Fender 75 amp transformation thread.

Discussion in 'The Squawk Box' started by chriseskew24, Jun 1, 2011.

  1. chriseskew24

    chriseskew24 Senior Member

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    Ok well first off I would like to say that this is not going to be a overnight build. I am well aware this could take a couple few months to get done. No worries. Cygnus X1 / Kevin has agreed to take this project on and I am looking forward to it.

    The Fender 75 for those of you that may not know is a Rivera era amp. It has two channels clean and lead. The lead channel has always had unusable tone, the clean is to die for but I already have a amp with a blackface circuit so I really have no need for a one trick pony clean amp.

    Anyways Kevin and I have gone back and forth and he came up with something that will better suite what I want in this amp. He has agreed to update this thread from time to time with progress reports. I asked him to do this as I/we love this type of thing.

    Anyways I look forward to the coming weeks here is a shot of the guts as I got ready to ship the chasi off this morning to Kevin.

    [​IMG]
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    [​IMG]
     
  2. hipofutura

    hipofutura Senior Member

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    This is great! Can't wait to see where it's headed.
     
  3. chriseskew24

    chriseskew24 Senior Member

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  4. Cygnus X1

    Cygnus X1 Senior Member

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    First thing to do is color all those white wires.
    :shock:

    I bought a brand new set of "El Marko" markers to get that done.
    They smell really good (Buzzzzz) and give a vintage tone.

    :laugh2:

    We settled on clean channel Pro-Amp (the one I built into a recent Conn organ rebuild), which is like a Tweed Deluxe but with more power.

    The dirt channel...which really needs the most work on the Fender 75 will be the Cygnus 30, which is the Cygnus 7 but with a 2x6L6GC power section.
    JTM45 all the way to JCM800 sounds are to be found there.
    Dave Stephen's new amp is now technically done and it sounds great...just going through stress testing now...that is the one.

    I'll tap the resources of Rude Mood (if he is willing) about how to set up the switching.

    Will be able to do that because the power and phase inverter designs are very similar.
    I tuned the Cyg-30 to run on vintage supply designs.

    We agreed to drop the idea of an effects loop but I might be able to save the reverb function...we shall see, no promises there.

    Thanks to Chris to let me do this, it will be a learning experience for both of us, and I look forward to the opportunity.
    And thank you Don for dragging me into it!
    :D
     
  5. hipofutura

    hipofutura Senior Member

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    The pleasure's all mine! :naughty: Now I get to sit back and be a spectator. Popcorn, Coke, and Pink Floyd!


    Note sure how complex you want to get, but I drew the layout (and built the prototype) that uses foot switch controlled relays for channel switching. I can email the layout diagram if it will help with this endeavor.
     
  6. chriseskew24

    chriseskew24 Senior Member

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    Also Kevin, just so you know. Currently the treble, middle and bass pots are push pull on this amp for a signal boost.
     
  7. Cygnus X1

    Cygnus X1 Senior Member

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    More toys to play with!
    :thumb:

    Don, I might take you up on that.
    That's the part that will be a learning experience for me.
    :cool:
     
  8. Cygnus X1

    Cygnus X1 Senior Member

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    Background discussions going on here.
    Chris,
    By the time we're done you might have a nuclear ICBM launcher included.
    Secret option...natch.
     
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  9. chriseskew24

    chriseskew24 Senior Member

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    Haha. That's what I'm talking about:naughty:
    Then I can plan to take over the world one note at a time!

    You guys are the experts and I have learnt threw life to give the people in the know creative freedom. I have yet to be disappointed using this approach!
     
  10. Tuya Customs

    Tuya Customs Senior Member

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    I've never had a bad meal when I go to a restaurant and ask for the chief to do his thing. Same thing goes with amps. Kevin will make you something great!
     
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  11. rocknhorse1

    rocknhorse1 Senior Member

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    Man, when I do coke I don't want to eat anything:laugh2: JUST KIDDING!!!

    This looks like it's going to be cool! You are in great hands with Cygnus!!!:cool:
     
  12. randelli

    randelli Senior Member

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    I don't have any switching in the RUDE MOOD. Both sides are always on and dialed into a blend, if desired. I have looked at using relays for the switch as they are supposed to be quieter than DPDT switches. I would help if I knew anything.....
     
  13. Cygnus X1

    Cygnus X1 Senior Member

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    Thank you Randelli.
    We can learn together.
    There's a couple of guys around here who have experience.
    :cool:
     
  14. chriseskew24

    chriseskew24 Senior Member

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    I think we have one of the biggest wealths of knowledge on this forum then any other I have ever frequented.

    Plus some nice guys willing to share there experience. :thumb:
     
  15. Cygnus X1

    Cygnus X1 Senior Member

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    Plugged it in after sniffing around inside and extracting a broken power tube locating center pin.

    POP!

    Should have used the light bulb limiter.
    I think a power tube socket is shorted out.
    Regardless the transformers are rusted, there are some stressed carbon comp resistors, and it looks like I'm going to see what I can use here and do what was
    planned: gut and make a new amp out of it.
    Which should take less time than trying to do mods.

    Biggest issue (I may have mentioned) is the way the high gain and low gain circuits are tied together.
    No way to really divide and conquer it.
     
  16. chriseskew24

    chriseskew24 Senior Member

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    Wow. Hppy I sent her to you when I did! I have been listening to clips of your amps and I am certain I picked the right guy to handle this!

    On a side note I have been in contact with sourmash the old cabinet is crap. I am in between turning it into a head and cabinet or making it a 2x12 combo. Any recommendations on what you would do?
     
  17. Cygnus X1

    Cygnus X1 Senior Member

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    :thumb:

    What a compliment!
    I think you know me well enogh.
    I prefer blondes (wimmin o' course).
    I mean heads.
    No, I mean head from...wait.
    :laugh2:

    Head/cab combinations can be mixed at will depending on venue, speaker choices, et al.
    Heads also can be swapped at will.
    I'm actually more inclined to spend a lot of money on cabs figuring they should last me a lifetime.
    The amps come and go.
     
  18. chriseskew24

    chriseskew24 Senior Member

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    Yeah kinda what I was thinking to! :thumb: is there any reason why I can't get sourmash started on the head cab? The overall dimensions should remain the same right?

    Thanks
     
  19. Cygnus X1

    Cygnus X1 Senior Member

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    Should be no problem.
    Remember the tubes will be hanging down in the head
    just like they are in the combo.
    Leave room for the reverb tank in case we preserve it.

    Was thinking about sawing the chassis in half and making two Champs but scratched that idea.
    :eek:

    :laugh2:
     
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  20. hipofutura

    hipofutura Senior Member

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    Cyg, you're a busy guy!

    In late August my son and family are coming from Alabama to spent a week on the lake in Maine. He's bringing with him a Fender 75. Small world! He wants me to turn it into a Deluxe. Haven't decided if it will be a Tweed or BF. I'll probably keep the reverb. Will have to decide what speaker to use.

    Be sure to post some gut shots as you go along.
     

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