The Technical Stuff
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amount of compression varies constantly, depending upon the fluctuating strength of the incoming
signal) and at the same time imparting a very fast attack time and dual-stage release time that is
musically very pleasing. (
see page 23 for more information
.)
Through careful attention to design, custom wiring, and the use of vacuum tubes that are carefully
selected and tested individually, we believe we’ve succeeded in creating a powerful second-
generation recording tool. The LA-610 combines a versatile, easy-to-use mic preamplifier with
unmatched sonic characteristics—similar to that of the original 610, but with lower noise—with an
equally straightforward yet sonically superior compressor similar to that of the original LA-2A.
The LA-610 has input and gain stages, each of which utilizes a dual-triode tube operating in a class A
single-ended configuration. The preamp is followed by an LA-2A derived T4 side chain circuit,
including dual triode and pentode tubes that send signal to the luminescent panel. Variable negative
feedback is applied to both preamp gain stages to control gain, reduce distortion, and extend
frequency response. Our transformer design features double-sized alloy cores with custom windings,
and all balanced inputs and outputs are transformer coupled.
The simple operation of the LA-610, combined with the unique program-dependent nature of its
optical compressor provides the same extremely musical control that has made the 610 and LA-2A
such well-loved classics for over 40 years. In combination with its powerful and versatile tube-based
preamp, it yields an enormous bottom end warmth that is unparalleled, making it an ideal front-end
for tracking with modern DAWs.
Compressor Basics
The function of a compressor is to automatically reduce the level of peaks in an audio signal so that
the overall dynamic range—that is, the difference between the loudest sections and the softest
ones—is reduced, or compressed, thus making it easier to hear every nuance of the music.
Compression is sometimes referred to as
peak reduction
or
gain reduction
, because a compressor (or
“limiter,” when acting more severely) “rides gain” on a signal much like a recording engineer does
by hand when he manually raises and lowers the faders of a mixing console. Its circuitry
automatically adjusts level in response to changes in the input signal: in other words, it keeps the
volume up during softer sections and brings it down when the signal gets louder. The amount of gain
reduction is typically given in dB and is defined as the amount by which the signal level is reduced
by the compressor.
Compression or limiting enables even the quietest sections to be made significantly louder while the
overall peak level of the material is increased only minimally. The dynamic range of human hearing
(that is, the difference between the very softest passages we can discern and the very loudest ones
we can tolerate) is considered to be approximately 120 dB. Early recording media such as analog tape
and vinyl offered much less dynamic range, so compression was a virtual necessity, raising the
overall level of the material (making it “hotter”) without peak levels causing distortion. While many
of today's digital recording media approach or even exceed 120 dB of available dynamic range, quiet
passages of recorded music can still be lost in the ambient noise floor of the listening area, which,
in an average home, is 35 to 45 dB.
