From Sound On Sound Magazine quote
SAMPLERS AS SYNTHS
Now that most modern samplers are equipped with resonant filters, simple waveforms can be sampled and treated, to create the digital equivalent of an analogue synth. In theory, you could just load up your sampler with square, pulse, triangle, sawtooth and sine waves, then start synthesizing, but it's often more productive to start off by sampling the raw waveforms from a real instrument. The reason for this is that virtually all analogue synths colour or distort the waveforms to some extent, so if you can capture these benign colorations, you may end up with some of the character of the original instrument in your new sound.
When sampling a synth, it's usually best to set its low-pass filter cutoff frequency at maximum and the resonance at minimum, so as to remove the effect of the filter altogether. This lets you re-create the necessary filter sweep using the filter and filter envelope controls in your sampler. Similarly, turn off all LFO modulation, so as to get as static a sound as is possible. Again, you can put all this back using your sampler's own controls.
If the waveform is constant, you only need to sample a very short section -- indeed, a single cycle will do the trick, and because the sample is very short, any auto-looping facility you have should make light work of finding the best loop points for you. Sounds that evolve have to be treated differently, because the waveform is changing over time. If you have enough sample memory, you can sample a phase sync sound or a ring modulation effect, but unless you multisample, you'll find that the effect speeds up drastically towards the top of the keyboard, and slows to a near crawl at the other. Similarly, LFO pulse width modulation will change noticeably in speed, even if you do manage to loop the sample at a point that coincides with one full cycle of the modulation frequency. All in all, it's probably best to fake this particular effect by sampling an unmodulated sound, then either adding chorus, or layering the sound with a slightly detuned version of itself.
A typical modern sampler has good modulation facilities, portamento, nice-sounding filters and powerful envelope shaping capability, so when you think about it, you've got everything you need in a synth except the basic waveforms. What's more, you can mix analogue waveforms with sampled waveforms, to create hybrid string patches and so on. This aspect of the sampler is probably the most underrated, but I suspect that over the next couple of years we shall see the fine line between synths and samplers dissolve altogether.
CD-ROMS: HOW MUCH??
Compared to straightforward sample CDs, CD-ROMs seem hugely expensive (£200 is a typical CD-ROM price, compared to more like £60 for a sample CD) -- but when you consider that they can contain 600Mb or more of ready-mapped samples, they still make good commercial sense -- as long as enough of what's on the disk is likely to be useful to you. Indeed, there's little point in bootlegging samples from CD-ROMs (which is illegal anyway), because the removable disks you need to store the data on tend to cost more per megabyte than the CD-ROMs cost in the first place.
One of the limitations of the CD-ROM is that the samples provided can't be edited unless you save the edited result to a writable drive of some kind. So if you want to change loop points or do other processing tricks, you'll still need an external SCSI drive. However, most samplers will allow you to save only the program information (key mapping, envelopes, filter settings and so on) to a floppy, without the need to save the samples themselves. That means you can make up program disks that allow you to use the existing samples in different ways, using inexpensive floppies.
Having made the case for CD-ROMs, the truth is that you still end up paying for some samples that you'll never use, and I don't think it's any secret that the major sample providers are looking at ways of selling individual samples, possibly via the Internet. Whatever direction they take, as more people start to buy samples, the more the price will eventually come down -- which has to be good news for all of us.
SAMPLE CDs
Sample CDs are a lot cheaper than CD-ROMs, and usually contain the same samples as their CD-ROM counterparts (though occasionally fewer of them). The trade-off is that you have to load all the samples into your sampler, map them into keygroups and create the programs yourself.
You'll find the key ranges for each sample listed on the accompanying sleeve or booklet, so the procedure is more tedious than it is difficult, but if any of the samples need looping, it's down to you to find the best loop points. This can be very time-consuming, and requires a certain amount of experience to get right. If it's something you're going to be doing a lot of, then a software sample editing package such as Alchemy is well worth considering. I'm still using Akai's bundled Mesa software, which does the job well enough once you've cracked its cryptic routines, but its main weakness is that that it can't perform crossfade looping -- you have to go back to the sampler front panel for that.
When it comes to mapping your samples, you don't always have to go along with what the CD literature suggests. For example, instruments such as strings and flutes can be transposed quite a long way before they start to sound wrong, so you could get away with just one or two keygroups, if most of your playing is near the middle of the keyboard. Even instruments that do suffer when transposed outside their normal range can be abused to create special effects: check out the Art of Noise's early material to hear excellent examples of this.
Human voices don't take kindly to being moved too far from their native pitch, and the same is true of acoustic instruments with strong resonant formants, such as acoustic guitars and pianos. Here, you may need to have a new sample every three or four semitones to maintain a natural sound. In this case, you should arrange the original pitch of your instrument to fall in the centre of the keygroup, then listen carefully for differences in tone as you move from one keygroup to another.
Whenever you play back a sample at a higher pitch, the whole harmonic structure of the sound is moved up, with the result that the highest sound in one keygroup is likely to sound brighter than the lowest note in the next keygroup up. If the keygroups are narrow enough, this effect may be trivial enough to ignore, but if you're using only one or two keygroups per octave, it may be advantageous to use the tracking filters set up with a negative value, so that as you move up a keygroup, the top end is tamed slightly. Some samplers allow you to crossfade from one keygroup to another, but this reduces polyphony and may produce unnatural chorus effects on solo instruments.
