Troubleshooting - Alesis 3630 Reference Manual

1.9 TROUBLESHOOTING

Noisy or "squeezed" sound- Too low a limiting threshold and/or too high
a compression ratio can result in such problems as squeezed, unnatural
sounds or excessive noise. Remember, limiting lowers the input signal's
dynamic range. If the input signal has a dynamic range of 60 dB and you
apply 15 dB of limiting (quite a lot), the dynamic range falls to 45 dB. This
degrades the signal-to-noise ratio by an equal amount. A 60 dB signal to
noise ratio can be acceptable; a 45 dB signal to noise ratio is audibly noisy.
If you encounter these types of problems, reduce the Ratio control or
raise the Threshold control. Be careful; because the ear is not particularly
sensitive to level changes, it is possible to add considerable amounts of
limiting before it becomes obvious. Monitor the Gain Reduction meter to
see how much limiting is being used, and adjust Threshold so that fewer
LEDs light. Also, compare the bypassed and processed sounds to hear
how much the 3630 affects the sound.
Some musicians use excessive limiting as an effect. Many of the monster
drum sounds you hear in records by artists like Phil Collins and Peter
Gabriel are due to heavy limiting, followed by high-threshold noise gating
to create an abrupt cutoff.
Noisy source signal- A noisy source signal may become more noisy
when processed. Use the 3630's onboard noise gates to quiet a noisy
signal.
Overall noisy operation- If the +4/-10 switch is set to +4, try setting it to -
10.
"Choppy" or "jittery" sound- If the sound is choppy or jittery and the
3630 is in peak mode, increase the Attack and/or Release times. There are
no fixed rules for optimum times since different instruments will work
best with different settings. Generally, low frequency instruments such as
bass will require longer attack times.
Dull attack- The noise gate Threshold must be turned as far counter-
clockwise as possible (with the gate still operating) to catch initial attack
transients. The gate may appear to be working with a wide range of set-
tings, but if the initial transient is being cut off, the signal may sound dull
or lack "life."
Attack and Release controls have no effect- The 3630 must be in Peak
mode for these controls to be active.
Heavy distortion- If the +4/-10 switch is set to -10, try setting it to +4.
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