I performed the measurements of the Western Electric 91E with my Audio Precision SYS2722 system.1 I carefully installed the tubes following the instructions in the excellent manual, and after turning on the amplifier, waited for the 91E to optimize the bias for the 300B output tubes. Once that was done, I waited another 30 minutes before starting the testing.
The Western Electric 91E preserved absolute polarity, ie, was noninverting, from its loudspeaker, preamplifier, and headphone outputs. The volume control operated in accurate 0.5dB steps. A level of 1Wpc into 8 ohms was indicated as approximately –12dB on the front-panel meters. The maximum voltage gain at 1kHz was a fairly low 29.6dB measured at the loudspeaker output into 8 ohms, 19.7dB from the headphone output, and –1.8dB from the preamplifier output, ie, an input of 1V resulted in
