User manual TL AUDIO PA-1

[. . . ] The HF and LF Cut stages are second order passive filters which are switchable to Off (i. e. maximum bandwidth), plus 3 frequencies per filter. Channel A is additionally equipped with a phase reverse switch to ensure correct phase relation of an overall stereo system. A solid state, balanced output stage completes the signal path by providing a high drive capability suitable for connection to virtually any mixing console, amplifier or PA system. [. . . ] If an unbalanced output is required, pins 1 and 3 should both be connected to ground. The unbalanced jack socket outputs should have mating plugs wired as follows: - Tip = Signal Phase ("+" or "hot"). - Screen = Ground. The nominal output level switch, located next to the balanced outputs, changes the gain of the output stage to provide optimum signal to noise ratio and headroom when the Pre-Amplifier is connected to professional equipment (+4dBu nominal) or semipro equipment (normally -10dBu). Ventilation. The unit generates a small amount of heat internally, mainly due to the valve heaters. This heat should be allowed to dissipate by convection through the grill in the front panel, which must not be obstructed. Do not locate the Pre-Amplifier where it will be subject to external heating, for example, in the hot air flow from a power amplifier or on a radiator. The unit may be free standing or mounted in a 19" rack, where it will require 2U of space. OPERATION. Front Panel. The front panel controls are shown in fig. 3. Ensure that the correct input connector, mic or instrument, is being used. Note that the instrument input will override the mic input if both are connected at the same time. +48V phantom power is available at the mic socket, selected by the switch adjacent to the input socket. CAUTION: Operation of the phantom power switch, or plugging a microphone in with phantom power applied, may cause a click or thump in your loudspeakers. To prevent this happening, ensure that the system gain is set to minimum (e. g. on your mixing console fader or power amplifier), before operating the switch or plugging in a microphone. Gain. The Mic gain is set in 10dB steps by the rotary switch, with fine adjustment available over an additional +/-12dB range from the trim control. The total maximum gain available on the mic input is +62dB. The gain available on the instrument input is 14dB lower than the mic, with a maximum of +48dB. The filters are second order (12dB per octave), with -3dB points at the frequencies marked. Each filter has 3 switched frequencies plus an "Off" position. With both filters in the Off position, the Pre-Amplifier will produce a frequency response of 2dB at 30Hz and 40KHz. Each channel is equipped with a large, rotary fader for control of the output level. 0dB output gain is obtained at the maximum clockwise position. Phase Reverse. [. . . ] The manufacturer cannot accept responsibility for damage caused during transportation. The unit is protected by a limited warranty for a period of one year from the date of purchase. During this period, any faults due to defective materials or workmanship will be repaired free of charge. The warranty excludes damage caused by deliberate or accidental misuse, operation on the incorrect mains voltage, or without the correct type and value of fuse fitted. [. . . ]