Crack;Bottlehead OTL

Discussion in 'Headphone Amps (full-size)' started by ironbut, Mar 9, 2010.
  1. mcandmar
    Change the alert-tone to a cha-ching sound, you will sleep much better :)

    I had to skip this sale, think its the first October in years i haven't bought a Bottlehead kit for my Birthday.
     
    Last edited: Oct 13, 2017
    LikeABell likes this.
  2. Paladin79
    IMG_2221.JPG I think one of those cha-Chings was mine but I am building amps for others in my rare spare time and this time I am not in a hurry for the last Crack kit to arrive. Tomorrow I start assembly on a barely recognizable crack. I have to stop accepting wagers and intimating that people have choices when I agree to build them a Crack.

    This is my latest Crack build, I will be using polished copper, front and back plates for control knobs and inputs, tube type vu meters, antiqued cabinet using several wax applications. I will call this one the Gemini Crack and I imagine the layout hints at at least one new capability. There will be three major changes compared to a stock crack. This is a one time build then I will do a more standard Crack. (standard for me anyway.)
     
    Last edited: Oct 14, 2017
    JamieMcC likes this.
  3. attmci
    Tom, What's this?
     
  4. Paladin79
    It is the early stages of an amp I am building for a friend. I am using left over Crack parts as well as some my friend provided. The circuitry will be similar to a Crack but I have been challenged to add some features to it. You will know a lot more when the front and back panels are complete.
     
  5. attmci
    looking forward...
     
  6. Paladin79
    Thanks, my fourth Crack build will be more traditional, I will be pushing the limits of dual 12AU7's and 6AS7G's to get the desired results. I also need to generate 240v DC for the dual magic eye tubes ( one of the curveballs I was thrown) but a bet is a bet.
     
  7. attmci
    Are you using a new transformer? I doubt the stock transformer (heat current ~3.5A) can support dual 12AU7 and 6AS7G. I cannot/am not dare to use even two 6bl7 and a 6SN7.
     
  8. Paladin79
    Two new transformers that were supplied to me. There is a wager involved and I will need to think through a few things to pull this off, but I like a challenge and I like my odds. Once you see the jacks on the front and back I bet you figure out what two of the goals are.
     
    Last edited: Oct 14, 2017
  9. i luvmusic 2
    Now I'am interested on the "CIRCUIT DIAGRAM" a PM of copy would be nice....:)

    Thanks!
     
  10. Paladin79
    It is a little early for that, I am still in the planning stages and parts of the design may not be mine to share.
     
    i luvmusic 2 likes this.
  11. i luvmusic 2
    F@#K speaking of schematics i just lost/misplaced(DIY and the CRACK schematics) mine......
     
  12. i luvmusic 2
    No worries/rush when ever it's ready,THANKS Tom!
     
  13. Paladin79
    IMG_2225.JPG Here is enough info on the front and back plates that should reveal two of the things I am going for in the build. I will not be using the chicken-head knobs but just slapped them on the dual volume controls for the time being. In between said knobs are a quarter-inch stereo jack and a standard size four pin XLR female. On the back plate there will be the obvious speaker jacks as well as dual three pin xlr females, four RCA jacks, AC input jack, etc. Now there will be a small toggle switch on the front as well and one on the back but that is work for another day. It has been a while since I have laid out and made a pc board but there will most likely be one in the power supply section with all supply voltages well marked. My trusty watch dog Woodstock is guarding the build, cave canem.
     
  14. Paladin79
    IMG_2234.JPG My amp build is starting to be less Crack like so I may have to move it to another thread. There is a good chance I will be using four 6AS7G tubes in the build. I am using a 12 inch square top plate to allow for such changes.

    I did come across some little plates that can be mounted behind Neutrik connectors. At the top they have a little area that will accept letters so I will be able to mark the left and right three pin XLR's on the input plate of my amp. One is shown on the bottom copper plate and above it is the style Neutrik jack I can use with it. Luckily Neutrik makes RCA jacks in the same configuration
     
    Last edited: Oct 21, 2017
  15. Paladin79
    IMG_2243.JPG Opinions needed..

    I was getting some scratches in the front plate so I went ahead and added a patina after a couple hours trying to buff them out. Do I :

    A. Use patina on all plates including the top?
    B. Start all over with front and back plates and keep them shiny?
    C. Do a combination of patina on front and back plates only and keep shiny copper on top?

    The patinization really jumps out against the waxed grey cabinet but so does the copper.
     

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