The Ratios and their Curves
Each "ratio mode" of the Distressor sets both the threshold and the ratio, in the standard sense of the
word. This was done to provide an easy to set, yet versatile group of curves. The 1:1 mode provides no
compression, but allows the audio to pass through the "warming" circuits of the unit (we'll get to the
distortion modes in a moment). Ratio's 2 through 6 are general purpose curves great for tracking. The
2:1 and 3:1 ratios are "parabolic" knees - very gentle curves that won't typically go into hard limiting and
therefore, also won't provide absolute overload protection. Ratios 4:1 and 6:1 have steeper knees and
are good general purpose curves that gradually move towards hard limiting, "nailing" the signal in its
place. The ratio of 6:1 is very useful for vocals, bass, and acoustic instruments. It has an easy slope at
first until after the knee, where an increasing ratio "musically" limits the peaks of the signal before
damage is done. The 6:1 and 10:1 Opto ratios employ shorter knee limiting, reminiscent of some old
classics from the 60's and 70's (see Classic Emulation).
"Nuke" is a different story. The "Nuke" ratio was developed for room mics, but we have since found it
useful in many areas. "Nuke" has a medium threshold but when the signal hits it, a nuclear blast won't
budge the output level. It is brick wall limiting, keeping any normal signal within 1 dB or so. Just patch
in a room mic while recording drums (or other instruments) and slam the meters. Try attack on 4 and
release on 2. The release curve of "Nuke" is logarithmic, meaning it lets off quickly at first and then
slows. This release curve is a big part of the Distressor's sound. Experiment with the release times -
this guy can release really fast without too much crackling, even on bass. 20:1 can be used similarly to
"Nuke". Each of these curves again has their own feel to them, with the release slopes slightly altered,
and the knees falling in slightly different places. Most exceptional are the 2:1, 10:1 and Nuke ratios,
which employ special detector circuitry.
Just what is a soft knee?
A "soft knee" is a compression curve where the first few dB of gain reduction occur at very low ratios,
gradually increasing as the signal increases (gets louder). This makes the onset of compression very
hard to detect. The knee usually extends for a few dB and gradually flattens out toward a final ratio. All
curves with the exception of 20:1 and "Nuke" have dominant knees. The 2:1 ratio has a knee that can
be as long as 30 dB, depending on attack and decay settings.
Classic Emulation
Since the unit is based on the oldest compressor topology, the unit can be made to sound very similar
to older classics. The nonlinear nature of the older gain control elements of opto-couplers, FET's,
pentode (or triode) tube bias or "mu" modulation, etc., can be closely emulated if proper settings are
used. A special "Opto" mode has been provided in the 10:1 ratio.
Some Examples:
* To simulate the opto-VCA models of old (the LA-2A, LA-3A, LA-4A), try 10:1 "Opto" ratio, with attack
on 10, release on 0, Det HP on. Adjust input and outputs to your taste. Keep the attack above 4 to
keep the OPTO flavor. Faster attacks will give you a more aggressive sound. Remember our LED
metering deflects much faster than the old VU's so don't be afraid to hit the unit quite hard (10-20 dB of
compression on peaks). To emulate tubes, try Dist 2 & 3 mode, but let your ears be your guide.
* For a classic “Over E-Z” type sound, try ratios 2:1 thru 6:1, att 9, release 2, clean mode.
* 1176LN 6:1, Att 0 - 3.5, rel 1 - 10.5. Use ratios 3:1, 4:1, 6:1, 20:1 to emulate 4 1176LN ratios. Clean
mode is appropriate (Dist 2 or 3 off). Remember that the 1176LN attacks extremely fast and you must
keep attack under 4 max. A familiar sound is 6:1, att2, rel 4.
* Old Fairchild IGFET - 6:1 att 3-5, rel 2 - 7 (start with att 4 and rel 4)
Due to the transformerless design, you will maintain a low transient intermodulation distortion, but will
get the warming grunge of 2nd and 3rd harmonic distortion, if distortion modes are enabled. Also,
unlike some of the older units, the Distressor is uniform and predictable from one unit to the next.
Precise factory calibration assures that if you go from one Distressor to another, these settings will all
sound the same.
Empirical Labs would like to thank Universal Audio for not only creating classic audio gear, but for
kindly allowing us to refer to their model numbers. As they say “Once a classic, always a classic.”
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