231- Dual Channel 31 Band Graphic EQ
Power Switch (231 only): Switches the power on and off. Always make audio con- nections with the power switch in the OFF position.
Power Cord Receptacle: Connects AC power to the equalizer.
Output Connectors: Two types of output connectors are provided for output con-
nections: male XLR type connectors, and 1/4" tip-ring-sleeve phone jack connectors.
Input Connectors: Two types of input connectors are provided for input connec-
tions: female locking XLR type connectors, and 1/4" tip-ring-sleeve phone jack con- nectors. The maximum input level that the equalizer can accept is +22dBu (ref: 0.775Vrms).
INSTALLATION CONSIDERATIONS
Hookups and Cabling: The 2-Series Equalizers are designed for nominal +4dBu lev- els. The equalizers can be used with either balanced or unbalanced sources, and the outputs can be used with either balanced or unbalanced loads, provided the proper cabling is used.
A balanced line is defined as two-conductor shielded cable with the two center con- ductors carrying the same signal but of opposite polarity when referenced to ground. An unbalanced line is generally a single-conductor shielded cable with the center conductor carrying the signal and the shield at ground potential.
Input Cable Configurations: The equalizer has an input impedance of 40kΩ bal- anced and 20kΩ unbalanced. This makes the 2-Series Equalizers’ audio inputs suit- able for use with virtually any low source impedance (under 2kΩ).
Output Cable Configurations: The equalizer’s output is capable of driving a 2kΩ load to +18dBu. For maximum hum rejection with a balanced source, avoid common grounding at the equalizer’s inputs and outputs. Most balanced (3-conductor) cables have the shield connected at both ends. This can result in ground loops which cause hum. If hum persists try disconnecting the shield on one or more of the cables in the system, preferably at the input of a device, not at the output.
OPERATION AND APPLICATION NOTES
The dbx 2-Series Graphic Equalizers are useful audio signal processing tools in situa- tions where precise frequency control is required across the audible frequency spec- trum.
When used with an audio spectrum analyzer the EQs can tune any acoustical envi- ronment -- from the studio to the concert hall -- to stop ringing, increase clarity, and flatten the overall frequency response of the environment. A real-time spectrum ana- lyzer or other types of audio environment analyzers are very useful in determining the amount of equalization needed.
