I imagine this drawing is a it intimidating. Rather than a single coil of wire, we now have two transistors; although they could easily be tubes, and many times are. This classic circuit was patented in 1936 by one of our hero's, Alan Blumlein. Like the classic transformer, put any two signals in that share the same qualities and nothing comes out. Should there be a difference in the two inputs, we get amplification; hence its name, 'differential amplifier'. Sequence multiple pairs of these, one feeding the other and you have one means of achieving a fully balanced (true balanced) audio circuit.
When we return to the subject at some point, I'll discuss how and why many audio circuits are not true balanced devices.
Differences
I imagine this drawing is a it intimidating. Rather than a single coil of wire, we now have two transistors; although they could easily be tubes, and many times are. This classic circuit was patented in 1936 by one of our hero's, Alan Blumlein. Like the classic transformer, put any two signals in that share the same qualities and nothing comes out. Should there be a difference in the two inputs, we get amplification; hence its name, 'differential amplifier'. Sequence multiple pairs of these, one feeding the other and you have one means of achieving a fully balanced (true balanced) audio circuit.
When we return to the subject at some point, I'll discuss how and why many audio circuits are not true balanced devices.
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