Specifications

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SOUND SYSTEMS
AUTOMIXERS
AS 4 + 3
AS 8/AS 8 TC
SOUND PROCESSING RANGE
AS 4 + 3
Automatic mixer with four gated microphone inputs and three
line level inputs. The microphone inputs provide switchable 24 V
phantom power and an integrated, adjustable compressor/leveler
that compensates for variations in level due to variations in working
distance. The microphone inputs and line output are on balanced
3-pin XLR connectors, the line inputs and recording output on unbal-
anced RCA connectors. A switchable ducking function will attenuate
all other channels when signal is present at the MIC 1 input. Bass
and treble controls in the master output section allow the sound of
the main output signal to be matched to individual requirements. The
AS 4+3 can be daisy-chained if more than four microphone inputs are
needed.
FEATURE HIGHLIGHTS
• Four automatic microphone inputs, three line level inputs
• Integrated compressor/leveler
• Ducking function
AS 8 / AS 8 TC
ADAPTIVE PROPORTIONAL GAIN SHARING
The patented Adaptive Proportional Gain Sharing algorithm con-
sists of two crucial elements that make it unique among automixers.
GAINSHARING
The first, “Continuous Gain Modulation” or “Gainsharing”, as it
is more commonly known, uses a microprocessor to control the chan-
nels with Voltage Controlled Amplifiers (VCA’s). The VCA’s act like
faders on a console mixer, adjusting the level of the microphones in
a few milliseconds through a continuous gain control. The AS 8
automixer proportionally assigns the amount of gain from the sum of
all active microphones equal to ONE open microphone. That means
all the active mics mixed together will deliver the same summed gain
as a single microphone at full gain. An advantage to this design is
that the constant gain means background levels remain the same
regardless of mic activity. In recording and conferencing applications,
this means the room ambient noise will be observed as constant.
That same noise is limited to the noise level you would get with only
one microphone on in the room - it will not vary or overpower your
signal. And the gain before feedback stability in sound reinforcement
applications is consistent.
ADAPTIVE SKEWING
The second (or adaptive) part of the algorithm is called “Auto-
skewing.” By monitoring input signal strength, duration and band-
width the mixer “recognizes” the signal at a microphone and assigns
a preference for that signal to that input. When it detects the same
signal at another input, it will not apportion gain to that other chan-
nel because it already has identified that signal at good level on the
first channel.
For example, an instructor in a given venue may be wearing a
lectern mic. As the instructor moves about the room he or she may
stop occasionally to speak from the lectern. The Auto-skewing will
realize that it already has the instructor’s audio on the lavalier and will
not “open” the lectern microphone to the same voice. This prevents
phasing and comb filtering problems. The other mic would “open up”
only if it detects the lectern’s mic as stronger, longer in duration or
“better” sounding in which case the gain will seamlessly be appor-
tioned up to the lectern mic and down to the lavalier. Or the other
mic(s) could be apportioned gain if a different talker(s) began speak-
ing in which case the algorithm will perform a mathematically perfect
NOM attenuation as any number of mics “open up.”
REMOTE LEVEL CONTROL CONNECTIONS
Remote control is easily accomplished through the DB-15 connec-
tor on the rear panel. This provides a direct connection to the VCA
level controller on each channel and the main output for external vol-
ume control pots, switches (or both) to be added.
“DAISY CHAIN” MULTIPLE AS 8 MIXERS
Up to 15 AS 8 mixers can be inter-connected in a
“master/slave” configuration for larger systems needing more than
eight inputs. In this configuration, all automatic mixing functions are
combined among the mixers, with the “master” unit providing the
reference signals and control over the gain allocation and skewing.
BUILT-IN COMPRESSOR/LEVELER
A compressor/leveler is included in the algorithm to compensate
for level differences between loud and soft talkers. Maintaining uni-
form sound levels provides a significant improvement in sound quality.
TWO VERSIONS AVAILABLE
The AS 8 is the basic version. The AS 8 TC provides additional,
separate bass and treble controls for each channel.
FEATURE HIGHLIGHTS
• Patented mixing algorithm
• Requires no manual threshold setting even in noisy or changing
environments
• Remote control via RS 232 or analog interface
• Several units can be daisy-chained
Please note:
Detailed information about specifications, and architects’ and engineers’
specifications are available from our website at: http://www.akg.com
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