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Will this OT placement cause issues?

Discussion in 'Shock Brother's DIY Amps' started by arielyitus, May 16, 2017.

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  1. arielyitus

    arielyitus Tele-Meister

    Age:
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    May 4, 2016
    Clarkston, Mi
    Hi,

    I am trying to build a single ended 5e3 just re-use a Hamnond 125ESE that I have.

    It is a BIG transformer and wanted to place it like this, do you think it will cause HUM/noise problems?

    Thanks a lot

    IMG_20170516_083055.jpg
     

  2. Mongo Park

    Mongo Park Tele-Holic

    514
    Nov 28, 2010
    Winnipeg
    arielyitus likes this.

  3. arielyitus

    arielyitus Tele-Meister

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    May 4, 2016
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  4. danlad

    danlad Tele-Meister

    185
    Mar 24, 2015
    Here and there
    Look up 'the headphone trick'

    I didn't do it last build and really wish I had. Just a slight background hum I'm sure I could have lost if I'd done it...
     
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  5. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    I have to ask...What is a "single-ended 5E3"? Would it be something like a 5F2A Princeton?
     

  6. arielyitus

    arielyitus Tele-Meister

    Age:
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    I guess it will be very similar but with two channels and 2 volume controls.

    The thing is I want to use one of those ubuyguitars.com 5e3 boards and power transformer with my only available OT which is for Single Ended Amps.

    So I am thinking in removing the second power tube and components and probably play with the phase inverter to make it an additional gain stage with a master volume (have not decided what to do with the PI)

    If it sucks, I can always invest in a real 5e3 OT and make it a 5e3 :)

    Do you have any ideas? Comments?
     

  7. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    No ideas, really. The 5F2A is an interesting amp, and imho that is basically what you are building. Unless you are an experienced builder, it might be advisable to stick to that 5F2A circuit....perhaps leaving space on that board for adding a gain stage with that unused triode at a later date?? I don't know if that OT will support 2 x 6V6's in paralleled singled ended mode, but there is a consideration. Perhaps one could switch one power tube in and out for output change??
    Don't let me get in the middle of your plans. I might get you all confused. (;^) A 5F2A build with two channels would be cool, imho. Or....make it single channel. That would leave you with not one but two triodes for extra gain stages!!!
     
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  8. arielyitus

    arielyitus Tele-Meister

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    Someone else here suggested the two power tubes in parallel too and that sounds nice, if the single tube thing sounds good I may go there. I will have to look at some schematics and try to steal the power switching and circuit around those paralleled tubes.

    I had been wanting a 5f2 as well and this board may turn in to that, who knows, I will post some pics and may be some lame playing once it is done.
     

  9. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Well, whatever it is, it won't be a 5E3 with that OT. (;^) good luck with the project.
     

  10. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    Your'e giving me crazy ideas, arielyitus - stop it.... I have two 5E3 chassis to use up, so I may have some SE fun with one of them. Since the 5E3 phase splitter doesn't have any gain and is not needed to split the phase, maybe it could be used as a cathode follower to drive a parallel 6V6 output stage. More gain there might get a little unmanageable driving a SE 6V6, but there are designs that use three gain stages, like the Trainwreck.

    The output could be wired with two sockets to plug in (1) 6V6, (2) 6V6 or (1) 6L6. And no, it wouldn't be a 5E3, but the trick is to not call it a 5E3.
     
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  11. arielyitus

    arielyitus Tele-Meister

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    May 4, 2016
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    :)

    It seems like you do know your tube amp design, could you please share the schematic you decide on?

    Also, if I wanted to do the least possible changes to my existing 5e3 board to make it work as a SE and keep the PI as a unity gain stage, could you recommend something?

    I call it the SE3 not 5E3 (see what I did there? :phahaha)
     

  12. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    Clever name. The nice thing is that changing a cathodyne splitter to a cathode follower is a pretty simple rewire. Compare the 5E3 splitter to the matchless Lightning's cathode follower and get out your red pen. There are (5) fewer parts. I don't have a finished schematic, but that's one way to get there. The output sockets can be wired in parallel, but with separate 470 Ohm cathode resistors and bypass caps, you could use (1) 6V6 or (2) 6V6. Plug and play. The (1) 6L6 option would require a switch to combine the cathodes for the right bias, Or... you could wire one socket for 6V6 (470 ohm cathode) and the other for 6L6 (250 ohm cathode) and play one at a time.

    Whatever you decide to do, there may be a little tuning to perform, like any design. Be prepared to take voltage measurements and come back with questions. There are a lot of sharp eyes on this forum.

    "Also, if I wanted to do the least possible changes to my existing 5e3 board to make it work as a SE and keep the PI as a unity gain stage, could you recommend something?"

    The bottom half of the 5E3 concertina (cathodyne) splitter is basically your SE output (capacitor off of the cathode circuit). You just don't use the top output (capacitor off of the plate circuit).

    Once you change the OT from P-P to SE, there are really very few changes to make. That's what makes the new circuit appealing (to me) and should also give you a little confidence that it is not major surgery. For a fresh build, the Lightning cathode follower stage is a fast, proven way to get there, with only a cathode resistor and a coupling cap.
     
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  13. arielyitus

    arielyitus Tele-Meister

    Age:
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    301
    May 4, 2016
    Clarkston, Mi
    This thing
    Wow, nice info here, I have some study to do.

    Thanks a lot for taking the time to share some knowledge.

    I am moving very slow because of the family, I will post some pics and progress
     

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