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Solid State Tube

Discussion in 'Amp Tech Center' started by Milspec, Apr 13, 2021.

  1. Milspec

    Milspec Poster Extraordinaire

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    sstube.JPG

    Okay, this isn't about guitar amps, but about a Zenith Trans-Oceanic SW radio that I am restoring. I am in need of some electronics advice and figure why not ask the smart people on my favorite forum?

    The radio in question was built in '49 or '50 (I forget which at the moment) and uses the miniature vacuum tubes including a 1L6 tube that has become rather expensive due to hoarding. Last check, it ran between $45 to $75 for a good tube. I have seen worse in the guitar amp realm, but it hurts just the same.

    Along comes a guy who sells a Solid State version built into an old vacuum tube. Basically, he took the SS design from the Zenith radios that ended up replacing the tube radios and built them into old glass tubes so they can be just plugged into the socket.

    The claim is that the specs are nearly identical but with the longer durablility of the Solid State design so you don't have to keep chasing the long discontinued 1L6 tube. Price-wsie, they are about the same price.

    What scares me a bit is that you really have to consider this an experimental design, but I am not sure what could really go wrong if it failed? I guess you miss out on the tube glow, but these radios are low watt (1W) affairs anyway, so the glow wasn't all that prominent.

    I also plan on adding an mp3 port to the chassis so I can just play old radio shows and sports broadcasts through the radio out on the porch in the evenings. I know, very nerdy, but that's me.

    Just looking for some 2 cents advice here.
     
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  2. ce24

    ce24 Poster Extraordinaire

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    It lives! (Young frankenstein).....I got nuthin but its a cool idea if it works.
     
  3. Milspec

    Milspec Poster Extraordinaire

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    He has been selling them for a few years now, so they sound like they work. He certainly gets an A+ for thinking outside of the box to solve a problem.
     
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  4. glenlivet

    glenlivet Tele-Afflicted

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    ....or inside the tube, as the case may be.....
     
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  5. Peegoo

    Peegoo Poster Extraordinaire

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    I see no reason why it wouldn't work, and I understand the rationale for installing it into a tube to make it plug 'n' play and sort of retain the original look of the chassis.

    But inside a glass container? Two problems I see here: (1) heat buildup, and (2) it's nonserviceable at the component level.

    Heat is the #1 killer of electronic components.

    If you need to replace a smoked resistor, you can't unless you break the glass.

    Why not mount the little PCB module on a Loktal base and call it good? No glass needed.

    About six years ago Korg developed a PCB-based vacuum tube technology called NuTube. Check that out...fascinating stuff.
     
    Milspec likes this.
  6. Jon Snell

    Jon Snell Tele-Holic

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    Westinghouse produced the very first transistors in glass bottles like that because people were used to valves that plugged in.
    A semiconductor has nowhere near similar characteristice of a valve. Semiconductors are basically, even up to the point of overload, linear and valves are logrithmic when driven hard ... which is why they are so good at matching the human ear for a pleasing audio sound.
    Mosfets get close as when they warm up the gain goes down, similar to a valve.

    If the designer of these 'solid state equivalents' knew his stuff, the heat issue would have been engineered into the design and not be a problem.
    Here's an idea of what could be in it;
    Screenshot 2021-04-14 at 09.08.58.png
     
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