Alesis 7-51-0121-A Operational advice, Gain structure, Setting Levels, About stereo compression

3 Using the Smashup

Operational advice

Gain structure

Extreme settings will lead to extreme results. If you turn the threshold down all the way, the Smashup will do what it's being told to do: turn the level way down. If you then try to compensate by cranking the [OUTPUT] control to its maximum, you'll amplify the noise of your source and the Smashup itself. The noise will fade itself in whenever the input signal stops, resulting in the classic "pumping" and "breathing" problems. Noise is present in every system, and improper use of any compressor will amplify it to an obnoxious level.

For low noise operation, make sure your mixer, Smashup, and amplifier settings are set properly. As a general rule, you want as much gain as possible in the front of the system (at the instrument or microphone preamp), so that a good line-level signal is travelling through the whole signal path. If you have a weak signal to start with, and then amplify it at the end of the signal path (by turning the main outputs of the mixer all the way up, for example) it will be excessively noisy.

When using a compressor on a live P.A. system, improper settings can cause feedback. Make sure that a channel is well below the feedback point when there is no gain reduction active. If you hear feedback every time the music stops, you must lower the overall level of the system.

Setting Levels

Proper setting of the output levels is crucial in order to achieve the maximum signal-to-noise ratio. As a good rule of thumb, it is usually best to first set the [OUTPUT] level control at 12 o’clock or 50%. Then, press the [BYPASS] button in and out while listening to signal through the unit. Turn the [OUTPUT] level up or down so that the output level is roughly the same whether the unit is bypassed or compressing.

About stereo compression

The Smashup is, in fact, two separate compressor channels joined by one set of controls. The detectors of the two channels are linked. This means that if the left channel's signal rises above the threshold, the right channel's gain will be reduced by the same amount as the left channel, and vice versa. This keeps the stereo image from wandering from left to right when compressing a stereo mix.

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