Latest build ... function follows form

Discussion in 'Shock Brother's DIY Amps' started by Diverted, Aug 28, 2019.

  1. Diverted

    Diverted Tele-Meister

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    Just finished up a really fun project that kind of evolved based on the parts I had on hand.
    I had a straight-faced Fender Princeton Reverb chassis laying around with pre-cut tube holes. I also had a nice power transformer that would give perfect B+ voltage with a diode bridge rectifier. Decided to build it and realized I'd have an extra octal socket since I wouldn't be using a tube rectifier. What to do with it?
    Finally settled on using an octal 6SL7 instead of 12AX7 in V4. So that took care of the open octal socket. But now I'd have an open 12AX7 hole. What to do with it?
    Finally decided to use it for an extra preamp stage, which I ended up voicing like a Marshall Plexi (tiny bypass cap, larger load and cathode resistor, etc). I put that in the original V1 position on the chassis and bumped the other two 12AX7s and 12AT7 over one spot to the left.

    Now with two independent channels but only one input jack and tone stack on the control panel, I ended up putting the input jack and plate outs from each channel on a DPDT switch. So in one position I'm getting the stock Princeton tonestack and in the other, the new Marshall-y channel.

    I ended up screwing around with the amp a lot more. Added Lar-Mar master volume, mid pot, bias test points, bias pot, and ran the ground from the mid pot to a foot switch (with 100K resistor across switch) to give a nice gain boost with the switch open. The resistor keeps a little bit of the tone stack flowing. Without it the gain boost was HUGE. Now it's at a nice midpoint I think.

    The chassis shot is an older one before I finished up. You can see two feedback resistors on a switch. Ended up taking that out after settling on the number I liked more. This is also before I neatened up the wiring a bit and ran shielded wire for the gain boost to a jack at far right.

    As for the cabinet I was out in California a few weeks ago and saw someone playing on a beautiful Matchless amp. I loved the backlit nameplate so I decided to give it a try. It works and I may do this from now on! The grill cloth is from the early 60s (old junked Hammond amp) and the knobs are vintage cool rounded chickenheads. I inset washers under the tolex for the chassis mounts, and drilled out some silver mercury dimes for on top of the Tolex. Why not?

    Also put all the controls that are usually on the back of the chassis (fuse, power cord, reverb stuff, footswitch jacks, etc) on the bottom of the chassis, so I wouldn't have to use back plates on the cabinet. I wanted to go for clean simplicity.

    The second channel bit took a little while to figure out but with some help online it's everything I hoped it would be and really adds a new dimension to this amp. I have a Celestion G10 Vintage speaker in there now.
     

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    Last edited: Aug 28, 2019
  2. D'tar

    D'tar Friend of Leo's

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    Awesome job! It may be even more evil with red jewels on the backlight! Love it!
     
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  3. Diverted

    Diverted Tele-Meister

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    Oh man great idea! Maybe red cellophane across the entire back? Hmmmmm.
     
  4. Wally

    Wally Telefied Ad Free Member

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    Wonderful work! Kudos. I will say that the ‘evil twin’ thing has been used for three decades now in reference to a certain big Fender Twin. I can’t help but visualize one of those Fenders when I see the name. And....it is a federal crime to deface legal tender. (;^)
     
  5. D'tar

    D'tar Friend of Leo's

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    It wasn't me Occiffer.... It was my "EVIL TWIN"!!!!:D
     
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  6. Diverted

    Diverted Tele-Meister

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    Huh. Didn't know about the Evil Twin thing.
    My identical twin brother has always said I'm the evil twin between the two of us, so I thought that would be perfect.
     
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  7. Wally

    Wally Telefied Ad Free Member

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    Diverted, it is no big thing...unless you were to start offering the amp as a boutique product. If it sounds as good as it looks, it might sell??? A more unique name would do better, imho..and ommv.
    As for the ‘evil twin’, it was not an official model name but rather is a well known nickname.
    http://ampwares.com/amplifiers/fender-twin-the-evil-twin/
     
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  8. Diverted

    Diverted Tele-Meister

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    Thanks. Well, I do build them for friends and acquaintances but it's pretty low key, mostly word of mouth and I have a wimpy little Facebook page that I don't update enough. Mostly just a hobby, I do mostly one offs and twists on established circuits, and I sell one now and then to pay off my costs. I don't think I have the desire or time to start selling them officially, as a product line on a dedicated website. Plus doing cookie cutter builds of a specific amp product would probably start to get boring for me and turn it from a fun diversion to more of a job. All set with that.
    Thanks for the info!
     
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  9. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    Wow! Nice work. Lots of nice details and creative ideas, beautiful amp.
     
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  10. Diverted

    Diverted Tele-Meister

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    Thank you very much Blue Bill. I tend to be crazy ADHD and building these is crucial therapy for me. This one sounds particularly good, I'm really happy with it!
     
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  11. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    You need one of these:

    adhd.jpg
     
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  12. Diverted

    Diverted Tele-Meister

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    Holy crap, I do.
     
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