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Yamaha TX81Z & MDF1

After April's In Brief review, Rick Davies sends us a user report on the latest FM synth module, and throws in a review of the MDF1 MIDI data filer for good measure.

Yamaha's latest synth module has shown promising sound quality, while their MDF1 MIDI disk drive looks like a versatile storage unit. But what are they like to use every day?

WHEN YAMAHA INTRODUCED the FB01, many FM enthusiasts were both very happy and very frustrated. Happy because they finally had access to an inexpensive multi-timbral sound module. Frustrated because they needed an external computer and voice-editing software to program it, and because the four-operator voice architecture didn't provide the flexibility that six-operator instruments offered.

The newest tone generator from Yamaha, the TX81Z, addresses both of these concerns. As we revealed in our In Brief appraisal not long ago, it is programmable from the front panel (although the process is a bit tedious) and its four-operator architecture has been beefed up by a choice of different waveforms with which you can begin the synthesis process. Like the FB01, the TX81Z is an eight-note polyphonic FM synth, capable of producing eight different timbres at the same time.


THE FM SOUND is certainly no longer a novelty, and the way it is produced is no secret: sine waves (generated by "operators") multiply with and add to one another to produce complex waveforms. The timbre of these waveforms depends on the number of available operators, how they are connected (determined by the voice's "algorithm"), their respective levels and tunings, and how they change each time a note is played.

I won't try to convince you that it's easy to program, but from experience, I can confidently say that it is possible to learn the system a little at a time. The real trick lies in getting access to all of these parameters with minimal hassle (but more on that later).

Given that the TX81Z is a four-operator instrument, one would expect its voices to resemble those of the DX27 or DX100 more than the DX7. But in fact the TX81Z's sound is different from all of those instruments, because its operators can generate seven different non-sine waveforms. To get even a static complex waveform on any other FM synth, you would have to use at least two operators, so there is a chance - in theory, at least - that the extra waveforms will compensate for the four-operator restriction. Do they in reality?

To a limited degree, the answer is yes. Three of the eight available algorithms have three operators running in parallel, so you can easily detune three distinct waveforms and get a thick sound, and through creative enveloping you could fade operators in and out - a poor man's additive synthesis, really.

But if you want filter-type effects, you're still going to have to use a couple of those precious operators as modulators, and though the range of timbres is greater with the new waveforms, this is no substitute for two additional operators.

A nice touch is the TX81Z's "reverb" control, which is not actually done with signal processing but gives a reverb-like effect by extending envelope release stages over a variable amount of time. It's not a substitute for the real thing, but it's worth using from time to time.

The TX81Z's 160 factory voices do a good job of showing off the new face of four-op FM - a cross-section of traditional DX-type sounds plus a few surprises. Brass, woodwind and various plucked and hammered instruments are well represented, as are a variety of strings which work remarkably well for a four-op instrument. (Sure enough, examination of the string voices reveals extensive use of the new waveforms.)

Now, 128 of the "Single" voices are arranged in four banks (A to D) of 32, and though they may be edited, they can only be stored in the remaining 32 user-programmable voice locations (Bank "I"). Bank I comes from the factory already loaded with voices (which are not duplicates of any of the other voices), so if you're planning on doing any editing, look for some form of voice storage right away. In this case, your only options are the cassette interface or MIDI.

When in Single Play mode, the Parameter and Data Entry switches select the voice bank and number, and the TX81Z behaves as a simple, eight-voice synthesiser - no splits or layers. Simple, predictable, and the best place at which to get acquainted with the TX.

To play more than one sound at the same time, you select one of the 24 programmable "Performance" setups. These automatically select up to eight Single voices, and set them up to suit whichever controller you are using - whether it's a keyboard, guitar converter or sequencer. This is how you can achieve splits, layers, or multi-timbral sequences. Although the options are many, setting up Performance programs is easy, and mainly entails selecting up to eight Single voices in Performance Edit mode, and then assigning them to any combination of note ranges, MIDI channels, audio outputs, transpositions, tuning offsets, and volumes. To make life easier, Yamaha provide several initialised performance setups, including splits and layers, which require you only to select the voices you want to combine - the defaults take care of the rest.

Each performance setup can invoke one of 13 microtonal keyboard tunings (11 preset and two programmable, as on the DX7II) and one of three programmable "effects" - "delay", "pan", and "chord". Except for the problem of using a preset LFO to pan voices across the audio outputs (which is essentially what happens if you use many of the preset voices in your Performance setups), the above effects are a lot of fun. The "delay" effect is, like the "reverb" feature, not a digital delay, but uses any available voices to repeat notes, and can raise or lower the pitch with each echo. The "chord" feature lets you program a four-note chord for every note you play. This is light years beyond the old "chord latch" approach, and is a boon for single-note soloing.

Needless to say, the Performance mode is where the TX81Z really gets a chance to show off. I've used it with two guitar-to-MIDI converters, and in both cases I found the TX81Z could adapt to anything I threw at its MIDI input: this makes it equally suitable for MIDI sequencing.


I DONT WANT to fill this report with "what do you want for £450?" remarks, but the TX81Z really would have benefited significantly from a data entry slider and better parameter organisation. Read the manual and you get the impression that the TX81Z's designers have left no stone unturned, but program this instrument in any detail, and you're left with some doubt as to how well some of the features interact.

The Single Utilities section is where the MIDI controls reside for the TX81Z's transmit and receive channels, and its response to note-on/off, program changes, pitch-bend, continuous controller, and System Exclusive messages. System Exclusive dumps are initiated from this area. The effects settings are also programmed here, though they can only be used in Performance mode. This is an example of the sometimes frustrating placement of functions within the TX81Z's system. There are several other MIDI-related controls which are accessible only in Edit mode, since they affect each voice individually rather than the whole instrument. These include the keyboard mode (poly or mono - not to be confused with the MIDI modes), and ranges for pitch-bend, breath controller and mod wheel MIDI messages.

When I was testing the pitch-bend response in Performance mode with a guitar controller, I had to enable the pitch-bend parameter in the Single Utilities area, and then make sure that all affected voices had the pitch-bend range set appropriately in the Function section. The trouble came when I tried to save preset voices after editing their pitch-bend ranges. The only place in which edited voices can be stored is Bank "I", and those 32 locations get used up really fast.

If you have a MIDI storage device such as Yamaha's MDF1 (coming up in a moment), you can get around the TX81Z's limited RAM by storing banks of voices, effects, and other system data separately. It's not as fast as random access, perhaps, but it's faster than reprogramming the TX81Z each time you need new voices.

If you're going to do any serious programming, you'll want to look into software support (in America, two companies - Bacchus Software and Poshek Productions - have announced editing programs already), but considering how few memories there are on the TX81Z, your computer could end up working overtime just as a librarian when it really should be doing other things. That's where dedicated MIDI storage devices come into the picture.

The MDF1

QUESTION: HOW DO you get excited about a disk drive? Answer: try writing a review on the same computer that you'd normally use for backing up synthesiser patches. Few musicians can afford a dedicated computer for every application, so there is obviously still room for specialised devices like the MDF1, Yamaha's first dedicated MIDI Data Filer. It's intended for the storage of patches, drum patterns, sequences, samples - or whatever the occasion calls for - on 2.8" Quick Disks. While this may not be everybody's favourite format, it has allowed Yamaha to sell the MDF1 at a competitive price, making it worthy of a parking space in a MIDI switcher where it can reach everything in a system.

It takes a while to get used to the way that the MDF1 communicates its messages with a single seven-segment LED display, but it eventually becomes clear that there's not a whole lot for it to tell you. Actually, that's fine: the less time spent with a disk drive, the more time there's left to make music.

The key to the MDF1 is its simple control layout. The number of functions does not heavily outweigh the number of controls, so life stays simple. You'll want to keep a note of the files you store, however, since the MDF1 doesn't supply file names or types when you prepare to load from disk, and you can save several types of data from several instruments in one file, and up to 19 files can be stored on each side of a quick disk.

There is one very nice feature on the MDF1: because it sends MIDI data back out over the channel on which it is received, you can connect it to any number of identical devices, and as long as they're on different MIDI channels, they will only accept data intended for them. This means you have to look out for instruments like the TX81Z which can receive and transmit on different channels, but the feature can still be very helpful in large MIDI setups. (Fortunately, the TX81Z puts both of these parameters in the same MIDI Control section of the Single Utilities, so there's no need to switch back and forth between modes.)

There are two stages to saving data to an MDF1 disk. First, you select the File function, then press the Save switch, which prepares the MDF1 for an incoming SysEx transfer (this must be initiated from the other instrument). Once a file is received, it is not saved to disk until you press Save a second time, which gives you the option of either sending more files to the MDF1 or aborting the operation.

Since you have a 19-file limit on each disk side, it is desirable to get as much mileage out of each file as possible. The MDF1 facilitates this by allowing several instruments to dump programs (sequences, or whatever) onto the same disk file. When the disk file is reloaded, the instruments receive their respective data files in the same order they were recorded. This makes the MDF1 particularly useful in live performance, where you might want to load fresh data into several devices for a particular track.

As I mentioned earlier, the TX81Z has a limited number of memories, but it only takes five seconds or so to reload effects settings, and seven or eight seconds to load either Bank I with 32 voices or the Performance memories with 24 new combinations. This really does help the TX81Z substantially, since its files are so small.

The MDF1 doesn't discriminate against non-Yamaha machines, either, so you can also connect effects units, drum machines (or whatever) with similar satisfaction. Don't get your hopes up if you own a sampler, though - Sample Dump Standard messages may be accepted, but 60,000 bytes (the size of the MDF1's input buffer) doesn't add up to much in today's world of 12-bit samplers; chances are you'd cause the MDF1's input buffer to overload if you tried to save anything but the tiniest of samples. (I verified this with a Prophet 2000.)


AFTER A WHILE, I decided it was indeed worth the effort to overcome my initial confusion about the TX81Z's parameter organisation. The instrument is fun, but like a lot of my favourite albums, it took several listenings before it really started to grow on me.

The four-operator sounds are clean and quite usable, and all the features are there to let you do just about anything you could want with them. The built-in selection of 128 preset voices acts as a good starting point, but in the end, the 32 programmable voices will probably get used up quicker than you might imagine they would on a Yamaha FM synth.

The TX81Z should appeal to anyone who wants to get started with sequencing but hasn't enough money to justify a keyboard instrument, particularly if a multi-timbral FM synth sound is called for. I found that it's well suited to control by guitar-to-MIDI converters, and though the complexity of programming may be a put-off initially, in the long run it's well worth the time and money.

Price TX81Z £449; MDF1 £329; both prices including VAT

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Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Jul 1987

Donated & scanned by: Mike Gorman

Review by Rick Davies

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