QSC Audio MD-FP122/94r, MD-FP122/64r Input/Output Connections, Gain Control, Filter Select Switch

Input/Output Connections

The active MD has a balanced 3-pin female XLR input marked IN and a male XLR output con- nector marked OUT. These connectors are wired in parallel, enabling connection of multiple enclosures in a “daisy-chain” fashion.

Balanced connections are recommended for less AC hum and interference, especially with long cable runs. Unbalanced connections may be suitable for short cables. The signal's source impedance should be less than 600 ohms.

Input connection

Insert the male XLR input into the jack marked IN. Ensure the connector is fully seated. The input impedance is 12k ohm balanced or 6k ohm unbalanced.

Balanced inputs: Connect to the plug as shown.

1= shield (ground)

3= minus (-) 2= plus (+)

Input (IN) and Output (OUT) Connectors

Unbalanced inputs: Connect to the plug as shown. Pin 3 and pin 1 must be connected with a jumper as shown.

1= shield (ground)

3= jumper to pin 1 2= plus (+)

Output Connection

Insert the female XLR connector into the jack marked OUT. Connect the other end of the cable to the next down-stream audio device’s input connector.

Gain Control

The Gain control is recessed and can be adjusted with a small screwdriver or flat tool. Turn the gain control clockwise to increase gain and counter clockwise to decrease gain. The attenuation in dB (from maximum) is shown on the label.

The Gain control is marked in dB of attenuation. There are 21 detents for repeatable adjust- ments. The upper 14 steps are about 1 dB each, and settings should normally be made within this range. The range below -14 dB should not be used for normal program levels, as the input headroom could be exceeded, but can be used for testing at reduced levels. At the minimum setting, the signal is completely cut off.

Filter Select Switch

Above the Gain control is a small toggle switch that selects either Full Range operation or applies a 100 Hz Lo-Cut filter to the system.

Full Range Setting

Use the Full Range setting for applications without subwoofers or dedicated low-frequency enclosures.

100 Hz Lo-Cut Setting

Use the 100 Hz Lo-Cut setting for applications with optional subwoofers or low-frequency sys- tems.

The two-way wedge will have its low-frequency content below 100 Hz filtered at 24dB per octave, yielding less distortion at low frequencies and provide improved clarity in the mid-fre- quencies.

Filter Select Switch

Gain Control

5