This amp is an evolution based on similar 100W CFA with unbalanced input only. It is possible to add an input balanced to unbalanced converter, but why not use the same electronic configuration to get it. CFA has very low impedance minus input not suitable to be used as balanced cold input. I used additional buffers to get high impedance cold input and in the same time to preserve CFA characteristic. I never saw something similar, but I could be wrong. By adding those buffers distortion did not increase.
To high CMRR, what is characteristic of balanced drive, it's very important to have very close hot and cold inputs impedances and there should be used 0.1% tolerance resistors.
Here is the schematic, the Loop Gain and Close Loop Gain (balance drive) plots.
Damir
To high CMRR, what is characteristic of balanced drive, it's very important to have very close hot and cold inputs impedances and there should be used 0.1% tolerance resistors.
Here is the schematic, the Loop Gain and Close Loop Gain (balance drive) plots.
Damir