Blues Briefcase

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JMPGuitars
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Re: Blues Briefcase

Postby JMPGuitars » Tue 06/04/19 4:20 pm

Here's my 2 cents:

Strip the lining on the inside of the briefcase. Add between 1/4" to 1/2" void-free plywood to the entire main panel that the speaker is being mounted on. Glue it on, and use weights on top and/or clamps to keep it pressed tight.

After that's done, drill the speaker mounting holes / speaker hole.

I would try to not cut out the tweed to the full size of the hole. If you can lift the tweed from the panel, and save an extra couple inches, you'll be able to wrap the tweed and cover the entire speaker hole edge.

This will give the speaker a much better sound than floating on a weak briefcase side. Also more stable for the rest of the stuff you're mounting.

Thanks,
Josh

PS. My wife made me do this: hurray :baby: :?: :evil: :D :D :o 8O
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Re: Blues Briefcase

Postby crgfrench » Tue 06/04/19 4:35 pm

Yes. I'm going to see after I cut the hole. Thanks!
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Re: Blues Briefcase

Postby crgfrench » Fri 06/07/19 4:37 pm

I cut the hole with a saber saw and mounted the Celestion on the inside and the grill on the outside with 4 through bolts. The briefcase is solid! I discovered it's 1/8" birch ply with the fur bonded to the inside and the tweed bonded to the outside. Same high quality solid construction as their tweed guitar cases. Will get some pix of the speaker when I get home from work.
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Re: Blues Briefcase

Postby JMPGuitars » Fri 06/07/19 5:00 pm

I don't recommend having less than 3/8" for a speaker baffle, and even that is on the thin side. Are you mounting the speaker on the same side as the circuit and transformers?
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Re: Blues Briefcase

Postby crgfrench » Fri 06/07/19 5:29 pm

JMPGuitars wrote:
Fri 06/07/19 5:00 pm
Are you mounting the speaker on the same side as the circuit and transformers?
Yes -- if you open the briefcase and turn it on its side it looks exactly like a combo setup, tubes sticking down from the chassis towards the speaker magnet. Like this pic:
Screenshot_20190607-185403_Gallery.jpg
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Re: Blues Briefcase

Postby JMPGuitars » Fri 06/07/19 8:54 pm

I don't know how much you plan on cranking that up, but with such a thin wall, the transformers and chassis will be subject to much more vibration. Excess vibration can lead to a lot of issues.

Typically the speaker baffle is thinner than the rest of the cabinet construction to allow for speaker response. Even 3/8" would be considered thin.

The chassis and transformers are mounted on to a stiffer piece of wood to reduce excess vibrations.

Personally I would mount the speaker opposite the rest, on a 3/8" or thicker baffle (1/4" added/glued to the wall would be fine). I would also recommend using lock washers and thread locking liquid on the bolts to make sure nothing comes undone from the vibrations.

If you do it the way you have it, it may be fine, but a little extra work now goes a long way to avoid problems.
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Re: Blues Briefcase

Postby crgfrench » Fri 06/07/19 11:28 pm

Thanks Josh -- good suggestions and I appreciate the feedback (no pun intended).
I keep seeing people using nail polish which is cool but I like loctite 242. Have not applied any here yet, since I disassemble and reassemble iteratively during my builds and I'm still in the "fitting up" phase here. I also like to use nylock nuts when possible. For #6 and smaller nuts I use star tooth lockwashers or keps nuts and for #8 and larger I use split ring lockwashers.

The essence of this briefcase amp is "cheap, simple, ultra compact and under-engineered". Think "Barefoot Willie found an old briefcase and some tubes in a dumpster on the south side of Chicago and he's throwing them together because he can't afford a Champ to play on the corner for wine money" rather than "the Mesa Boogie production line"... it's a gritty, grungy craft brew not a Bordeaux.

Here are some pix of the speaker installation -- the rubber ring is a little distorted around the bolts, I might trim a bit off the bottom side of the ring at each bolt to smooth that out, or maybe not. I might just remove the ring altogether to give it a rougher look.
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Re: Blues Briefcase

Postby JMPGuitars » Sat 06/08/19 7:06 am

If you do decide to add some wood, you can get that fabric at a fabric store and use spray glue to adhere it to the wood. Then you'll still have the look you're going for. ;)
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Re: Blues Briefcase

Postby crgfrench » Sat 06/08/19 11:10 pm

Chassis initial mounting, still need to drill for pots & jacks
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Re: Blues Briefcase

Postby crgfrench » Sun 06/09/19 2:29 am

JMPGuitars wrote:
Fri 06/07/19 8:54 pm
I don't know how much you plan on cranking that up
https://youtu.be/4xgx4k83zzc
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Re: Blues Briefcase

Postby JMPGuitars » Sun 06/09/19 6:59 am

My suitcase goes to 11!

I'd get some form of grill cloth on that grill. Or paint the grill if you want it open.
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Re: Blues Briefcase

Postby crgfrench » Wed 06/12/19 2:58 am

Installed the AC inlet/fuse/power switch tonight
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Re: Blues Briefcase

Postby crgfrench » Thu 06/13/19 1:25 pm

Made the panel cutout, it's tight at 7" x 1.5". Just perfect for 2 jacks and 4 pots. The chassis side is 8" x 2" abutting inside. Just need to find some small trim for it. Not sure which knobs to use but I'm leaning toward the 1939 black bakelite chickenhead ones. Still need to drill the chassis for jacks & pots.
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Re: Blues Briefcase

Postby crgfrench » Thu 06/13/19 1:59 pm

JMPGuitars wrote:
Sun 06/09/19 6:59 am
I'd get some form of grill cloth on that grill. Or paint the grill if you want it open.
In the Aftermath of this excellent feedback, I decided to take the advice of Keith Richards and Paint It Black. Happily, it is already, so nothing more to do on that front!

By the way, did y'all know about that time Keith electrocuted himself in 1965 playing "The Last Time" in California -- brushed his guitar strings against an ungrounded mic stand, blew him backstage in a flaming blue electric arc, ended the whole show. Almost killed the poor bloke!
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Re: Blues Briefcase

Postby crgfrench » Fri 06/14/19 2:10 am

Drilled chassis for pots & jacks
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