User manual PEAVEY AUTOMIX

[. . . ] The Peavey Automix is a classic "automatic mixer" combining several time proven techniques to deliver maximum gain before feedback in an easy to setup and easy to use configuration. The Automix uses VCAs (voltage controlled amplifiers) and gain computing circuits in each channel to ride the gain downward as more microphones become active. By dropping the gain 3 dB every time the number of active microphones double, the overall system gain remains at unity for ideal gain before feedback performance. A precision rectifier and logarithmic converter in each channel computes the amplitude of the audio signal present at each microphone in real time. [. . . ] Notch Filter Frequency Control (12): The notch filter frequency control is used to select the center frequency of the notch filter. 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 downward expander clockwise until the background noise between words is attenuated. 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 ambient 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 operational settings. When trimmed to a safe margin below feedback, no combination of user controls can cause feedback. BACK PANEL FEATURES MIC INPUTS (15) For use with low impedance microphones or low level sources. LINE INPUTS (Channels 3-8) (16) These allow line level inputs to be used in channels 3-8. 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. MUTE (18) Channels can be muted individually by shorting this terminal to ground. STATUS OUTPUT (19) The status is a DC logic output that is low (0 volts) when the channel is active and high (3. This DC voltage can be used to key video cameras or trigger key lights on active microphones. LOOP (Channels 1 and 2) (20) This is a signal loop that allows an external device such as an EQ to be inserted into the signal path of the first two channels. MUTEBUS (21) The Mutebus is a control port that when shorted to ground will mute all channels that are assigned to the mutebus (approximately 45 dB). The channels to be muted must be attached to the mutebus using the internal switch marked OFF/MBUS. [. . . ] The vinyl covering used on some units can be cleaned with a damp rag or an ammoniabased household cleaner if necessary. Care should be taken so that objects do not fall and liquids are not spilled into the unit through the ventilation holes or any other openings. This product should be used only with a cart or stand that is recommended by Peavey Electronics. Exposure to extremely high noise levels may cause a permanent hearing loss. [. . . ]