SoundCraft Rac Pac manual Controls in Detail, Mono Input Channels Trim

Clipped

Signal

Noise

If the signal level is too high, clipping distortion may occur.

100

1

2

3

THE CONTROLS IN DETAIL

MONO INPUT CHANNELS 1-10

1 TRIM

The TRIM control sets how much of the source signal is sent to the rest of the mixer. Too high, and the signal will distort as it overloads the channel and causes clipping. Too low, and the level of any background hiss will be more noticeable and you may not be able to get enough signal level to the output of

the mixer. This is shown in the diagram on the right:

Setting the knob to the "+4U" mark gives unity gain on the LINE input for nominal +4dBu sources, which will be suitable for most professional equipment. Note that some sound equipment, particularly that intended for semi-professional use, operates at a lower level (-10dBV) and will therefore need a higher gain setting to give the same output level. A second point marked "-10U" indicates the unity gain setting for -10dBV sources.

SignalNoise

If the signal level is too low it may be masked by the noise.

5-6

10

4

5

6

7

8

See "Initial Setting Up" to learn how to set the

GAIN correctly.

MIC INPUT

The mic input accepts XLR-type connectors and is designed to suit a wide range of BALANCED or UNBALANCED low-level signals, whether from delicate vocals requiring the best low-noise performance or close-miked drum kits needing maximum headroom. Professional dynamic, condenser or ribbon mics are best because these will be LOW IMPEDANCE. While you can use low-cost HIGH IMPEDANCE mics, you do not get the same degree of immunity to interference on the microphone cable and as a result the level of background noise may be higher. If you turn the PHANTOM POWER on (top right-hand side of the mixer) the socket provides a suitable powering voltage for professional condenser mics.

DO NOT use unbalanced sources with the phantom power switched on. The voltage on pins 2 & 3 of the XLR connector may cause serious damage.

Unplug any mics if you want to use the corresponding LINE Input to avoid the load presented by the mic from affecting the Line Input gain.

LINE INPUT

Accepts 3-pole ‘A’ gauge (TRS) jacks. Use this input for sources other than mics, such as keyboards, drum machines, synths, tape machines or guitars. The input is BALANCED for low noise and immunity from interference, but you can use UNBALANCED sources by wiring up the jacks as shown in the "Connectors" section earlier in this manual, although you should then keep cable lengths as short as possible to minimise interference pick-up on the cable. Unplug anything in the MIC input if you want to use this socket.

2 100Hz HI-PASS FILTER

Pressing this switch reduces the level of bass frequencies only, and is a real bonus for such a small mixer. Use this in live PA situations to reduce stage rumble or ‘popping’ from microphones.

7 SPIRIT FOLIO RAC PAC