Bassman project

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jzucker, Aug 23, 2003.

  1. jzucker

    jzucker Supporting Member

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    I'm looking for a 50 watt fender reverb head/combo. Here's my idea. Take a '60s or '70s BF Fender bassman head. Remove the circuit board and rewire the thing to be a single channel Fender AB763 reverb amp. I'm thinking that a small reverb tank might fit in the bassman head enclosure.

    I'd probably remove the existing circuit board altogether and try to make or purchase a blank turret or eyelet board, preferably a "glass" one. I took a look at some of the board kits out there but they are fairly expensive ($250 or more) and the AB763 board is for both channels and includes vibrato which I wouldn't be implementing since the bassman only has 4 preamp tubes.

    Anyone done anything like this?
     
  2. jzucker

    jzucker Supporting Member

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    I was looking through some fender schematics last night and figured out that the bandmaster may be really what I'm looking for. The '71 version has 445V on the 6L6 plates with a 5U4 (370-0-370 PT) I could use a GZ34 to get a little higher voltage if I decide I need it too. (Caps are OK but I'll have to check the rating on the choke). Of course, I'll need to replace the output transformer with something more stout because that's the sound I'm looking for and especially if I "up" the plate voltages...

    Anyway, the bandmaster seems to be a good platform for what I'm looking for.

    Jaz
     
  3. AlNelson

    AlNelson Guest

    Hoffman amps has some notes on adding reverb to a Bassman and plenty of board making supplies. If you have a drill press, you can build almost any board with the stuff he sells.

    Get the 1/8" glass board by the inch and as many turrets or eyelets as you need and you are set. He also sells a little swaging/staking tool for mounting the turrets to the board. It works well - I use mine all the time.
     
  4. jzucker

    jzucker Supporting Member

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    I need to get a drillpress. I used to have some nice tools before my divorce! :D Jet 17" drillpress, Delta 14" bandsaw, yada-yada...Now I'm looking at a $50 table-top grizzly drillpress. You think that would work for amp-making projects?
     
  5. AlNelson

    AlNelson Guest

    I am sure that would work fine for turret boards. It might strain a little when drilling into a 16 gauge steel chassis however.:)
     
  6. Jon Silberman

    Jon Silberman 10Q Jerry & Dickey Gold Supporting Member

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    Jaz, I'd post this type of question also on the WeberVST Amps board.
     
  7. jzucker

    jzucker Supporting Member

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  8. Ayan

    Ayan Member

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    Jack, I have always used a hand drill for my boards, and a 3/8" centre punch to steak the eyelets. The third "magical" ingredient is a jigsaw...

    You definitely don't need anything fancier than that to make amp boards that look as good as anything else out there. Caveat: as far as chassis go, I had mine NC drilled when they were made. I drilled large (up to 1/2") additional holes for transformer mounts and cable routing holes using a unitbit.

    Gil
     
  9. jzucker

    jzucker Supporting Member

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    Thanks Gil. You just tap the eyelets in with a hammer and the 3/8 center punch? I assume you prefer eyelets to turrets, then? Do you use any kind of jig to do straight cuts with the jigsaw? Where do you get your board-stock?

    Thanks for all your help.

    :)
     
  10. BWilliamson

    BWilliamson Guest

    I'm not Gil but I'm playing him on the internet!!!! :eek:

    Can't remember exactly what punch I used when I use to flair eyelets, just a broad one. But yep, flip the board and give it a whack! When flairing I prefer the .158" eyelets as they don't break up as much. Rolling eyelets myself now and prefer the .187" for that.

    I use a chop-saw now, but use to use a miter jig and a hacksaw. Worked pretty decently. Imagine it would be pretty easy to clamp a rail on the board to use as a guide to get a real nice straight cut with the jog saw.

    McMaster Carr sells precut stuff now. Also bought from Hoffman in the past. Also Ruby Amplification sells some boards.

    Personally, I prefer eyelets and that really started when I was drilling holes by handtools. You'll find with turrets unless you use a drill press, hard to get a perfect staight up and down hole and it's quite noticable with turrets. Eyelets are a bit kinder in that regard.

    Me changes back into my bwilliamson robe....
     
  11. Blue Strat

    Blue Strat Member

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    Wow, you mean you were able to "get out" by swapping power tools? Give me your attorney's number just in case:D

    On a more serious note, I think a Bandmaster Reverb would be perfect.

    One of my customers had one of these with TWO (count 'em, TWO !) 10's installed in the head cabinet! Smallest 2-10 combo ever.
     
  12. Ayan

    Ayan Member

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    As someone already stated, flip the board around, and make sure the eyelets are NOT in contact with any rough surface (like concrete, otherwise you may scartch them too much, which will make it harder to solder to them). I use a hammer and the center punch, but gently, so that the eyelets roll and "mushroom out" as opposed to "petal out."

    Never tired turrets, Jack. They probably afford a better mechanical connection between components, but if you take advatange of that by tying components' leads around them, it's probably a mess to change parts afterwards...

    I do use the jigsaw to cut the G10 board... Draw the cuts with a Sharpie, and then I just saw away. I don't use clamps or anything fnacy either, just a good blade and I hold the work with one hand. I have bought G10 from several people over the years, I think a good place to get it from is:

    http://www.mcmaster.com/

    and search for G10

    Good luck,

    Gil
     
  13. jzucker

    jzucker Supporting Member

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    Not sure what you mean by mushroom out but I'm sure I'll figure it out once I try it. Thanks again Gil. :)
     
  14. Ayan

    Ayan Member

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    Let's cal it "the art of rolling without ripping" (plain English: hit the eyelts softly with the center punch so as to roll them, unless you want them to split open... only difference is cosmetic). :D

    Gil
     
  15. Bill Morgan

    Bill Morgan Guest

    I used the turrets on my first 5 amps. Like Gil said, they make a great mechanical connection, but if you have to change anything later, they're a real pain in the butt. I just started using the eyelets and they are much easier to work with. I get my boards and eyelets from Doug Hoffman, and I use his staking tool.

    Bill
     
  16. AlNelson

    AlNelson Guest

    It is just one man's opinion, but I use both eyelets and turrets and I like the turrets better.

    I use the hollow ones and mount the parts on top. I put the bus wires, with a good mechanical connection, around the shaft of the turret, since that is unlikely to change. You can change components really quickly with turrets - quicker (and cleaner) than eyelets. The only bad part is, they cost 3 times as much as eyelets. So, I use eyelets for tone stack boards, power supplies sometimes and other areas that require fewer changes/updates. The preamps and PI are good places for turrets.

    I recently changed over from using wide Marshall/Fender type boards with multiple rows, to Hiwatt-style 'skinny' turret boards and now I am hooked. They work great and let you get higher circuit density in the same size chassis.

    Maybe I am being anal, but it seems like no big deal to use a drill press, fence and clamp so that all of the holes are straight up and down, evenly spaced and in a line. Ditto for tube socket holes and holes for pots.
     
  17. jzucker

    jzucker Supporting Member

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    Where do you get your turrets and boards? Do you use a template for spacing the holes?
     
  18. AlNelson

    AlNelson Guest

    I use multiple vendors - McMaster-Carr, Mouser, Hoffman. If I was doing one or two amps, I would get everything for boards from Hoffman.

    So many of the amps I do are one-offs and custom jobs that I do not use templates.

    If you use Hoffman's 3.5" wide by 1/8" thick epoxy board, just use a pencil and ruler to space your turrets 3/8" apart on a line about 1/4" to 1/2" back from the edge. You can use the board full width or cut it in half on a bandsaw for the skinny Hiwatt-style boards.

    BTW, on the full-width board, if you need holes in the middle, like for the PI, use eyelets for those. You can use either, but the eyelets are lower, so it keeps the board tidier if the 'traffic jam' of parts converging on a single spot runs downhill a little from the taller turrets at the edge of the board.
     
  19. jzucker

    jzucker Supporting Member

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    Thanks Al. Great tips.:)
     

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