Recording - February 2015 - 26

Compression
Early analog consoles did not have built-in compression, so
compressors were outboard, intended more for the full mix than
for individual signals. Broadcasting was monophonic in those
days, so most compressors were too. The Holy Grail units are
the Fairchild 660 Limiter (and the 670 stereo version), the
Teletronix LA-2, and the Universal Audio 1176.

The 1176 adds a little edge to the sound, which makes it
extremely popular for aggressive rock bass and guitars as well as
vocals. The secret mojo of the 1176 happens when you press all
4 ratio buttons down at once and get them all to stick. This was not
an intentional part of the design, and is sometimes called "British
mode" due to its popularity among some British engineers in the
1960s and 1970s. In British mode the compressor basically freaks

5
The Fairchild 660 tube limiter has controls for input level,
threshold, and a "time constant" click-stop knob, which provides
different combinations of attack and release times, as fast as 0.2
and 0.3 milliseconds respectively. In the extreme settings,
release gets as long as 25 seconds! The non-adjustable ratio
starts at 2:1 and gets as high as 30:1 depending on how much
gain reduction is happening. The compression is done directly
by the tubes using the "Variable Mu" technique.
Like a Pultec EQ, the 660 improves the sound even when
doing nothing, thanks to its 20 tubes and 14 transformers.
Many engineers use this box to barely compress vocals, with the
time constant at the fastest settings and the needle barely moving-the 660 can get rather squashy if you let it. Engineer Geoff
Emerick would run just about all Beatles vocal tracks through it,
even without engaging any compression, just for the enhanced
presence. I don't have a 660 photo handy, but Figure 6 shows
the Waves plug-in version from the Jack Joseph Puig package-
we'll talk about plug-ins later on.
The LA-2 (see Figure 7 for the still-available Universal Audio
LA-2A) is a different beast entirely. It is an all-tube design with
transformers, but the compression is controlled by an electroluminescent (EL) element that gets brighter as the audio gets louder. This is why the LA-2 is referred to as an "optical" compressor. This light shines on a photosensitive resistor that controls the
compression. The resistor will provide a 10 ms attack time, but
when the audio gets quiet and the light goes out, the resistor
exhibits a two-stage release time, falling in 40 to 80 ms to 50%
of its "off" resistance, and then the rest of the way over several
seconds. Additionally, the photo resistor has "memory", and
takes even longer to reach its off resistance depending on how
bright the EL element had been shining and for how long.
Therefore the LA-2 has program dependent release, recovering quickly after a few loudly shouted words and slowly after
long passages of sustained loudness. This is a very desirable
attribute! The compressor will act quickly on short-term program
material but also gently ride the level over longer sections.
Skillful use of program dependent compressors can reduce the
amount of level automation needed in your final mix.
The 1176 (see Figure 8) is a solid state, class A compressor
with the compression controlled by a FET (Field Effect Transistor)
circuit rather than an optical device or tubes. The attack time is
ultrafast, 20 to 800 microseconds! The release time is slower,
50 milliseconds to 1.1 seconds, with some program dependency. (By the way, the 1176 attack and release times get faster as
you turn the knob to the right.)
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RECORDING February 2015

out; distortion increases, ratio moves around between 12:1 and
20:1, attack time is magically delayed, and release time alters fluidly. Nobody has ever actually documented exactly what happens
because it is very complex and chaotic!
British mode can be used for drastic audio smashing. Listen to
Audioslave's self-titled debut: extreme vocal compression with a
slowish attack time and fast release. This makes the beginnings
and ends of the words pop out, which improves intelligibility.
Aside from that, the vocal is held at a very constant amplitude
with some added edge, which is magic in a loud mix.
You can achieve this sound easily with an 1176. Press in all the
ratio buttons, and the gain reduction meter will slam all the way
to the right-wham! Set a slower attack time, 1 to 3, and fastest
release (7). Increase the input knob until the meter shows 10-20
dB of compression. You'll need to decrease the output by a lot!

Use your ears and tweak the input and attack/release knobs
until the beginnings and ends of the words pop and the sustained syllables remain at a very constant level. You can use this
same trick on soft vocals in an exposed folk mix. It just involves
speeding up the attack time so the beginnings of the words even
out, and slowing down the release a bit. You can end up in a
sweet spot where the vocals become very close and intimate
without actually sounding supercompressed.
Putting it into practice
First of all let's pretend money is no object-we'll get to
more affordable alternatives after we describe the method,
which involves getting some iron and maybe tubes into the
chain. Chandler Limited makes a line of outboard gear based
on the REDD circuitry, plus some other Beatles-era processors
not mentioned in this article. You can get hold of vintage

Recording - February 2015

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