[Scott Dorsey]

Keith W. Blackwell wrote:
Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

The actual volume DOES stay the same, but then you can adjust the DC
offset to make your waveform fit into a fixed range of values with a
higher peak value.

Can you elaborate?

The Foti and Orban paper "What Happens to my Recording when it's Played
On the Radio" has a little info, but the manuals for the old Orban Optimods
are probably best to check out for how the process works.

As far as I know, the first device to do this was the Garron Stereo Phase
Enhancer, a device for which I have been looking for real documentation for
many years.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."