Sampling The Japanese Way
Akai S612 MIDI Sampler
A reduction in price and the introduction of their Quick Disk make Akai's S612 MIDI Sampler an even more attractive investment. Paul Gilby was suitably impressed.
A reduction in price and the introduction of the add-on Quick Disk unit make Akai's S612 MIDI Sampler an even more attractive investment. Paul Gilby was suitably impressed.
At present there are three sub one thousand pound samplers on the market that allow MIDI control, notably the Akai S612, Powertran MCS-1 and Korg SDD-2000, all of which are rack-mounting, though none include a keyboard. Of the three units, the Akai is perhaps the most complete in that it offers MIDI control of the sound plus quick and convenient storage of samples via the optional MD280 disk drive.
So, if money limits your choice then you're going to have to opt for one of the three systems mentioned, as samplers with an integral keyboard retail at over £1500. However, money isn't necessarily the determining factor and you may be equally attracted by the idea of not having another physical keyboard around and look towards the neatness of a rack-mounting unit for the space saving it offers.
As a musician or studio owner who's considering buying a sampler or has, in fact, bought this particular unit your main concern is obviously towards the real creative possibilities of using such a device. Paul Hardcastle and 'N-N-N Nineteen' aside, the potential of a sound sampler is, like they used to say about synthesizers, literally endless! But, of course, we all hear the same sounds time after time. The sheep syndrome is still alive and well in sampler land, but unlike the cliche vocoder and syndrum sounds of the 1970s, the sampler should pass through this stage unscathed. Its pedigree is far too impressive and many, if not all, of the major equipment manufacturers are taking the idea seriously and will all probably have a sampler of some description on the market by 1986. Yes folks, sampling is here to stay. So, let's have a look at what the Akai S612 system can do.
Having plugged the sampler and disk drive system together, nothing will happen unless you connect some sort of MIDI controlling device to the S612. So, we came up with the highly original idea of using the Akai AX80 keyboard and one of those five pin DIN MIDI cables with which I'm sure you're all familiar. Connecting the keyboard to the sampler via the MIDI In and Out sockets seemed to follow all the usual rules except in this particular instance it's a one-way conversation ie. the keyboard is controlling the pitch of the sampler so in actual fact the MIDI Out on the S612 is not used.
With everything connected up MIDI-wise, you obviously need to patch the audio outputs of both the keyboard and sampler into a mixer ready for monitoring and recording the sound. On power-up, the S612 shows its MIDI channel selector reading O, this means it's in Omni mode rather than what you may think is MIDI channel 0 which doesn't exist, of course, though you might be a little confused at first (remember: MIDI channels are numbered 1 to 16). The point of putting the unit into Omni mode is to save having to worry about setting the right MIDI channels on the controlling keyboard, sequencers or whatever. If a particular MIDI channel is required you can easily set it up later by using the MIDI channel up/down buttons under the LED readout. One point though, the S612 can only receive control data on MIDI channels 1 to 9 so it's worth bearing that in mind when using a powerful multitrack MIDI sequencer.
Sampling on the S612 is fairly self-explanatory and doesn't take a lot of time to understand. But, before delving into some of the more interesting and detailed aspects of the sampler, it's worth spending sometimejust running through how to record a straightforward sample.
First set all the LFO controls to zero, Filter to high, Decay to ten and Output level to whatever suits the mixer input. Set the two slide controls which are used for editing the sound so that the Start slider is fully to the left and the End slider fully right. In other words, you are hearing the whole sample rather than a spliced section of it (if you imagine the sliders as representing a variable length of audiotape it'll help you to visualise what's going on). Finally, press the button marked 'One Shot'. You're now almost ready to sample a sound but you will have to decide whether this is to be via a line input or the microphone input; we'll opt for the microphone in our example.
When the S612 is powered up the sample time defaults to two seconds duration, and if a MIDI keyboard is connected (which it is in our case), the two seconds sample time corresponds to middle C on the keyboard - MIDI key number 60. More of that later. Having plugged a microphone into the mic input on the front panel of the S612, set the Rec level so that the record level meter just flashes past the +3 range. Now you're ready to record a sample.
Press the Rec Mode New button and say something imaginative like HELLO. The audio level of your speech will automatically trigger the record mode of the sampler and make a recording. You can now hear the sampled HELLO by pressing middle C on the keyboard - it's as simple as that!
The word HELLO isn't two seconds long, however, so we've wasted some of the sample time. This breaks one of the golden rules of sampling, but more of that later too as it's related to middle C on the keyboard. Obviously something intriguing is going on there...
However, for our purposes we have sampled the word HELLO into a two second time slot. Once a sound has been sampled it can be edited, which is achieved by simply moving the two sliders that affect the splicing of both the sample Start and End points. You could trim the sample to play back only the beginning of the sound and get the 'HE' part of the word, or move to the middle and listen to the 'LL' bit or the end section and hear just the 'O'. By moving the sliders and listening, you can edit the sample down and create some very interesting results - even reverse the sound by moving the sliders to their opposite extremes. The most useful option, however, is the looping facility.
The above method of capturing a sound utilises the Akai's 'One Shot' technique which is great for sound effects and staccato playing but not quite so good for real musical exploration of samples. The looping feature, as it's known, is provided on the Akai and very simple to use it is too. The sampling method is exactly the same as before but this time you press the Looping button instead of One Shot, set your recording level, press the New button and sample a sound. It's at this point that a little experimentation tells you a lot about how to sample sounds that make good loops.
If you have a two second sample slot and you sample the sound of a chord being struck on an electric guitar, what you will hear on replay won't be a satisfactory sound as it will start with a good healthy whack on the guitar and then die away over the two seconds only to suddenly jerk back up to full volume again for another trip around the loop. Clearly, this is not what we want. A long sustained guitar chord that remains at a fairly constant level is the order of the day. To achieve such a good loop you need to use the footswitch control function on the front panel.
Plug a footswitch unit in and then prepare to sample the guitar sound. Having pressed the Record New button, a sample will not be made until you press the footswitch. The best sample will result by letting the guitar chord just start; then hit the switch. This misses the attack off the beginning of the sample, and if the chord can be sustained long enough until the sample time is over you can miss off the end of the guitar sound where the level dies away. Doing so, results in only the central section of the guitar sound being sampled.
The Akai S612 has some clever software whizzing around it that automatically selects the best point to edit the sound to form a loop. This is done by the microprocessor looking for what's known as a zero crossing point - a suitable point in the sample where the sound waveform passes through a zero point in its cycle. When the sound has been automatically looped you can then play a note on the keyboard and you should hear a smooth sounding guitar chord that sustains for as long as you hold down the key. Well, that's the theory anyway.
The major problem in looping sounds on any sampler is avoiding the horrors of glitching. This nasty little click sound can often be heard and its a pain. It spoils the sample and once more takes a fair bit of patience to remove.
Once you have sampled the sound and found much to your horror, that it contains a glitch, the S612 allows you to enter manual splice mode, move the sliders around and edit the sound. Obviously, you need to ascertain where the glitch is first ie. if at the end, you can move the End slider to trim off some of the sample tail. This can sometimes take ages because you need to move the control very slowly a fraction at a time since what you are actually doing is looking for a new zero crossing point. With a little intense listening you should eventually hear the glitch disappear and the looped sample will sound a lot smoother. It's at this point that you should save your superb glitch-free sample to disk, for there's nothing more annoying than realising you haven't stored a sound just as you switch the machine off! Be warned.
Included on the front panel of the Akai sampler are two sections which are perhaps a familiar and welcome sight to those with analogue synthesizers, namely a Low Frequency Oscillator, Decay envelope control and Filter. The LFO allows you to modulate any sampled sound and includes a delay function for more realistic vibrato effects. It would have been nice to have had a full-blown multi-stage envelope shaper but you have to be satisfied with just a humble decay control. However, it is useful and is certainly better than none at all. Likewise, the filter is very basic, just a treble cut really (that's low pass filter in technical jargon).
One good point about all of these analogue sound shaping controls is that their settings are saved to disk when storing a sample. This means you can load a sound back at anytime and not worry about the finer points of where all the knobs were set for that particular sound. However, when you do load a sample back and the controls are set to different positions from the original, everything will remain as before until you alter one of the control parameters which will then override the previous stored setting.
The real beauty of the Akai S612 is that any sound you have sampled and laboured over until perfect can be stored for future use onto small 2.8 inch disks via the MD280 disk drive. This only takes around eight seconds which may seem a little long to some people, but obviously doesn't matter too much when you're working in a studio environment. For live work, however, it may be an unintended show-stopper if you don't organise yourself and make sure the vocalist keeps the audience entertained between songs.
Sound storage on disk is a truly wonderful concept but it isn't without its drawbacks: the Akai only stores one sound per side of the disk and at around £3 or so each, you could be forgiven for not saving everything you sampled. But one thing is for sure, don't be a miser for the sake of it; you'll regret it one day.
Anyway, you always can console yourself in the fact that Ensoniq Mirage owners have to buy their specially formatted disks from the music store or distributors at a much higher price than the Akai's. The disks for the S612 are just the ordinary unformatted type available from your music store or local computer shop.
One final point while on the subject of disks. Akai have started a users' club for people who are interested in the sampler and other Akai products. Apparently the club hopes to build up a large library of sounds and promote an exchange of information and samples between members. (Further information on the club will appear when it's available.)
As previously mentioned, the sample time on the S612 defaults to two seconds on power-up and when controlled by a MIDI keyboard this corresponds to middle C. Sample time is programmable via the keyboard and works in a very simple and logical way. In fact, it's one of the quickest and best ways I have encountered.
If you refer to Figure 1 you will notice that middle C (MIDI note 60) equals a two second sample, and results in an 8kHz sample bandwidth. Pressing the key C one octave higher will set the unit for a one second sample with an improved bandwidth of 16kHz. And likewise going in the opposite direction, C below middle C results in four seconds at 4kHz and down another octave to bottom C - MIDI note 36 - offers eight seconds at 2kHz.
If you consider the implications of the Akai's method of sample time programming, two points arise. Firstly, because the sample time follows a simple mathematical procedure you can quite easily set an intermediate sample time incremented in twelfths of a second eg. by pressing the key F sharp above middle C (MIDI note 66) it should equal a one and a half second sample time. After you've been working with the unit for some time you start to get a real feeling for the length of sounds you wish to sample and can programme the optimum sample time very quickly.
The best quality sample is obviously made with the highest sampling frequency which, in this case, is C above middle C giving a one second sample time. You can't programme a shorter time as you are stuck with not being able to increase the machine's own internal sampling rate, though a shorter sample time can in fact be obtained by using the editing slider controls to splice any unused sample time off the end of a sound. The second implication of the Akai's sampling time procedure is that sample fidelity is directly related to how far up the keyboard you are. Therefore consider what you do in a situation where you want to sample a bass guitar sound with a one second duration.
Pressing the C (MIDI note 72) above middle C fixes the sample time at one second for the best audio quality. However, the sampled sound will be sitting at key 72, but it would be more usual to play a bass guitar sound down the bottom end of the keyboard around MIDI key 48. Akai have been thoughtful in this situation and provided a Key Transpose facility. It's simple to use and quick too, you just press the Transpose button on the front panel and then press the key where you want the sound to be transposed to. Using it, you can move a sample around on the keyboard very easily and place it in the range where you are used to playing such a pitched instrument.
One further point that springs to mind is that some people maybe looking towards the Akai sampler for studio use, as a general purpose sampling unit. Problem-if you're not the keyboard playing/engineering type you're going to be a little upset when I tell you that other than the default sample time of two seconds, there's no way of programming the sampletime unless you have a MIDI keyboard or computer software package attached. This is clearly a limitation and one that'll stop some
studios from buying the Akai. Then again, they need something to improve on for the next version don't they? It's still a good idea though, it just imposes a limitation on the type of users. Additional front panel control of sample time would have been the answer as on the Powertran MCS-1.
With aII this talk of sample time and sound quality we nearly got dragged off into the realms of frequency plots but luckily we're back on course for creativity and it's here that we find the Overdub button. No prizes for guessing what this function allows you to do. Simply record a sample by the normal method and then press Overdub to record a second sound without erasing the first one. A couple of points need to be mentioned here, you can layer sounds one on top of an other if you wish or record the new sound after the first one ie. HELLO followed by GOODBYE. You can overdub again and again with different sounds though as each one is overdubbed the volume of the previous sample drops. This problem may be overcome by carefully setting the new sound level to be quieter than the first, then they'll appear fairly similar in level.
Once you've overdubbed the word GOODBYE with HELLO, in our example, you can move the editing sliders around and pull out a section like LLOGOOD, what's more you can have it play back in reverse. When you start doing these sort of experiments you find all sorts of interesting sounds which after careful editing can be stored to disk and given some weird name which only you will ever understand!
Practically speaking, the use of the overdub feature does take time to get the best out of it. Not all sounds compliment each other and you'll find that separate sounds which are harmonically related yet of a different texture, work well as starting points for some good ruthless hacking about with the splice controls.
Listening to sounds forwards, backwards and looped around and around is all good fun, but it doesn't stop there. Akai have a little trick called Alternating, which replays the sample first forwards and then backwards.
On the face of it, this seems to offer some interesting possibilities, but you're going to have to work hard to find a good application for it. Splicing, looping,the right decay time and a spot of modulation all come into play here. You'll eventually hatch an interesting sound that's well worth the effort, so don't be put off by the feature and alternate straight back to the easy option. Creative sampling isn't all easy you know.
After all that, you're probably wondering what extra facility connecting a MIDI keyboard can offer?
Six voice polyphony is the first answer, velocity sensitivity the second and full pitch bend and modulation control of samples via a MIDI keyboard is the third. One of the more interesting pieces we created during the test used a human! whistle sound for one second (remember the quality) in the loop mode and after some tidying up in the manual splice domain, with a little taken off the top end by the filter and the Decay control set to full, the sample was indeed a very usable musical source. Now, it's at this point that you may consider the work complete, so you can play the sound via a keyboard or have a sequencer do it all for you.
We actually created a flute-type voice patch on the Akai AX80 synthesizer, this sound complimented that of the sampled whistle we had made, all that needed to be done was to tune the two sounds together with the aid of the S612 tuning control. Once tuned, a little modulation was added for effect.
The beauty of mixing the synthesizer and sampled sounds together is that you obtain a totally new and usually more interesting texture than any one sound alone can't achieve. On the mixing desk you can add treatments such as reverb, echo or chorus and transform the result into something quite magical. You could then record the sound onto tape and re-sample the whole thing back into the Akai and there you have another sound source at your fingertips ready to shape yet again. That's what creative sampling is really all about. (There's more about the practicalities of sampling techniques in the Photographing Sound series elsewhere in this issue.)
If you haven't used a sampler before you'll soon find out the first time you do so, that a sample can only be played over a certain musical range. There's no fixed rule to this range as it varies according to the sound, but your ears will tell you whether a sample is musically useful or not. The major problem is usually at the low end for although the pitch may be correct, the sounds are much longer in duration which makes them practically useless. This is one point on which the Akai loses out because it's currently incapable of layering multiple samples across the keyboard, but for the cost something had to be sacrificed.
So, to summarise, the Akai S612 sampler/disk drive combination is without doubt the best of the bunch in the under a grand league. Sound quality is variable and dependant on the sample duration in use but at its best the 16kHz bandwidth on offer is perfectly respectable as is the fact that it's a 12-bit resolution system. You should always choose the highest sampling rate possible when recording a sound and then tailor it to your needs.
A few points of concern have already been mentioned to do with the S612, the problem of only being able to programme the sample time from a MIDI keyboard is the major one; multi-sampling isn't a problem because the Akai doesn't have it, it's merely a limitation. Finally, the lack of any manual triggering facility on the front panel is a nuisance especially if the S612 has been rack-mounted and your keyboard is across the other side of the room. Running back and forth isn't exactly the most immediate way of listening to what you've just sampled!
Room for improvement there certainly is, but then we'll have to wait and see. Nonetheless, the Akai S612 is an excellent sampler that's very user-friendly (nearly got through the whole review without saying it), good value and has low running costs in terms of disk storage.
S612 Sampler £749;
MD280 Disk Drive £199;
Review by Paul Gilby
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