Need help with Output line amp gain

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Well-known member
Nov 25, 2020
racking some channels from a yamaha pm-400. I have attached schematic of a single channel with its monitor/echo send and the output line amps that are configured for 8 channels summed thru 47k summing resistors, Im not summing anything, just want to use the line amp as an output amp to drive a 600ohm transformer for a single channel, same with the echo send aswell so I'll basically have 1 in 2 out.

1. how would i configure the output amps with proper gain for a single channel rather than the original summing configuration?

2. Should i relocated the 10k pot on the second stage to replace the 25k pot to the output amp and terminate the post EQ amp with a 10k resistor?

3. Is adding an insert point after the second stage prior to the output amp feasible?

4. finally any recommendations for attenuation resistor values for more flexibility, just 2 to 3 steps on inputs or in feedback loops?

FYI already replaced all coupling caps with 5uf polycarbonate and electrolytics with higher value nichicon/Panasonic. output amps b+ is 34v the rest comes from a seperate b+ tap at 32v.

mic transformers are 600:3k output transformers are 600:600
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