TL Audio 5050 - Manual (Page 4)

7 SERVICE
1. INTRODUCTION
Congratulations on purchasing the Ivory 5050 Mono Preamp & Compressor by
TL Audio!
The Ivory 2 Series consists of a range of hybrid valve signal processors, which
utilise low noise solid state electronics in conjunction with classic valve
circuitry to produce audio processing units offering very high quality signal
paths with the unique valve audio character. The Ivory 2 Series units offer
comprehensive control facilities, whilst remaining straightforward to operate,
and represent excellent value for money.
The 5050 is a single channel pre-amplifier, accepting a wide range of inputs,
coupled to a compressor with fully variable parameters. Twin LED bargraph
meters display output level and gain reduction. The optional DO-2 digital
output card provides 24 bit A-D conversion of the 5050 analogue output, via a
coaxial SPDIF connector. 44.1kHz and 48kHz sample rates are selectable,
and an external BNC wordclock input is also provided on the D0-2.
The block diagram of the unit is shown in Fig.1. There are three input sources
- balanced microphone via an XLR connector, balanced line input via a TRS
jack socket, and an instrument jack socket located on the front panel, where it
provides a convenient means of patching a guitar or keyboard directly into the
processor. The input stage is a hybrid valve circuit, containing one stage of an
ECC83/12AX7A dual triode valve, run from a 150V DC stabilised supply. The
input gain is governed by a centre-detented control, calibrated for 0dB nominal
gain from the line input sources at the centre and providing up to 60dB of
microphone gain. The instrument input is also controlled by the input gain
potentiometer, and will accept a wide range of sources from passive pickups
through to active guitars and keyboards. Phantom power and a 30dB pad are
provided on the mic preamp stage, and a switchable 90Hz high pass filter is
active on all three inputs.
The compressor stage offers variable control of threshold and ratio, with
switchable attack & release times and a choice of soft or hard knee
compression modes. The compressor is based around TL Audio’s trademark
transconductance amplifier stage, and also utilises the other stage of the
above-mentioned ECC83/12AX7A valve.
An independent gain make-up control is provided, to retain the subjective
loudness of a compressed signal, plus an overall master output level control.
The output control has a nominal 0dB of gain at its centre, with up to 15dB of
further gain available to achieve the high level required for some digital
recorders.