Attached is a hand drawn schematic of a mic preamp; the manufacturer is unknown. The tube used is the octal dual triode 6SC7, socket mounted on rubber. The preamp uses a UTC A-11 input transformer and a UTC A-24 line output transformer. There is a variable wirewound "T" pad on the output. The AC power input is through a two prong Amphenol fitting on the chassis. The audio input and output are through Cinch socket & plug. These preamps were made for tray mounting since the power transformer primaries are unfused.
The audio response may be lacking, based on the value of the capacitors in the audio path. The input and output transformers are good quality.
I have photos, but the size of each photo slightly exceeds the attachment size limit. The unit appears to be of late 1940's vintage.
The audio response may be lacking, based on the value of the capacitors in the audio path. The input and output transformers are good quality.
I have photos, but the size of each photo slightly exceeds the attachment size limit. The unit appears to be of late 1940's vintage.