This is one of our designs and I hesitate to show it because it might be intimidating. There are a lot of squiggly things! For simplicity sake, we colored the inputs and outputs red. Input 1 and 2 are where the XLR cable would connect for the input—a simple diff pair (J1 and J2) as I described earlier. This feeds another diff pair (J3 and J4) that becomes the output. (for those technically inclined, ignore R11, it is not supposed to be there).
This is an entire true balanced amplifier with very few parts. Completely symmetrical from input to output, zero global feedback, and cheap. Less than $5 in parts. If we really wanted to use this in a product, we'd want to add some buffers to the outputs so it could drive complex loads, but basically, this isn't all that hard.
Tomorrow I'll cover balanced phono cartridges then we'll wrap up the series.
Diff, diff
This is one of our designs and I hesitate to show it because it might be intimidating. There are a lot of squiggly things! For simplicity sake, we colored the inputs and outputs red. Input 1 and 2 are where the XLR cable would connect for the input—a simple diff pair (J1 and J2) as I described earlier. This feeds another diff pair (J3 and J4) that becomes the output. (for those technically inclined, ignore R11, it is not supposed to be there).
This is an entire true balanced amplifier with very few parts. Completely symmetrical from input to output, zero global feedback, and cheap. Less than $5 in parts. If we really wanted to use this in a product, we'd want to add some buffers to the outputs so it could drive complex loads, but basically, this isn't all that hard.
Tomorrow I'll cover balanced phono cartridges then we'll wrap up the series.
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