A12.2P Super Pencil Build...... - diyAudio
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Old 4th July 2012, 03:22 AM   #1
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Default A12.2P Super Pencil Build......

As promised, here are a few pics of my new Super Pencils. These are all low rez, as Chris was worried that the brad nail holes would show. Material is 15mm Baltic Birch, with an extra 9mm added to the front baffle. There is about 10" of Ultratouch at the top of each box, and approx. 280 grams of Polyfil. This combination sounds pretty good, but there will definitely be some experimentation down the road. I have material to raise the speakers up a few inches, so that's next on the list.

So, a big thanks goes out to Chrisb for cutting all the material, which is a LOT of work, even for a fairly straight forward design. Also, for letting me help with the assembly. These boxes went together very quickly. On my own, they would have taken much more time to assemble.

Also, thanks to Dave for providing the drivers and the drawing, Scott for the box design, and of course Mark for designing and producing such a lovely driver.

jeff
Attached Images
File Type: jpg A12.2p SP open back small.jpg (166.0 KB, 1115 views)
File Type: jpg A12.2p SP back with polyfil small.jpg (87.2 KB, 670 views)
File Type: jpg A12.2p night shot small.jpg (97.3 KB, 666 views)
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Old 4th July 2012, 03:33 AM   #2
Bigun is offline Bigun  Canada
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very nice cabinetry - the joints and cutting are way better than I have achieved with my builds.
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Old 4th July 2012, 03:39 AM   #3
doorman is offline doorman  Canada
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Chris has done a few pairs!
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Old 4th July 2012, 03:46 AM   #4
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Chris has done a few pairs!
And it shows. He is also very efficient.

jeff
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Old 4th July 2012, 03:47 AM   #5
ejfud is offline ejfud  United States
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I wish I lived near Chris!

Nice job gentlemen.
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Old 4th July 2012, 05:20 AM   #6
zman01 is offline zman01  Bangladesh
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Looking great Jeff, and nice work indeed - also probably the first build of its kind!

I like the bracing too - nicely done and holding up the fluff very nicely.

Your dog is sleeping/resting peacefully in between the pair, so must have been good stuff playing?


Aside to Dave and Chris,

Choice of 15mm BB vs 18mm - extending the stiff and lighter philosophy?

- Zia
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Old 4th July 2012, 04:44 PM   #7
chrisb is offline chrisb  Canada
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Aside to Dave and Chris,

Choice of 15mm BB vs 18mm - extending the stiff and lighter philosophy?

- Zia

more a case of "we had lots on hand" - several years ago we settled on using 18mm (or sometimes more) for baffles, and 15mm for the remainder of most enclosures. It would make for an interesting experiment to build identical pairs with different thicknesses, but I just can't seem to get excited about trying that

Note that even 18mm is a bit thin for the baffles if rebating for flush mounting of the 12Ps - even allowing for minimal compression of gasket, the total "Z"=10mm, so I laminated 15+9 - much more than that and the relief of rear side of opening would need be fairly severe.
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Old 4th July 2012, 05:16 PM   #8
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Looking great! Will we get to have a listen at DIYFest?

Kyle
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Old 4th July 2012, 05:36 PM   #9
zman01 is offline zman01  Bangladesh
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Originally Posted by chrisb View Post
Note that even 18mm is a bit thin for the baffles if rebating for flush mounting of the 12Ps - even allowing for minimal compression of gasket, the total "Z"=10mm, so I laminated 15+9 - much more than that and the relief of rear side of opening would need be fairly severe.
Chris,

Do you extend the lamination all the through the length of the baffle, or pad up only the area around the driver mounting?
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Old 4th July 2012, 05:53 PM   #10
chrisb is offline chrisb  Canada
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Chris,

Do you extend the lamination all the through the length of the baffle, or pad up only the area around the driver mounting?

I've done both at different times, but in this case ran full length as it simplified both the rabbets in side panels for insetting the baffle*, as well as eliminated the need to notch the front to back holey brace - which is already a fiddly enough part to machine & fit.

*Jeff or my photos don't show the little fill blocks glued in to the rabbeted shoulder of side panels that would be otherwise exposed at the front terminus opening. Not the most elegant solution, but certainly quick
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