Studer D19 MicVALVE User manual

PROFESSIONAL AUDIO EQUIPMENT
Prepared and edited by:
STUDER Professional Audio AG
Technical Documentation
Althardstrasse 30
CH-8105 Regensdorf-Switzerland
Copyright by STUDER Professional Audio AG
printed in Switzerland
We reserve the right to make alterations.
STUDER is a registered trade mark of STUDER Professional Audio AG, Regensdorf
PI 11/96, Order No. 10.85.0161 (ED 0397)
PRODUCTINFORMATION
STUDER
D19 Echo Canceller

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STUDER Echo Canceller
The Echo Canceller has been designed to over-
come problems in live broadcasting, when trans-
mission delays due to digital transmission and
data compression processes do not allow using
the broadcast signal as monitoring source.
When switching between different channels dur-
ing on-air programs, the local reporters should
be able to monitor the final broadcast signal to
keep the overview and react to forced switchings
due to more important events on other channels
(e.g. sports events).
For listening to the current program without be-
ing disturbed by the own delayed voice, the echo
of the local signal has to be deleted from the re-
turn signal.
The delay range of currently available echo sup-
pression products like telephone hybrids is not
sufficient for these situations (some 100 ms).The
Echo Canceller is using a separate delay line
which allows to remove echo signals up to one
second. This pre-delay either adapts to the cur-
rently measured delay automatically, or it can be
set manually for fixed installations.
After being removed from the returning broad-
cast signal, the local source can be directly
added again. The volume of this direct signal is
adjustable, and it is added automatically when a
return signal is present.

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1. Operation
The Echo Canceller is operated locally with a
few frontpanel elements. A serial remote port
will be available as option. In addition to the
power switch, the following elements are pro-
vided.
A 3-digit display indicates the currently selected
pre-delay in the range of 0…999 ms.
With the MODE key, one of the following oper-
ating modes can be selected:
CONT In continuous mode the predelay circuit
is adapting automatically to the current
situation. It is looking for a correlation
between local and return signal; the
delay line is modified after two valid
measurements in sequence.
MAN The manual mode allows to set the pre-
delay with an UP and a DOWN key,
which increment or decrement the cur-
rent delay.
ONCE The one-shot mode is setting the delay
line once. After the first two valid meas-
urements in sequence the delay will re-
main constant.
The return signal may be bypassed to the
LOCAL
OUT
output with the BYP key.
With the DIRECT VOLUME potentiometer, the
volume of the directly added local signal is ad-
justed from mute to full level position.
A
LOCK indication is switched on during cor-
rect operation of the unit. Whenever no correla-
tion is found or the delay time is being modified,
the LOCK indication goes off.

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2.Inputs / Output
LOCAL IN
Analog line input of local source signal (XLR,
transformer-balanced)
FAR IN
Analog line input of return signal (XLR, trans-
former-balanced)
LOCAL OUT
Analog line output of processed return signal
(XLR, balanced)
3. Specifications
Sampling Rate 16 kHz
Bandwidth 140...7300 Hz
Compensation Range 1 s maximum
Echo Suppression typ. 15…35 dB,
depending on quality
of return signal
Power Supply 90…260 VAC
50…60 Hz
Mechanical Size 19" rack mount size,
1HU