Dual 31 Band Graphic Equaliser Operation Manual 1 EQ231G User Manual
1. Introduction The EQ231G is a high quality dual 31 band 1/3 octave graphic equaliser. The EQ231G also has a switchable 12dB per octave Hi-pass filter. A delayed by-pass relay allows silent on/off switching and also provides direct throughput when the unit is not powered. Centre detent long stroke faders give up to 12dB of cut and boost at 31 ISO centre frequencies, covering the entire audio spectrum (20 to 20KHz). Inputs and outputs are electronically balanced.
service centre or to the factory with a dated receipt as proof of purchase. After repair the unit will be returned to you free of charge. Limitations: This warranty does not cover damage resulting from accident or misuse. The warranty is void unless repairs are carried out by an authorised service centre. The warranty is void if the unit has been modified other than at the manufacturers instruction.
(A 100 Volt special transformer is available for Japan). (A 220 Volt special transformer is available for the Republic of Korea). 3.4. External connections The input connector is a female XLR type and the output is a male XLR, both wired as follows: Pin 1 : Ground Pin 2 : Hot Balanced signal Pin 3 : Cold Balanced signal 3.5.
Should the power on the unit fail the unit automatically switches into bypass through a delay circuit. The switched Hi-pass filter on the EQ231G is a 2nd order (12dB/octave) with the corner frequency fixed at 35Hz. 4.2. System check (Refer to the installation section before applying power) Set the controls as follows : ALL faders to the central position. (0dB) Master Level Controls to 0dB.
c) Elimination of "sibilance" Sibilance is the noise which occurs when someone is speaking who either has a "hissy" voice or who is using words with the letter "s" in them, e.g. "Pressure", "Rose", etc. This can become annoying to a listener and the graphic equaliser can be used to overcome this problem by either removing or reducing the offending frequency. d) Elimination of "proximity effect" Cardioid microphones usually have a low frequency emphasis, which in certain situations can present problems.
6. Techniques 6.1. Room measurement and equalisation There are several ways of measuring a room's frequency response, and these are usually all similar in technique, although differing in hardware. Usually a known quantity of an audio signal is generated and transmitted through the sound system. The result is then read through a calibrated microphone and a graph of the frequency response is indicated to the user usually in 1/3rd octave intervals.
frequencies will not be contributing to the output. Since the frequency was unwanted anyway, there seems little point in allowing it to trigger the limiter. Sometimes a graphic equaliser may be placed in the side chain of a limiter/compressor and tune it to limit certain frequencies. The graphic equaliser is particularly good at this, since it can notch very accurately. This is the usual way to remove sibilance (known as "de-essing") or annoying background noises such as air-conditioning units etc.
7. Specifications Frequency Response Signal to Noise Ratio Input impedance Output impedance Output Load Impedance Maximum Output Level Total Harmonic Distortion (THD) 1 kHz, +4dBu Output, Peak indicator Threshold 20 Hz to 20 kHz +4dBu output 20 kΩ balanced 100Ω balanced 600Ω to infinity 600Ω Load, 1 kHz +0, -1dB -96dB 600 Ohms Load 2dB before clipping 0.003 % +20dBu Centre frequencies : 20, 25, 31.
