APOGEE ELECTRONICS
14
AMBus FireWire card
– User’s Guide
Working with Windows XP
When multiple Apogee AMBus FireWire cards are connected, we recommend that one interface be
designated as the clock master and configured as in example
2
, that the remaining units be configured as
clock slaves as in example
3
, and that word clock be distributed from the clock master to the clock slaves.
Settings Window
Three buffer settings are provided in this window,
Stream buffer depth
,
ASIO buffer depth
, and
WDM sound buffer depth
. Found below are a
few general guidelines for setting buffer depths
- please note that the right setting depends on
the speed of your computer’s processor and the
amount of processing needed for a particular
session in your audio application (as determined
by the number of I/O, the number of DSP plug-
ins, soft synths, etc.).
• Lower buffer depths result in lower latency from input to output, but can result in buffer overruns which
cause clicks and pops. Buffer overruns occur when the computer’s CPU runs out of processing power
and cannot provide data quickly enough to the driver. If clicks and pops do occur, either the buffer
depth must be increased to give the CPU more time, or the CPU’s load must be reduced by removing
plug-ins, tracks or other DSP.
• Higher buffer settings result in higher latency but allow the use of more DSP (plug-ins, soft synths)
without clicks and pops.
• During the recording phase of a session, it’s best to compromise DSP usage in order to minimize
latency, so the performers being recorded are not disturbed by latency. To eliminate latency in
performer’s cue mix, use Apogee’s Firemix Software Mixer.
• During the mixing phase of a session, latency is in most cases not an issue, thus it’s possible to
increase buffer depths so more DSP may be used without clicks and pops.
Stream buffer depth
This is an
expert
setting, and should be left at 2.0 ms in most cases. If your processor is exceptionally
fast, you may try lowering the buffer depth for lower latency. If the Apogee host interface is locking
intermittently to FireWire, Stream buffer depth should be increased..
ASIO buffer depth
This setting controls buffer depth when using the AMBus FireWire card with ASIO-compatible applications
(Steinberg Nuendo-Cubase, Sonar 4 (not 3), Samplitute, and others.
WDM sound buffer depth
This setting controls buffer depth when using the AMBus FireWire card with applications which employ
WDM.