E-Mu ProteusX Operation Manual page 18

1 - Introduction & Installation
Setting up the Preferences
Buffer Size
This control sets the number of sample periods between updates of the synthesizer
parameters. The buffer size can be adjusted according to the speed of your computer's
CPU. A faster CPU can handle a lower buffer size. The default setting is 128 sample
periods, a good compromise of performance to CPU usage.
Use Optimal Buffer Size
When this box is checked, the Proteus X will choose the best buffer size based on the
ASIO Buffer Latency setting (located in the ASIO control panel). You should normally
leave this feature enabled for best audio performance. In certain rare cases you may want
to manually set the buffer length to improve MIDI or synth performance.
Sample Rate
This control sets the output sample rate of the Proteus X, and will always match the
sample rate of your sound card. The default setting is 44.1kHz.
CPU Cap
This control sets percentage of CPU resources that will be used by Proteus X and conse-
quently the maximum number of samples that can be played at the same time.
Depending on the design of the preset, a single Proteus X voice may contain multiple
samples which play simultaneously. The maximum setting is 80% CPU usage. If you
hear notes being "stolen" in your sequence or as you play the keyboard, or if the disk
meter readout at the bottom of the window goes into the red, increase the value of this
control. If you have other applications running, you may want to reduce the setting of
this control to free up more CPU for them.
Headroom/Boost
Headroom is the amount of dynamic range remaining before clipping occurs .
The amount of headroom is adjustable from 12 dB to -30 dB in 1 dB increments.
A headroom setting of 12dB provides the hottest output level, (and the highest signal to
noise ratio) but may produce "clipping" if too many notes are played at once. The
default headroom setting is -15 dB, which maintains an excellent signal to noise ratio
while keeping a reasonable amount of headroom in reserve. If you hear the signal
clipping or breaking up, make the headroom value more negative. In practice, you can
think of this control as adjusting the control range of the Master Volume control.
Ultra-High Precision Interpolation Button
This button allows you to select between E-MU's ultra-high precision pitch shifting
algorithm or a lower quality pitch shifting scheme which uses fewer CPU resources.
If you are using presets with a sample placed on every key, as is the case on many banks,
you can switch high precision off to free up CPU with no penalty in audio quality. No
pitch shifting is occurring anyway. High quality pitch interpolation is only needed when
you are playing presets which have a few samples mapped across the entire keyboard. In
this case, the Proteus X shifts the pitch of the available samples to fill in the keyboard.
ASIO Control Panel
This button brings up the E-MU ASIO control panel which allows you to set the ASIO
buffer latency in milliseconds. This important setting determines how fast notes will
sound after you play them. If this time is too long, (>10mS) the keyboard response will
feel slow and sluggish. If set too fast, however, you will hear the sound break up and
crackle when you play too many notes. Experiment to find the setting that gives the best
performance on your computer.
18
Warning: Sounds
with long release times
will exhibit "voice
stealing" more than short
percussive sounds.
Proteus X Operation Manual