Pair Vintage RCA BA-31 UTC AR-535 Input Transformers Tested

Description

Pair of vintage RCA BA-31 input transformers, made by UTC (AR-535). See schematic in photos for strapping information and usage ideas. The BA-31 was a germanium transistor based, solid-state mic preamp from the 1960s. There is a lot of information out there on this classic piece of gear, particularly on groupdiy.com. These have a 1:1.58 ratio, with a versatile primary that facilitates various impedances from 37.5 up to 600 ohms. Very well suited for use in a vintage style or modern mic preamp, either discrete or IC based. 20-20k response.
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