16 RCA phono INPUT 1 to 3 for units with line output (e. g. CD player, cassette recorder, etc.); the signals of the stereo channels L and
R are internally mixed to a mono signal
17
18
Control METAL LOSS CORRECTION
Jack SLAVE I/O for connection of another loop amplifier.
Connections at the plug :- tip = output , ring = input , body = ground
(only active if the jumper J8 is placed to the ON position)
2 Safety Notes
This unit corresponds to all required directives of the EU and is therefore marked with
It is essential to observe the following items:
The unit is suitable for indoor use only. Protect it against dripping water and splash water, high air humidity, and heat (admissible
ambient temperature range 0 – 40 °C).
Do not place any vessels filled with liquid, e. g. drinking glasses, on the unit. The heat being generated in the unit must be car-
ried off by air circulation. Therefore, the air vents at the housing must not be covered.
Do not set the unit into operation, or immediately disconnect the mains plug from the mains socket if
1. there is visible damage to the unit or to the mains cable,
2. a defect might have occurred after a drop or similar accident,
3. malfunctions occur.
The unit must be repaired by skilled personnel.
Never pull the mains cable to disconnect the mains plug from the mains socket, always seize the plug!
For cleaning only use a dry, soft cloth, by no means chemicals or water.
No guarantee claims for the unit and no liability for any resulting personal damage or material damage will be accepted
if the unit is used for other purposes than originally intended, if it is not correctly connected, operated, or not repaired in an
expert way.
WARNING :- The unit is supplied with hazardous mains voltage (230 V~). Leave servicing to skilled personnel only and do not in-
sert anything through the air vents! This may cause an electric shock hazard. Only make or change all connections with the
sound reproduction system switched off.
3 Applications
4 Installation
The LA-300/600 are the active loop amplifiers in constant
1. Install the loop.
2. Before connecting a loop to the amplifier use a multimeter to check the loop is not shorted to ground at any point, ( it will
6. Connect music or speech input signal to the amplifier. The peak line level of this signal should be approximately 1V.Ensure
7. Increase the input levels controls until the ‘limit’ led is just flashing.This indicates that the dynamic range processor is
8. Adjust the drive control until the required current peak is produced. Care should be taken when doing this to ensure the
9. Using an induction loop receiver listen to the signal inside the loop. It is advisable to check the system with a field strength
meter. Please note that the orientation of the field strength meter may influence the reading.
current is within the recommended rating of the cable. The average current output should be approximately one quarter of the
maximum peak.
receiving a signal of the correct level. If you are usings both inputs the level controls acts as a simple mixer.
level controls and drive control are fully anticlockwise.
almost certainly damage the amplifier if it is).
current technique with dynamic compressor for creating an indu-
ctive sound reproduction system. It allows transmission of audio signals to hearing aids with a “telephone coil” and to inductive
receivers.
The wireless transmission is an advantage of inductive sound reproduction systems. Thus, the user is able to move
freely within the loop.
Inductive sound reproduction systems are used for various applications, e. g. as an aid for persons hard of hearing in churches,
theatres, cinemas, waiting rooms, meeting rooms, as interpreting installation
,for lectures in museums, exhibitions, etc.
In inductive sound reproduction systems, an induction loop is triggered with a constant current amplifier. An induction
loop consists of a wire winding laid into the floor, into the wall, or into the ceiling. Within this loop, a magnetic field is generated
which will induce a voltage in the induction receiver. The receiver will reconvert this voltage into an audio signal.Any number of
receivers can be operated within an induction loop.
The maximum size (600 m for LA 600 & 300m for LA300)
2 2 of an induction loop may be reduced due to field strength losses
which are caused by metal in ceilings and floors. Small losses
can be compensated with the function METAL LOSS CORRECTION.
The LA-300/600 has three channels to which units with a line output (e. g. CD player, tape deck, tuner) and microphones
phantom-powered) may be connected. The channel INPUT 1 is equipped with a talkover function which attenuates the volumes of the
other two channels by approx. 40 dB in case of an announcement. The loop amplifier may be used as a mixing amplifier or be
integrated into a PA system.
GB
3. Prior to installing the sound reproduction system check for any magnetic interference at the place provided for it. This may
impair the operation or even make the operation impossible. Interference is caused e. g. by transformers,high power
cables, fluorescent lamps with a standard choke, and data cables.
4. Besides magnetic noise fields, interference in inductive sound reproduction system may also occur due to reinforced concrete
floors or floor heating with copper cables. In this case, too, the magnetic field does not spread equally and in the extreme case
the use of an inductive sound reproduction system is not possible. If the interference caused by the reinforced concrete is
not too extensive, the frequency response may be adapted accordingly by means of the function METAL LOSS
CORRECTION.
5. When laying the induction loop in tubes, these must be made of plastic as metal tubes may strongly impair the magnetic
field of the loop.
3
