EMT 240 Reverb Foil User manual

Instruction Manual
EMT 240
Reverb Foil
GERMANY
BARCO-EMT
CONTACT: BIRDGETTE HEBDING nee (ZIMMER)
TELEPHONE: [phone]

ATTENTION!
The unit contains an additional protection against shock, in order to
prevent any damages caused by shock or other impacts due to rough handling
in transit.
Before operation please remove the shock protection in the following se-
quence:
Open one side of the housing - take the wrench of the accessories and
loosen nuts at the lower wooden blocks until the bolts will release the
inside housing - take of f laterally the squeezed upper blocks - take off
laterally the lower blocks.
The inside housing should now swing freely in all directions.
If shipment has to be made by you occasionally via carriers, such
as railway, airfreight or forwarding agents, we would recommend in your
own interest to re-mount the shock protection and to ship the unit only in
its original packing.
The shock protection and the packing is not necessary for transportation
by car, truck or Broadcasting Van, provided the unit is handled with care
during such transportation and when loading and unloading the equipment.
8. July 1977 Vo/sh/ge
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You have acquired a precision instrument when
you bought the EMT 240 Reverb Foil. It was de-
signed for field use and is therefore made to
withstand mechanical shock found under normal
operating conditions. Do not subject the
unit to excessive accellerations — treat it with the
same care with which you would handle a tape
recorder, for example. This will assure that the
excellent performance specifications of the EMT
240 will be maintained for some time to come.
Unpacking instructions and
preliminary set-up
You have just opened the outer packing case
— please read on before you unpack the unit any
further.
1. Remove the foam cushions on top of and on
the left and right of the inner carton. Check to
see that all of the accessories in the plastic
covered boards correspond to the list on page
4.
2. Carefully lift out the inside carton. Do not lay
the unit on its side under any circumstances!
3. Open inside carton.
4. ATTENTION!
The unit contains an a d d it io n a I protection
against shock, in order to prevent any dam-
ages caused by shock or other impacts due to
rough handling in transit.
Before operation please remove the shock
protection in the following sequence:
Open one side of the housing — take the wrench
of the accessories and loosen nuts at the lower
wooden blocks until the bolts will release the
inside housing — take off laterally the squeezed
upper blocks — take off laterally the lower
blocks.
The inside housing should now swing freely in
all directions.
If shipment has to be made by you occasion-
ally via carriers, such as railway, airfreight or
forwarding agents, we would recommend in
your own interest to re-mount the shock protec-
tion and to ship the unit only in its original
packing.
The shock protection and the packing is not
necessary for transportation by car, truck or
Broadcasting Van, provided the unit is handled
with care during such transportation and when
loading and unloading the equipment.
5. Locate unit at desired spot and connect electri-
cally (page 8). Check proper line voltage set-
ting!
Turn unit on. Push the reverberation time
button (—) for about 10 seconds. The unit is
now ready for operation.
6. Save all packing materials! Re-ship only in the
original packing.
TRANSPORT IN UPRIGHT POSITION
ONLY!
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Technical Description
The Reverb Foil EMT 240 is a device for produc-
ing reverberation.
The principle involving the use of a flat, tensioned
plate for the creation of reverberation, which has
been used for the past decades, has been re-
tained in this new device. In the course of techni-
cal improvement and the significant reduction in
size, the material used in the vibrating plate has
also been changed: The EMT 240 Reverb Foil
uses an electroplated gold foil of great purity (24
carat “coin gold”) with a thickness of only 18j.jm
(.00071”) and 270x290 mm (10.6”xl 1.4”) size.
This foil is mounted in a frame under tension,
excited by a driver, and sensed by a pick-up
system.
Changing the Reverberation Time
The reverberation time is changed as before by
bringing a damping device in close proximity to
the foil. Avibrating foil such as this gives off
energy to the surrounding air (sound field); by
bringing an absorber more or less close to this
sound field, energy is removed and the decay is
damped to a greater or lesser extent.
This method not only has the advantage of damp-
ing all frequencies equally and without erratic
behavior (as may occur due to the complex input
impedance of a mechanical system when damp-
ing is done electrically by changing the imped-
ance of the transducer), but it is also possible,
using suitable means, to make this absorption
frequency dependent and thereby to compensate
the response of the reverberation time. These
frequency dependent resistances are produced
by openings in the damping plate. The picture
shows slots in the actual damping material which
serve this purpose. By varying the slot widths and
the ratio between slot and damping surface, the
required equalization is obtained.
Remote Reverberation Time Control
The damping plate may be moved by remote
control. A complete description, including connec-
tion means, is given on page 9.
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