EXS 24 Logic Sampler Users Group

Ned Bouhalassa wrote: 
>
> Following a posting on osxaudio regarding problems with EXS, I decided 
> to do a test of EXS' polyphony:
>
> My questions are: what about the 1,000 voices from the G5 unveiling? 
> How about just 150, without drop-outs/crackles? Is this related to my 
> use of the factory drive, as opposed to using another, audio-dedicated 
> drive? Can anyone confirm any of this?
>
> Here's my setup: G5 Dual/2gig ram + Panther + Logic 6.3.1 + internal 
> 160 gig factory drive.


Hi Ned,

1000 voices could only be achieved  with DFD off. Samples loaded into RAM in 32
bit mode would be the most efficient way for the EXS24 to operate in terms of
CPU cycles consumed per voice.

The maximum number of streamed voices would probably be obtained with a setup
where you had many drives operating in parallel with the instrument audio files
distributed over the set of drives -- whether in RAID 0 or just distributed
across the set. 

A bunch of SCSI or SATA controllers with multiple drives attached would be the
ultimate solution -- whatever is most CPU efficient. All samples streamed from
disk must be converted to 32 bit format and this consumes CPU so there are CPU
limits associated with disk streaming.

Such a setup would definitely deliver more voices than your single sample drive
setup but would chew CPU cycles ( esp with Software RAID controllers)  are and
would eventually overload the PCI bus.

The people who are getting terrible disk streaming performance -- your sample
drive should be defragged, your samples should be in the fastest section (first
partition)  of a dedicated sample/audio drive which is preferably at least 7200
rpm. If there is a choice of cluster size when formatting you may get better
performance with larger cluster sizes (I have no evidence on this wrt Macs).

In recent tests on a P4 2.4 PC with the EXS24 (and also with the freeware Sfz
sf2 player) and the free Maestro grand piano (gig format converted to SF2 and
EXS24 using CDExtract) I am getting over 60 sustaining voices (pedal down,
every note playing a different audio file, no repitching of samples) from a
Seagate Barracuda ATA 5 120 gig drive without clicks or pops. 

Regards,
Murray