User manual TL AUDIO C1

[. . . ] T L Audio User Manual C1 VALVE COMPRESSOR Tony Larking Professional Sales Limited, Letchworth, England. International +44 1462 490700. INTRODUCTION The T L Audio Valve Compressor combines classic valve techniques with low noise solid state circuitry to produce a unit offering a fully controllable compressor on each of its two channels. Both channels feature balanced and unbalanced line level inputs, plus a mic input with switchable 48V phantom powering. Further flexibility is provided from a front panel auxiliary input which accepts mono or stereo keyboard and guitar inputs. [. . . ] The mating connectors should be wired as follows: - Pin 1 = Ground (screen), - Pin 2 = Signal Phase ("+" or "hot"), - Pin 3 = Signal Non-Phase ("-" or "cold"). If an unbalanced output is required, pins 1 and 3 should both be connected to ground. A switch on the rear panel allows the output to be matched to equipment at a nominal operating level of +4dBu or -10dBu. Most professional equipment requires +4dBu (approximately 1. 2V rms), but some small mixing consoles, portable tape recorders or domestic audio equipment require -10dBu (approximately 225mV rms). The switch should be set to the position which results in the best signal to noise ratio, whilst preserving sufficient headroom. An unbalanced line output is provided for each channel, on a 0. 25" mono jack socket. - Tip = Signal Phase ("+" or "hot"). - Screen = Ground. The unit generates a small amount of heat internally. 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 unit where it will be subject to external heating, for example in the hot air flow from a power amplifier, or on a radiator. The compressor may be free standing, or mounted in a standard 19" rack. The rear panel connectors are identified in fig. 3. OPERATION. Front Panel. The front panel controls for one channel are identified in fig. 2. Ensure that the correct input connector, mic or line, is being used and that the front panel switch is set to the appropriate position. Note that both mic and line inputs may be connected at the same time, but only one is selected. The input selector switch selects between the line input, mic input, mic with +48V phantom power (signalled by a red LED), and the Aux input. CAUTION: Switching phantom power on, 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. If the gain required is not known, set the control to minimum with the EQ by-passed, and gradually increase the gain until the required output level is achieved. The front panel auxiliary input sockets may be switched between high level signals ("Keyboard") and low level pick-ups ("Guitar"), and are provided with an input gain control. Note that the channel gain controls remains operative when the Aux input is selected. [. . . ] The input gain and gain make-up controls remain separate to allow relative input/output gain balance adjustment. In stereo mode, the control voltages are also linked, ensuring that the same amount of gain reduction is applied to both channels (even if one signal is below the threshold). This ensures that the stereo image is preserved. The compressor is equipped with twin, illuminated VU meters. [. . . ]