WIRING THE INPUT TRANSFORMER

The input transformer for the kit uses a 4:1 ratio a loss of about 12dB to tame levels before they hit the gain reduction FET. The FET cant handle high input levels so the transformer is used to step the input signal down.

The Cinemag transformer offered with the kit is a 4:1 ratio transformer. The leads attached are different colors Red, Black and Green. Twist these 3 wires together before soldering. Connect the Input XLR's pin-2 (hot) to the Cinemag's red wire. Connect Input XLR's pin-3 (low) to the Cinemag's black wire. Connect the Input XLR's pin-1 to the Cinemag's green wire.

Position the input buffer amp PCB and the transformer in close proximity to the Input XLR. Trim the transformer leads if necessary to keep the runs as short a possible.

The secondary of the transformer consists of blue and white wires. Twist these two wires together, measuring out a length that will reach the FET input PCB at header J1. Trim the wires if needed. Punch the white wire to pin-1 of J1s receptacle. Punch the blue wire to pin-2 of J1s receptacle. The input transformer is now connected.

If you use a St. Ives 31267 multi-tap transformer, you will need to wire the primary in series and the secondary in parallel in order to use it as a step-down 4:1. Tie pins-3 and -4 together. Pin-2 of the XLR Input connector goes to pin-2 of the transformer. Pin-3 of the XLR input connector goes to pin-5 of the transformer. 

Tie the St Ives secondary pins-7 and -8 together. Run a wire from pin 7-8 to the FET input PCBs header receptacle J-1 at pin-2. Pins 9 and 10 will also be tied together. Run a wire from that junction to header receptacle pin-1. Pin-6 the screen of the St. Ives transformer should be connected to chassis ground.