628
11
COMPRESSOR
(Sec)
RELEASE
(dBFS)
THRESHOLD
(X:1)
RATIO
-9
-15
-18 -12
-3
-6
ACTIVE
The THRESHOLD knob sets the COMPRES-
SOR threshold level. Audio signals arriving
at the COMPRESSOR stage above the set
value (in dBu) will trigger the COMPRESSOR
into action. Signals arriving at the COM-
PRESSOR below the threshold level will pass
through unaltered.
To change the threshold level, gently turn the
THRESHOLD knob until you feel one click.
The MASTER numeric display will show the
present threshold level in dBfs (decibels full-
scale). For example: if the THRESHOLD control is adjusted so that the MASTER display shows
a value of -30 the threshold is now set at a value 30 dB below clipping. Since the 628 clips at
+22 dBu, the threshold is set at -8 dBu (+22 dBu minus 30 dB).
To change the threshold value, turn the knob until the new threshold level which you want is
displayed. To save the change, momentarily press the SAVE button in the MASTER section. The
MASTER display will show the flashing letters Sto (Store). Push the SAVE button again and the
628 will record the change to the threshold. This edits the program and permanently records the
change. The new threshold value has now been loaded into the program. The LED meter in the
COMPRESSOR section will now display the amount of compression applied when a signal is
present.
Use the RATIO control to vary the compression ratio of the COMPRESSOR. Use low ratios (for
example: 2:1) for gentle level control. Save the higher ratios (for example: 5:1) for more aggressive
processing (rock & roll DJ use). Change the ratio by turning the RATIO knob until a single click is
felt. The numeric display in the MASTER section will show the current ratio expressed in a value
to 1 (for example: XX:1). To change the ratio, rotate the RATIO knob until the desired ratio appears
in the MASTER numeric display. Save the change by pressing the SAVE button. The MASTER
display will show the flashing letters "Sto" (Store). Push the SAVE button again and the 628 will
record the change to the preset program. This edits the program and permanently records the
change. You will note the result of the change in compression on the LED meter in the COMPRES-
SOR section.
The RELEASE control allows you to change the release time of the COMPRESSOR. Long release
times (for example: 2.0 Sec.) produce gentle, transparent processing. Fast release times (for
example: .5 Sec.) result in aggressive, hard compression which some may find irritating. Most
operators compromise and select a release time somewhere in the middle range. Find what release
time the current preset uses by turning the RELEASE knob until one click is felt. The value in
seconds will display in the MASTER numeric display window. If you need to change the release
time, turn the RELEASE knob until the desired time is shown on the numeric display. Pushing the
SAVE button causes The MASTER display will show the flashing letters Sto (Store). Push the
SAVE button again and the 628 will record the change to the release time. This edits the program
and permanently records the change. You will note a change in the amount of compression on the
LED meter in the compressor section of your 628.
We have one more knob to turn before we weigh anchor on the compressor. The 628s compressor
lowers the output level in direct proportion to the amount of compression which you dial in. When
you see the 628 compressing your voice by 6 dB, you will notice that the output level drops by
about 6 dB.
Here's where we use the OUTPUT LEVEL control to compensate for the signal lost in compression.
Grab the OUTPUT LEVEL knob and turn it until the number 6 appears in the MASTER display.
This adds 6 dB of gain to the output of your 628. Check for clipping on the MASTER output
meter. If everything looks OK, push the SAVE button twice to save this change to your compres-
sor program.
