Seems like I’m doing this backwards...

Discussion in 'Shock Brother's DIY Amps' started by RollingBender, Mar 29, 2020.

  1. RollingBender

    RollingBender Tele-Afflicted

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    My “gain” knob is the “volume” on an AB763.
    My “volume” knob would normally be called “master volume” from RobRob’s site...the Trainwreck Type-3 Post Phase Inverter Master Volume (PPIMV)
     
    Pick_n_Strum likes this.
  2. Pick_n_Strum

    Pick_n_Strum Tele-Meister

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    Nice - I put the Trainwreck Type 3 in my 5e3. Comes in handy when my little man is sleeping.

    I asked because I really liked the overdrive sound in the clip above.
     
  3. JuneauMike

    JuneauMike Poster Extraordinaire

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    That sounds like a job for a decade box.

    Your builds look great. I'm a big fan.
     
  4. RollingBender

    RollingBender Tele-Afflicted

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    Thanks a lot @JuneauMike...
    Because of your post, I went and bought a resistor and a capacitor substitution box. Probably should have bought those years ago anyway.

    something is definitely wonky with how the reverb interacts with the rest of the circuit. If I pull the reverb tube, that wierd shape on the oscilloscope disappears.
     
  5. RollingBender

    RollingBender Tele-Afflicted

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    I’ve been meaning to post an update for this project. Got a little “inspiration” to do that today.

    I’ve been gigging with this amp for a year now, 4-5 shows a month. I am absolutely loving it. Ahead of the amp, I have an overdrive, chorus, delay, and wah but 80% of the time it’s just the guitar and amp. It has a great chime/jangle tone with a bit of growl when you dig in with the gain set just below half way.

    Originally, it had a BJ spec OT. I noticed that the PT was running quite hot and suspected the undersized OT as a contributor so I replaced it with an 18 watt spec OT. That didn’t seem to effect the heating issue much. I think I am just 1 preamp tube over what the PT wants to run. I switch it all the way off on breaks…so far, so good.

    …until today… I was practicing at lowish volume before the rest of the band showed up for a rehearsal and noticed the amp start losing tone and getting quieter. I walked around back and saw one of the power tubes replating!! I quickly shut it off and when the tubes had cooled, the naughty tube had broken.
    B9FAF2FA-AA58-4E8E-82F0-462467965D86.jpeg
    The PT did not feel hot at all right after I shut it down. I replaced both power tubes with a pair of old tubes from a Baldwin organ donor and it started right up with no replating.

    I’ll open it up tomorrow and check things out, replace the power tubes and check the bias.
     
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