Manley VOXBOX - MVBXA 4/2003 - Manual (Page 7)

COMPRESSOR SECTION
J. COMPRESSOR BYPASS: With this switch up the compressor is engaged. This switch is
uniquely designed to be used during music. No clicks, no pops and the change of level occurs
smoothly. The compressor is uniquely before the preamp so that transients are “tamed” before the
signal enters the tube circuit. This makes it possible to have exceptionally clean, smooth tracks. It
also allows the normal “mic preamp into outboard compressor into tape” to be essentially “purist
mic pre direct to tape” with compression invisibly taking place. We use a passive opto-isolator for
the gain control element which adds no measurable distortion or noise and only 0.1 dB of inser-
tion loss.
K. COMPRESSOR THRESHOLD: Turning this control clockwise increases compression. This
control is after the INPUT control. There is no “make-up gain” control so some degree of balanc-
ing between INPUT and THRESHOLD is expected. Adding the make-up gain or output level
would have compromised the sonic integrity for the sake of conventionality. The compressor
“ratio” is program dependent and non-linear but is generally similar to 3:1 ratios on VCA based
compressors.
L. ATTACK: This controls how the compressor reacts to transients such as explosive consonants
or drums. Slower settings tend to “ignore” transients and let them through untouched. Faster set-
tings tend to reduce transients which has an audible effect of reducing, for example, the strike of
a drum or the “P”s as in “puppy”. Vocals will usually be best with medium settings. Engineers
most familiar with compressors will notice the unusual way the “attack” rides above the reduc-
tion set by the release. Attack changes are most noticable on slower releases on this unit.
M. RELEASE: This controls how fast or slow the compressor returns to full volume. Because
various RC networworks are switched in this control also has some effect on attack rates. The final
release as reduction approaches 0 dB is a “bonus” function of the Opto. Each setting is actually
a separate complex set of “tuned” time constants. The FAST setting mimics the Manley Electro-
Optical Limiter and works best in the range of 3 to 8 dB of compression. The MED FAST setting
is much like old LA-2A’s but is also tuned for drums and bass and works well with dynamic
broadcast audio. This setting is designed to pump a bit with the Attack at Slow. MED and MED
SLOW are the usual choices for vocals. SLOW is a very slow release and is for the most inaudible
compression. RELEASE SLOW + ATTACK SLOW uniquely mimics a good engineer “riding” a
fader. Good for great singers, questionable for dynamic material.
LA-2A = FAST ATTACK & ME-
DIUM FAST RELEASE or FAST RELEASE (or LIMITER) LA-3A = SLOW or MEDIUM ATTACK &
MEDIUM SLOW RELEASE
N. LINK: Switching up connects or links a second VOXBOX for stereo applications. It ensures
that when either compressor channel reduces gain that both units will reduce the same number of
dBs. This is so that a center image does not drift when a peak is on one side. Both sets of controls
should normally be set to the same positions. It links both the compressor and the de-esser to the
second VOXBOX if RCA LINK interconnects are between both units. The RCA male to male
interconnect can be any typical stereo hi-fi type.
7