New Weird Amp Day

Discussion in 'Glowing Bottle Tube Amp Forum' started by dannyh, Jul 11, 2020.

  1. dannyh

    dannyh Tele-Afflicted

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    Hello all...

    I posted a while back about a little 1964 or '65 Magnatone 421 (Starlight, I believe it's called? Starlite maybe?) I was looking at. Long story short, I got it for pretty cheap, and finally got around to having it serviced. Thought I'd post a few pics for anyone that might find this amp interesting.

    The amp sounds really good. It has bias vary Trem and the Lonnie Mack Vibrato, or at least a student amp version of it (yeah, I had to re-learn the riff to "Wham"). It has a single 6HU8 power tube, which is pretty rare and pricy these days, but fortunately this one checked out fine. The speaker is a 10" alnico McGregor...I'd never heard of that company. The speaker sounds pretty good; a little too bright for my taste, but for an original early 60's speaker it's in pretty good shape. I'll probably box it up in favor of something else (the amp sounds REALLY good through my Princeton Reverb cab and the 1028K that lives in there). The amp wants to see a 4 ohm load , so I'll either live with the mismatch and go with something I already have, or maybe grab a WGS Vet 10. They are available in 4 ohm and are $50 right now on the WGS webpage (though I remember when they listed at $40 a few years ago...).

    Anyway, not exactly a Dumble barn find, but still a pretty cool little amp and the price was right...and I'm not exactly swimming in gigs to take up my time these days, so I figured this would be a cool little distraction.

    Some pics if anybody wants to see the inner workings...It has quite a few blue molded caps in it.

    IMG_0560.JPG

    IMG_0563.JPG
     
    Last edited: Jul 11, 2020
  2. dannyh

    dannyh Tele-Afflicted

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    IMG_0568.JPG IMG_0496.jpg IMG_0569.JPG
     
  3. tce63

    tce63 Tele-Afflicted

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    Looks great, nice scoore
     
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  4. Ebidis

    Ebidis Tele-Afflicted

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    HNWAD:)
     
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  5. tah1962

    tah1962 Friend of Leo's

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    Sweet amp. Congratulations.
     
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  6. teleman1

    teleman1 Tele-Afflicted

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    I have a 412.
     
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  7. powerwagonjohn

    powerwagonjohn Tele-Meister

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    Congratulations on the new amp. I thought it looked familiar, one just popped up on my local C/L. Enjoy
    Thanks John
     
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  8. Wally

    Wally Telefied Ad Free Member

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    Nice amp, Danny...clean!! One thing....it would be a bit of trouble to do with that inline fuse, but it would be safer to have the fuse
    situated prior to the switch rather than after it.
     
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  9. rangercaster

    rangercaster Poster Extraordinaire

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    That's so awesome !!!


    I bet it sounds good !!!!
     
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  10. dannyh

    dannyh Tele-Afflicted

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    Thanks Wally...that internal pic was actually “pre service”, I’ll have to look and see if that was addressed.
     
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  11. Engine Swap

    Engine Swap Tele-Holic

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    Nice - looks like you had the filter can cap replaced.

    I have a 421 too. Mine has some hum and spurious noise. Did the cap replacement help?
     
  12. Peegoo

    Peegoo Friend of Leo's

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    Ooooo Minty!
     
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  13. Wally

    Wally Telefied Ad Free Member

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    Okay, so I have never looked at the schematic for this amp before.
    03E9E0DC-D462-49CD-A9C5-5A6129AEF270.gif

    Can someone explain how one path for that Vib/trem circuit is a pitch-altering vibrato and one path is simply a volume fluctuation tremolo? It seems to be a difference of where the bias variation takes place in the signal path? The vibrato path goes to the input grid of the Third stage and the tremolo path takes effect on the input grids of the power tube. If the vibrato circuit varies pitch, how does it do that?
     
  14. dannyh

    dannyh Tele-Afflicted

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    EDITED

    The hum is a lot better but still there, slightly. Apparently it is coming from the way the preamp tube socket is grounded to the chassis; apparently an old cost cutting method rather than the 6.3 volt wire to both filaments? Forgive me if I’m mistaken on this...still learning this stuff.

    I just opted for a basic service, I’ll look into that later....the hum is not that noticeable, I’m just use to dead quiet fenders...
     
    Last edited: Jul 11, 2020
  15. Wally

    Wally Telefied Ad Free Member

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    The heater filament circuit is not wired in a pair but rather one end goes to ground...at least it does on V2...pin 9. It is difficult to see the other tubes, but this type of heater filament wiring can introduce hum.
     
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  16. dannyh

    dannyh Tele-Afflicted

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    Wally I hadn’t seen this when editing my prev post....yes, this was what I was referring to.
     
  17. dannyh

    dannyh Tele-Afflicted

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    This may not be what you’re asking, but the way I understand it Magnatone used “varistors” to achieve their vibrato. I’ve heard the varistors and the power tube I have are worth more than the amp these days....


    Sent from my iPhone using Tapatalk
     
  18. Jakedog

    Jakedog Doctor of Teleocity Ad Free Member

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    That’s super cool. Setting straight up $$$ values aside, I’d much rather have something like that than a Princeton or Champ or something.
     
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  19. archiemax

    archiemax Tele-Meister

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    Way cool! I once had the Mag similar to yours but the one with reverb--Same weird dual-pentode output tube, same vibrato/tremolo circuit, had a huge reverb tank. Bought it on Ebay from someone in Canada for $99. It was trashed inside and out. Found the schematic in The Tube Amp Book. It'd had some "modifications" done to it by someone who had no clue; when I got it it had low output and none of the effects worked. Sold it during hard times; wish I still had it, it was a cool amp.
     
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  20. Engine Swap

    Engine Swap Tele-Holic

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    Here's my 421. Got it at an estate sale a few years back.

    [​IMG]

    When I got it home, I could hear some stuff rattling around inside. Here's what I found:

    [​IMG]

    The previous owner was a gigging accordian player. Nice that the foot switch was inside.

    I replaced the speaker with a 4 ohm Weber and it sound nice. The temolo and vibrato are both really cool. I need to do a recap and a little work on mine to get in in top shape. All in all, a fun and unique amp.
     
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