M472A — Stereo Equalizer Module

M47ZA STEREO EQUALIZER MODULE The left channel of the M472A Stereo Equalizer wili be described . Input The unbalanced audio input appears at pin of the module conn- ector It is routed directly to the normally closed contact of Equalizer Insert switch SWZA and to buffer amplifier U1B. Mid-Frequensy Equalizer The output from the input buffer amplifier 418 feeds summing amplifier UIA and the Mid-Frequency cut/boost control R4: R4 bridges between the input and output of summing amplifier UIA.

The arm of Rb connects the signal to the state variable filter U3A, U3B, and U4A . C6 through C9 along with R15 and R18 determine the resonant frequency of the filter_ R8 adjusts the overali filter gain and therefore its 0 High 0 is nominally four and Low is nominally two. The filter output is fed back into summing amplifier UIA via C5_ This feedback signa/ adds or subtracts from the maln signal in proporation to its magnitude and Phase relationship.

Lew_Frequency Equalizer The output from UIA feeds the audio signal to the Iow frequency summing amplifier U2B, Low Frequency cutlboost control R23 bridges across 42B, with the arm of this control coupling the audio signal through C11 to Low-pass filter u4B. The frequency determining components of this filter are the LF shelf control Rz7 , Rz9 , C12 and C13.

The filter output is fed back to summing amplifier 028 through R3o . Dependent upon the setting of cut/boost control R23 the signal, is added or subtracted from the main signa/ path thus affecting the frequency response characteristics of the Low Frequency portion of the audio spectrum. 4-1

M472A STEREO EQUAL IZER MODULE Note Specifications are based on voltage levels of 600 ohm system unless otherwise specified. Gain: Unity +/-0.25 dB _ Frequency Response +/-0.5 dB from 20 Hz to 20 kHz with the equal- izer inserted and cut/boost controls in the detent pos ton Noise -90 dBm absolute (20 Hz to 20 kHz) equalizer cut/boost controls in the detent position Harmonic Distortion Less than 0.1% from 20 Hz to 20 kHz at +20 dBm output Ievel or Iess Less than 0.

01% at kHz at +20 dBm output Ievel . Source Impedance Less than 10 ohms unbalanced_ Input mpedance Greater than 4k ohms unbalanced_ Input Level ~6dBm nominal +20 dBm maximum. Output (mpedance Less than 50 ohms unbalanced_ Load mpedance Sk ohms or greater Output Level -6 dBm nominal +22 dBm maximum. Channel Separation: Greater than 60 dB _ Phasing Input and output are in phase with the equaliz- ing controls in the 0 detent position.

Equalization Tracking: Within 0.5 dB_ Power Requirements: +/-25 volts dc 65 mA . Ambient Temperature Dimensions to 60 degrees Celsius. 1.60" wide 7 . 00" high 6.50" deep (41 Mm 178 Mm 165 mm) . Weight: M472A Ib oz (0,565 kg) net . 1-1

M47ZA STEREO EQUAL ZER MQDULE MISCELLANEOUS COMPONENTS USED ON DESCRIPT ION MFG MFG PART NUMBER DSI LEd Mounting Bracket WBS A91-011 R4) R5) Knob (Black) Cap (Red) Elma 023-3525 040-3635 R1s) R16 R17) R18) Knob (Black) Cap Red) 021-2225 04o-1635 R23 ) R24 ) Knob (Black) Cap (Green) 023-3525 040-3665 R27 R28) Knob (Black) Cap White) 021-2225 040-1665 R34 ) R35 ) Knob (Black) Cap Yellow) 023-3525 040-3655 R43 R44) Knob (Black) Cap (Yellow) 021-2225 040-1655 SW1 Cap ( Grey ) Tt FM-GRY Sw2 (Red) FG-RED UI-U10 Pin Dip Socket AMP 640463-3 WBS recommends the use of replacement parts made by the specified manufacturers for continued opt Mum equipment performance , 6-6