Alpair 12 - Damped Air Coupler box design - Page 2 - diyAudio
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Old 24th November 2009, 10:56 AM   #11
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All vented boxes by definition have to have some features in common.

For reference, MLTLs aren't strictly Martin's, although his work, and that of Augspurger, has meant they can be easily modelled (no small feat). As a cabinet type GM was building MLTLs in the late 1960s, & Olson IIRC was, as usual, first out of the starting gates back in the late '40s.
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Last edited by Scottmoose; 24th November 2009 at 10:58 AM.
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Old 24th November 2009, 12:16 PM   #12
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Tell me if I'm wrong, these are big BR boxes, as they used to do long time ago, with Vb much bigger than Vas, but tuned not really low, and to experiment with stuffing material to best fit in the particular room situation?
On the prototype pictures they look pretty simple and quite appealing...
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Old 24th November 2009, 01:31 PM   #13
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Quote:
Originally Posted by planet10 View Post
I'm working on a standmount.

dave
Well let me know.
I have a relatively compact reflex in mind so I'd like to know how your project works out..
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Old 24th November 2009, 04:01 PM   #14
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Quote:
Originally Posted by Mosquito View Post
Tell me if I'm wrong, these are big BR boxes, as they used to do long time ago, with Vb much bigger than Vas, but tuned not really low, and to experiment with stuffing material to best fit in the particular room situation?
On the prototype pictures they look pretty simple and quite appealing...
Half right from the POV of Vb swamping Vas.
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Old 24th November 2009, 04:31 PM   #15
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Quote:
Originally Posted by super-panda View Post
Well let me know.
I have a relatively compact reflex in mind so I'd like to know how your project works out..
For the size of the driver it is quite small (i would have liked a bit bigger, but that is where the curves fall)... i am working on getting everything in the box and trying to maintain some aesthetic.

And we'll need to build a proto-type to make sure it all works.

dave
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Old 24th November 2009, 04:40 PM   #16
Vix is offline Vix  Yugoslavia
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How about half-chang with these?
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Old 25th November 2009, 07:18 AM   #17
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How about enclosure like Omega? Bit wider but not deep. Could there going to be too much BSC then?

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Old 25th November 2009, 08:39 AM   #18
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Hi Guys,
Fitting the damping was easy. I had the right volume of damping material by rolling it into the rear of the cabinet - see pic 10. The low mass damping weighs 8 OZ (227 grams). Drivers connected, back screwed on.
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Old 25th November 2009, 09:01 AM   #19
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Pensil 12 - Initial listening impressions.

Well guys, all credit the Scott and Michael, I'm impressed. Prior to turning on the amp, I thought the bass might struggle with so much damping but I have to say its very nice. Bearing in mind the drivers still need another 100 hours gentle run in, we have a rich detailed bass, mids with loads of detail and highs clean and clear.

I'm currently listening to Burt Bacharach's "At This Time" album. The Pensil is delivering a nicely balanced reproduction across the range.

It's early days but its an excellent start for sure. I'm not going the rush as the I'm already impressed so I'll gradually play around with the damping and set-up in the coming weeks. I'll also be comparing the Pensil 12 to a 19 Litre BR I built earlier.

Set-up as at 25 Nov 09.
Studio is around 1000 square feet.
2 X Alpair 12 with 20 hours run time fitted in Pensil 12 Damped Air boxes.
Source is CD, Denon DCD-3000 -All Japan model on 100 V with mains convertor and power cleaner.
Amp is Sansui AU-@-907-DR - All Japan model on 100 V with mains convertor and power cleaner. Operating in Source Direct mode.
Direct feed to drivers, no filters or compensation of anykind.

Thanks

Mark
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Old 25th November 2009, 09:58 AM   #20
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Do you have pictures/dimensions of the 19 litre?
Edit: Whoa! That's the hugest 19 litre box i've ever seen! I'm assuming the box is not very deep. How did you ever get a port fitted? What is the tuning freq?

Last edited by super-panda; 25th November 2009 at 10:04 AM.
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