Biamp AUTOTWO User Manual

autoTWO

Automatic Mixer

Operation Manual

Biamp Systems | 9300 S.W. Gemini Drive | Beaverton, OR | 97008 | USA | +1.503.641.7287 | www.biamp.com

Front Panel
Rear Panel
Logic Outputs
Specifications & Block Diagram
Warranty

TABLE OF CONTENTS

pg. 2
pg. 3

pgs. 4 & 5

pg. 6
pg. 7

August, 2009

autoTWO

y

INTRODUCTION

The autoTWO Automatic Mixer is affordable, extremel
threshold sensing, speech-frequency filtering, manual priority override, selectable channel-off attenuation, and selectable last mic
hold. The autoTWO is covered by a five-year warranty.

autoTWO features include:

♦ eight balanced mic/line inputs on plug-in barrier connectors
♦ trim, pad, level, & combined active/peak indicator per channel
♦ channel 1 manual ‘override’ via external contact-closure
♦ channel 8 ‘mix-minus’ assign & ‘ducking’ via channels 1~7
♦ balanced main & aux outputs on plug-in barrier connectors
♦ selectable last mic on, hpf, automix, & 48V phantom power
♦ selectable automix channel-off attenuation (-12dB or -40dB)

versatile, and easy to use. Features include NOM attenuation, adaptive

♦ pre/post automix assignment to main, aux, & direct outputs
♦ options selectable via external switches (no internal jumpers)
♦ logic outputs from channels for switching of external circuits
♦ Adaptive Threshold Sensing minimizes false gate triggering
♦ Speech-Frequency Filter minimizes false gating due to noise
♦ 6dB of hysteresis reduces gate ‘flutter’ when near threshold
♦ ‘stacking’ of two units to expand system input capability
♦ incorporates AES recommended grounding practices
♦

marked and UL / C-UL listed power source

♦ covered by Biamp Systems' five-year warranty

1

FRONT PANEL

Active Indicator (Channels 1~8): These dual-color LEDs provide
indication of two channel functions: channel active & peak level.
When a channel is assigned for automixing (gated) operation, the
Active indicator will light green
(on). NOTE: The Active indicator does not

channel assigned for manual (ungated) operation. See Channel
DIP Switches on next page. The Active indicator will also light red

whenever channel signal levels reach +10dB (8dB below clipping).
Use this feature to aid in adjusting the Trim controls (see below).

Trim (Channels 1~8): These controls adjust the channel gain
(0~60dB) to compensate for different input signal levels. For best
performance, adjust these controls so the channel Active indictors
flash red

control settings are essential prior to Threshold adjustment (see
Threshold below). Once Threshold has been set, individual
channel sensitivities may be fine-tuned using the Trim controls. If

input signals exceed normal operating range of the Trim controls,
assign the Pad switch (see DIP switches on next page).

Level (Channels 1~8): These controls adjust the amount of signal
sent from the individual input channels to the mixer output section.
Optimum Level setting is near the 12 o'clock position (unity gain).

Threshold: This control adjusts the minimum signal level
(threshold) at which channels will become active (gate on). The
Threshold circuit also has 6dB of hysteresis, which allows a
channel to stay open until the signal level drops below the
threshold by 6dB. This hysteresis reduces the tendency for a
channel to ‘flutter’ on & off when it detects a signal that is right at
the threshold level. Because of the hysteresis, different threshold
settings will be arrived at depending on how you adjust this control.
If Threshold is set fully clockwise, then turned counter-clockwise
until all channels are easily activated by normal signal levels, the
threshold will be as high above ambient noise as possible. If
Threshold is set counter-clockwise, then turned clockwise until no
channels are activated by ambient noise, the threshold will allow
for greatest channel sensitivity. The threshold is further controlled
by Adaptive Threshold Sensing (ATS). ATS monitors signal from
active channels and automatically adjusts the threshold to prevent
false activation of other channels. NOTE: Accurate Trim control

settings are essential prior to Threshold adjustment. Once
Threshold has been set, individual channel sensitivities may be
fine-tuned using the Trim controls.

(+10dB) on occasional peaks. NOTE: Accurate Trim

whenever the channel is active

light green on a

Release: This control adjusts the length of time that any channel
remains active (on) after signal level has dropped below threshold.
Release Time is adjustable from 150 milliseconds to 4 seconds.
Since channels activate very quickly (4 milliseconds Attack Time),
precise adjustment of Release Time may not be critical. However,
when using Logic Outputs to control external switching circuits
(such as cameras), moderate Release Time settings may provide
more appropriate timing (see Logic Outputs on next page).

Master: This control adjusts the level of overall signal sent to the
Main Output. The Main Output level is also affected by automatic
NOM attenuation, which reduces the output level by 3dB for each
doubling of active (gated) channels. Optimum Master settings are
near the 12 o’clock position (unity gain) or below.

Aux: This control adjusts the level of overall signal sent to the Aux
Output. The Aux Output may be assigned either ungated (pre) or
gated (post) signals from the channels (see Master DIP Switches
on next page). NOTE: Unlike the Main Output, The Aux Output

does not

-20 Indicator: This dual-color LED provides indication of both
signal present & peak level at the Main Output. This indicator will
light green when (internal) signal levels reach -20dB (signal
present). This same indicator will light red
levels reach +10dB (8dB below clipping). Use this feature to aid in
adjusting the Master control. For best performance, adjust the
Master control so the -20 indictor flashes red
occasional peaks in signal level.

On Indicator: When the Power Cord is plugged in, and power is
applied to the autoTWO, the red On indicator remains lit.

provide automatic NOM attenuation.

when (internal) signal

(+10dB) only on

2

REAR PANEL

DC Power Cord: The included power supply module provides 24
Volt DC power to the mixer. It is connected to the DC Power Jack
on the rear side of the mixer. To ensure compatibility, only use a
Biamp Systems supplied power supply.

Logic Outputs: This 9-pin Sub-D (male) connector provides logic
outputs from the eight channels, plus a common ground. When a
channel becomes active, the associated logic output turns on.
Logic Outputs are used to control external circuits for switching
speakers, cameras, or indicators (see Logic Outputs on pg. 4).

Expansion: This 6-pin Modular jack is for connection of a second
autoTWO mixer to add system inputs. When using two autoTWO
mixers in a system, it is necessary for the mixers to share
information regarding active channels. This information allows the
mixers to properly perform NOM Attenuation & Adaptive Threshold
Sensing. This connection requires a single Modular cable
(provided). The information shared is processed primarily by the
‘master’ autoTWO. To prevent system errors, the second
autoTWO mixer should be assigned as ‘slave’ (see Master DIP
Switches below). Channel 1 override

can be achieved by shorting

pins 3 & 6 (see Logic Outputs on pg. 4).
Main Output: These plug-in barrier strip terminals provide the

balanced line-level Main Output from the mixer. For balanced
connection, wire high (+), low (-), and ground (
connection, wire high (+) and ground (

d

). For unbalanced

d

), leaving (-) unconnected.
Signal level will be reduced by 6dB when output is unbalanced.
Main Output level is affected by the front panel Master control, as
well as by automatic NOM Attenuation, which reduces the output
level by 3dB for each doubling of active (gated) channels.

Aux Output: These plug-in barrier strip terminals provide the
balanced line-level Aux Output from the mixer. For balanced
connection, wire high (+), low (-), and ground (
connection, wire high (+) and ground (

d

). For unbalanced

d

), leaving (-) unconnected.
Signal level will be reduced by 6dB when output is unbalanced.
Aux Output level is affected by the front panel Aux control, but not
by automatic NOM Attenuation.

Stack In: These plug-in barrier strip terminals provide a balanced
line-level Stack In to the mixer. Signal entering here is combined
with signals from the input channels, and is then sent to the Main
Output section. When using multiple autoTWO mixers within a
system, connect Main Output of one mixer to Stack In of the next
mixer, and so forth. All mixers except the final autoTWO should be
assigned as ‘slaves’ (see Master DIP Switches below). For
balanced connection, wire high (+), low (-), and ground (
unbalanced connection, wire high (+) and ground to both (

d

d

Inputs & Direct Outputs (Channels 1~8): These plug-in barrier
strip terminals provide the balanced mic/line Inputs to the mixer.
For balanced connection, wire high (+), low (-), and ground (
For unbalanced connection, wire high (+) and ground to both (
(-). Phantom power (+48VDC) is available (see DIP Switches
below). Unbalanced 'pre-fader' Direct Outputs are available on
Channels 1~8, using the (d. out) & (

d

) terminals.

Master DIP Switches: These switches assign functions to the
mixer as a whole (when pushed up). Slave

assigns the mixer as
an expander to a ‘master’ mixer. -12dB selects -12dB channel-off
attenuation (instead of -40dB). HP Filter assigns a high-pass filter
of 6dB/octave @ 170Hz. Last Mic causes the most recently active
channel to remain on. Aux Post assigns post-gate/level channel
signals to the Aux Output (instead of pre-gate/level signals).

DIP Switches (Channels 1~8): These switches assign functions
to the individual channels (when pushed up). Pad

attenuates input
signal -18dB (line input). Ungated turns channel on (defeats gate).
Phantom turns on +48V phantom power (for condenser mics).
Duck Ch 8

-12dB attenuation on Channel 8 (ducking). Aux Off

(Channels 1~7 only) assigns channel signal to activate

(Channel 8
only) removes Channel 8 signal from Aux Output (mix-minus).
D. Out Pre

assigns pre-gate signal to channel direct output (d.

out), instead of post-gate signal.

). For

) & (-).

d

d

) &

).

3