Here's a slightly unusual (to me) balanced line output circuit.
I thought I'd put this up in case it's of use or interest.
I Couldn't find a schematic so had to trace it out.
The main things I noticed are:
a) the BJT's boosting the opamp outputs that invert and add open loop gain
b) the feedback configuration.
It seems Meridian have used this form of BJT opamp bosting in their CD players, etc.
The feedback isn't a bridge circuit, it wont cope with one output shorted.
It works with unbalanced input if you ground the other input. Meridian used it to provide both balanced and unbalanced outputs.
I've attached LTSpice sim files if you want to play with it. It seems to work fine and will drive 600R balanced although max output at HF seems a little limited.
I thought I'd put this up in case it's of use or interest.
I Couldn't find a schematic so had to trace it out.
The main things I noticed are:
a) the BJT's boosting the opamp outputs that invert and add open loop gain
b) the feedback configuration.
It seems Meridian have used this form of BJT opamp bosting in their CD players, etc.
The feedback isn't a bridge circuit, it wont cope with one output shorted.
It works with unbalanced input if you ground the other input. Meridian used it to provide both balanced and unbalanced outputs.
I've attached LTSpice sim files if you want to play with it. It seems to work fine and will drive 600R balanced although max output at HF seems a little limited.
