Tell Me About Those Blue Molded Caps

Discussion in 'Amp Tech Center' started by Paul in Colorado, Aug 8, 2019.

  1. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    I was watching an Uncle Doug video on You Tube where he works on a Recording King amp that has the blue Molded caps like '50's and '60's Fender amps. The Recording King is from the '40's as far as he can tell (though the title says it's a '30's amp).



    Anyway. It got me curious. What is the history of those caps? How are they made and what from? What makes them so special? Would those caps be original to that Recording King amp?
     
  2. schmee

    schmee Poster Extraordinaire

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    I assume you mean NOT the ones on that opening video page. No time to watch it. The Blue caps in Fenders and some other amps are durable and are claimed to be good tone caps. I often wonder about "tone" from caps, but still I value keeping those. I once put all Orange Drops in an amp in my early "messing with amps" years. I swear that amp was never the same. Pro Reverb. But still, I'm not sure two amps in front of me if I could really tell the difference.
     
  3. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    No. Not the ones shown on the opening video page. Those were replaced and the new ones remounted. I guess orange drops are sort of the same idea as the blue Molded ones..

     
  4. BobbyZ

    BobbyZ Doctor of Teleocity

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    I skipped ahead to a shot of the coupling caps. Some of the blue ones are the same as you'd see in a 60's Fender. Some of the blue ones look like the different caps.
    I don't know the history of the blue molded caps. Other they seem to be the first coupling caps Fender used that last a long time.
    Coupling caps from before about 1960 are always suspect and often on amps old enough all the capacitors will need to be replaced. I've had a few things where the electrolytics still sorta work but the coupling caps are spilling their guts.
    Yesterday I saw the insides of a radio from a 50 something Chevy pickup my buddy got stuck fixing. Coupling caps were replaced with orange drops at some point but the electrolytics are original.
    That reminds me I need to drop my tube tester off with him today. Things got an oddball rectifier and he wants to see if it's dead or not.
     
  5. Wally

    Wally Telefied Ad Free Member

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    Replacing the coupling and tone caps but leaving the electrolytics is like changing the points I. That old distributor but leaving the old condenser in place....since that condenser is an electrolytic cap. Your buddy will relate to that...when replacing pints one always replaces the condenser. Just as in an amp, a weak condenser can not provide strong voltage upon demand.

    And...the yellow molded Astrons from the second part of the ‘50’s are far superior to the paper in oil caps that came earlier..with regard to lifespan at least.
     
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  6. BobbyZ

    BobbyZ Doctor of Teleocity

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    Yeah Wally he's going to replace the electrolytics and the vibrator straight away. With any luck the last guy that replaced the coupling caps fixed the rest of it in the process. Who knows when that was done? The owner has been restoring the truck for some years now as I understand it.

    Oh for those of you thinking "what the hell's a vibrator?" It's the part in old tube radios my dad used to replace working in full service gas stations all the time in the 50s and early 60s when he quit working in gas stations.
    Or more technically. . . .
    https://en.wikipedia.org/wiki/Vibrator_(electronic)
     
  7. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    Back in the day, we used to build a "get home" box with a 12 volt radio vibrator, and an ignition coil. Plug the coil wire in place of the original, and you had enough spark to get in as long as the rotor and cap were ok.
    (I still remember "parking" with a girlfriend, and the constant buzz coming from the radio! KOMA of course!)
     
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  8. Wally

    Wally Telefied Ad Free Member

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    KOMA..booming 50K watts east/West at night time....every might in my youth in this area. WLS out of Chicago. The X out of Mexico with the Wolfman on a good night...”I’m gonna slap you upside the head with my little brown Bible!” Running through the night with the Milky Way shining bright....haven’t seen it in a long time.

    Good times...
     
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  9. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    Funny thing, almost no radio reception in my area then until night, and then KOMA! I moved to Nebraska with a friend, and lived in a little town out from Omaha, KOMA. Up into South Dakota, or down into Kansas, still the only station at night. When I lived in San Diego, we would listen to the Wolfman.
     
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  10. BobbyZ

    BobbyZ Doctor of Teleocity

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    We moved back up to the tundra from Iowa in 77. WLS doesn't come in here but there was KFYR from Bismarck that played the "devil's music". Only came in at night of course.
    Back then FM was what old people listened to, but that was probably already changing. Just took awhile to catch on in the upper Midwest.
    Now I find myself listening to KPRM FM pretty often. They play "the music of our lives", mostly pre rock and roll songs. Hated that station as a kid but not now it's something different from the corporate stations that play six songs of their assigned genre all damned day.
    Translation. . . . . .
    Welcome to Oldsville Bob!
     
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  11. powerwagonjohn

    powerwagonjohn Tele-Meister

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    I remember listening to Beaker Street and Beaker Theater late at night on AM radio, usually while riding or sitting in a car or truck. I am not sure what station it was. About the only time you heard people like Frank Zappa and Captain Beefheart on the radio.
    Thanks John
     
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  12. archetype

    archetype Fiend of Leo's Silver Supporter

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    Sounded like hornets in a box. Or a tweed Champ. :lol:
     
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  13. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    XERB is where we heard Wolfman Jack back in my youth. "I heard it on the X!"
     
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  14. David Barnett

    David Barnett Doctor of Teleocity

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    Beaker Street was on KAAY 1090 AM, Little Rock AR. They had a 50,000 clear channel transmitter. They switched the antenna to bi-directional at night and could be DXed from as far away as Manitoba and Panama under the right conditions.

    The host of Beaker Street was Clyde Clifford, whose real name is Dale Seidenschwarz. Dale's day job was as the transmitter technician and RF guru. His did his show from a small room at the tower, rather than working it in the main KAAY studio facility.
     
  15. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    Wait. Weren't we talking about caps in amps?
     
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  16. David Barnett

    David Barnett Doctor of Teleocity

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    When did they stop making the blue molded caps? When did Fender stop using them?
     
  17. mndean

    mndean Tele-Meister

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    I was lucky enough to pick up XERB most evenings while doing my homework.
     
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  18. BobbyZ

    BobbyZ Doctor of Teleocity

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    Don't know when the stopped making them but Fender used them from early on in the brownfaces. When they went away from the yellow Astrons of the last tweed years, some brownface amps will have a mix of both.
    They stopped I'd say in about 1968 when the first silverface circuits showed up.
    Good caps that normally are still good today.
    Now if they really sound special I can't say simply because I've never pulled working ones and compared then to anything else.
     
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  19. FenderLover

    FenderLover Friend of Leo's

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    I think they may be a vintage mojo story more than anything else. I thought I read that they were just mylar caps with a molded plastic shell. Not much different than the Mallory 150 in construction, but without the vintage mojo story. Either ones should outlast our grandchildren if the leads don't get damaged, which I have seen on the magic blue molded caps but not the Mallory 150's.

    I prefer the Mallory 150's over the orange drops strictly because of their geometry. The orange drops are formed, then deliberately squished into shape to decrease their center to center spacing for PCB assembly. The squish deforms the internal dielectric material and it seems like it would be better not be deformed, or altered, once formed.

    Ultimately, Vintage-ness is the rose colored glasses of our mojo existence. Can I have another beer? ;)
     
  20. IamBlue

    IamBlue TDPRI Member

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    These are Agax caps....theyre about the same size/shape as the yellow Astrons used in previous years only much more reliable. My '63 Brownface Vibrolux still has all of them on the board with no issues. If and when they do go bad, Ill probably replace them with Mallory 150's.
     
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