Notch Filter Frequency Control (12): The notch filter frequency control is used to select the center frequency of the notch filter. The bottom filter has a range of 40 Hz to 925 Hz. The middle filter has a range of 260 Hz to 6 kHz. The top filter has a range of 500 Hz to 12 kHz.
DOWNWARD EXPANDER (13)
The downward expander can be used to attenuate the system gain when all of the input signals are low. This can be used to prevent background room noise from being amplified.
Setting the Downward Expander:
Have someone speak into a microphone at the softest level you expect to encounter. Slowly turn the down- ward expander clockwise until the background noise between words is attenuated. Be careful not to go too far. The more downward expander that is used, the less “natural” sounding the system will become.
This method will get you to a good starting point, but the best way to set the downward expander is during an actual meeting or event. While doing this, the downward expander can be adjusted for the best sound. If you have to deal with both loud and quiet events, you will need to trade off between natural sounding ambi- ent and background noise.
MASTER GAIN TRIM (14)
The Master Gain Trim sets the maximum overall system gain. This control should be set with the front panel master gain at maximum (all channels at unity) and external power amps turned up and locked at opera- tional settings. When trimmed to a safe margin below feedback, no combination of user controls can cause feedback. This trim provides up to 25 dB of attenuation.
Back Panel:
23 | 24 | 15 | 16 |
21 | 22 | 17 | 18 | 19 | 20 |
BACK PANEL FEATURES
MIC INPUTS (15)
For use with low impedance microphones or low level sources. This is a transformer balanced input with an impedance of 2,000 ohms.
LINE INPUTS (Channels 3-8) (16)
These allow line level inputs to be used in channels
DIRECT OUTPUTS (17)
Each channel has a set of direct output terminals that can be used for recording or anytime the output of an individual channel is required. The level of this signal is independent of “Automix” gain manipulations.
6
