In the aftermath of February's musical instrument exhibitions, we report on some revolutionary machines that most show visitors didn't even stop to look at. They could change the face of music-making as we know it.

It's exactly a year since we first told E&MM readers of hi-tech music developments behind the Iron Curtain — more specifically, at the Zlatna Panega laboratories in Plovdiv, Bulgaria. As you may recall, Zlatna's first machine was the ACS100, a revolutionary sound synthesis machine based on the newly-harnessed principle of anticipation control. The ACS was the first (and so far only) musical instrument capable of making up sounds before users even think they need them, and as such, has been a runaway success all over the Eastern Bloc. UK imports of the machine have been limited, as the British importers, Carcass Music, have been going through some chronic cashflow difficulties.

However, it now seems that general UK distribution of the ACS (and its thought-controllable add-on, the TCS100, which can make music simply by tapping the thought patterns of the player using it) is due to start at the beginning of April this year, which is good news.

Even better news comes in the form of an extended press release from the Zlatna plant in Plovdiv, received by E&MM just 48 hours before this issue went to the printers. The release details two new innovations (first seen at Frankfurt in February) currently being worked on by the keenest team of electronics R&D people in the Balkans, and confirms our suspicions that the ACS100 is but the tip of an astounding technological iceberg.

It's significant that, whereas MIDI was fitted as an afterthought to the first Zlatna instruments, the Bulgarians are now entering into the MIDI spirit of things with great enthusiasm. Initial fears that the interface was too crude to be compatible with Zlatna's very advanced technology have been allayed, and all the organisation's most recent developments are based around MIDI and what can be done with it.

The first machine being pioneered by Zlatna's engineers is the NeuroFeedback MIDIplay Sequencer. Its aim is to help complete novices perform music with the same levels of accuracy and inspiration shown by great virtuoso players.

As painful experience will no doubt have taught many of you, learning to play a musical instrument is an uphill struggle at the best of times. Not only do you have to tell your brain what to do, but your body has to acclimatise to the new physical tasks required of it. For example, a competent piano player has to stretch the fingers of one hand across a keyboard octave without strain, which involves many hours of painful exercise.

Zlatna to the rescue, in the shape of a new machine — the MIDIplay Sequencer — that harnesses the principle of motivating human muscles by the application of minute electric currents. The device is a spin-off from work done at the Gabrovo Institute of Creative Microsurgery, and is primarily the work of one man, Professor Igor Mamarian, whose once promising career in medical science came to a premature end when he was caught smuggling the arms from research corpses home for his pet Doberman. Unceremoniously transferred to the Plovdiv Balkan Noseflute Factory (an annexe of the main musical instrument research institute), Dr Mamarian quickly rose to become Head of Research & Development, a post from which he steered a course far different to that of his predecessors. He conjectured that musical information stored in a MIDI sequencer could be further processed using a fast but basic computer, to provide the minute control voltages necessary to motivate human muscles.

The outcome of this theorising is a machine capable of actually controlling a musician's muscles, so that even a player of little or no skill can play a relatively complex piece of music — provided it's been digitally encoded in some form. In practice, this has been achieved by offering a range of software packages containing digitally encoded versions of popular pieces of music, all originally played by virtuoso musicians, and with instrumentation options for piano, guitar and Balkan noseflute.

Physically, the workings of the Zlatna unit are as follows. Two velcro armbands (similar to those used in blood pressure tests) contain the skin electrodes, and one of these must be fitted to each of the player's arms, between elbow and wrist. A lightweight multicore cable plugs into the main Zlatna module, into which the appropriate software disk is inserted. Once the Start button is pressed, the neural information is delayed for five seconds, to give the player a chance to put his fingers on the keyboard, or pick up his guitar.

From this point on, the player's arms are under the control of the MIDIplay Sequencer, though it's possible to override the machine's instructions by using a conscious exertion of willpower. This safety feature is essential, as otherwise, players could do themselves serious physical harm by trying to play the piano after inserting a noseflute software package by mistake.

Inexperienced players should use the Zlatna process in small doses at first, as over-exposure can cause muscular strain. To this end, self-limiting software packages for beginners will be available. Also on the horizon are additional 'performance' disks, containing System Exclusive information relating to the playing technique of the virtuoso player concerned. Thus an average musician could play the same piece of piano music in the styles of Vladimir Ashkenazy, Oscar Peterson or Elton John.

As for the music itself, far too much of the current catalogue is devoted to Balkan folk music. At the time of writing, disks for only four familiar pieces were listed: Rachmaninov's Piano Concerto No 1, Kraftwerk's 'Autobahn', 'Angel Face' by the Glitter Band, and Sigue Sigue Sputnik's recent smash, 'Love Missile F1-11'. While this situation is understandable, we can't help thinking the Sequencer's chances of achieving mass market penetration will be hindered so long as the library of Western standards remains small.

Also in the pipeline is a visual music display system which enables music sight-reading ability to be acquired subliminally by correlating an illuminated manuscript display, with the music being transmitted to the neurophysical link. The dots will never be the same again...

Second on Zlatna's list of Things To Do is the astonishing Multitrack MIDI Multiplexer. Like the MIDIplay Sequencer, the Multiplexer is loosely based on existing MIDI data recording technology, but any resemblance between this machine and traditional digital multitrack sequencers is entirely coincidental.

The Multiplexer has been developed as the ultimate in easy-play, auto-accompaniment systems, the playalong music companion to cap them all. It's the work of Romanian MIDI software writer Mikhail Beecherescu, who regular readers will remember as being responsible for fitting MIDI to the original ACS100. Aside from the interface, Beecherescu's main fascination lies with auto-accompaniment facilities such as those fitted to home organs and contemporary portable keyboards.

It was during his time as Romania's Bontempi importer that Beecherescu became aware of a public desire for an auto-accompaniment section that went beyond the mundane, pre-programmed drum patterns and arpeggiated basslines of the keyboards he was selling. When his pleas received little or no positive response from the Italians, Beecherescu decided to design a system of his own. The system, he opined, had to fulfil two basic criteria: it should offer home keyboard users a wider variety of backing patterns, without lumbering them with the burden of having to write those patterns themselves.

Several months of nurturing later, Beecherescu unveiled his QuasiCompositional Musical Data Extrapolation System (now shortened to the convenient acronym QCMDES). The first device to use the system was the MIDI Multiplexer, presented a few weeks after Beecherescu's initial research programme to a committee of Zlatna bigwigs, who grudgingly gave him the production go-ahead.

The machine as it stands now is a complex microprocessor-controlled device capable of extrapolating up to seven individual channels of music from one simple melody, and playing back all eight tracks simultaneously over a user-variable selection of MIDI instruments and voices.

All you do to get the Multiplexer going is hook it up to a MIDI keyboard the way you would any other sequencer, and enter a simple (say, 10-note) leadline, ensuring that the notes are exactly as they should be and that you've played them in the correct style. Once your music has been converted into digital information and received by the Multiplexer, the machine begins analysing the data in terms of pitch, rhythm, structure, mood and performing style — in other words, all the musical parameters from which the rest of the piece is to be extrapolated.

Of course, no multiplexing machine, however powerful, is capable of responding sympathetically to a piece of music if it has no reference point as to the type of extrapolation required by the user. To help solve this problem, Beecherescu and his team of scientists have developed a revolutionary new system of music data storage (the Ultra High Speed Musical Parameter Memoriser, or UHSMPM for short) whereby musical information pertaining to the above parameters is contained within ROM cards, with each card relating to a particular genre of music. The Multiplexer ROMs vary in capacity depending on the musical style they're intended for. The smallest is the 16-byte Status Quo ROM, which contains all the musical permutations used by the band in their 20-year history, while the largest — still under development — is the 512 Terrabyte Brian Eno ROM, which will contain, in addition to his complete musical output to date, a sub-memory annexe housing a variety of extra-mural details such as those contained within Eno's song lyrics, illustrative sketches, notebook entries and interview quotes. The reason for the delay in getting the Eno ROM into production is that a further storage system (the Peripheral Artistic Information Storage and Retrieval Network, or PAISRN) has had to be developed so that the Multiplexer is capable of responding to non-musical artistic details. Some may doubt the usefulness of this facility, but Beecherescu reasons — quite rightly — that "if electro-musicians are capable of being influenced by extra-curricular minutiae, then any system intended for automatic musical extrapolation should be, too".

A number of successful musicians and producers — fed up with the arduous task of actually having to create new music every now and again — have already expressed interest in the Zlatna Multiplexer, among them Trevor Horn, Paul Weller, Philip Glass and Shakin' Stevens.

Yet even with two revolutionary machines like the MIDIplay Sequencer and the MIDI Multiplexer already entering production, there's no sign that the Bulgarians are finished with pushing music technology beyond currently accepted limits.

Our sources indicate that many other new machines are presently undergoing initial research programmes inside the Zlatna complex.

These include the Polytrack, a tape expansion device capable of time-division multiplexing 24 tracks of signal onto a single audio tape track, thus enabling users to convert a domestic two-track tape recorder into the equivalent of a 48-track machine; the MultiVoice Processor, a huge crossbreed between vocoder, harmoniser, digital delay, sampler, pitch transposer, reverb and chorus unit, which could theoretically be capable of making any singing voice sound like Nana Maskouri (or indeed anyone else) using a complex network of signal processing and resynthesis circuitry, controlled by a human voice; and the MIDI Song Analyser, a sophisticated music data development system originally devised for musicians and producers anxious to know the chances of their latest song being an international chart success — though with more software being written all the time, this will be but one of the Analyser's possible functions.