Toa AX-1000A Specifications

TOA ENGINEERED SOUND SYSTEM

AUTOMATIC

AX-1OOOA

DESCRIPTION

The TOA AX-1000A automatic microphone mixer is ideally
suited for applications such as churches, board rooms,
conference rooms or courtrooms, where multiple
microphones are in use.
Conventional mixers require an increase in total level as the
number of input connections increases. The room loop from
speakers to microphones not currently in use causes the
feedback margin to be lowered.
The US. patented Automatic Mixer Apparatus (U.S. Patent
No. 5148491) on The TOA AX-1000A compensates for each
input, thus doing away with unwanted noise and room loops.
The increase in total level is proportional to the number of
inputs, and attenuation takes place regardless of the input
quantity. This makes it possible to maintain maximum
feedback margin without having to rely on a specialist to
operate the system.
The AX-1000A is a modular eight-channel automatic micro­phone mixer incorporating the technology required to gate
on, configured to shut out unnecessary sound, or to gate off
quietly, quickly and automatically.
The NOM (Number of Open Microphones) attenuation
control circuitry automatically adjusts gain level according to
the number of active inputs. This allows the system to
deliver maximum acoustic gain while preventing feedback.
Each of the AX-1000A’s eight input ports can accept any of
TOA’s 900 Series family of Microphone, Line Level,
Auxiliary, Bridging, Input/Output (except T-01) or Sound
Processing Modules. This allows the contractor or specify­ing engineer ultimate flexibility in system design. Ten (10)
AX-1000A’s may be linked together to create a system with a
maximum of eighty (80) active input channels. When units
are in link mode, any mixer in the chain can operate as the

MIXER

master. This is accomplished by utilizing the Master/Slave
switch on the rear panel. In addition to the main output, the
AX-1000A provides direct and logic outputs for each
channel. The Logic Out is an open collector circuit that can
be utilized to trigger external devices.
The direct output can be used as an input for a logging
recorder to provide an account of the proceedings in a
courtroom communication system.
For flexibility and ease of set-up, each channel is provided
with input volume, threshold and off-attenuation controls.
The Threshold Level control adjusts the level at which the
input gates on. The Off-Attenuation control allows attenua­tion of inactive inputs from 0 to -40dB. In addition, it allows
the adjustment necessary to assure smooth turn on without
any missed syllables.
The input remains on when the Off-Attenuation control is set
at 0dB.
To match virtually any type of application, the NOM attenua­tion control permits adjustments between 0dB (functioning
as a standard mixer) and 20logNOM (6dB attenuation for
each additional active input). The center 10logNOM
position (3dB attenuation for each additional input) is the
standard automatic setting.
Other features include Muting, especially attractive in
conference systems where the chairman must override
other delegates, and a Master Remote Volume control
circuit.
The Off-Attenuation, Threshold and NOM-Attenuation
controls are protected by a security cover to prevent
unauthorized or unnecessary adjustments.
The AX-1000A includes the hardware necessary for
mounting in standard 19” equipment cabinets.

Front View

Input Volume Control

Gate-On LED

Master Volume Control

Master/Slave LED

Channel Controls:

Variable Threshold

Variable Off-Attenuation

THR

OFF ATT

NOM ATT

Power Switch
and LED

Each threshold control adjusts its channel’s detector, raising and lowering the
baseline sensitivity to an incoming signal. It determines how easily the input will
gate ‘on’. Threshold is independent of the Off-Attenuation setting.

This control, permitting continuous adjustment of a channel’s Off-Attenuation

(depth), operates from 0dB (full CW) to -40dB (full CCW). In the 0dB position, the
channel acts as a conventional mixer input. At that setting there is no attenuation
of the input whether it is above or below threshold.

Channel
output:

Relation of Threshold
and Off-Attenuation
Controls (simplified):

Channel

System Output Gain:

Adjustable NOM Attenuation

Automatic gain reduction is continuously variable from none to 20logNOMdB.

(NOM=‘Number of Open Mics’.) At the center detent, the attenuation of system
output gain follows the standard formula “10logNOM”. When the control is moved

clockwise, the attenuation is deeper, moving from 10logNOM to 12logNOM,

15logNOM, etc.

Attenuation is at a maximum fully clockwise, following the formula 20logNOM.
With the control set fully counterclockwise there is no system output gain attenua-

tion and the AX-1000A functions as a normal mic/line mixer. Between no attenua-

tion and the detent, output gain is attenuated more and more up to 10logNOM.

2
Active Inputs (NOM)

20logNOM

20logNOM

0 dB Attn.

4

8
Inputs

10 16 20 40

80
Inputs