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flexible collection of circuits. Mixer manufacturers need to make
trade-offs to keep prices down while keeping performance up. Imagine
the price of your mixer if each channels’ EQ cost over $200 (and we’re
not talking about those of you who have one of those $250,000+
consoles!) The use of external processing (equalizers, preamps and
compressors) has sonic and practical benefits when you consider that
most recording is done one or two channels at a time. For those of us
on a budget, it just doesn’t make sense to spend a ton of money on a
“Cadillac” console when a budget mixer and a few pieces of external
gear is more cost effective. Even those engineers who regularly work
on “big” consoles use external EQs, compressors and preamps!The
goal of any recording is to get the sounds right before you commit
them to tape. The Tube Channel exists to help you get it right so you
don’t have to “fix it in the mix”.
Design Notes
The Tube Channel is a multi-purpose tool for audio engineering and
recording. Enclosed in a one rack space (1U) chassis are three
independent circuits featuring a tube-based analog preamplifier, a
VCA-less, optical compressor, and a semi-parametric, four-band, tube-
based equalizer. Used as a direct recording channel, a mic/line
preamp, or a DI (direct) box, the Tube Channel is designed to work
seamlessly with any recording, sound-reinforcement, or electronic
instrument setup. A R T’s Tube Channel circuitry is a hybrid design
utilizing the latest, most advanced, solid-state and tube technology.
With a transformerless design, the Tube Channel maintains
exceptional signal integrity and extremely low noise. The compressor
circuit follows the preamp and the equalizer follows the compressor
(although you can change the order of the circuits by utilizing the
insert points). While the preamp is always active, the compressor and
equalizer may be individually bypassed. The preamplifier’s active
balanced solid-state input provides extremely low noise and excellent
CMRR. The ¼” input has a high impedance, which prevents the
loading of any device connected to it and makes the Tube Channel
perfect for DI or line level applications. The preamplifier’s second
stage 12AX7a tube runs on a regulated DC voltage providing an
additional 40dB of gain. Our design enables the tube to overload
before the input or output stage. This allows you to manipulate the
tube gain to meet different sonic requirements.The compression circuit
features a VCA-less design and utilizes optical (Vactrol) electronics
for superior musical performance. The compressor is soft knee by
design. Although it is capable of providing a thoroughly “squashed”
