing, the Amplitude Envelope will be used and the Pitch Envelope is for creating special effects.
When playing the instrument, the range of instrument voices that you can construct has to be heard to be believed and the DX1 can bring two of these together in unique performance formats.
Here lies the strength of the machine — but of course, you have to take the trouble to exploit all this potential — will you bother with breath control, will you explore the individual pressure action of the weighted keys, will you create new sounds when such a variety of good stuff is accessible from the ROM cartridges? Certainly the sound making can be like analogue synthesizers, but the scaling and FM synthesis in general brings us much closer towards producing sounds of the 'lasting' quality of traditional instruments.
It's very useful to have the LCD illuminated because this is where you'll be glancing during playing. Ordinary LCD's tend to require a limited viewing angle.
What this overview has not tried to do is explain how to program. We'll save that for another article!
Put the DX1 under MIDI control from a home micro and you're nearer to getting a picture of the tremendous possibilities. Price is to be somewhere between £7,000 and £10,000 - does that make it a dream machine for most of us? We shall have to wait and see. Still, it's encouraging to see that Syco Systems have taken on this exciting instrument - their expertise in the large scale computer/synthesizer field should put the DX1 into the right perspective.
I'll leave the final comment to Dave Bristow, Yamaha's chief demonstrator: "With the DX7 you've got the fundamental FM synthesis, with the DX9 you've got a smaller, simpler version of the DX7, and with the DX1 you've got a DX synthesizer that's a programmable GS1 with no expense spared!"
For further information on the Yamaha DX1, contact Syco Systems Ltd., (Contact Details), or Kemble/Yamaha Ltd., (Contact Details).
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Review by Mike Beecher
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