Operator`s manual

Version 1.21 243
/ VIRTUAL SAMPLES
HOW DOES IT WORK?
The problem with playing back recordings from disk has always been disk speed as it takes a finite
time for the disk heads to actually find the data to play back (known as the seek time). Fixed hard
disks are relatively fast. Removable drives, however, tend to be much slower with seek times as
great as 50 milliseconds or more and to compound the issue, seek times are not consistent - if the
head only has to move from track on the disk to another, seek time can be relatively fast but if has
to seek from one end of the disk to another, seek time will be proportionally slower.
All of this (combined with other factors as well) means that it is not feasible to play directly from
disk without getting unacceptable delays so the S6000 gets around this by keeping just a small
portion of the start of the virtual sample - we call it the ‘nose’ - in memory. When you trigger a virtual
sample, the ‘nose’ is played from RAM giving the disk time to find the rest of the sample to play
back directly from disk. Thus you have note-on times that are as fast as ‘normal’ samples whilst
sample length is limited only by the size of your disk.
Because only very short ‘noses’ are loaded, this has the benefit that load times for virtual samples
are very fast and you could have a program that contains a lot of stereo virtual samples that
amount to maybe 200Mb or more that would load in seconds rather than minutes!
But there is a catch!
All hard disks have a finite bandwidth - that is, they can only transfer data up to a finite limit. The
result of this is that you cannot expect the same polyphony from virtual samples played from disk
as you can from normal samples played from RAM.
Another problem is that samples are often transposed in pitch as you play them, sometimes some
considerable distance from their original pitch. In this case, a virtual sample recorded on C3 but
played at C4 means the drive is having to work (literally) twice as hard and so polyphony will be
even more restricted. Add pitch bend and/or vibrato to that and the disk is working even harder!
So, a disk that can nominally play 16 mono samples simultaneously could only manage half that
(or less) if every one was transposed an octave.
Finally, virtual samples use the S6000’s voices to play (this is how they can be played in programs
using the filters, effects, etc., just like any ordinary sample). However, because it is not possible for
several voices to access the same data simultaneously from the same place on disk, virtual samples
cannot be played polyphonically and so each individual virtual sample is automatically set to play
monophonically when it is recorded or loaded (a mono virtual sample will use one voice and a
stereo virtual sample will use two). This doesn’t mean that you can only play one virtual sample at
a time - it means that if you place a single virtual sample into a program, whilst you can play it up
and down the keyboard, run it through the filters, add pitch bend and modulation, etc., (i.e. all the
things you can do with normal samples), you cannot play chords with it. However, if you have
several virtual samples in the program mapped across the keyboard as appropriate, you could
play them all together (notwithstanding the polyphony restriction imposed by the speed of your
disk drive) and so effectively, you can play ‘chords’ with several virtual samples
16
.
16 You cannot assign the same virtual sample to several keygroups and expect to play chords. The
same restrictions described above apply in this case.