T L Audio
User Manual
C1 VALVE COMPRESSOR
Tony Larking Professional Sales Limited,
Letchworth, England.
Tel: 01462 490600. International +44 1462 490600. Fax: 01462 490700. 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. Typical applications include direct recording to tape, instrument preamplifier, use as outboard equipment during mixdown, and as a main stereo compressor for monitoring and PA systems.
The block diagram of one of the channels is shown in fig.1. A solid state, electronically balanced input amplifier is used, to achieve state of the art performance with very low noise, low distortion and wide bandwidth. The input includes a switchable second order high pass filter, -3dB at 90Hz, to remove unwanted LF noise. A triode valve is used as a second stage voltage amplifier, to obtain the classic valve sound and gradual overdrive characteristics.
Two XLR input sockets are provided per channel, for mic and line inputs. The mic input is suitable for low impedance (150-600 ohm) microphones, with a gain control range of +16 to +60dB. 48V phantom power is available on each channel. The line input has an effective overall gain range of -10 to +35dB, allowing the valve stages to be fully driven from line level signals in the range -20 to +20dBu.
A front panel mounted auxiliary jack socket for each channel allows mic or line level inputs to be easily connected to the compressor. The aux input may be used for a stereo keyboard or mono guitar, etc.
An insertion point is provided in the sidechain circuit to allow an equaliser or other processor to be used for frequency conscious compression, etc. The insertion point is unbalanced, at a nominal operating level of -2dBu. The sidechain processing is solid state, whilst a second triode valve stage is employed in the compressor circuit.
The compressors feature continuously variable controls for threshold, attack, release, ratio and gain make-up. A certain degree of programme dependant variation is incorporated, particularly of the attack and release times. Full stereo operation is supported, with ganged controls and linked control voltages. The compressors may be by-passed for A-B comparison.
Twin illuminated VU meters are provided, which may be switched to monitor the output signal level or compression applied. A solid state, electronically balanced output stage with XLR connector completes the channel. Dedicated unbalanced outputs are also provided on jack sockets. The outputs are switchable for +4dBu or - 10dBu nominal output level.
Please read this manual fully before installing or operating the Compressor.
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