FS - LECTROSONICS MODULAR AUDIO PROCESSOR - EC1 EXPANSION CONTROLLER
AND AP4 16 AUTO MIC PREAMP MODULES


Lectrosonics Inc. Modular Audio Processor -
EC1 Expansion Controller Chassis with 4 AP4 Automatic MIC Preamp modules.
4U 19-inch rack mount, made by Lectrosonics (Lectronsonics) of New Mexico,
USA.

The EC1 Expansion Controller chassis has a 120VAC, 80W power supply section
(fused), and 9-pin D-Sub connections for Expansion Interface In (from EC1
Expansion Controller) and Expansion Interface out (to another EC1 chassis).

This chassis includes 4 AP4 MIC Preamp modules. The AP4 Automatic Mic Preamp
Module provides balanced, low-noise pre-amplification of signals from
microphone
to line levels. In addition, the AP4 (in combination with an AC1 Automatic
Main
Module) implements all necessary functions to perform fully automatic
mixing.
The AP4 has 3 modes of operation; automatic, priority, and direct. These
modes
are switch selectable from the front panel.

The microphone preamp uses a discrete design for lowest equivalent input
noise
and low distortion. This preamp topology also provides a convenient means
for
adjusting preamp gain to maximize signal-to-noise ratio for any microphone.
This is in contrast to many automatic mixers which employ fixed gain
microphone
preamps. The AP4 uses 2:1 expansion rather than abrupt gating to attenuate
the
channels which have no activity. Maximum attenuation is 15dB. The use of 2:1
expansion results in the total absence of "signal chopping" or other
anomalies
often associated with automatic mixers that gate. The detection circuitry
associated with the expansion function is filtered specifically to respond
to energy in the voice range, rejecting both low and high frequency signals.
The release time constant on each channel can be jumpered to either slow or
fast.

When a signal is presented to an inactive channel, it is compared to the
current
threshold voltage value. The threshold is a combination of a fixed voltage
(set
via the Threshold control on the Automatic Control Module) and a variable
voltage.
This variable voltage consists of a signal proportional to the highest
individual
channel level at any time. For a system in which only one person is speaking
on the
system at a time, the mic channel for that person begins to increase in gain
when
the level exceeds the fixed threshold. As the signal in the channel
increases in
level, channel gain also increases. When the channel signal level is 15dB
above
threshold, the channel is at unity gain and no more gain increase happens.

The release time option (fast/slow) represents the time for the channel
attenuation
to reach 15dB after signal is removed. The fast setting is most useful in
situations
where background noise is high, because it allows rapid return to full
attenuation
when signal is not present. This will minimize feed through of background
noise into
the system. The slow setting is useful for situations where there is not
excessive
background noise. Indicators, in the form of LEDs, are provided to indicate
the
operational status of each channel. A yellow Trim Set LED shows when the
trim control
is set for optimum performance for any microphone. A green Channel On LED
proportionally
indicates channel gain, allowing simple adjustment of the Threshold control
(on the
Automatic Control Module).

An optically coupled Logic output is provided on a rear panel terminal strip
to
indicate when a channel is open. The output may be wired active high or
active low,
depending on the application. A post-attenuator Send/Return Loop is also
provided on
a rear panel terminal strip to facilitate the use of signal processing on a
per
channel basis.

Each of the Mic Preamps has front panel controls for INPUT TRIM, OUTPUT
LEVEL, MODE
Switch (PRIORITY / AUTO / DIRECT), and TRIM SET yellow and green level /
CHannel ON
Led Indicators.

INPUT TRIM - Controls the gain of the microphone preamp. Mic preamp gain
ranges from
15dB to 55dB. This range is more than sufficient to accommodate all types of
microphones.
This control is before the level sensing automatic circuitry, and will
affect the
relative sensitivity of the automatic action. Maximum gain occurs when this
control
is fully clockwise.

OUTPUT LEVEL - Controls the level of signal from the channel sent to the
main buss.
This control is after the level sensing and attenuation circuitry, and will
not effect
the sensitivity of the automatic action. Maximum gain occurs when this
control is
fully clockwise.

TRIM SET LED - Indicates proper adjustment of the Input Trim control.
The Input Trim control should be adjusted until the Trim Set LED flashes
regularly on normal speech input.

CH ON LED - Indicates relative gain of the channel. The LED illuminates
proportionately
as channel gain increases. The Threshold control (on the Automatic Control
Module) should
be adjusted until there is little or no illumination of the "CH ON" LED
because of
background noise.

MODE - Selects the operational mode of the channel.

Priority Mode: Activity on priority channels fully attenuates nonpriority
channels.
There is no limit to the number of priority channels for a system.
Activity on priority will not effect channels in the Direct Mode.

Auto Mode: Channel functions as an automatic channel.

Direct Mode: Channel functions as a standard channel.
In this mode, the "CH ON" LED will be on continuously to indicate no channel
attenuation under any circumstance.


Rear channel connections for each Mic Preamp include a balanced XLR MIC
INPUT,
and terminal-type LOGIC OUTPUTS - SND / RTN / GND / + / -.

SPECIFICATIONS -
Gain Range: 15dB-55dB
Maximum Channel Attenuation: 15dB
Equivalent Input Noise, 20 to 20KHz: -128dBu
THD, 20 to 20KHz: Less than 0.05% (40dB gain, 0dBu out)
IMD, 60/7KHz: Less than 0.08% (40dB gain, 0dBu out)
Input Impedance: 6K Ohms, balanced / 3K Ohms, unbalanced
Input:
Type: Electronically balanced RF filtered
Maximum Input Level +5dBu (Gain set at 15dB)
Phantom Power: +48 Volts, internal jumper
Send (SND) Maximum Output: +20dBu
Return (RTN) Maximum Input: +20dBu
Power Consumption: ±100mA at 15 Volts


The operation manuals for the Lectrosonics Modular Audio Processor can be
found he
http://www.lectrosonics.com/manuals/ec1man.pdf

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This Lectrosonics EC1 Expansion Controller with 4 AP4 Automatic Mic Preamp
modules is in good to very condition,
and does power up and appears to be functional.

$100 obo + shipping.


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Mark