Sound System and Other Random Stuff
M-S Recording Resource
This is a collection of files describing some of the hardware used
for M-S recording. There is a short discussion of the theory, several decoder circuits, and a
Bibliography - Revised 2006
An overview and bibliography of articles and papers about MS-Stereo technique along with
brief descriptions of the three MS decoder circuits.
Circuit 1 Simple decoder #1, viewable gif.
Circuit 1 (pdf) Simple decoder #1, PDF format.
This is a simple decoder circuit using two opamps to perform the sum
and difference operation. Good for conceptual understanding.
Circuit 2 Simple decoder #2, viewable gif.
Circuit 2 (pdf) Simple decoder #2, PDF format
This is a slightly more complex circuit using four opamps to perform
the sum and difference operation. This circuit does not use a
diff-amp to perform the sum and difference operation.
Circuit 3 Complex Decoder, viewable gif.
Circuit 3 (pdf) Complex Decoder, PDF format
This circuit has a stereo spread control, which varies the output's
separation from mono to normal stereo to super-stereo.
The classic Neumann passive MS-matrix circuit
A blast from the past, this circuit shows how it used to be done.
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Radar Sites I Have Known
I spent four years in the US Air Force, during the time that young men were being sent to VietNam to die in the name of Democracy. That's
a statement of fact, at least how that fact was sold to the American People. For me, joining the Air Force was my countermove to being
drafted and a becoming an unwilling member of the Army, which would have nearly guaranteed me a free trip to VietNam.
Instead, as a voluntary Air Force enlistee, I got to spend the majority of my enlistment stateside, with my last major tour being in South Korea, at Osan Air Base.
My job title (AFSC) was 30454, Ground Radio Communications Equipment Repairman. It was nearly all tube gear, mostly UHF AM, 225-400mHz, about 100W output. There was some
prehistoric digital gear, all discrete, with germanium transistors everywhere. You had to go to a special school to learn about that gear, and I believe that one
of the selection criteria was how well they (the ruling class) believed you were likely to stick around after four years.
That was not for me. I was assigned this AFSC
because I had an FCC commercial radiotelephone license when I enlisted. I was supposed to be a clerk (because that was the opening that they had at the time I enlisted, and I was
under the gun because I had already received my order to report for induction), but I waved my license around and someone finally noticed. A few weeks later, I was
summoned to appear to take a test. This was aparently (unbeknownst to me) the final exam for the 304x4 tech school. I must have passed, because a few weeks after that, I
received orders to report for duty in Charleston WV. No tech school. So much for the know-it-all in my flight (Jones) who said, "They never give DDAs in electronics."
The gear that my AFSC qualified me to work on was in use at Radar Sites, and there was a network of them all across the United States, and a few other places as well.
Each site had search and height radars and radio gear to communicate with military aircraft in their sector.
I don't know if we fed radar coverage to the FAA for commercial aircraft. The time I spent at three different radar sites was good time, away from the pomp and circumstance
of the big bases, with their collection of military brass and the
merde de poulet
associated thereto. At the radar sites, it was mostly just do your job. Inspections were infrequent, as was the time doing seemingly meaningless duty, like painting rocks. The
mess halls were run by a military cook, but staffed by civilians, so there was no KP. Really, it was not a bad gig.
I spent my stateside time at three different radar sites (which are now all closed/deactivated):
- 783rd Radar Squadron, Charleston, WV
- 776th Radar Squadron, Point Arena, CA
- 757th Radar Squadron, Birch Bay, WA
I haven't had the opportunity (or the desire) to return to Charleston. Point Arena is on the California coast, on Hwy 1, and that is without a doubt, my favorite
stretch of road in the world. I've been up and down that road many, many times, and I've stopped in on occasion to see what's left of the radar site. I last visited the
site in October 2008. It's a remote location (150mi N of San Francisco), so if you're stationed there, your off-duty times are spent on site, or in one of the neighboring
towns. You need a weekend to get to San Francisco, because it's about 3.5 hours one-way to get there. The site is decaying, and some of the buildings are falling in on themselves.
It's the gravity of the situation, y'know?
If you just drive up there, you'll get as far as the main gate. If you want to look inside, that requires an appointment with the caretaker.
In May 2009, I was able to return to Birch Bay and see what is left of the site. This site is far less remote, being about 30 minutes north of Bellingham and 60 minutes south
of Vancouver BC. The DOD gave the site to Whatcom County, and they in turn leased part of it to the Lions Club, who turned it into a camp for kids with special needs, Camp Horizon.
These links take you to sites created for each of these former radar sites.
I don't know when I'll get back to Charleston.
783rd Radar Squadron. Not yet. Highly unlikely.
776th Radar Squadron. Online. Pictures added Nov 2009.
757th Radar Squadron. Online.
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Bad Idea Dept.
Have you ever had the idea of making adaptors to convert a common-ordinary extension cord (with NEMA 5-15 connectors)
into a speaker cable? Did you shelve the idea quickly after the briefest reconsideration? I hope you did!
These guys got the same idea and actually tried to take it to market, but I guess they never thought twice about what they had
done. These are two separate instances of the same idea, almost 10 years apart.
Don't even think about trying this. Do you know the expected lifespan of a 8-ohm loudspeaker that has been connected to 120VAC? Yeah, I know about Cerwin-Vega (who used to do this); that's a special case.
These are real data sheets. At least the
developer/inventor(?) of these products thought so.
I picked the J-Con one up at the 1996 AES convention. A friend
picked up the SpeakerLinx one at the 2005 NAMM Show. The product pictures were taken at that NAMM Show.
Talk about a bad puppy that keeps coming home!
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