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Webcor Reel to Reel conversion thread

Discussion in 'Shock Brother's DIY Amps' started by ArcticWhite, May 17, 2018.

  1. scnewber

    scnewber NEW MEMBER!

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    I know this a relatively old thread... but I just picked up one of these, so I'd like to see how your story ended. Maybe I can apply what you learned.
    I picked up my 2612 last weekend from an estate sale and was told it was working... will see, haven't powered it yet. But if it's in relatively good shape, I'm thinking about trying to leave it almost as-is with a few tone-improving mods. But its setup is interesting... it has an input easily converted to guitar. It has an output for driving external cabinet. And a selector switch to operate in normal (input to tape,) external (playback to external cab,) and monitor which is a live output to the built-in speakers. While meant to monitor recordings... this means it already functions as a live amplifier. And then if the tape deck still works, either leave it as-is for a recording device... or convert into a tape delay effect. This unit was designed to be a "two-track" and setup to record in both directions - so maybe some interesting effects could be conceived with a few mods. Either way, I want to try to keep the magic-eye in the circuit as an interesting retro level indicator.

    So, ArcticWhite, how did yours turn out?

    Any other thoughts?
     
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  2. Jake Nelson

    Jake Nelson Tele-Meister

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  3. ArcticWhite

    ArcticWhite Tele-Afflicted

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    I think I mentioned back a page or two that I was abandoning my Webcor for now. I have a bunch of Hammond organ amps, and decided they'd be a more robust platform for the amp I decided on making - which is a Silvertone 1482.

    I still have the Webcor, and I may do something with it eventually. The cab is pretty cool looking..
     
  4. fumblesmcdrum

    fumblesmcdrum NEW MEMBER!

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    Time to dredge up an old thread again -- I just picked up a Webcore Royal Coronet, model 2712-1. ArcticWhite, you posted a picture a while back of the 2612 schematics... any chance someone has schematics for the 2712? Absent that, Could someone post a higher res version of the 2612?
     
  5. ArcticWhite

    ArcticWhite Tele-Afflicted

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    After two short years, I am ready to build this amp into something.
    Would love to do the Gibson GA-20T, but before I do I just want to make sure the transformers are up to the task..

    The Webcor transformer B+ is only 250 volts, while it looks like the Gibson is 320 or 355v.

    I don't understand the voltage chart on the Gibson Schematic..


    20180517_004646.jpg
     

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  6. Jake Nelson

    Jake Nelson Tele-Meister

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    If you use a solid state rectifier you will have enough voltage. I tried a 5y3 and it was too low. Overdrive wasn’t smooth. Worked great after I switched to solid state.
     
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  7. Nickfl

    Nickfl Friend of Leo's

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    I think the gibson voltage chart is specifying a 320-0-320 transformer with a rectified B+ of 350v.

    You can probably get 310 volts out of the web core transformer if you used solid state rectifier. Not the same as the Gibson schematic obviously but I think you could make it work.

    The other issue is that those webcore output transformers are kind of weird. Notice that the power tube cathodes are run through a center tapped coil in the primary side of the output transformer, with the cathode resistor and bypass cap apparently coming off the center tap. I really don't know what's going on there, maybe someone else can chime in to explain exactly what's happening, it would definitely help to understand that transformer before you proceed.
     
  8. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Did you build a GA-20T?
    What did you start with? Was it a conversion, or a scratch build?
     
  9. Nickfl

    Nickfl Friend of Leo's

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    I found some comments elsewhere online suggesting that the 2712 schematic should be pretty much the same as the 2612, is your tube complement the same as the 2612? If so I'd take a look at that schematic and look inside your machine and see if it appears to be the same . The actual 2712 schematic seems like it's going to be difficult to find without buying a manual or something.
     
  10. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Stripped the chassis last night.
    Plenty of room, but I will need to add a couple of tube sockets for the tremolo.

    The chassis shape lends itself to a 5e3 sort of cab, but it is quite wide. Most of the speaker will be covered.

    I may wind up using transformers from Hammond organ pulls, given the weak B+ of the Webcor, and its very weird OT.

    20200927_204134.jpg
    20200927_234738.jpg
     
  11. Jake Nelson

    Jake Nelson Tele-Meister

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    Scratch build 5e3 with a Mojotone small parts kit.
    [​IMG]
    [​IMG]
    [​IMG]
     
  12. Jake Nelson

    Jake Nelson Tele-Meister

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    The output transfer works fine. Just use these
    [​IMG]
     
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  13. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Did you use the Webcor PT?
    What is your B+ voltage?
    What rectifier tube did you use?
    What's up with the DeKalb logo? I grew up in Dekalb County, Georgia.
     
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  14. Jake Nelson

    Jake Nelson Tele-Meister

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    I did use it with a solid state rectifier and it was around 350v.
    One of my buddies raises corn and we thought the purple seed bags where cool so we pealed off the outside layer to use as a grill cloth.
    Another guy I know thought it was bad because he sells pioneer seed so he gave me some orange ones that I haven’t used yet.
     
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  15. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Did you try a tube rectifier? I wonder what voltage I could get out of one. I want to be as close as possible to the original design.
     
  16. Nickfl

    Nickfl Friend of Leo's

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    Was that 350v under load? I saw a picture of you measuring 350v from that transformer in your reverb build thread, but it looked like that was with no tubes in.
     
  17. Jake Nelson

    Jake Nelson Tele-Meister

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  18. Nickfl

    Nickfl Friend of Leo's

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    But the one in the reverb is the one that came out of a unit similar to @ArcticWhite's reel to reel, right?
     
  19. Jake Nelson

    Jake Nelson Tele-Meister

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    Yes but it seems like the voltage was higher than his. I’ll have to dig it out of storage.
     
  20. ArcticWhite

    ArcticWhite Tele-Afflicted

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    The Webcor schematic calls for a 6x5 rectifier.
    Can I try a 5U4 or does that draw too much current? I'm wondering if the transformer has excess capacity since it was built to power a bunch of tape player stuff.
     
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