Jen Musipack 1.0
Article from Electronic Soundmaker & Computer Music, May 1984
Exclusive instrument review
Ex-E&MM Editor Mike Beecher examines an economical computer musical instrument from Italy
Only two other micro music systems currently exist that employ hardware to enable the digital production of sound (under £2000) — the alphaSyntauri and the Soundchaser. These are now joined by the new Jen Musipack 1.0 system which uses Italian software and hardware developed by Jen Elettronica with the assistance of the 'Edgar Varese Studio of Computational Sonology' in Pescara.
At first glance, the three systems look very, alike, although alpha Syntauri and Soundchaser are now established in their own right as useful compositional and educational tools for the musician, and this is Jen's first diversion from manufacturing organs and small synthesizers.
Jen Elettronica have also produced their own 48K Apple II+ lookalike micro called the LEMON II which is available in Italy at low cost. It's also slightly different physically in that it has a rear sliding panel for accessing the main PCB more easily and a numeric keypad in addition to the qwerty keyboard. Jen also make a disk drive (single-sided), but it's unlikely that either will appear over here at present as separate items unless you overwhelm Jen's UK distributors, British Music Strings Ltd, with enquiries.
Whether you use the Apple or a lookalike is of no consequence, so let's assume the system is to be set up with an Apple II+ or IIe with 48K memory that's compatible with Apple DOS3.3.
The most significant factor for considering the Musipack 1.0 system over the others is its low price. Its Musipack software programs will allow the most inexperienced micro musician to perform sophisticated digital sound synthesis.
The hardware consists of a separate 61-note C-C music keyboard in a polished wooden cabinet, an interface card to connect the keyboard to the Apple micro, and two sound generator cards featuring 16 digital oscillators for 8 + 8 polyphonic recording and playback in stereo.
The keyboard has a very playable key mechanism, unlike Syntauri's more heavily sprung keys, but there is no velocity sensitivity control at present. It is supplied with a removable ribbon cable for connection to the interface card. This card and the two sound cards have to be inserted into slots 7, 4 and 5 respectively in the micro. Two 'floating' female phono sockets emerge from the sound cards at the rear for linking to left and right signal inputs of your mixer, hi-fi or other amplifier. Since the cables can all be disconnected, it's easy to pack up the system for a gig, whilst leaving the cards and (tied up) wires in the micro.
In addition to the basic micro, you need a video monitor (or a B&W TV set with an optional RF modulator that's available), one or two disk drives with Apple disk controller card, two Apple games paddles, plus something to take the stereo line outputs as mentioned.
The Musipack 1.0 software contains three main programs which allow you to create your own original preset voice timbres by means of additive harmonic synthesis waveform drawing, using the games paddles. The presets can then be played from the music keyboard (up to eight notes at a time) from its two sets of digital synthesizers that go to left and right outputs.
Two other programs also offer multitrack polyphonic recording in real time, with a storage capacity of over 4000 notes. All the Musipack programs come on one 5¼" floppy disk and this cuts down the amount of changing around of disks on a single disk drive setup. Two disk drives are preferable so that waveforms, preset sounds, track recordings and other information can go straight to drive two, while keeping the master program disk in drive one. A second floppy is supplied with a set of prepared waveforms and sample presets/recordings, along with an instruction manual.
Loading of any of the main programs such as 'Spectre' takes around a minute and all the software is well protected against errors (giving an audio 'beep' and return), and illegal listing (system crashes). Copying of the master and data disks is possible (and highly recommended!), and there's a user 'End' routine that usefully inputs the date of your work for that session in the disk catalogue file. Since it is quite easy to forget what information is on disk, you can always jump out of the program temporarily to check your disks' catalogue, with auto return afterwards to the same place in the program (using Control D).
The first program 'Gestast' recalls a preset voice in real time from the micro keyboard, organised in groups of 10, and a large library of preset groups can be stored on floppy disk. Each preset consists of two fully independent digitally synthesized voices, with on-screen control of ADSR and LFO depth for each oscillator, as well as setting of overall 'Octave' pitch for the music keyboard (covering five octaves), LFO speed and general volume level.
Changing of any of these parameter values (in Hex code rather than decimal) can be done at any time (including during playback of a recorded piece) by calling the Gestast screen display and simply typing in the new value at the keyboard. The parameter selected flashes until 'Return' is pressed. This real time interaction is a boon to creating just the right sound envelope and modulation for your preset oscillator waveforms. There is, however, no filter control as in analogue systems, and the tonal character comes entirely from the combination of the individual waveforms chosen for oscillators one and two, and the way these are modulated by a selected LFO waveform.
With the 'Digitrack' program you can simulate a 4-track polyphonic digital recorder in 'Track' mode, with each track having a storage capacity of over 1000 notes. During playback you can alter the preset voice assigned to any track and turn a track to off, play, or record. A 'Mono' mode makes a single 4000 note polyphonic recording with optional repeat as well as having increased tempo on playback. Complete pieces (called Tracks) can be saved or loaded to disk. Access to the Gestast program is simply done by pressing the 'Escape' key at any time.
The successful creation and storage of sounds depends on your understanding of the file management system for Musipack 1.0. There is nothing complicated about the filing — it's just that if you don't prepare the required files you will not be able to complete a set of presets (unless you stick to the sample files given on the data disc).
The first step in making a preset sound to play from the keyboard is to create a waveform (called 'Wave') that makes the tonal character of your final sound. A similar or different wave is required for both left and right output oscillators. The LFO also needs its own wave — usually a standard wave such as sine, square, triangle or sawtooth is employed for the traditional vibrato and trills (it only affects pitch), although some exotic pitch runs and jumps and pseudo FM sounds can be created with a drawn wave.
Two methods can be used to make a wave. The 'Spectre' program will construct a wave using the screen displays for setting the amplitude value (1-100) and phase value (0-360 degrees) of up to 24 harmonics. A graphical representation of the wave is then plotted that can be verified aurally and further modified as required.
Since you might consider using the same wave for both oscillators within a preset voice, a chorus 'detuning' effect between the oscillators can also be tried out for later setting (in the Gestast program). Besides making new waves, you can also load an existing wave from disk (provided it was made with the Spectre program) and edit it.
The second program 'Grafond' gives an interesting alternative wavemaking method by using the games paddles to 'draw' a waveform on the screen. You may then listen, edit and draw again until you find a new and original timbre you like. The rotary control of one paddle sets up the wave position vertically over a centre axis, whilst the paddle 'fire' button joins up the points with straight lines. Curved lines are made by continuously holding the fire button whilst turning the control knob. The second paddle lets you edit an existing wave.
As with Spectre, you can store on disk any wave that you create, but you can edit not only Grafond-derived waves but also take a Spectre harmonically created wave and insert some drawn portions into its cycle. This facility, plus the possibility of using harmonics with different phase angles is what makes the Jen's sound so versatile.
The next step in sound management is to take waves from your disk file and organise them into a preset 'Master' consisting of three waves for Osc.1, 2 and LFO. This is done by means of the 'Digital 2.1 ' program, called from the main control menu (like the others). Incidentally, a Spectre-derived wave when saved puts two files on disk as it needs to hold the specific values for each harmonic as well as the actual wave plotted out on the screen (filed as Wave, and WD. plus your inspired wave name on disk file).
When a Master is saved on disk (called MASTER.), it will take an existing sound shaping set of parameters (the ADSR, LFO and octave values) onto the file so that it will actually play from the keyboard (called ADSRP). A further nine masters can be collected together using the Digital program to make a 'Live' group of 10 preset masters. By means of the Gestast program, any of the ADSRP settings can be experimented with and saved. The masters within a live group can then be given a name (Prename) that specifically identifies them within a live group (creating files called SYSW and ADSR).
Finally, there are two more files that you'll spot in the disk catalogues — SYST that holds a recorded piece of music done with the Digitrack program and SYSP that sets the overall pitch of concert A from 200 to 600Hz. So transposition of recorded or real time music away from standard A = 440 is possible. This pitch control is one of the Gestast program options, along with save, load or delete of a Track recording, a Master preset, an ADSR set, or a full live group of presets complete with allocated ADSR set. The term 'Live' is used to indicate that they are played live from the keyboard and selected in real time from the micro keys 0-9. The supplied Data disk contained four sample Tracks (each with a Live group of Master presets and ADSR's), 20 Spectre waves and 13 Master presets.
The 8-bit digital sound generating boards provided by Jen look and sound every bit as good as those used with alphaSyntauri and Soundchaser. Some system noise is apparent and the frequency range is restricted at the top end.
With continued use, the system is enjoyable and versatile to use, allowing creation of almost unlimited sound waves with Spectre and Grafond. Spectre allows you to add together a total of 24 harmonics instead of the usual 16. In terms of wave plotting this definitely improves the appearance of, for example, a sawtooth wave, but does not dramatically change the sound output due to the restricted upper end. However, the harmonics do produce the expected sound output for most waves.
The main Spectre display shows the value of each harmonic entered (rounded on the histogram to tens) in the top half of the screen and the phase angle below. The actual values given to these can be seen by calling the 'Data' screen display. Some discrepancy in making a standard wave like sawtooth, by using all the harmonics dividing the fundamental (1st harmonic, set at 100) by 2, 3, 4 up to 24, occurred as the result was always a whole number, but this is still good compared with other systems.
Trying to draw a sawtooth with Grafond was considerably harder, as it is quite tricky to plot individual points that don't move horizontally and vertically for the 'skyscraper' wave effect. The standard Apple paddles have a rotary knob that does not help accurate plotting of the wave either, although Jen have their own special joystick in the pipeline. Higher values take a few seconds longer to plot too.
Spectre takes around two minutes to plot 10 harmonics and four minutes to plot all 24. The choice of phase angle lets you create many more waves of richer character, but this and the other systems all lack modulation of phase, filter tone and amplitude. The chorus effect available during the making of a wave helps greatly, along with pitch modulation (from the LFO), to make up for this and create a 'moving' sound.
Spectre provides organ-like, bell-like (Casio-like!) and bright mixture sounds. On the other hand, Grafond adds the guts and makes bizarre ring-modulated sounds, brass, very good strings and woodwind (even sax) with chorus. It's possible to make a random wave like white noise, but the resolution is not very high and the final sound will be more like a gong or thunder! So, unlike the Syntauri which has a noise source generating routine for percussion and natural sounds, the Jen does not have a full effects department.
It's a tremendous advantage to be able to call up a Live set of 10 presets and ADSR's from disk (taking some 15 to 30 seconds) and still be able to modify them as you wish using the screen display and micro keys during a performance. The rather 'musician-unfriendly' use of hex values for changing ADSR, LFO, octave and volume is not really a problem as counting up or down of the chosen parameter is done in 1 's or 10's by use of the two arrow keys. It also takes a while to get used to the highest value (FF in hex = 255 in decimal) being the shortest time for attack, decay and release!
A dramatic "FATAL ERROR" sign comes up on the screen quite frequently when finding your way round the system, and no indication of why you went wrong comes from this 'one only' error statement. One particular reason for a disk not accepting a saved file was simply because a disk which is full has no way of telling you! Mind you, reading the manual closely and using a space checking routine for DOS would solve that problem.
The 4-track recording 'Digitrack' system (called Track mode) is very easy to use and allows complete freedom in changing presets for tracks. This becomes essential for matching levels rather than setting tone as the system only has an overall volume level (this could be a disk error as each preset does have volume control access). Recording of each polyphonic track is done by recording track one, playing one back as you enter track two, and so on, with any or all recorded tracks playable. This mode allows recording and playback at real time speed and stop/start procedures are done with the micro's 'space' bar.
The 'Mono' mode is more versatile in that it offers much longer recording of a single (8-note polyphonic) track with faster variation of speed on playback, plus a repeat option.
The system's ability to play all tracks polyphonically is valuable and, as a general guide, quite fast pieces with 1/16 notes last about 2'30" per track, while pop music lasts around four to five minutes (in Track mode). This is probably more realistic than the quoted 1000 notes per track. There's no indication of the number of notes used, although a full memory is shown aurally and visually. You can't overdub or do any editing to a particular track — you just have to do the whole track again, but you can play the keyboard from a selected preset voice along with the playback of your digital recording.
With a price tag that's well below the other two systems at £900 inc VAT (less the micro and disk drive(s)), Musipack certainly is an attractive proposition for anyone wanting to get into computer music making.
If you read between the lines, you'll detect a little tidying up is required here and there. For example, the manual needs a much more informative approach, including help with system resets and restarts, and the addition of a noise source is important.
Musipack is meant to be a complete system in itself and as it stands has no external triggering or sync to tape available. Jen promise that these are all planned as disk updates, along with 16-track recording and music printout which are really essential to ensure the future expansion of the system (these facilities are already available for Syntauri and Passport systems at additional cost).
As a first system for the budding electronic musician, it's ideal, with easy control and good screen displays and file management — provided you organize your files!
The Jen Musipack 1.0 System is distributed in the UK by British Music Strings, (Contact Details).
Review by Mike Beecher
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