Bob Orban interview

[emrr]

https://www.radioworld.com/blog/bob-orban

[mediatechnology]

Thanks Doug! I was just reading this article as I saw your post.

This caught my eye:

But the story of the stereo synthesizer — I was at an Audio Engineering
Society meeting in New York City, and one of the speakers was the
famous and distinguished acoustics Ph.D., Harry Olson of RCA Labs.
I saw him checking a train schedule. RCA Labs was in Princeton, so I
perceived the opportunity and introduced myself and offered him a ride
back. We had a chance to chat for about 40 minutes on that drive back
from New York City to Princeton.

He said that RCA Labs had a sort of junk building where they had all the
castoffs on their various experiments. I told him of my involvement in the
radio station, and he said, “Come on by and go through it and see if
there’s anything you need.”

McLane: Toy store!

Orban: Yep. One of the things I found was a 90-degree phase difference
network, a pair of all-pass filters designed to produce a 90-degree phase
difference throughout the audible range.

I’d previously had the idea to make fake stereo by synthesizing a stereo
difference channel. The reason we did this was that the radio station was
playing rock and roll singles, which was fairly unusual for FM at the time,
but all the singles were in mono, and in 1963 we had converted to stereo
FM transmission, which was very early in the game for college radio.
We wanted to be able to play those singles in fake stereo. So my first
attempt at doing stereo synthesis was just to EQ the mono and create a
stereo difference signal. But that didn’t work all that well; the effect was
weak.

Once I had this 90-degree stage difference network, I decided to find out
what happens if I take one side and use that to generate the left minus
right. And lo and behold, there was this very dramatic sense of space. It
turns out that it created a complementary comb filter, so I built my own
all-pass filter that I could tune for maximum effect.

That was also my first patent and my first AES Journal article. I proved
mathematically that if the synthesized L minus R is all-pass, not only is
the sum of the two channels the original mono — which is pretty obvious,
because it’s just how the matrix works — but also the sum of the power
spectra of the two synthesized channels is equal to the power spectrum
of the original mono. So it maintains the EQ texture of the original, which
honors the intent of the creators as well as you can while still creating
artificial stereo.

That’s the long story of how the Orban stereo synthesizer came to be.

[emrr]

Interesting to see the 90 degree network was apparently on everyone's mind.

[AnalogJoe]

Nice! I always thought Bob Orban was/is an eclectic personality. He is a lot more focused on broadcasting equipment these days. I've seen him giving interviews discussing how good X-broadcast equipment that I never heard of sounds. Also, he looks completely British but he is not