Blues Briefcase

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crgfrench
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Blues Briefcase

Post by crgfrench »

The final major components arrived from mouser
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Re: Blues Briefcase

Post by crgfrench »

Mounted PT
attachment=0]20190602_110230.jpg[/attachment]
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Re: Blues Briefcase

Post by crgfrench »

Initial Layout
20190602_105623.jpg
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Re: Blues Briefcase

Post by crgfrench »

Installed OT on chassis and drilled socket holes
20190602_175959.jpg
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Re: Blues Briefcase

Post by geoff 1965 »

same OT as mine Craig,what primary resistance do you have for each plate wire from the centre tap?
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Re: Blues Briefcase

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geoff 1965 wrote:
Sun 06/02/19 5:23 pm
same OT as mine Craig,what primary resistance do you have for each plate wire from the centre tap?
This one is 307 Ohms brown to red and 345 Ohms blue to red.
The tap is at "half the windings" rather than "half the resistance".

For comparison, the Heyboer HT 6135 I used in my Denim Deluxe was:
305 Ohms brown to red and 324 Ohms blue to red.
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Re: Blues Briefcase

Post by geoff 1965 »

i've got 354 & 317,
are you going to fit a baffle board for the speaker?
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Re: Blues Briefcase

Post by crgfrench »

I'm going to cut a 9" diameter hole in the side of the briefcase and mount the Celestion Ten 30 directly to it with 4 bolts.
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Re: Blues Briefcase

Post by geoff 1965 »

will that be strong enough? you don't want the cone to be able to flex.
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Re: Blues Briefcase

Post by crgfrench »

I think so. I'm going to try it and find out. I seem to be capable of only learning things the hard way. If it's not sturdy enough I could easily add a birch ply or aluminum baffle.
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Re: Blues Briefcase

Post by geoff 1965 »

okay,i was thinking you could sandwich some mesh or grillcloth between the baffle & case to protect the speaker as well as strengthen it.
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Re: Blues Briefcase

Post by crgfrench »

Good idea, thanks. I'm mounting the Celestion on the inside, with this grille mounted on the outside:
https://www.parts-express.com/heavy-dut ... l--262-862
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Re: Blues Briefcase

Post by crgfrench »

This is the schematic, it's a Fullerwell circuit.
I used a 125 Ohm bias resistor instead of the 250 listed here.
BBschematic.png
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Re: Blues Briefcase

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geoff 1965 wrote:
Mon 06/03/19 5:54 pm
okay,i was thinking you could sandwich some mesh or grillcloth between the baffle & case to protect the speaker as well as strengthen it.
Here is the plan
20190604_154424.jpg
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Re: Blues Briefcase

Post by geoff 1965 »

so are you going to bond it to the outside of the case? if you cut the hole a bit smaller you could push it through from the inside and use a baffle to sandwich the rubber rim.i'm sure you'll get better resonance from the speaker with a ply baffle. it's your project so what do you think?
20190604_154424.jpg
it means you will have to remove some of that "lovely" red fur!!
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Re: Blues Briefcase

Post by JMPGuitars »

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

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

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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.
20190604_154001.jpg
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Re: Blues Briefcase

Post by JMPGuitars »

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

Post by crgfrench »

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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