This is a RCA 6 into 1 mixer with BG2 compressor for the mix. It started out as a 3 input into 1 output mixer, but had 6 preamps in it, some used for boosters. The first 4 pres have RCA input transformers and the last two have UTC 0-1's. Output amp of each pre is basically a copy of the back half of a UA 610 with Cinemag output transformers, so there is balanced direct outputs for each pre. For summing, the original RCA output amp and original UTC output transformer are used but with a Ampex input transformer. The meter on the right is gain reduction next to the compressor controls. The original mixer had a 6V6 push pull amp to drive the studio loud speaker, this was modified into a #bg2compressor with variable attack, 9 position release and UTC input transformer added. The compressor runs fully independent with separated inputs and outputs unless you engage the "compression to mix" switch, then is it inserted after the main mix output amp, as if you patched it in. This is at @adrianyounge studio, more to come soon.