Blackface Bassman Board Layout (AA165 w/ Trainwreck Chan)

Discussion in 'Shock Brother's DIY Amps' started by Phrygian77, Jun 9, 2017.

  1. Phrygian77

    Phrygian77 Tele-Afflicted

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    My original intent was to create a complete layout drawing of my build, but progress has been slow so I decided to draw just the board and the wires only. I'm ready to build out my board so I wanted a printable reference with all of the resistor color codes, and the X-Y-B wires drawn on the board in the correct colors. I used the few pictures of AA165s that could find to figure out those X-Y-B jumpers.

    BF-Bassman-Layout.jpg

    A copy of my schematic is also attached.
     

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  2. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Doing a layout like this can really help you learn an amp's circuit.
     
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  3. peteb

    peteb Friend of Leo's

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    Did you get all the aa165 info you need?I have one and pictures are no problem.
     
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  4. Phrygian77

    Phrygian77 Tele-Afflicted

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    Sure, pictures would be great. Most of them that I've seen have been hacked up in some way. This is one of the better ones...

    [​IMG]

    This is the same amp, but with the power section reworked and cleaned up...

    [​IMG]

    This one is really sad...

    [​IMG]
    [​IMG]

    And this is another one on this forum. God only knows what power transformer was put in it:
    http://www.tdpri.com/threads/bassman-blackface-aa864-or-aa165-or-ab165.599723/
     
  5. peteb

    peteb Friend of Leo's

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    image.jpeg image.jpeg image.jpeg image.jpeg Here's a few I all ready have, I could take close ups of any area you need
     

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  6. Wally

    Wally Telefied Ad Free Member

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    Just an observation...but the AB165 Normal channel is that T'wreck Express in the making.
     
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  7. Phrygian77

    Phrygian77 Tele-Afflicted

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    On the bass channel, I'm borrowing from the Express and Liverpool. The normal channel is stock.
     
  8. Phrygian77

    Phrygian77 Tele-Afflicted

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  9. Wally

    Wally Telefied Ad Free Member

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    So you are adding a gain stage to that Bass channel...and changing the tone stack..?
     
  10. peteb

    peteb Friend of Leo's

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    thanks Phrygian,

    it doesn't get played as much as it should, I mostly play smaller amps, but it is on tap for whenever the need arises.
     
  11. Phrygian77

    Phrygian77 Tele-Afflicted

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    I'm following the AA165 layout, which has 3 gain stages in the bass channel like the AA864. The Wreck style preamp fits into it perfectly with just a few component value changes. I'm not really adding anything. On the AB165, both channels are mixed into the 3rd gain stage instead of going to the PI. You said 'AB165' in your post, so maybe that's what you were thinking?
     
  12. Wally

    Wally Telefied Ad Free Member

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    My bad....you are correct in that those Bass channels do have 3 gain stages.
    I did an interesting thing on the last AB165 Bassman amp. This is the second I have done for this young player. I not just just revoice that Bass channel, but I utilized that blank eyelet that once held the contact for the Deep switch cap as a contact point for a midrange boost circuit. A small terminal strip attaches at that screw that holds the board down on that end...lots of room there. That switch became a really nice boost. I am thinking of making it footswitchable from the front panel using the #2 input Jack.
     
    Last edited: Jun 14, 2017
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  13. Peterquelle

    Peterquelle Tele-Meister

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    With which Programm did you do the layout ?
     
  14. Phrygian77

    Phrygian77 Tele-Afflicted

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    Visio, because I'm used to it, and I wanted everything exactly to scale. I tried to use DYILC, but it doesn't give you enough control over the geometry. There's no way, for example, to specify an exact X,Y coordinate for an object, or even see it for that matter. All you get is a grid.
     
  15. Ibanezgrind

    Ibanezgrind TDPRI Member

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    Hi Phrygian,

    I am going to be building a Blackface Bassman from scratch and as you know, there are so many directions to take. I know stock the Blackface circuits (AA165, AA864, AB165) all sound great as is. Doing a bit of research, it could sound even better. I came across your layout and schematic and it caught my attention for sure! I am narrowing down my choice and almost ready to build. I was curious to know, how did this amp turn out and if you ended up going with what you did in the DIY layout? Did you tweak it further for the better? Hopefully you will see this soon. Just curious, thanks!
     
  16. Phrygian77

    Phrygian77 Tele-Afflicted

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    Sorry I overlooked this post. The only change that I made from my original layout was upping the phase inverter input coupling cap to 1000pF. I know at least one guy that I respect has said that the typical Fender 1000pF or 500pF values can cause intermodulation distortion with a high gain preamp. I haven't seen any evidence of that problem with the Trainwreck channel in my build.

    My schematic also has an error showing a 12AX7 for the phase inverter, but it's a 12AT7.

    It's a fantastic sounding amp, and I've been gigging with it since I built it. The Trainwreck channel is very midrangy, in a good way, but it also makes it VERY loud.
     
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  17. Ibanezgrind

    Ibanezgrind TDPRI Member

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    Sorry, I just checked your reply. Shame on me! I just created a thread for the first time ever today. I apprecaite you lending me your knowledge. I ended up doing the Longhorn modded Bassman ab165, very sweet and LOUD like yours. Cheers!
     
  18. Paul G.

    Paul G. Friend of Leo's

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    Looks good.

    Yes, the bass channel is now Trainwreck express with the 3rd stage having a cold clip. Use silver mica for that 500pf treble cap, you'll hear the difference. I recently put that tone stack in the bass channel of my AB165 and I like it, although I don't have the cold clip because my channels share the 3rd stage. I'm planning to use the unused triode to separate the channels so the "Fender" channel can have a conventional 3rd stage, I just have to draw it out.

    What values are you using for your switchable NFB?
     
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  19. Phrygian77

    Phrygian77 Tele-Afflicted

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    The NFB looks like this...

    [​IMG]
     
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