Mark Evans and Andrew Banner explore the world of sampling on the ZX Spectrum, the ST and PC compatibles in part one of a definitive guide to micro-based samplers

What is sampling?

The process of sampling - as the name suggests - is to monitor the level of an input at regular intervals. To complicate the matter, the audio source has to pass through an analogue to digital convertor (ADC) so that it becomes binary data which the computer can then manipulate. Some samplers also offer the capability to convert the digital data back into analogue signals, and then play them back via an amplifier. This usually has the advantage of a better signal quality than from the computers internal electronics. There are major two factors which govern the quality of a sample.

The first is speed of sampling. This is usually measured in kilohertz, and corresponds to the number of conversions the sampler can make per second. For reasons I won't go into, the sampling speed needs to be at least twice the highest frequency you want to reproduce. For the full spectrum of the human ear, the sampling speed should be at least 40khz (around 20Khz being the upper limit of the ear.) The second factor which governs sampling is the resolution of the analogue-to-digital converter. Most ST based samplers convert sound into 8-bit data. This allows only 256 steps across the whole frequency bandwidth of sound to be reproduced and, thus, the sampler will therefore not reproduce exact frequencies.

The system used in CD players, where digital data is converted to analogue signals, replays at 44.1 khz and at a resolution of 16-bits (giving 65536 levels.) This results in a much more satisfactory quality than anything you can expect to find on the ST, but watch out for 16-bit samplers arriving on the ST soon.

Where now?

Once you have decided what exactly you require from a sampler, you can begin the search for a suitable unit. However, there is quite a choice for ST owners in terms of quality and price and choosing the sampler that suits both your needs and your pocket can be a bit daunting.

Here we give a round-up of some of the more popular samplers available for the musicians favourite micro.

REPLAY 4

Replay was one of the first commercially available samplers for the ST, and although it is now on its fourth software revision - which is actually a complete overhaul - the actual hardware has not changed dramatically over the past couple of years.

The sampling cartridge itself looks little more than a small grey box with a multi-coloured sticker proclaiming that it's "REPLAY 4". The only exposed electronics are two rather flimsy phono plugs and a recessed PCB edge connector. However, the cartridge is quite robust and would probably withstand just about everything a user may want to do to it.

Once Replay is installed in the cartridge port of your ST, all that is required is a mic level input of around 2.5v peak to peak. This is fed into one of the phono sockets, while the other provides a similar level for connection to an amplifier and speakers (recommended.) As mentioned above, two factors determine the quality of samples. Replay is an 8-bit sampler with a maximum sampling speed of 50khz. The internal architecture of the cartridge also boats anti-aliasing circuitry to provide a cleaner, filtered sound on the cartridges input and output lines as well as a software filter for "cleaning up" samples.

The first of the two supplied disks contains two versions of the Replay sampling software. One is version 3 of the software, which is simpler and requires less workspace, thus leaving you with more room for your samples. The other is version 4.2 which incorporates the more advanced features of the sampler, and so this is what we will concentrate on. On booting up the software you are presented with a screenful of rather flashy looking icon buttons and an oscilloscope type display, all set in a GEM environment.

Preset functions are accessed by standard GEM dropdown menus, while the buttons icons are activated by clicking on them. In addition, some functions can also be accessed by single keys. The software allows sampling at 5, 7.5, 10, 15, 20, 30, 40 and 50khz. However to obtain the last two rates, the cartridge must be connected to an external amplifier, as the STs internal electronics cannot cope with these high frequencies. A toggle on the menu allows you to select the appropriate sample/playback rate, as well as the output device (monitor or external.) Usefully, if using a monitor as an output device, the higher two frequencies are automatically disabled.

Actually sampling with this software couldn't be any easier. Connect a microphone, Walkman or whatever to the input plug, select the "LISTEN" button and when the desired sound is heard, clicking the "SAMPLE" button or pressing "S" on the keyboard will commence sampling. Alternatively, the sampling process can be triggered automatically once a certain threshold volume has been reached. Once your sample is in memory, it is shown as a graphic waveform. The type of interpretation can be selected from filled, outline or envelope type display. Moving two sliding cursors allows the user to select the start and end of each sample, and therefore offering simple editing.

More advanced editing features can be found on the buttons below. All editing features work on predefined blocks. Defining a block requires setting the cursors to a desired position and clicking on the "BLOCKS" icon.

Once this is done the COPY, INSERT, DELETE and CLEAR options will operate and are all fairly self explanatory. REVERSE will reverse whatever's between the cursors, while OVERLAY will copy a sample onto another area, but has the side effect of reducing volume. Fading in and out is also possible by positioning the cursors and clicking the appropriate buttons, and if the sample needs cleaning up the FLITER option can be used. SPECTRUM and SCOPE allow the user to monitor the incoming signal on either a spectrum analyzer with a 5Khz bandwidth or a real-time oscilloscope. Unfortunately, no sound can be heard while these functions are operating. MIDI support was one major addition to this latest version of the software. It is available in two forms but, alas, both of which seem a little basic. This first allows you to assign a sample to a specific note on your keyboard or synth. For example, you could have a dog bark on middle C and a duck on A2 but all other keys would function normally. The operating MIDI channel can be selected under software, so there's no need to fiddle with keyboard controls. The second MIDI option allows a sample to be selected and then pitch shifted across an eight octave keyboard (one octave can be simulated on the STs keyboard.) To change the current sample, one of the ten presets can be called up with the appropriate function key. The major snag with this system is the stretching effect that occurs when shifting more than an octave. Both the software and hardware work very well, and it is this that has made Replay one of the most popular ST samplers available.

PRO SOUND DESIGNER

Pro Sound differs from Replay in that it is plugged into the STs printer port and requires a power line from the joystick port. The size of Pro Sound itself is roughly the same as the mouse, with the only visible connections being a tiny 3.5mm input jack and a 25-pin D connector. The software supplied with the system exists in two forms. The first is for users with colour systems and has an extra feature allowing you to edit the STs internal sound chip. For monochrome users a second version is supplied which has a data compression system instead of the sound chip editor. Bas-relief icons make the software for Pro Sound probably the neatest and most visually stimulating of all the samplers reviewed. All the functions are mouse controlled using a screenful of bas-relief icons. Top marks for being user-friendly!

The editing options offered are similar to Replay's and include all the usual cut and edit features. Two windows are shown which provide a graphic display for both the incoming signal and the sample currently held in memory. Playback and sample speeds range from 3khz to 30khz, so the unit is not quite as versatile as many. The actual sampling quality is on a par with the price of unit, ie. fair but not up to that of Replay or Mouse Music. If you plan to trigger samples from this unit via Midi, then you will need an additional piece of software from Eidersoft. For £19.95 they will sell you Pro Midi, a full featured Midi controller program for Pro Sound.

PRO SAMPLER STUDIO

This is one of the newer offerings on the market from veteran peripheral company Datel Electronics. The unit is most aesthetically pleasing and fits snuggly into the cartridge port of the ST. Opposite the cartridge port are now three 3.5mm jacks for audio output, line in and mic in. One good feature of the cartridge is being "L" shaped, there is little chance of accidentally removing it, but I did experience some problems in fitting the thing in the first place! It was at this point I decided to consult the manual. I found it at the bottom of the carton and nearly had a heart attack. The manual is a stapled affair with a brief (and I mean brief) paragraph on each of the functions. Come on Datel, a decent manual doesn't cost the earth and adds so much to the real value of a package. If Microdeal can write a 68-page squarebacked manual for Replay, why can't you?! Armed with the manual, I booted the supplied software. I was presented with a rather tacky looking front-end with the words "Datel Electronics" splattered across one box. The system has a similar bas-relief style as Pro-Sound, but without the elegance. The manual is bad, maybe the software is just poorly documented?

No such luck. The features and execution left quite a lot to be desired. Everything is mouse controlled, but there tends to be a time-lag after any recording or playback function which becomes very annoying. There is also no provision for immediately interrupting a sample. On the subject of playing samples, the only way to hear Datel samples is from the jack supplied on the cartridge, there appears to be no output from the monitor. Samples can be recorded and played back at intervals of 1000hz between 5 and 30Khz. This function is controlled by two arrow icons which has the tendency to 'over-shoot' the desired setting and therefore making setting an exact frequency quite tricky. The rest of the functions seem to fall into the same mediocre category, and consist mainly of the standard editing feature found on other samplers. One function that really amused me was the 3-D plot of a sample. Could this be a full 3-D Fourier graph I asked myself; no, a crummy pseudo-3D plot. MIDI support for Pro Sampler seems to work adequately, but I really must quote the manual to give you a complete understanding of this complex process:- "If the sample has been recorded at the frequency of middle C, then you will get a perfect 2 octave range at you disposal." Sadly, there isn't a lot to recommend the Datel Sampler, which is a shame really because the actual hardware performs quite well and the supplied demo sample seemed really quite crisp. Perhaps a re-write of the manual and software could provide the necessary boost for the system? Are you listening Datel?

If it's professional 16 bit quality you need then if you have an ST you're already half way there. All you need now is the A-16S Sample rack from Audio Visual Research. The A-16S costs £595, considerably cheaper than the £2,000 Lynex unit and the Hybrid Arts ADAP system which is in the same price range. Cased in a black rack box which can be securely screwed into a rack of other music equipment, the front panel is void of controls and merely has an on/off rocker switch with a tiny power LED indicator alongside.

The Sample rack is a professional sampler which will turn your ST set-up into a most powerful computer sampling, editing, workstation. The sound quality it provides is superb, and according to co-designer, Dave Woodhouse, provides "CD Quality output". He went on to demonstrate this by getting the sampler to monitor an incoming signal from a CD Walkman. Being diverted through an audio amplifier allowed the inputs to be switched from the computer to the CD and there was absolutely no audible sound alteration between the two. The reason for this is that the A-16S is a true 16-bit stereo sampler which gives high quality stereo sound without using any more memory than a standard 8-bit unit such as the ST Replay package. Because of the high sound quality provided by the A-16S Sample rack, the unit can sample at lower frequencies and still attain a good quality output. Sampling at slower frequencies allows more of the sample to be in memory and so longer clips can be stored.

Or if you wish, you can sample a whole song using not the memory in your ST but the vacant space on your hard drive. The software provided with the package allows direct to hard disc sampling, so that you are not restricted by the volume of memory in the computer but by the 20 or so megabytes on the hard drive.

The A-16S connects to the ST by a long ribbon cable which disappears into a largish "L" shaped grey box. This contains an interface which allows the unit to be plugged into the cartridge socket of the ST.

The software supplied with the package includes many features unseen on other sampling packages before. One of the most powerful of these is Fast Fourier Transform - FFT. This provides a three-dimensional landscape graph of the sample in memory, showing the levels of frequency and amplitude and show the distribution of frequencies. Using these graphs you can see which frequencies provide certain sounds such a symbols, drums, vocals etc and then subject the sample to a high or low pass filter so that the frequencies specified will be cut out. Very good for isolating certain sounds.

The software also provides a real-time scope and special effects can be added to the sample, either in real-time or the sample in memory. Just in case you don't like the outcome of a certain effect, you can preview it without physically altering what is already in memory. One of the most useful features is pre-sample. This causes the system to continuously samples what it is receiving. Once you have heard the bit you wanted to sample, press a key and it is there instantly without having to set up your source media to the precise point you wanted to start the sample at.

Like ST Replay, the A-16S package supports full MIDI control and samples can be assigned to certain keys on the MIDI keyboard. The software also provides a MIDI frequency shift function as well as full looping control.

Previous sampling software from 2-Bit Systems was often not very user friendly and was quite a chore to use. The new software, across the range of products, is fully GEM orientated and much simpler to use. It occupies little memory to make the most of sampling and contains features which were not available on previous 2-Bit Systems products.

Also supplied with the A-16S Samplerack is a four channel stereo sequencer which allows up to 100 song entries using 99 patterns with full MIDI implementation.

But however much cheaper the A-16S is when compared to the Lynex sampling package, the Lynex does provide a better quality sound, but that is for the perfectionist only. It really depends whether you are prepared to pay an extra £1,400 on the equipment for a slightly better package.

But for some serious musicians, £595 is still a lot of money, and for those of you on an even tighter budget, Audio Visual Research have launched ST-14 a 12-bit input, 14-bit output mono sampling module. Retailing at £245, ST-14 is a much cut-down version of the A-16S. It comes housed in a grey "L" shaped box which, again, attaches to the cartridge port of the ST. The sound quality provided by the ST-14 is very good, especially for the relatively low price, but obviously isn't in the same league as the professional Samplerack.

The software supplied with the ST-14 is much the same as that of the A-16S, and includes the such features as FFT, real-time scope, a cut and paste buffer and filters. Like the other new sample packages from AVR, it too is MIDI controllable and includes a four channel output sequencer.

For those who prefer to use IBM PC machines, you too are in for a treat. IBM Replay will soon be finding it's way onto the market sporting some impressive specifications.

Supplied on a half card, IBM Replay is a mono sampler package with the ability to give stereo output. Although the unit is just an 8-bit sampler, the sound quality can be very good, and the length of you sample can be incredibly long. Most serious IBM PC owners already have a hard drive installed in their machine and Replay makes good use of this by allowing direct to hard disc sampling.

The card is professionally made and will fit into any vacant slot in the IBM. With the card fitted, the rear of the machine now has three phono sockets and one 9-pin D type connector poking through the hole. One phono connector is the mono input, the other two are the pseudo stereo output ports while the D connector provides MIDI control. While MIDI is traditionally connected with DIN plugs, the nature of the IBM machines is such that a DIN socket would not fit in the card hole at the rear. Manufacturers of MIDI boards for the IBM, therefore, began to employ D type connectors. A lead is supplied to convert the non-standard plug to DIN sockets.

Using MIDI with IBM Replay allows keyboard frequency shift as well as assigning samples to certain keys. Further functions within the software include fast fourier transfer which operates in the same way as the other packages, and two landscapes are available for left and right channels. Using this display it is possible to determine the distribution of frequencies and cut out certain sounds using the high and low pass filter routines which are built into the software.

IBM Replay will retail at about £150 and should be available by the time you read this.

Perhaps one of the strangest products to come from Audio Visual Research is Spectrum Mastersound. After the company started in 1986 with an Atari 8-bit sampler, they progressed into the 16-bit world and have now taken a step backwards to cater for the machine which has become a household word.

The first thing to mention is that Spectrum Mastersound has been designed for 128K Spectrum computers only and will not work on anything with less memory. Costing just £39.95, Spectrum Mastersound will be marketed by Kempston who have set up a joint company with AVR called Pandora Marketing. Pandora will market Spectrum Mastersound package as well as Mastersound, previously commissioned by ill-fated software company Software Horizons.

The physical sampler plugs into the expansion port of the Spectrum and consists of an interface and sampling circuit, this is essentially a modified ST Replay board. The software comes on either tape or disc at no extra cost and has some impressive functions for such a basic and old machine.

The main screen contains icons which are selected by pressing corresponding keys. At the top lies the sample window which provides a visual display of the audio clipping in memory.

Sampling frequencies range from 5 Khz to 25 Khz which allows approximately 10 seconds of sample at 5 Khz. Also provided is a real-time oscilloscope which makes adjusting the input volume very easy and you can see when the signal becomes too loud as the peaks begin to flatten out at the top and bottom boundaries of the sample window.

The software can also create effects in real-time, acting on the incoming signal from the source. Effects such as echo, flange and pitch shift can all be added to the audio just by pressing a few keys.

The user interface on Spectrum Mastersound is very friendly. The screen display is very tidy and is not cluttered by unnecessary illustrations and fancy drawings. As with all 2-bit Systems products, it employs a down to earth approach to attain ease of use and works well. Certain sections of the program cause window to open and display a new array of commands, the effects section is a good example of this.

The sample window is equipped with the standard vertical cursors which can be positioned on the sample. The positioning of these lines allows you to play only what appears within them any you can also zoom in and view the section in more detail and this allows more precise cursor positioning.

The software allows up to eight samples to be held in memory at one time. These can be assigned to certain Spectrum keys which trigger the sample. Output from Spectrum Mastersound can be heard through the television of monitor speaker or piped through an external amplifier using the output socket on the sampler.

Surprisingly, the sound quality provided by the package is remarkably good. At 25 Khz you only get a very short sample, but the quality is excellent for such a simple computer.

But, what will appeal to most Speccy owners is it's ability to include samples within BASIC programs using a short routine provided in the package.

Another product from Audio Visual Research - yes there's more! - is Replay Professional for the ST, to be marketed by Microdeal. Replay Professional is not a replacement for ST Replay 4 but another product in a different price range.

The £129.95 package is a new design which comes complete with an array of software and different cartridge. The all new product contains sampling hardware capable of inputting at 8-bits and output in 12-bit 4 channel, giving a higher sound resolution than provided with the previous ST Replay 4 package.

Replay Professional is supplied with full sampling and sample editing software as well as a sample sequencer - Drumbeat Professional - and a MIDI synthesiser in the guise of MIDI play.

The sample software offers frequencies ranging from 4 Khz to 48 Khz and includes FFT which works in the same way as with the other packages. A new feature is the sample buffer for use with the updated cut and paste facility.

All of the new sample software will be very similar and has been written to use the full potential of the hardware. What makes Replay Professional special is the inclusion of Drumbeat Professional which allows you to sequence your samples. With up to 15 samples being allowed in one song, and 99 song entries, Drumbeat utilises the four channels of the hardware. The software is fully MIDI compatible and is extremely easy to use. In just a short time, it is possible to produce a quality track.

With the addition of MIDIplay, the package is complete. This software allows 128 voices to be held in memory and allows the use pitch bend which is sensitivity selectable.

It seems that Audio Visual Research have been very busy of late and still have other projects in the pipeline.

I am told that if Spectrum Mastersound sells well, an update will be written which will include MIDI capabilities. However, that is all to come, the above mentioned products exist and the small Luton based company looks set to take on the world.

Bye for now...

Next month we'll be taking a look at some other ST samplers and providing a complete round-up of the samplers covered, as well as taking a peek at what the professional market has to offer. See you then!

Audio Visual Research: (Contact Details)
Kempston: (Contact Details)
Microdeal: (Contact Details)