755a unit

 

 

 

 

Altec 755As were originally designed to be PA speakers

 

and were renowned for their accurate reproduction of the human voice.

 

The 755A speakers have a single-diaphragm full-range driver with alnico magnets. 

 

This provides a smooth impedance curve, high sensitivity, and flat frequency response all the way from 70Hz to 13kHz.

The number stamped on the rim is 501239,

 

which if it is an EIA number, may indicate that they were manufactured in September 1962.

 

(3 digit EIA manufacturer code [501] +

 

last digit of year [2] +

 

two digit week of that year

 

Technical Specifications for the 755A:

 

Power handling capacity (Pe) = 8 W
Resonant Frequency (Fs)= 106 Hz
HzDC Resistance (Re) 3.32 ohms
Voice Coil Inductance (Le) = .07 mH
mHMechanical Q (Qms) = 1.28
Electromagnetic Q (Qes) = 0.452
Total Q (Qts)= 0.33404

Compliance Equivalent Volume (Vas) = 12.18 L
Maximum Linear Excursion (Xmax)= 0.1 mm

Surface Area of Cone (Sd) = 182.41 cm²

Sensitivity = 96.92 dB/W/m