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About Compression
The dynamic range of a sound is the difference between its loudest and softest
points. For example, as you play your bass, you’ll probably find that some
notes (for example, notes played on the upper frets of the lowest string) are
considerably louder than others. The function of the Compression circuitry in
the Model 5000/7000 Bass Amplifier is to reduce overall dynamic range by auto-
matically reducing the level of the loudest sounds you play so that they are clos-
er in level to softer ones—the end result is that the sound “evens out” and all
notes played have pretty much the same level.
The front-panel Compression control determines the amount of compression
(peak signal reduction) by simultaneously adjusting both threshold and com-
pression ratio (which ranges from 2:1 to infinity [limiting]). At the fully counter-
clockwise “Off” position, the circuitry is bypassed and no compression is applied
(the knob clicks when set to the “Off” position). As the knob is raised clockwise
(at settings from “1” to “∞”) increasing amounts of compression is applied. At
the highest settings, loud sounds will not just be compressed, but
limited, where
the output remains virtually constant regardless of input.
In addition, there is a front-panel Compression LED which acts as a useful
visual indicator of the continuous activity of the compression circuitry. When lit
steadily green (for example, when the Compression knob is set to “Off”), no
compression is being applied. When unlit, compression is being applied to the
incoming signal at a ratio of approximately 2:1. When flashing red, the
compression ratio is approaching infinity (limiting is being applied). When lit
steadily red, the signal is being limited. This LED “follows” the incoming signal,
changing continuously as different amounts of compression and/or limiting are
being applied.
Compression has three main uses. First, as just described, it “evens” out the
notes played by your bass so that they all appear at virtually equal level.
Second, it adds “punch” to a sound; since all levels are nearly the same, you
can play with greater force without worrying about the loudest notes distorting.
Finally, it serves to protect your loudspeakers from damage as a result of brief
(
transient) high output levels, as might be caused by finger-popping or other
performance techniques.
Whether or not you need to use compression with your Model 5000/7000 will be
a matter of personal taste and playing style—experiment and see if you like the
effect. If you usually play at low volume levels, you’ll find that, even with the
Compression knob turned up, the compression circuitry may have no audible
effect, so it might as well be off. In general, if you don’t need compression,
leave it off.
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