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ST Replay 4 Sampler

Article from Sound On Sound, January 1989

Martin Russ has fun turning his Atari computer into a multi-function sampler, drum machine and digital effects unit with the aid of Microdeal's low-cost Replay 4.

Martin Russ has fun turning his Atari computer into a multi-function sampler, drum machine and digital effects unit with the aid of Microdeal's low-cost Replay 4.

Do you use your Atari ST just for sequencing? I doubt it. I suspect that, like me, you have a few games hidden away for those quiet moments! In any case, you may have noticed that the sound effects employed in ST games fall into two types: rather nasty overgrown 'beep' sounds, or sampled voices and soundtracks. Using the Yamaha three channel sound generator chip isn't really the domain of hi-tech music, so we can forget the perils of the first type. The second type promises to be more interesting — but how do the games programmers manage to sample sounds and make their software replay them?

With only an 8-bit sound chip inside the ST, it probably comes as no surprise to learn that the programmers do not use Akai S1000s to do their sampling. In fact, the 8-bit sampling they use has more in common with a cheap Casio SK1. This gives away the major topic of interest here - we are talking very low-cost sampling: below £100 for typical hardware/software packages.

Simple, cheap sampling hardware for use by programmers to liven up computer games is all very well, but what use is it for 'real' music?

In order to find out, this article looks at a representative 'second generation' sampler package called Replay 4, from Microdeal - a software house with a well-known music product: Super Conductor, a very nice entry level 16-track MIDI sequencer.


The first generation of samplers for the Atari ST were designed solely for incorporating sounds into games, and so had only rudimentary editing and playback facilities. By the time the second generation were being designed, even the games people had noticed that the ST had MIDI sockets, and so the latest samplers have some sort of MIDI capability and more sophisticated editing functions, turning them from a programmer's tool into something with much more potential for the hi-tech musician.

Replay 4 is just such a system - a hardware add-on to the ST that provides the necessary sampling and playback functions, and several programs to exploit the capabilities. Hardware-wise, you are supplied with a grey dongle-sized box that houses two phono sockets and a PCB edge connector which plugs into the ST's cartridge port. Inside there are the expected Analogue-to-Digital and Digital-to-Analogue convertor chips (from a UK semiconductor manufacturer!), together with an 8-bit latch, some miscellaneous TTL gates and, most importantly, two active filters - an anti-aliasing filter on the ADC input and a reconstruction filter on the DAC output. With a maximum sampling rate of 50kHz, they are probably second order filters with a cutoff frequency of about 20kHz.

Since the ST's internal sound chip can be used as a simple unfiltered DAC, you can utilise the speaker on your TV or monitor for audio playback - as used in games programs - but the Replay 4 quality is much better when using the Replay unit's own output socket, and so this is to be preferred for serious work. Overall, this seems to be a neat and adequate design without any unnecessary frills or major shortfalls.

Version 4 of Replay refers to the software, which has undergone the traditional 'new and improved, much better than before' rewrite so familiar in sequencers - the sampler unit itself seems unchanged. The hardware may be the same as in the original unit, but the software really has evolved and improved considerably. In fact, two different versions of the Replay software are included in the package, as well as programs to exploit the hardware as a real-time effects program and a sampling drum machine. Everything works on both high and medium resolution monitors, which is more than can be said for some software. Two, almost full, single-sided 3.5" disks are provided, as well as an A5 size 70+ page manual.


It's the software that makes or breaks a sampler these days, and you get lots of options with the Replay 4 package. Two versions of the basic program are included - one is the latest version (3.01) of the original non-MIDI software, and this is really only suitable for the programmer/dedicated user. It has a Function key/QWERTY key control format which is not very user-friendly, although restricting the control functions in this way does mean that the program is very compact and this frees more memory for longer samples.

With this version, you can sample at rates from 5kHz up to 31kHz, which gives sample times of three minutes down to around 20 seconds on a 1040ST. The lack of MIDI compatibility really means that you are restricted to little more than using it as a solid state tape recorder emulation. I had great fun sampling CDs, looping and 'munchkinising' sections of music, and even jamming along with famous names. But apart from creating atmospheric reversed loops for backgrounds, I really can't think of much in the way of serious use. However...


The second program supplied is Version 4.1, and this is considerably more usable, mainly because of its use of GEM, MIDI compatibility, improved sampling speeds, and better editing and sample manipulation utilities. You can use the mouse to control the program, and QWERTY keyboard command alternatives are provided for non-rodent lovers - the frequent use of the 'Escape' key may also persuade you away from too much dependence on the mouse!

Sampling with the Version 3.01 software is a bit 'hit and miss', with little feedback until after the event (you may be familiar with other samplers that are like this!). However, Version 4.1 adds a level-based trigger option to start sampling only when the audio signal starts, but most importantly lets you pre-check the level of the input via a real-time sampling Oscilloscope feature; very pretty as well as useful. In the same vein, there is a simple real-time Spectrum Analyser which measures frequencies up to just over 5kHz and displays them in bargraph form. Another useful function enables you to monitor the incoming audio through the digital conversion system, but without actually storing it - another 'why can't all samplers be like this?' type of feature, since you can verify what the end result will really sound like without actually taking the sample.

Once sampled you can do the traditional silly things, like playing back the sound at a different sample rate - using the Replay audio output you can sample and playback at eight different sample rates, from 5kHz up to 50kHz.


Two cursors, which are moved either by clicking on the arrow boxes or by dragging with the mouse pointer, are used to define areas of the sample in all the editing operations. You can loop a sample between the two cursors, reverse it, smooth it out with a simple low-pass filter, copy it, insert it, delete it and even clear it! Once defined, a sample can be named and stored in Function key memories or on disk.

The use of two cursors means that you cannot perform Macintosh-style dragging to select areas of the sample. Also, they can be quite cumbersome to position precisely, although the sample block between the cursors can be magnified until there are only 600 sample values shown - at which point the options for displaying the data become useful.

The Filled option is the default, but the Outline mode shows a more traditional oscilloscope type display. The Envelope mode reflects the Filled mode about the x-axis to give a good display of bursts of activity. Simple fading in and out controls, together with an overlay function, allow crossfades and mixing of sample segments.


It hardly needs me to tell you that you can concoct 'n-n-n-nineteen' sound-alikes by stabbing frenetically at the 'R' key, so I won't. If you select the looping option the sample will repeat until you press the 'Escape' key - so beware! Of more interest are the ways you can make things happen via MIDI.

There are two MIDI control options: the obvious one is to use the incoming MIDI notes as transpositions for the current sample (you can also do this in real time, enabling a crude SPX90-style pitch shift function to be achieved), but with the second option you can assign up to 10 notes to act as triggers for separate samples. You are restricted to a single MIDI channel, monophonic playback and there is no velocity sensitivity, but this could be used for triggering sampled effects, dialogue, or special drum sounds.


Two parts of the Replay software are improved and extended in two additional programs: realtime effects, and drums.

The GEM button-controlled Effects program provides simple audio effects which suffer from the quality limitations of the 8-bit sampling rather more than the straight samples seem to. There are several presets: two 'Ramp' buttons modulate the volume level at different rates, while the 'Hall' and 'Room' buttons offer multiple echoes, and 'Distortion' does exactly what it says! Three user-programmable effects allow control over the delay and repeat volume of a simple single Echo and a multiple echo 'Reverb'. The 'Reverb Up' option combines elements of the echo with the real-time pitch shifting to give multiple echoes which increase in pitch. Very nice.

The Drumbeat software turns the Atari ST into a sampling drum machine. Up to 16 Replay-derived samples (at 20kHz) can be loaded and played back using this program, and sets of samples can be saved as drum kits on the disk - a default kit is provided when the program loads. You can store 99 drum patterns of between 4 and 32 steps each, and songs can be built up from 70 pattern entries with looping, and both real-time and step-time recording is possible. Songs and patterns can be saved to disk as well.

Drumbeat does not have any MIDI capability, and the sample volume is fixed. Most important of all, you can only have two samples playing back at any given time - but this doesn't prevent you from putting the program to good use. The playback tempo is displayed in 50 or 70Hz counts per beat, which means that faster tempos have smaller values - very strange!

The program is made more difficult to use because it works with the GEM-style Menu bar but not the mouse; you use the cursor keys to move around the screen and the Escape key to exit from selections. Despite this, using Drumbeat is not difficult, and editing a pattern or song is much easier than on many professional drum machines because of the large screen and ease-of-use of the cursor keys. However, the lack of dynamic control and external synchronisation facilities makes Drumbeat more of a diversion than a serious contestant in the drum machine race.


A combined sampler, digital effects unit and drum machine cannot cost less than £100 without making some sacrifices - 16-bit resolution and quite a lot of functionality (like using the 'Escape' key to exit every playback function!) go out of the window for a start, but what is left is something which lies just on the edge of viability. If you use your Atari ST for sequencing full-time, then an ST-based sampler unit like Replay 4 may not be so useful, because it ties up a valuable resource. But if your micro is only sequencing for some of the time, then you might be able to exploit it more fully with an add-on sampler, and at the price it is almost worth it in fun and education value alone.

In the end it comes down to creativity, using appropriate technology, and working within restrictions - would you use a CD-quality sampling system to make jingles for answering machines? If you want a MIDI sampler then can you afford to lose your ST-based sequencer, and what sort of 'dedicated' sampler could you swap for five hundred pounds worth of Atari ST and Replay? If you want background sampled loops low down in a mix, then don't forget that if the sound is below about 50dB down, then the digital noise from Replay 4 will be comparable with that of a CD player! Additional MIDI-triggered drum sounds could be played back from Replay 4 if your sampler is not multitimbral and is used as a keyboard instrument or expander.

If you want to explore the wacky world of reversing, looping, cutting and pasting on a limited budget, then Replay 4 could be your route to learning the skills to 'toast', 'rap', 'scratch' and 'house-ify' today's music...


£79.95 inc VAT.

Microdeal, (Contact Details).


Many of the companies currently producing low-cost add-on samplers also offer more comprehensive and professional features from other units in their range, at increased cost. Most of these seem to be under development at present and we should soon see several 12 or even 16-bit, 44.1kHz samplers for only a couple of hundred pounds.

Fully professional computer-based samplers with digital signal processing capability currently cost well over £1000. For example, Lynex from Commander Electronics and ADAP from Hybrid Arts are two ST-based systems which offer comprehensive facilities on a par with the most sophisticated stand-alone samplers.

Closely associated with these are the hard disk recording systems, where the sounds are stored directly onto hard disk as they are recorded, instead of using the more traditional tape-based storage devices. Because of the large amounts of RAM and the size of the hard disk required to store any truly usable segments of music, these systems tend to be very expensive.

Lynex - Commander Electronics (Contact Details)
ADAP - Syndromic Music (Contact Details)


The Amiga, Macintosh and Atari ST computers can all play back sample data through their internal sound chips without additional hardware. The Amiga has a more sophisticated system than the ST - a custom designed sound chip called PAULA, whereas the ST uses the Yamaha YM2149 chip (also used in the Spectrum +2 and Amstrad CPC computers. The Macintosh uses a direct conversion system which directly drives an internal DAC, and so is similar to Replay in its basic capabilities. The Mac II uses the Ensoniq 'Q' chip (as used in their Mirage sampler) and so has very good facilities without any need for additional hardware.

Because the sounds are usually stored as plain sample data with just header and trailer information, it should be quite easy to convert between one format and another, although there are only a few programs that actually do this. The original advertising for the Amiga mentioned quite prominently that its sound files were compatible with those of the Fairlight!

In games programs in particular, the combination of coarse sampling and TV speakers tends to degrade the quality of the resulting sounds quite markedly. But you can dramatically improve the playback quality by feeding the output of simple 8-bit units like Replay through hifi loudspeakers. The forthcoming 12-bit or 16-bit versions, which use CD player technology, should be capable of very high quality indeed.


- Pro Sound Designer (£49.95 ST & Amiga)
- Pro-MIDI software (£29.95 ST, £39.95 Amiga)
Eidersoft (Contact Details)

- Digisound ST (£89.99 ST only); includes MIDI software
Siren Software (Contact Details)

- IS Digitiser (£69.95 ST only)
- IS MIDI Sample Player software (£24.95 ST only)
Chips Computer Centre (Contact Details)

- Pro Sampler Studio (£69.99 Amiga only)
Datel Electronics (Contact Details)

- Sophus S5 (£148.35 Amiga only)
Amiga Centre Scotland (Contact Details)

- MacRecorder (£145 Macintosh only)
Any good UK Mac dealer

Also featuring gear in this article

Previous Article in this issue

Brian Eno: Thoughts, Words, Music and Art

Next article in this issue

Amiga Music!

Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

The current copyright owner/s of this content may differ from the originally published copyright notice.
More details on copyright ownership...


Sound On Sound - Jan 1989

Donated & scanned by: Mike Gorman

Gear in this article:

Software: Sampler > Microdeal > Replay

Gear Tags:

Atari ST Platform

Review by Martin Russ

Previous article in this issue:

> Brian Eno: Thoughts, Words, ...

Next article in this issue:

> Amiga Music!

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