Cap upgrade

Discussion in 'The Workbench' started by BowerR64, Jul 21, 2019.

  1. johnfv

    johnfv Well-Known Member

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    Yes, I suppose it's possible you got a dud somehow but bottom line it sounds like the amp is not what you want and you've tried a lot of things. Might be best to move on? We've discussed this stuff in PM but I'll repeat myself here.
    I love my Amelia. It sounded damn good with the stock tubes. I did eventually replace V1 (Mullard 12AX7 RI) and output tubes (I had some EH EL34 tubes "in stock"). You mention trying other tubes (6CA7 and 6L6), I definitely appreciate the EL34s in mine. I did some small mods but bottom line, I was very happy with mine right out of the box. YMMV...
    http://www.marshallforum.com/threads/new-jet-city-amelia-50-watt-head.94259/#post-1612720
    http://www.marshallforum.com/threads/epic-amplication-jet-city-mods-amelia.105904/#post-1802297
     
  2. Cadorman

    Cadorman Well-Known Member

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    Probably got diodes in the preamp.
     
  3. ampmadscientist

    ampmadscientist Well-Known Member

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    "...a production version of the Earhart, which was in turn a semi-clone of a Cornford Mk.50H II...."

    Fucking amp scholar of note.
     
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  4. BowerR64

    BowerR64 Well-Known Member

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    It does seem like the same as the conford MK II, that amp even has the 2 channels with the boost and the 2 master volumes.
     
  5. gldtp99

    gldtp99 Active Member

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    Use a full set of these !!!!:

    https://jupitercondenser.com/product/round-beeswax-audio-capacitor/

    They have beeswax inside to sound "sweeter" (like honey) and they have the "Controlled Deep Cryogenic Treatment" that improves everything (or so they say).

    They are only $30+ USD/ea.

    But be 100% sure that you orient them with the Outside Foil closer to the Low Impedance point in the circuit.

    Or else you'll be in a World of Hurt, for sure !! (or so we've been told by the "Knowledgeable Experts" on this very forum). :blah::blah::blah:

    Seriously----- you've bought an amp that is too bright/fizzy sounding for your taste.

    Get another amp that you actually like the sound of instead of modding this Jet City into something it was never designed to be.
     
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  6. Nik Henville

    Nik Henville Well-Known Member

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  7. Nik Henville

    Nik Henville Well-Known Member

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    NOT...

    I used Google - to show the OP he could just look it up.
     
  8. BowerR64

    BowerR64 Well-Known Member

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  9. BowerR64

    BowerR64 Well-Known Member

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    One thing that puzzles me is the tube layout. I tried putting a BBE sonic maximizer in the loop ive had good luck with other amps using this unit to add some richness but in the Amelia it didnt sound good at all it didnt handle much level before it distorted and sounded bad.

    On the "specs" it says "tube driven FX loop" but in the manual of the "tube layout" non of the tubes claim to be for the loop. I thought maybe swapping the loop tube for a 5751 or an AT7 would smooth that out but i dont see which one they are even using for the loop.

    There is one that says "tone controls" thought which seems weird

    Amelia tube layout.jpg
     
  10. Chris-in-LA

    Chris-in-LA Well-Known Member

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    You’re right, it sounds as if something is missing, kinda sterile and buzzy.
     
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  11. BowerR64

    BowerR64 Well-Known Member

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    Nah i never said buzzy
     
  12. Chris-in-LA

    Chris-in-LA Well-Known Member

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    That was my interpretation of the sound in the video.
     
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  13. BowerR64

    BowerR64 Well-Known Member

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    The blue Harheart?
     
  14. Nik Henville

    Nik Henville Well-Known Member

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    .
    .
    .

    In fairness to the blue Earhart 50...
    ...that may have been the recording.
    .
    .
    .
     
  15. Im247frogs

    Im247frogs Well-Known Member

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    Dude, The Sonic Maximizer?!!! How much are those?
     
  16. Nik Henville

    Nik Henville Well-Known Member

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  17. Nik Henville

    Nik Henville Well-Known Member

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    Ahh... just replace ALL tha caps with Audio Note Paper in Oil Signal Capacitors, or better yet, their Silver Foil units...

    [​IMG]
     
  18. Im247frogs

    Im247frogs Well-Known Member

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  19. 67Mopar

    67Mopar Well-Known Member

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    A signal cap refit isn't going to give you what you think you want. Most of the "vibe" comes from the transformers, and filtering. As far as the Earhart 50 is concerned, I doubt there's anyone here that is as familiar with that circuit as I am.
     
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  20. 67Mopar

    67Mopar Well-Known Member

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    If the Amelia shares the same design and values as the MK50/Earhart 50, and you are primarily a humbucker user, change the cathode bypass caps (V1A/V1B) from 2.2uf to 1uf electrolytic. This will make a HUGE improvement overall. I'd also drop the tone stack bass cap to 47nf or 33nf. The MK50/Earhart 50 was "tuned" around single coil pickups. Switchable bypass caps (between 2.2uf and 1uf) would be ideal.

    MK50:

    [​IMG]
     
    Last edited: Aug 7, 2019
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