Four 5” Micro Bassman build

Discussion in 'Shock Brother's DIY Amps' started by JohnnyCrash, May 6, 2021.

  1. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I’ve cut out many many chassis cutouts, but that was when I had more tools...

    The router I’ll be borrowing isn’t very powerful and its router table is practically a joke. But I still might be able to rig up a jig and give it a go. Afterall, it’s soft pine. Thanks for making me reconsider giving it a shot... even a less-than ideal router would probably be much better than my rickety hands and a coping saw.
     
  2. SomeGuyNamedRob

    SomeGuyNamedRob Tele-Meister

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    I like this project idea. Reminds me of the old Traynor YGM4 which was a 4x8 combo amp.
     
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  3. Peegoo

    Peegoo Poster Extraordinaire

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    Oh....it's a router table? That's even easier. If you have a fence on the router table, no need for a template or guide bearing on the cutter. Just set up stop blocks (simple wood blocks clamped to the fence) to limit the travel of the cabinet as you make your cuts.

    This is more involved, but it shows you the basics of the idea:

     
    Last edited: May 8, 2021
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  4. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    It’s got a fence. A plastic, thumbscrew adjustable type of thing. Like I said, it’s not ideal :D

    The “table” is fiberglass junk.

    But I could probably make it work.

    Might as well, if I’m already borrowing it for corners.
     
  5. s0cko87

    s0cko87 TDPRI Member

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    Thats awesome! One of these days I want to do a 22w 4X8 5F6 build, this might make me move that idea to the front of the queue :)
     
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  6. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Some progress today. Glued together the bee box and clamped it:



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    I’ve also glued together some 1/4” x 1” wood strips to act as fascia boards for mounting the baffle. The top and bottom boards of the bee box have a channel routed in the lip, 3/4” deep and 1/4” high. I’m gluing the glued wood strips to this channel.

    I might need to rethink the fascia boards... 1” isn’t much to screw a baffle to, especially considering I lose 1/4” due to the channel I’ll be gluing into.

    I couldn’t find 2” online, so I may have to go to a hardware store.
     
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  7. PhredE

    PhredE Tele-Afflicted

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    Don't intend to derail the thread, but just wanted to say -- re: frequency curve of most of your guitar type 8" speakers, most will be fairly close to the larger brethren (10s, 12s, etc). Where you'll sacrifice primarily is on efficiency. Very few 8"ers possess ratings above 96db. Most are less than that something like 91db-94db, and only a couple check in at 95db or above.

    Maybe also consider 6"/6.5" speakers too (?). Can't speak about older vintage/NoS type speakers, but the newer 6" units from Eminence and the like are built strongly enough to handle decent power levels (15w-20w nominally) and have sensitivity ratings of 95db or so. I put 2 20w 6.5" eminence speakers in a sealed and ported box (to bolster low-end primarily) and was surprised what volume was produced as well as the amount of air that gets pushed around. I'd bet 4x6" would work even better. I designed the box size/port scheme using one of the many online design 'calculator' sites.
     
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  8. NSB_Chris

    NSB_Chris Tele-Meister

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    Thanks for the input. I started a separate thread on speaker selection for this and will document the rest of the build on that thread. https://www.tdpri.com/threads/4x8-speaker-options.1071200/page-2
    Can't wait to test this out and see how it compares to my other cabinets in different applications. Also can't wait to see how the build on this thread works out with 4X5"! Glad to see it moving forward!
     
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  9. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Couldn’t find shippable 2” x 0.5” strips for the fascia, so I’ve glued two 1” x 0.25” boards together for thickness, I’ll be gluing the double stick to the edge of another double stick to make them 2” wide and 0.5” thick.

    Other than corner clamps, I got no clamps, so I’m using gravity :D

    Next: glue in the fascia boards, cut the chassis cutout with a coping saw, and then I’ll need a sheet of ply for the baffle. Just ordered a 4.5” hole saw for the speaker holes.

    The final step: solder up the amp.



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  10. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    It’s actually kind of fun trying to build a cab without my old woodworking tools (table saws, etc.) :D
     
  11. marshman

    marshman Poster Extraordinaire Silver Supporter

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    I need to acquire the woodworking skills WITH the good stuff so I can then actually woodwork without them.

    Lookin’ good.
     
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  12. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I never really picked up those skills, so now I’m extra in trouble :D
     
  13. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    A little bit more progress... ghetto-clamping the double thick sticks together for the top and bottom fascia boards :D



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  14. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    A little bit more progress.

    Gluing the top fascia panel (for speaker baffle mounting later) into the prerouted channel.

    Starting to cut the chassis cutout... by hand, with a coping saw :D



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  15. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I used my camping hatchet to split a sliver off of a board for a shim XD

    The bottom fascia board was about 1/16th too short.

    I’m reaching new lows in cab building!

    This is some Macguyver stuff... but it’s looking like the glue is strong enough to hold the warped pine boards together.

    I also ordered another bee box (this one a deep [9.75”] 8-frame) for my 6L6 single ended Supro Coronado 1x10” (7-11 watts). That combo cab will be built differently (baffle glued in flush with the front, all corners rounded, grille cloth attached to the speaker hole on the inside of the baffle, the outside of the baffle will be tolexed like the rest of the amp).
     
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  16. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    More progress.

    I refuse to let not having tools keep me from building, so I assumed the handtool job would look like an uneven hack job.

    It could’ve been worse :D

    Anyway, got the chassis cutout cut today.

    A bit of hole saw drilling, hacksaw cutting, coping saw cutting, Dremel sanding (with straight line guide), and hand filing to finish.

    Next step: glue in the back panel rails, putty up any gaps (including the bee box’s top notch-out handle/grip), and roundover the edges.

    I’ve ordered a 1/2 birch ply for the baffle. I’ll cut it to size when it gets here, then I’ll use the 4.5” hole saw bit (also coming in the mail) to cut holes for the four 5”s.



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  17. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Got one back panel cleat glued in, letting the glue cure before I move my only four (brand new cheapy) clamps to the other side’s cleat/rail.

    Sanded my initial pencil marks off, too. Drilled chassis mounting holes.

    The cutout isn’t perfect, but it’s a lot better than I thought it’d turn out :D



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  18. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Well... the rough superstructure is finished. And I emphasize “rough” :D

    Side and bottom back-cleats are in. 1/4” gap for a sheet of clear acrylic plexiglass to show the amp’s guts (haven’t ordered it yet), while offering a modicum of protection. Lower kick panel will be a few inches tall, so as to not impede the view of the tiny speakers.

    Don’t worry... it’ll look worse when I get my hands on some wood putty/filler. I’ll just use my large Marshalltown archaeology trowel to putty the big notched handle recess.

    I got a sheet of 1/2” birch ply on the way for the speaker baffle. I got amp feet and a tweed leather amp handle coming tomorrow.

    Then I’ll need to router a roundover on the puttied and sanded corners. After that, sand off the writing on the pine. Then wire up the chassis.

    Doh! I forgot, I gotta patch one of the speaker’s cones. It has a slight tear.



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  19. NSB_Chris

    NSB_Chris Tele-Meister

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    Are you going to tolex it or just leave it painted wood? You could leave the bee box handle cavity in there and just put your handle over it. Has a utility factor to make it easier to get under the handle if using a typical handle that lays flat and has a cool flare that it was crafted out of a bee box! I hope you leave it in rather than close it up.

    The early stages of the cutout for the chassis looked sketchy but then super nice for the finished product! It is really taking shape. Post your speaker repair. Interested how that comes out.
     
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  20. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I was considering covering in tweed, but my tolexing days should’ve been over on my last build. I’m not cut out for it. Don’t have the patience.

    I was then considering a tweed-ish color of truck bed liner spray, but I can’t find a suitably yellow-tan color in aerosol format.

    Now, I’m not sure what I’ll do. It’ll probably be bare for a while... maybe forever.

    Got my hole saw in the mail. Getting closer.
     
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