Manley VOXBOX - MVB 1996 - 2/2000 and MVBX 6/2000 - 4/2003 User Manual

Page 5

COMPRESSOR SECTION

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 insertion loss.

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 balancing 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.

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 settings 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 reduction set by the release. Attack changes
are most noticable on slower releases on this unit.

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 & MEDIUM FAST RELEASE or FAST RELEASE (or LIMITER)
LA-3A = SLOW or MEDIUM ATTACK & MEDIUM SLOW RELEASE

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.