Setting Input Trim Levels; Peak Led Method - Alesis Studio 12R Reference Manual

Setting input trim levels

Proper setting of the [TRIM] controls is crucial to low-noise, distortion-free operation. If
the trim is set too high, there will be distortion even if the channel faders are low. If the
trim is set too low and the channel faders are raised to get the signal loud enough, you will
be amplifying the noise of the mixer.
Instead of doing this, get as much gain as possible as close to the signal source as possible.
If you've plugged a synthesizer or other line-level source into the Studio 12R, set its output
volume to maximum. If a microphone is the source, the Studio 12R's [TRIM] control will
determine the gain of the system.
The goal is to get the signal as loud as possible as early as possible in the
signal path, without causing clipping (distortion) anywhere in the path or
in the sound system.

PEAK LED method

Each channel of the Studio 12R has its own [PEAK] indicator, which
will light when the signal level rises to within 6 dB of clipping. In
situations where the maximum signal-to-noise ratio is required
(such as digital recording), use the PEAK LED as a guide for setting
the [TRIM] control.
When the PEAK LED is flashing, it does NOT necessarily mean that
distortion has occurred.
PEAK LED is flashing momentarily on the loudest peaks.
1. With the sound source active, and the channel fader down to
minimum, raise the [TRIM] control until the PEAK LED flashes
occasionally on the loudest transients.
2. If desired, lower the [TRIM] control slightly until the flashing
stops.
Note for extremely high level line inputs in stereo channels: If the
[TRIM] setting is set below unity (12 o'clock position) on a stereo
channel, it is possible for the first input stage to clip without the
PEAK LED coming on. If distortion is still heard after lowering
the trim to its minimum setting, it means the source is
extremely high (+22 dBu or higher). In this case you must lower
the output level of the source, use an external pad, or repatch to
a LINE IN on channels 1-8 (which can take up to +32 dBu levels
before clipping).
Studio 12R Reference Manual
There is usually some headroom left if the
Operating Instructions
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