User's Manual

Apollo Solo USB Manual Latency & Apollo Solo USB 223
Console Latency
Apollo Solo USB’s Console mixer is used for low-latency input monitoring (cue mixing)
of Apollo Solo USB’s analog inputs. Using Console to monitor Apollo Solo USB’s inputs
may or may not add to the inherent analog I/O round-trip latency, depending on how it is
configured, as described below:
Console without UAD plug-ins – When Console is used without UAD plug-ins, monitoring
Apollo Solo USB’s inputs via Console does not add any latency. In this configuration,
Apollo Solo USB’s analog I/O round-trip latency is still 1.1 milliseconds at 96 kHz.
Console with Realtime UAD Processing – When Console is used for Realtime UAD
Processing with UAD plug-ins that are not upsampled, monitoring Apollo Solo USB’s
inputs via Console does not add any latency.
In this configuration, Apollo Solo USB’s analog I/O round-trip latency is still 1.1
milliseconds at 96 kHz, even if up to five UAD (non-upsampled) plug-ins are serially
inserted (chained) on a single Apollo Solo USB input.
Multiple Apollo Solo USB inputs can have up to five UAD (non-upsampled) plug-ins each
(up to the limit of available DSP resources), and this configuration also does not add any
latency.
Note: Upsampled UAD plug-ins add latency when used in Console or a DAW. See
Upsampled UAD Plug-Ins for details.
Console Auxiliary Buses – The outputs of the auxiliary buses in Console have 32 samples
of additional latency. This is necessary to maintain the lowest possible input latency.
DAW UAD-2 DSP Latency
When UAD plug-ins are used within a DAW (not Console), I/O buffering is used to shuttle
audio data back and forth between the UAD-2 inside Apollo Solo USB and the DAW,
which induces additional latency.
UAD-2 DSP latency from UAD plug-ins within the DAW is determined by the DAW’s I/O
Buffer Size setting. This latency is unrelated to the (indiscernible) audio interface I/O
latency — they are separate processes.
DAW UAD-2 DSP latency makes tracking through UAD plug-ins in the DAW via
software monitoring problematic for the performer because an artist cannot hear their
performance in realtime.
The issue of UAD-2 DSP latency when recording with Apollo Solo USB is eliminated
by using Console for live performance input monitoring with optional Realtime UAD
Processing, where buffering latency does not apply.
Does all this latency stuff matter?
With Apollo Solo USB, not really. Performance input latency is not a factor because of
Console’s low latency hardware input monitoring, and recording (track alignment) latency
during recording, overdubbing, and mixing is automatically compensated by Apollo Solo
USB’s device drivers and the DAW’s automatic delay compensation engine.