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Zlatna Panega ACS100

Tucked away in one corner of the Frankfurt Music Fair was an astonishing sound-sampling device with origins in Eastern Europe. Paul White and Dan Goldstein have managed to get their hands on the first model to appear in the West.

As from this coming Spring, the acknowledged centres of the hi-tech music world are going to be under threat from a new Eastern European hardware co-operative. The company's first product is a revolutionary sound-sampler from Bulgaria, and E&MM has managed to get hold of the first production model for an exclusive review.

While there's no doubt that the established musical instrument manufacturers are doing a sterling job in maintaining the levels of innovation on the hi-tech side of the industry, it could also be argued that it's been some while since a totally new approach was adopted by anybody.

True, plenty of people are forever seeking new ways of achieving the usual musical objectives, but too often, those objectives have remained unquestioned, and few designers or engineers have sought to produce a music system with new goals as well as new methods of approaching them. Because no matter how revolutionary their operating principles, the DX7 is still just another poly-synth, the Music 500 a computer add-on no different in conception from a hundred others, and the LinnDrum simply an attempt at confining the role of drummers to playing Space Invaders in the games room.

Thankfully, this situation looks like being changed, thanks to some timely technological intervention from an unexpected quarter. It's been known for some while that electronics engineers in Eastern European countries have been working on a variety of musical projects, but until the beginning of 1985, it seemed unlikely that their work would ever escape the confines of the laboratories. Then, tucked away in a corner of one of the Frankfurt Music Fair's gargantuan halls, E&MM's illustrious Publisher came across a stand taken by Germany's importer of Balkan musical instruments. Now, most of the gear on the stand was of the traditional balalika-and-panflute variety, but the Germans had booked a soundproof booth at the rear of the stand in which they were demonstrating the abilities of a revolutionary Bulgarian sound-sampling device and showing a number of interesting-looking peripherals.

'Have you seen the Transbalkan stand?' quizzed said Publisher when Music Maker staffers next congregated at the Press Bar. They've got a f***ing amazing sampler in there - looks great, and it's gonna be under two hundred quid!'

So off we went, armed only with a hurriedly-prepared A4 factsheet and five words of Serbo-Croat between us. And for the first time in many years, it seemed our Publisher was actually telling the truth. For there, lurking in the Musik Messe's uncharted backwaters and housed in an unpromising gunmetal grey 19" rack-mounting case, lay the Zlatna Panega ACS100, besieged by a number of worried-looking Oriental gentlemen in navy blue and orange sweatshirts.

The pitch of the ACS was being controlled via MIDI by a Yamaha DX1, but the Bulgarian demonstrator, Louda Yana, was using none of that keyboard's sound-generating circuitry in his performance. Every sound we heard was, in fact, generated from within this apparently innocuous little grey box, and we were intrigued as to what might be going on inside the unit.


The only spokesman of a technical bent on the stand turned out to be Professor Gerganin Izvor, a systems analyst who for the last three years has devoted his attention to the development of this revolutionary electronic sound system. In what can only be described as the Bulgarian equivalent of a Geordie accent, he explained that the ACS only came about because somebody at the Central Office of Technology in Sofia thought that lessons learned by the Bulgarian State Railways in the course of updating signalling equipment could equally be applied to the hardware used by local folk musicians.

But Izvor wasn't satisfied. He realised that the potential of such technology would never be fully realised while its range of applications was limited to the music-playing population of the Balkans, and deliberately set about designing a product that was just too complicated for most of the locals to appreciate.

And luckily for him, The Bulgarian People's Export Committee approved of his aims and gave him a grant to enable him to continue his work. Thus, two years after the project had commenced, Professor Izvor unveiled his finished ACS100 towards the end of 1984. As things turned out, it proved to be a technological revolution - and not just for the Eastern Bloc.


Using negative-ion implant IC technology, Izvor had developed an entirely new concept in sound synthesis. He called it Phase Reversal Autocorrelation, or PRA for short. For the technically-minded, this principle works by paying particular attention to the fact that nothing ever occurs without something causing it to occur. That may sound obvious, but Izvor reasoned that by using ultra-high speed logic circuitry to examine spatial and temporal minutiae, it should theoretically be possible to predict the outcome of the interaction of a finite number of parameters before that outcome actually takes place in real time.

Izvor and his growing team of collaborators encountered no small amount of difficulty in putting this principle into solid state practice, but eventually discovered that if the interacting parameters exist in software, the extrapolation becomes both more viable and more accurate.

The musical outcome of all this is that pre-echoes can actually be generated in real time, and by selecting the pre-delay time in accordance with an algorithm embodying the concepts of advanced Fourier synthesis and Bessel transforms (and developed by Professor Izvor himself), it's possible to create multidimensional comb filtering effects, which in turn enables a homogenous ambisonic sound field to be created from a single point source. And because this circuit works on the principle of Phase Reversal Autocorrelation, that source need not actually exist at the time of musical performance, although in order to get the system to function correctly, the user must sincerely undertake in writing to acquire one at the Bulgarian Institute of Creative Art in Plovdiv.

Incidentally, and frankly this was where our credence became somewhat overstretched, it appears that Izvor has since had to return to Bulgaria to face charges of Pre-Emptive Embezzlement after attempting to predict future football results using several ACS100s connected together in series.

Further Development

So, there we were at Frankfurt, utterly agog at what Professor Izvor appeared to have succeeded in creating. For a few uncertain and terrifying moments, all our technical and musical knowledge seemed to pale into insignificance by comparison with the genius that was this tiny, undernourished Bulgarian scientist. Fortunately, Izvor was a man of humility, and, realising that the concepts he was discussing were way above our editorial heads, he went on to discuss a new subject about which we thought we knew everything - MIDI.

It seems that the redoubtable Professor considered MIDI technology to be a spent force not worthy of inclusion in his magnificent musical creation, and that as a result, the first production ACS100s could be pitch-controlled only from the keyboard of an obscure (and somewhat outmoded) Russian mainframe-based electronic harpsichord.

However, pressure from the Romanian Central Bureau of Export and Commerce forced him to reconsider. And although Izvor himself remained unconvinced as to the merits of the hybrid interfacing system, he did at least deign to commission Mikhail Beecherescu, the Romanian importer of Kawai products, to design a suitable MIDI interface for the ACS.

Beecherescu's unparalleled working knowledge of MIDI (acquired largely through retrofitting the interface to obsolete Kawai organs and Teisco mono-synths) enabled him to complete the necessary work in time for the first public demonstration of the ACS100 in Frankfurt.

But there were problems. Izvor's reservations concerning MIDI's viability in such a technologically-elevated arena were to some extent justified by the fact that, when several MIDI-compatible ACS100s were connected together, the last machine in the chain invariably anticipated what form of data was going to be sent to it and started playing a fraction of a second before all the others. And the more machines the Balkans connected together, the more acute this potentially rather embarrassing phenomenon became. Which is why only one MIDI interconnection was attempted at Frankfurt, in spite of protests from the Beecherescu contingent.


Upon returning to Cambridge after our Teutonic sojourn, we were a little doubtful as to whether or not an ACS100 would actually turn up for review purposes. An intensely busy Izvor had been eager to promise us an exclusive review sample, especially as none of the other UK magazines had even bothered to visit the Transbalkan stand, let alone express any interest in the ACS. At first, it seemed our worst fears had been confirmed. No new packages arrived from Bulgaria, Romania or any other nation situated behind the ferrous window-covering material, and we were forced to come to the conclusion that the whole thing had been an elaborate hoax.

However, it was during an Indian Restaurant conversation with the Editor of Organist Today, Malcolm Harrison, that we realised the machine had anticipated our desire to review it and arrived at the Music Maker offices shortly before we all left for Frankfurt. Between mouthfuls of succulent chicken pieces marinated in piquant nitromors sauce, the bearded home keyboardist told us of a strange rack-mounting box he had taken home to Reading one day, mistaking it for a Wersi organ kit. He was at a loss as to explain the machine's uncanny ability to play Bulgarian folk favourites whenever he touched any of its front panel controls, but we were already familiar with the technology that was at work.

It was another fortnight before E&MM's Production Editor found a small black box on the banks of the River Cam while feeding the ducks one lunchtime, and this transpired to be the production model of one of the prototype peripherals displayed - but not demonstrated - at Frankfurt. Preliminary investigation revealed that said box was the eagerly-awaited Zlatna Panega TCS100 thought-control biofeedback add-on, but it was some while before we realised the full potential of this even more innocuous-looking unit.

Thought Control

It has long been the dream of the musician to produce music by thought alone without the physical restraints imposed by a keyboard or some other mechanical controller, and although the TCS100 add-on is far from perfect in this respect, it is capable of following fairly complex mentally-generated melodies with uncanny accuracy, and with any voicing you have the imagination to dream up. However, the device's built-in quantisation mode should be employed if you don't have perfect pitch.

Of course, the machine can't pick up human thoughts directly, but by using a pair of hand-grip electrodes and a lightweight headband, minute changes in skin resistance and alpha wave patterns are converted into a 16-bit binary code for subsequent digital filtering and processing within the TCS100 itself.

We found that pitch-tracking could be improved by sitting in a bath of tepid saline solution during performance, but this is not recommended for reasons of both electrical safety and artistic credibility.

In practice, almost everybody at the Music Maker offices succeeded in getting a reasonable musical output from the thought-control device, with the exception of the Publisher, who managed only a disjointed gurgle interspersed with impromptu arrangements of Glenn Miller classics.


The ACS100 is a remarkable machine at any price, but the fact that it retails for less than the VAT on the latest Fairlight software update makes it a thoroughly irresistible investment. The only possible problem we can foresee is that of spare parts, but as the machine can foresee this also, it is capable of ordering replacements by modem before the failure actually occurs. Which means the system can be up and running again before you even realise it's gone wrong.

On its own, the ACS100 is a revelation, and should prove of immense musical value to anyone currently forced into working with altogether inferior MIDI-based hardware. Yet it's in conjunction with the thought-control interface that things become really exciting: just think, now even the family pet can compose music. The only problem could be getting the headset to stay on the tortoise...

The Zlatna Panega ACS100 retails at £199.99 including VAT, while the TCS100 is a further £99.99. More information from The Body Shop at Carcass Music, above the Abattoir, Brick Lane, London E1. Regular deliveries are expected to begin around April 1.

Previous Article in this issue

Linn 9000

Next article in this issue

Delta SX301

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


Electronics & Music Maker - Apr 1985

Donated & scanned by: Stewart Lawler

Previous article in this issue:

> Linn 9000

Next article in this issue:

> Delta SX301

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