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Old 19th April 2012, 08:44 AM   #81
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Yes.

dave
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Old 20th April 2012, 12:18 AM   #82
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Originally Posted by skeeter99 View Post
Curious why there was such a drastic departure from the original?
Hoffman's Iron Law. To get more efficiency, you either get less bass, or a bigger box. A12.2p gives a bit of both to get the efficiency up. Bass not as extended means a shorter line. With a shorter line, the other dimensions need to grow to make a bigger box.

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Old 20th April 2012, 02:13 AM   #83
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Quote:
Originally Posted by planet10 View Post
Hoffman's Iron Law. To get more efficiency, you either get less bass, or a bigger box. A12.2p gives a bit of both to get the efficiency up. Bass not as extended means a shorter line. With a shorter line, the other dimensions need to grow to make a bigger box.

dave
Oh got ya. Makes sense to me.

Scott
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Old 20th April 2012, 04:43 PM   #84
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Would bambo ply or bamboo strand ply be good materials to work with for the Super Pensil?
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Old 20th April 2012, 05:06 PM   #85
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Hi Guys,
Here's the results (see jpeg) for 3 drivers selected from this first production run. We've opted to use a 2nd revised spider (more about this later). The parameters change slightly. Scott advises us both Pensil 12.2 cabs remain the same as per Dave's drawing.

I'll post more data from the production drivers soonest possible. We're also recording each driver's resonance frequency, written on the label and box.

Cheers

Mark.
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Old 20th April 2012, 05:11 PM   #86
chrisb is offline chrisb  Canada
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Would bambo ply or bamboo strand ply be good materials to work with for the Super Pensil?

absobloodylutely - but certainly not as cheap as hardwood plywood - speaking of which you might want to look into the Murphy Hardwoods Maple Multi-ply, over the past 6 months or so I've noticed a huge drop in quality of Russian sourced Baltic Birch, and have started using the Murphy - costs more, but is a gorgeous product (for now, anyway)
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Old 20th April 2012, 06:09 PM   #87
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Would bambo ply or bamboo strand ply be good materials to work with for the Super Pensil?
Do note that there are nominally 3 grades of bamboo ply. The most common is the middle grade and it is very good. The stranded variaties are better (middle grade has ~65% pf the stiffness as the top grade). The stranded also gas a much tougher surface so it is harder to damage cosmetically.

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Old 20th April 2012, 06:12 PM   #88
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Originally Posted by chrisb View Post
speaking of which you might want to look into the Murphy Hardwoods Maple Multi-ply, over the past 6 months or so I've noticed a huge drop in quality of Russian sourced Baltic Birch, and have started using the Murphy - costs more, but is a gorgeous product (for now, anyway)
We went ahead and ordered a lift of this and are changing over to it. To counter the increase in cost, it is more consistant (so far), stiffer (18mm has 15 plies as opposed to 13 in BB), and has prettier face plies.

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Old 20th April 2012, 06:17 PM   #89
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Quote:
Originally Posted by chrisb View Post
over the past 6 months or so I've noticed a huge drop in quality of Russian sourced Baltic Birch
Is the Finish BB not available here, or is it basically the same as the Russian BB?

jeff
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Old 20th April 2012, 06:20 PM   #90
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Great info Chris and Dave. Whatever I decide to do will be my first speaker build. The room I'm building these for is 8'x11' and they would be powered by a Pass F5 amplifier. My music varies across the board, but I don't necessarily need the deepest rumble of bass. Am I looking at a good match with the Super Pensil and Alpair 12p?
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