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.

REPLAY 4

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.

LET'S TALK SOFT...

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...

VERSION 4.1

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.

EDITING OPTIONS

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.

MIDI PLAYBACK

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.

EFFECTS AND DRUMS

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.

CONCLUSION

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...

FURTHER INFORMATION

£79.95 inc VAT.

Microdeal, (Contact Details).