Thursday, June 13, 2013

TUBE-TYPE MIC MIXER, PART 2

     A reader complimented the schematic I posted yesterday.  Of course, that's the "clean copy."  Here's the one I drew as I traced it:
     You will note several layout errors that are corrected in the later version -- don't know why I omitted the headphone jack wiring in that one, though.  Schematic drawings can nearly always be improved after the first draft gets everything on paper (or on the screen, if you work that way).  The rules are simple, applying them sometimes isn't.

     And here's what I traced:
     The Thordarson "Tru-Fidelity" mic transformers are not original -- the fellow who gave me the mixer salvaged the original UTC transformers.  The Thordarsons are at least as good.  They're also larger.  I'm not happy with the length of unshielded wire in the grid leads, it will want changed.  Looks like I took most of the wire harness lacing out when I traced it, too, so that needs redone as well.  I wonder how those Sprague "Atoms" electrolytics are holding up?  (They're on the terminal board behind the right-hand mic jack.)
    
     Back panel:
     Blank and ready for call letters!  (It's traditional.)

     2" Cannon connectors, with a penny for scale and ancient masking tape stuck on the chassis:

     12-pin Jones plug, holes where a previous user had relocated the output terminals, fuseholder:

     Rannie the cat loves my fancy screwdriver set:
      This made disassembly a little more difficult.

     (Here's another take on a small mic mixer, kind of interesting...if you have the parts.)

Wednesday, June 12, 2013

TUBE-TYPE MIC MIXER

     It's been awhile since I traced the circuit and got it working:


     Naturally, it was not working when I took it down from the shelf.  Time to get out the signal tracer.
     At some point before I got it, the front panel was covered in wood-grain laminate.  I'm thinking a nice coat of plastic-friendly matte black would do it a world of good.  And perhaps some RCA-type knobs that had not been painted, too.

     (A word about the '2" Cannon' notation for the input connectors: that's what they are, great big old-fashioned microphone sockets.  A mic-connector roundup post is in the works to provide examples.)

Thursday, June 6, 2013

THE FIRST PLAY-BY-PLAY MAN

     In fact, he probably invented the idea.  And he was a Hoosier.

    ...It was The Big Game -- and not a home game for his school's team.  The year was 1903.  University of Michigan student,  Indiana resident (and part-time telegrapher) Floyd J. "Jack" Mattice had already dreamed up (and sold to Western Union!) the notion of having sports-knowledgeable telegraphers transmit moment-by-moment scores and high points directly, instead of waiting on copy from print reporters and now he'd come up with another idea: a long-distance telephone line.  He'd describe the game to the other students back at UM as it happened.

     Bell Telephone installed a phone booth on 40-foot poles along the sidelines at mid-field and a direct line back to the auditorium UM. Shortly before the game began, Mattice climbed up and placed the call--

     But remember, this is 1903.  Electrical amplification is still several years away.  Backstage, ten more sports-fan students were listening in, each one in turn memorizing a few minutes' play and rushing onstage to relay it to the audience, and then back to his listening post as the next "sportscaster" took over, on after another.

     It was a popular notion.  At UM, the practice continued until radio broadcasting took over in the 1920s.  As for Mattice, he had another career; you see, he'd arrived at college already a member of the bar.  After graduation, he went home to Rochester and practiced law, serving a couple terms as county prosecutor.  Even that wasn't enough -- during WW I, he went to work for the Bureau of Investigation's office in Indianapolis and then at the U. S. District Attorney's office.  He went back into private practice a few years later and then served in various posts with the city, then back to Federal work during WW II, ending up as a prosecutor at the war crimes trials in Japan.

     Still, inventing sportscasting probably made more people happy than any of his legal work.  He retired to Rochester and passed away in 1971.  He maintained a lifelong interest in telegraphy and if you've ever wondered about the curious number of attorney/sportscasters (Howard Cosell, for instance), while I don't think Mr. Mattice can be blamed for it, he was certainly one of the first examples.

     (Crossposted from my personal/political blog.)