From the Langevin catalog…
7 POSITIONS FOR ULTIMATE CONTROL
OF SPECTRAL QUALITY IN RECORDING, TV-BROADCAST AND MOTION PICTURES
GENERAL
The Langevin Model EQ-252-A Graphic Equalizer fufills the critical need for multiple control at the subjectively important points of the audio range. It employs miniaturized, military quality, gold plated, etched circuitry in each of the 7 plug-in filter units, resulting in a passive assembly requiring no tubes or power supplies. Only input and output connections are required. Sliding Levers permit 8 db of equalization and 8 db of attenuation in 1 db steps at 50, 130, 320, 800, 2000, 5000 and 12,500 eps during the program through noise-free gold-plated switch-ing. Modern controls give quiet operation at -70 up to +24 dbm.
Filter assemblies use sealed toroid coils for hum-free operation. Careful design delivers #½ db accuracy. Overlap from one filter to the next gives combined flat output when levers are in a straight line in any equalized or attenuated position (see curves). Special frequencies are available to order; overlap may or may not provide combined flat output between adjacent positions as the standard frequencies shown have been calculated for this effect. In zero position each or all filters are flat (resistive only, 16 d loss) from input to output. Because all passive circuitry is used there is no distortion when operated up to plus 24 dbm.
Impedance is 600 ohms in and out; for other impedances use Langevin line to line transformers, Model TF-602-C. The model E0-252-A is limited to 600 ohms impedance for the reason that lower impedances would double the size of the equalizer components every time the impedance is halved.
SPECIFICATIONS
Circuit: Bridged T; Impedance: 600/600 ohms; Insertion Loss: 16 db;
Operating Level: -70 to +24 dbm: Positions: 7, with 8 db of equalization and 8 db of attenuation at 50, 130, 320, 800, 2000, 5000 and 12,500 cps in 1 db steps; Distortion: none; Coils: Sealed toroids; Power Requirements: none; Response: See curves; Panel Finish: Black, satin finish, non-halation, anodized aluminum; Terminals: solder type, turret;
Filter Sections: 7 plug-in, printed circuit type; Size: 3½” high bý 10½2* long by 5¾* deep overall.
FEATURES
7- Selected Positions of Variable Hi-Lo Equalization and Attenuation.
Gold plated, Noise-free, Switching through #8 db in 1 db steps during
active use.
Hum-free performance through toroid coils from -70 to +24 dbm.
No tubes or power required —all passive Bridge T circuits in one
integrated unit.
Small size: 3½”‘ x 10½* x 5¾* deep.
ORDERING INFORMATION
Model EQ-252•A Graphic Equalizer equipped with red knobs, complete with mounting hardware and instructions. Weight, net 9 lbs.; 14 Ibs. shipping. Price, Net $475.00.
Recommended Accessories
When lower impedances than 600 ohms are required, use the following matching coils in and out:
Model TF-602-C Line to Line Transformer, Weight, Net, 2¾ Ibs.; 3½ Ibs. shipping. Price, Net, $25.50.
20O:C