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Mixdown Amiga Software

Software for the Amiga

A British company have a comprehensive sampling package for Commodore's Amiga. Does it set a standard against which subsequent Amiga software will be judged? Chris Jenkins finds out.

As Commodore in America struggle through a financial crisis, a British company comes up with the Mixdown Music System, a comprehensive package for the new Amiga. We preview the software that could turn the world's most powerful home computer into a sophisticated musical instrument.

Without question, the concept of the 'home computer' has had to be redefined with the advent of Commodore's Amiga PC. With the advent of the Mixdown Music System for the Amiga, we may soon have to examine our definition of 'computer music', too.

The Amiga, as most of you will know from previous E&MM features, is a high-end home/low-end business machine, recently launched in the UK at around £1500 for the basic system. This system consists of a central 512K processor unit with built-in disk drive, detachable keyboard, colour monitor and mouse. There's an £1800 version available with an extra disk drive.

The Amiga is not to be confused with the IBM PC lookalikes which it so closely resembles physically. Its central processor is the fast, powerful 68000, as used in the Apple Macintosh and Atari ST, and it has three special chips which handle data transfer, graphics and sound.

Although the data handling and graphics are stunning (ten times the speed of an IBM PC, 4096 colours, multi-tasking of eight simultaneous jobs, full window/icon/mouse interface and so on), it's what the Amiga sounds like that should interest musicians. Using Mixdown, the Amiga becomes more than a computerised musical box. It can be a complete sampling, FM synthesis and MIDI composition workstation, to use a popular phrase.

The Mixdown system owes a good deal to the Commodore Sound Sampler and FM Voice Module for the CBM64. Designed by the same developers, Music Sales, Mixdown takes the concept to limits which only the Amiga could allow. A July release is planned, and on the version we looked at, the software was 90% complete, with hardware finished save for a temporary case. The Mixdown hardware looks unimpressive: a flat case about 8' x 6" featuring cable connectors for the Amiga's serial and parallel ports, and a number of MIDI In, Out and Thru sockets.

The Mixdown software allows four-note polyphonic sound-sampling at the limits of the Amiga's possible quality, full editing routines, and control of a built-in nine-voice digital sound synthesiser. The samples and synth sounds can be played either from a MIDI keyboard, or from an optional five-octave Commodore keyboard which attaches to the Mixdown module. This keyboard is identical to the models available for the Commodore 64 music packages, and is of perfectly decent quality - though it lacks such 'pro' features as velocity or touch response, mod wheels and the like.

Using the Mixdown system, sound-sampling is performed through the interface, which has a Gain pot to adjust for either microphone or line inputs. The main control screen features six boxes, which in the final version will be labelled with icons, and five menus at the top.

The first menu is the standard project menu (options are New, Open, Save, Rename, and Quit). Most of the recommended Amiga operating system standards are adhered to in Mixdown, so that, for instance, Mixdown samples can be integrated with Electronic Arts Music and graphics programs. The project menu, then, allows you to name a sample, decide which of the four available sample windows it will be displayed in, and to define the sample time used. All the control options are carried out by moving the mouse pointer to the correct menu or option and clicking the mouse button - an incredibly fast and easy way to work.

The total sample time available on the 512K Amiga is eight seconds, at a reasonable sampling rate of 16kHz. Unfortunately, the Amiga's sound output filter cuts off any signal above a frequency of 7.5kHz, which limits the sound quality possible to well under that of, say, the Mirage or Emulator II. Pity.

Sampling is carried out by setting the input trigger level (displayed in the form of an LED bar), selecting the Record gadget, then simply playing the sound, at which the screen blanks to indicate that sampling is in progress. Anyone who's used computers of the Spectrum generation will be familiar with software that blanks the monitor screen during the most work-intensive tasks, but I'd have thought the Amiga had enough processing power to maintain some kind of graphics display during sampling. Maybe it isn't so clever after all...

Once you've made your sample (or recalled one from a disk, which can store around eight full-length samples), the waveshape can be displayed in the appropriate sample window.

The x-axis (time) of the sample display can be rescaled to show the whole sample, where one pixel on the screen represents one six-thousandth of a second. Alternatively, the sample display can be compressed into a single window, or you can slide through the whole sample display a piece at a time. All four sample windows can be resized, by 'dragging' the corners using the Amiga's mouse controller, and all have full auto rescaling.

After sampling, the pointer changes into a keyboard shape, and you can play back a monophonic sample at any pitch from either MIDI synth or Commodore keyboard. This mode is designed to allow you to edit the sample to your own requirements, before going into Multiplay (four-voice) mode to set various performance parameters.

One of the most important facilities is looping, by which two loop points can be defined and highlighted on the sample display. There are two forms of looping; either playing from the beginning of the sound, then around and around between the loop points; or, using the Truncate option, just looping around the loop points. Needless to say, the Amiga's graphics displays make this routine a joy, and a stark contrast to the pleasures of interpreting hexadecimal LED displays on the Mirage, which have driven many keyboard players to the verge of hysteria. Score one to the Amiga.

Should you have an unwelcome click on your sample, you can select the Draw option, and use the pencil pointer to redraw the unwanted part of the sample display. You can even use this option to create a whole new sound, but, as with more powerful systems like the Fairlight, it's almost impossible for a human operator to have any real control over the results - most efforts just sound like distorted sinewaves.

The Edit menu allows you to Cut out unwanted sections of the sample and close up the gap, or take sections and Copy them to new positions, or Paste sections into the middle. You can 'mix and match' sections cut from the four available samples, to create weird sounds such as the attack of a guitar with the sustain of an organ and the decay of a piano. Plenty of novelty value, if nothing else.

The next menu contains a Help section, and the following one a Digital Equalisation page. This allows you to create vibrato and tremolo effects using variable rates and depths of frequency and amplitude modulation. You can also define filter settings, with parameters for filter centre point, resonance, and low, middle or high pass filters. A six-stage filter envelope is provided, and the program recalculates the whole sample according to these filter characteristics. The results can be some extraordinarily 'unreal' sounds.

The Special Effects options can only be used on outside sound sources, not applied to the samples themselves. They include Echo, which gives a fixed-pitch forward or reverse repeat with variable delay, and Harmoniser, which allows you to produce double-tracking effects at any required musical interval.

Keyboard Mapping and Split options provide a display of a five-octave keyboard, and allow you to define three split points, assign any sample to any keyboard section, and define different MIDI control channels for each keyboard section. Using a MIDI sequencer, you can play three different instrument sounds from the Amiga, while adding a solo on a fourth sound played live on the keyboard. And you could, of course, use this option to produce more convincing multi-samples, too.

The MIDI section enables you to set up the Amiga to accept MIDI In signals on any channel, and to transmit MIDI data, should you want to use the Commodore music keyboard as a master controller (unlikely, but you never know).


Amiga Mixdown

1x MIDI In, 4 x MIDI Out, serial and parallel connections, non-MIDI keyboard connector. Nine-voice FM module

Four-voice sampling

Sample length
6 seconds at 16kHz

Filter cutoff

3 definable split points

Edit facilities
Loop from start, truncate, redraw, cut, combine, reverse, etc

Low/med/high, cutoff, resonance

Forward/reverse, harmonise, delay

Six-stage envelope

Full load/save facilities, six full-length samples per disk

Demo routines only

Price £200 approx

More from Commodore UK, (Contact Details)

Mixdown's capabilities don't stop there, since the hardware also includes a nine-voice polyphonic FM digital sound synthesiser. Based on chips licensed from Yamaha (the same ones responsible for the sounds of the DX series), the Mixdown FM chips work on the familiar system of sinewave operators which modulate each other according to complex algorithms. Sadly, the Mixdown package reserves much of the Amiga's memory for sample storage, so use of the FM chips is limited to a 'teaser' routine. You can select any one of 12 instrument icons, and play the FM sounds from the keyboard (or listen to demo tunes from the disk which also use Amiga sampled drum sounds). But you can't program your own FM sounds, or use them under MIDI control.

Much more complex FM software is in the pipeline, though. It's due to include a sound-editing package and a fully-blown composer program featuring 16-track MIDI composition using the Amiga's samples, the output of MIDI keyboards and the Mixdown FM sounds.

So what, exactly, do the Amiga and Mixdown offer the musician? First of all, if you're willing to invest £1800 in the computer, you'll be getting a machine which has a number of unique abilities not limited to the music field. The Amiga will accept a video input using a Genlock interface, and can manipulate video images. It's capable of high-speed three-dimensional colour animation. It can do your accounts, word-process, keep databases and link to communications systems, which is no more than most other computers can do. The difference is that the Amiga can do them all simultaneously.

It also has a built-in speech synthesis device, and the sound chip is capable of producing some pretty good synth noises, even if you're just programming it in Basic (or Pascal, or C, or Forth).

For the musician, the choice is harder. For £2000 - the cost of the Amiga plus Mixdown - you can get an Akai S612 MIDI sampler (which is six-voice polyphonic, velocity responsive and has fast disk storage), a Yamaha DX100 (which features the same FM synthesis as Mixdown, plus a keyboard), and a sequencer such as the Roland MSQ700, which is powerful enough for most musicians.

To the Amiga owner - and as yet there are but a handful of them in the UK, and not many more in the States - I'd recommend Mixdown unreservedly. To the musician, I'd say that unless you're convinced that the speed and ease of computer operation are what you need, and that you'd appreciate the Amiga's non-musical functions, it might be a rash move to commit yourself to a computer-based system.

Previous Article in this issue

Out Of the Shadows

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


Electronics & Music Maker - Jul 1986

Scanned by: Stewart Lawler

Review by Chris Jenkins

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> Out Of the Shadows

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