Lectrosonics ASPEN - Manual (Page 5)

Low Latency
The throughput latency of a single master board is only
1.33 ms, regardless of how much processing is being
used. Each additional PCB adds only 0.125 ms.
200 inputs can be handled with only 4.33 ms latency
(1.33 ms for the master PCB plus 24 additional PCBs at
0.125 ms each.
Other examples include:
• 264 inputs with only 5.33 ms total latency
• 328 inputs with only 6.33 ms total latency
• 456 inputs with only 8.33 ms total latency
• Unlimited maximum with 1 ms added for each ad-
ditional 64 inputs (8 boards)
Latency is not affected by the amount of processing be-
ing used at any stage in the signal chain.
Every input is automatically synchronized to eliminate
phase differences between the inputs included in the
final mixes.
*US Patents 5,414,776 and 5,402,500
Seamless Automatic Mixing
Lectrosonics pioneered adaptive proportional gain auto-
matic mixing algorithms. The proprietary algorithm* em-
ployed in ASPEN is a seamless process that eliminates
abrupt switching (gating), controls acoustic feedback and
suppresses background noise.
All active input channels are summed, and then the level
of each channel is compared to the total sum. Channels
are then attenuated so that the resulting sum is equal to
one channel at full level (NOM=1) with the loudest chan-
nel still the loudest in the mix. The algorithm operates in
the same manner that a human operator would in mixing
a conference manually on a console. Unused mics are
attenuated and those in use are emphasized.
This auto mixing algorithm, working in conjunction with
the AEC in the ASPEN Conference processor, provides
impressive echo cancellation and noise reduction.
The algorithm includes a unique automatic skewing
process that applies a subtle priority to the channel that
has been the loudest for the longest period of time. The
skewing further reduces inactive channels and prevents
comb filtering by never allowing two channels to be
mixed at the same level.
The auto mixing takes place at the matrix crosspoints,
which allows each input signal to exhibit a different be-
havior at every output in the system. For example, input
channel 4 could be configured for Auto behavior (normal
auto mixing) at output 6 for local sound reinforcement,
Direct behavior (no attenuation) at output 10 for record-
ing, and so on. There are five different behaviors avail-
able:
• Direct - no attenuation
• Auto - normal gain proportional auto mixing
• Phantom - special mode for mix-minus systems
• Override - dominant in auto mixing activity
• Background - subordinate in auto mixing activity
The Phantom mode allows the channel to participate
in the auto mixing algorithm at any crosspoint, but not
deliver the actual audio signal to the output. This is used
to combine zones for room-wide auto mixing activity in a
mix-minus reinforcement system. The auto mixing action
is common to all zones, but the audio signal routing to
the loudspeakers remains as is it configured in the setup.