Outputs; Considerations; Ground Loops; Audio Connections - Ecleree SMAC PRO40 User Manual

4.10. Outputs

Headphones: in order to obtain a high performance, these should be of the high
impedance type (200-600Ω). Plug them to the HEADPHONES, PHONES (16) output, by means
of a standard 1/4" stereo jack. Sleeve is Ground, Ring is Right Channel and Tip is Left Channel.
The SMAC PRO40 have two main outputs, OUT1 (29-30) and OUT2 (28) with
independent rotative volume controls. A Balance control (36), common to both outputs,
completes the possibilities of the mixers.
You must be careful when setting up the general output level of the mixer. The "clip"
display of the connected power amplifiers must never remain permanently lighten up, but do it
occasionally by following the rhythm of the bass signals that are being played.
The SMACs are factory adjusted to 0dB/1V, though this can be internally adjusted to
-10dBV/316mV, +4dBV/1,6V or +6dBV/2V (Fig.2). Just changing some soldering bridges.
ATTENTION: The modification of the output gain must be carried out by a qualified
technician.
The SMAC series mixers have a REC output (31) of -10dBV over 10kΩ of load for a
nominal level input.

5. CONSIDERATIONS

5.1. Ground loops

Ensure at all times that no signal sources reaching the mixing desk and no devices
connected to its output have their earths interconnected; that is, earth should never reach them
via two or more different paths, as this coul lead to humming which could even interfere with
sound reproduction quality. In order to avoid earth loops, ensure that the shieldings of cables, if
connected to the chassis, are never connected with each other.

5.2. Audio connections

As a general rule of thumb, make the signal connections as short as possible and use
the best connectors and cable available. Cables and connectors are frequently undervaluated,
forgetting that a bad connection can result in a poor sound quality.

5.3. Background noise

The use of active circuitry can yield, depending on the configuration, to a significant
noise level. The SMAC series mixers have been designed for the minimum possible noise.
Anyway, the noise level will always depend on the correct use and installation of the mixer.
It is not the same setting up the "FADER" at "2" and the "MASTER" at "10" that the
other way round; "FADER" at "10" and "MASTER" at "2". In the first case you get a poor
signal to noise ratio that will be fully amplified by the master while on the second we have a
good signal to noise ratio only amplified by "2". As a result, the background noise is greater in
the first case than in the second one.
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