While I'm waiting on Quadrature Summing Filter boards to be delivered I fired up the Protoboard to make some sample files.
Some time ago I downloaded a problematic synth sample from Gearspace that was posted in this thread:
https://gearspace.com/board/so-much-gea ... oting.html
I hadn't had the opportunity to process that file until now.
The first section is the uber-wide original version which on the vectorscope looks like a big round ball of steel wool.
The second section is conventional (L+R)/2 mono.
The third is I+Q/1.4 mono.
For identical in-polarity inputs the gain is structured so that (L+R)/2 is unity gain and (I+Q)/1.4 is also unity gain.
When the inputs are out-of-polarity the conventional mono output has no output.
The (I+Q)/1.4 output - when the inputs are out-of-polarity is also at unity gain.
Thus on the "I+Q" output in-polarity and out-of-polarity fold down to mono with equal weight.
The first section is the uber-wide original version which on the vectorscope looks like a big round ball of steel wool.
The second section is conventional (L+R)/2 mono.
The third is (I+Q)/1.4 mono.
Quadrature Summing Filter Synth Demo wav file: https://proaudiodesignforum.com/content ... h_Demo.wav
Quadrature Summing Filter Synth Demo
I also tried a fully-uncorrelated noise file: https://proaudiodesignforum.com/content ... e_Demo.wav
The first section is stereo noise.
The second section is conventional (L+R)/2 mono.
The third is (I+Q)/1.4 mono.
Quadrature Summing Filter Uncorrelated Noise Demo
Somehow, as if by "magic" - but actually predictable - the RMS power of the I+Q sum is 3 dB greater than L+R.
The powers of the "stereo" and I+Q segments are statistically identical.
