User manual AUSTRALIAN MONITOR KLA

[. . . ] The layout, grounding, decoupling and componentry have been optimised to provide the user with stability, reliability and longevity. ltu Austdlan Monitor KLa Loop Amplifiers 2 Front Panel Controls and Indicators Your KLa loop amplifier is furnished with simple controls and indicators to assist in the set up of the amplifier for driving a properly calculated lnduction Loop. The indicators provide visual detail to show the proper operating levels of input signals and output current. 1 Input Level Control. A "lnput Level" attenuation control is provided so as to adjust your incoming signal to a level suitable for processing by the internal limiter. The circuit is based on a fixed gain and thus the lnput Level Control provides attenuation only. The input of the unit can deal with Gain Levelled lnput Signals between -10 and +10d8 but OdB (. 775v) is preferable. 2 Operating Window Indicator. This Bi-Colour LED indicates signal level to the unit's limiter circuitry. Green indicates the threshold of the limiter and is factory preset for 250mV (-10dB). [. . . ] A male XLR connector is provided as a strapping connector wired in parallel with the input XLR allowing strapping/looping between multiple amplifiers. Pin allocation is: Pin-l = Signal Ground, Pin-2 = Cold (reverse phase), Pin-3 = Hot (in phase). 2 Signal Ground Lift Switch When this switch is engaged it disconnects signal ground from the amplifier. lt is intended to be used when "HUM" is caused by earth loops or stray magnetic fields. The amplifier should be tumed off before engaging this switch. Loop Outputs. Your Kla Loop Amplifier is provided with 2 options for output termination of the loop. Heavy cunent Binding Post outputs are provided as well as a Neutrik "Speakon" connector. The Speakon connector is wired 1+ = positive & 1- = negative. Mains Lead Your amplifier is supplied with a heavy duty mains lead (power cord) appropriately rated for the mains supply voltage marked on the rear panel of your amplifier. The wires in the mains lead are coloured in accordance with the following code. Brown = Active, Blue = Neutral, Green/yellow = Earth. Your unit must always be earthed! Mains Circuit Breaker A "push to reset" thermal circuit breaker is supplied to provide overall protection of amplifiers power supply. lt will isolate the "active" mains conductor in the event of a current internal fault or in continued overload conditions, your high D. C. Rail Fuses 3AG "fast bloy/' type fuses are provided and are in series with the positive and negative supply rails for your amplifiers output stage. These fuses provide overall protection of the output stage. The fuses must be replaced with the same type fuse. KLal = 8 Amps, l(La2 ='10 Amps. /tu Aushalian Monitor KLa Lpop Amplifiers 5 To set up your KLa Loop Amplifier: Once all connections have been made: I 2 3 Make sure all the controls are down before you tum the amplifier ON. npply signal (applied signal should be gain levelled and be around odB - 0. 775 volts ) Turn up'INPUT LEVEL'knob until 'OPERATING WINDOW" LED is flashing between green and red illuminations. NOTE: The red LED should not be on constantly, but should flash with programme peaks. 4 Tum up 'OUTPUT DRIVE" control to the desired cunent level. KLa 1 Green = 3Amps, Red = 6 Amps. KLa2 Green = 5 Amps, Red = 10 Amps. NOTE: These LEDS are to illuminate on peaks only. 5 Use a field strength meter or loop listening device to monitor level and coverage in the loop. The do's and don'ts There are a few precautions you need to consider when installing your lnduction Loop System. As there is a strong field radiating from the cable it can interfere with other electronic equipment thus your loop should be restricted (as far as possible) to a defined listening area. Do: Always ensure the installation of your Loop is in accordance with wiring regulations. As far as possible have your loop at the same elevation as the listening position, 1 to 2 metres above or below this is acceptable but more cunent drive may be required. Run balanced signals / cables wherever possible. Do Not: - Do not install the loop with other cable runs - never run the loop cable in parallel with other cables and always cross other cables at right angles. Do not run your Loop cable in conduit or in performance. / or near shielded trays as this may effect its ' I Do not have dynamic type microphones, which may be a part of the signal source, inside or near the loop. The coil may pick up the radiated field from the loop and cause feedback to occur in the system. Do not run unbalanced signals feedback. / cables as they may be affected by the Loop and cause /tu Ausbdan Monitor KLa Loop Amplifiers 6 Why An Induction Loop system. Usually, an lnduction Loop system is installed as an aid to provide audio for the hearing impaired. The system is driven by an amplifier which can provide a constant cunent into a wire loop encompassing the listening area. A field is radiated from the cunent flowing in the loop, and this radiated field induces cunent to flow (more often than not) in a "T-Coil" in the hearing aid device of the hearing impaired. Because a length of wire is used as the load from which the signal is radiated, it makes special demands on the amplifier driving it. [. . . ] The hearing impaired can detect more detail in the programme if dynamic range is reduced. For this reason lnduction Loop Systems should be fed with gain levelled signal. The KLa amplifiers have a built in limiter to further reduce transients in the applied programme source. /tu Ausbalian Monitor KLa Loop Amplifiers 7 Calculating the Induction Loop. The following information is provided as a guide for the proper calculation of your lnductive Loop installation. You will need to know the size of your loop to ascertain the peak drive cunent reguired and to select the appropriate gauge of the wire for the loop. LOOP H|GH cuRRENr TERMTNA-floN ", o"" I OUTPUT TFRMINAI ')cS: LENGT H I LOOP FEED PARALLELING LINKS IIF REOUIRED} . - BREADIH -. . . . . * Chart (page 8) shows the relative cunent required for different size loops - Pick the closest cunent (Ampere) curve. [. . . ]