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First Build - BFM J12 - Check It Out!


discreet
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[quote name='JTUK' post='986348' date='Oct 12 2010, 10:24 PM']It sounds like you haven't got the right tools, frustratingly...[/quote]

Powered hand tools save time, but they're just not that accurate (at least mine aren't -- when I'm using them!) and frankly, I find them a bit scary. I'm going to use a decent handsaw for the 90-degree cuts on the next build. And I'm thinking of replacing my jigsaw with a keyhole saw or a fretsaw for the baffle/phase plug and the driver spacer, which would (in my case) increase accuracy.

Having said that, you can't avoid using a circular saw for the angled cuts, and a decent router would certainly save a mountain of time when rounding off the cab edges and corners. And I really wouldn't want to give up my electric drill. ;)

So let's keep digging those fossil fuels out of the ground and burning them to make electricity...

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Anyway, that's enough politics. :)



Final fitting of the back plate using pozi-pan machine screws, flat washers and nyloc nuts with a neoprene seal around the plate cutout.
These are Neutrik combo sockets, you can use Speakon and/or 6.3mm (1/4") jacks. Very handy! And less soldering.





Cover the rest of the cab in black vinyl... not too shabby. But quite sticky.



Now the grille... this a perforated sheet steel grille, 1.5mm thick with 4mm perforations, which I had made to size.
Would have preferred slightly larger perforations really, but there it is.



The handle. After perusing the whole top-mount/side-mount/flush-mount/surface-mount/spring handle/one handle/two handle debate,
I got bored and opted for a single large heavy-duty strap handle, top mounted. So nyahh!

According to the plans, the centre of gravity is at the baffle position... approximately :lol: The handle is large enough to allow screwing
through into the baffle itself, either side of the top port, so I did so, using long wood screws.

I'm hoping when the driver is installed, it will be just the right weight to balance everything nicely.



I bought both black plastic and chrome nickel corners, but looking at the way it's going, the chrome corners make more sense stylistically.
Seems to be a bit of a classic retro-yet-modern look emerging. Or something...



I bought some cheapo plastic feet to save myself two bob, but they were really very crappy indeed.
So I got these big premium rubber feet with integral steel washers, instead. A lesson learned.





All hail the mighty Kappalite! 400W, 8 Ohms, xmax 6.3mm.

Break in at 28Hz at 10V for 24 hours. What harm can it do? Smoke furiously and drink about four pints of tea.
Keep returning to it during this process, 'to see if it's all right'. :)

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Had to split this post up due to 'number of images' restrictions... :)



Some damping. 12mm premium carpet padding fore of the driver.
This is TREDAIR 'Seventh Heaven' if you're interested -- £8.95 per square metre. :lol:



Then 25mm acoustic foam aft, pinched from my studio walls. Fixed with vinyl spray adhesive.



Same deal with the back panel. Note clear area for driver magnet.



Now to install the driver... I'm using four pozi-pan machine screws with flat washers aft, and hex nuts with lock washers fore, through the
baffle/phase plug (where it's possible to get a socket on them), and four large pozi-pan self-tappers with lock washers screwed
into the spaces behind the throat reflectors (where it's not).

For future builds I'll fit the driver spacer to the baffle/phase plug much earlier in the build and wind some tee nuts into the
driver spacer/baffle before further assembly.

This should ensure consistent compression of the driver gasket, and get the driver more accurately centred on the spacer.

Next up... the finished item. :)

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:) [quote name='discreet' post='978542' date='Oct 5 2010, 04:37 PM']North Americans please note:

Fag = Cigarette.

Now read on.

OK plywood fans, this is my first cab build. I've done a little joinery previously some while back, in a reasonably well-equipped workshop.
The cold reality of my crappy (and broken) workmate-thing, cheap saws and pitiful collection of toy clamps and tools is not really filling me with confidence.
Just getting my excuses in early, you understand...



Made a Circular Saw Sled -- it's the law. I notice my baggy T-shirt is getting sucked into the circular saw air intake, like a hoover. Tea and a fag.
Decide to change shirt. I note the workmate-thing is too low for me (backache) and more disconcertingly, means using lethal power tools at knob-level...



Note how I cleverly cut Top and Bottom Panels at the same time, thus ensuring [i]both[/i] panels are [i]precisely[/i] the wrong size!
Decide to ignore this early setback and deal with it later. No doubt you are already snorting into your PG Tips with mirth.



Marking out the Baffle/Phase Plug. Make compasses from (mrs discreet's) measuring spoon -- with a screw in it.
I'll get a slap on the wrist for this.



After quite a lot of swearing, I got the Baffle/Phase Plug cut. Yes, I need more practice with the jigsaw.
Should have got my eight-year-old to do it instead.

Thrilling, eh? Don't miss the next exciting instalment, adrenaline junkies -- I'm going to get the glue out.[/quote]
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[quote name='larrybassman' post='988317' date='Oct 14 2010, 07:18 PM']Very funny, me and the misses couldnt stop laughing at your comments. great looking cab though. Larrybassman[/quote]

Thanks, Larry! I was testing whether the sockets were airtight (after a query on BFM forum) by blowing through them.

The current mrs discreet (now a long-suffering plywood widow) came home to find me with my lips around one of the sockets.
Wearily she said, 'You've gone too far'.



A bit of soldering, and it's on with the back panel.
I used 20mm X 5mm adhesive-backed neoprene strip on the back panel flanges in the hope this will keep everything airtight.



Back Panel fixed with woodscrews into chrome nickel cup washers.
I fervently hope never to have to take this back panel off again!

Ran a 30Hz tone through the cab at 10 volts and spent some time checking for air leaks,
feeling faintly ridiculous with a plastic tube stuck in me earhole (It's In The Plans).
And that's about it! ;)

















Stand by for comparisons and review, though inital impressions are extremely favourable, to say the least.

This build has been a fairly steep learning curve for me, but also loads of fun.
It's been great to make something cool and useful that actually exists in the real world, if that makes sense.
I'll deffo be making at least one more J12. Very addictive. Bit like heroin -- or checking your email. ;)

Cream Tolex with oxblood grille, gold hardware and brown leather handle, anyone?

Mark

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Looks very nice. I don't think you can underestimate how important a decent finish is. I've seen some cabs on websites of builders that look, frankly, awful.

If it were me, I'd have used black countersunk screws where ever I could, but whatever, the pics come across very well.

I hope it sounds as good as it looks

Well done.

Might ask you to make me one :)

What are the Dims again..?

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[quote name='JTUK' post='989135' date='Oct 15 2010, 01:00 PM']Looks very nice. I don't think you can underestimate how important a decent finish is. I've seen some cabs on websites of builders that look, frankly, awful.
If it were me, I'd have used black countersunk screws where ever I could, but whatever, the pics come across very well. I hope it sounds as good as it looks
Well done. Might ask you to make me one :) What are the Dims again..?[/quote]

Thanks! I wanted to sport the maximum of chrome and metal for the 'retro' look.

But I may make a black/yellow stealth version in the style of Schr**d*r.
Or possibly M*rkb*ss (whoever they might be). :)

It does sound good! Stand by for my review.
Cab is 22 X 18 X 18 inches.

Edit: Spelling! :lol:

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[quote name='discreet' post='989502' date='Oct 15 2010, 06:06 PM']Thanks! I wanted to sport the maximum of chrome and metal for the 'retro' look.

But I may make a black/yellow stealth version in the style of Shr**d*r.
Or possibly M*rkb*ss (whoever they might be). :)

It does sound good! Stand by for my review.
Cab is 22 X 18 X 18 inches.[/quote]


I can see the Retro angle and I agree, it works.

So, 40lbs, and the dims aren't too bad.
Can't wait to read the review.

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[quote name='Musicman20' post='988870' date='Oct 15 2010, 09:34 AM']Have you considered doing this as a mini-business?! I think you should....youve clearly got the 'knack' for it :lol:[/quote]

Thanks!

I did think about it, but given the build costs and the considerable amount of labour involved, the price may be prohibitive!

But I would certainly build to order if the price was right! :)



And thanks very much for all the other positive and encouraging comments, guys! And gals (if any)! :)

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  • 2 months later...

[size=7][font="Arial Black"][b]WOW WOW WOW - WONDERFUL - WOW WOW WOW[/b][/font][/size]

Never knew cabinet building could be such fun - what a wonderful laconic style and approach to the black art.

I'm up for building some kind of JACK cab - 2 x 110 a big 15 - still thinking about it.

One thing for certain - having read this - I WILL BUILD ONE.

This is a wonderful article - thank you

Bruce Boogie
[font="Arial Black"][url="http://www.boogiebopboys.co.uk"]BOOGIE BOP BOYS[/url]
[/font]

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  • 8 months later...

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