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Alpair 7.3eN/12pw WAW build
Alpair 7.3eN/12pw WAW build
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Old 21st February 2018, 12:39 AM   #11
planet10 is offline planet10  Canada
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Alpair 7.3eN/12pw WAW build
I should also say that the volume of the midTL is not critical, one can increase the height to of the box to do that. Minimal height was drawn to ensure minimal A12pw-A12pw centre-to-centre when a second set of bass cabinets is flipped upside down on top of what Quattrofish already has to make a tall MTM.

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Old 21st February 2018, 03:20 AM   #12
astrojet is offline astrojet
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Dave, any chance you'd be willing to post the drawing for the 7.3 midTL? No stress if not.

Quattrofish, can you share details of your pllxo? Beautiful work on your cabinets. I share your enthusiasm for the 12pw.

Thanks.
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Old 21st February 2018, 03:38 AM   #13
planet10 is offline planet10  Canada
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Alpair 7.3eN/12pw WAW build
Click the image to open in full size.

Details are in the paid planset.

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Old 21st February 2018, 01:57 PM   #14
Quattrofish is offline Quattrofish  United States
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Thanks for the kind words, all.

Quote:
Originally Posted by astrojet View Post
Dave, any chance you'd be willing to post the drawing for the 7.3 midTL? No stress if not.

Quattrofish, can you share details of your pllxo? Beautiful work on your cabinets. I share your enthusiasm for the 12pw.

Thanks.
The PLLXO consists of:
Low Pass: inline 10k resistor and 52nf shunting capacitor.
High Pass: 5.2nf inline capacitor

I was shooting for 53 and 5.3, as the impedances of my pre and power amps dictated that for a 300hz crossover, but the selection of caps I had only got me to 52. This puts the crossover a little high, but hopefully not high enough to run afoul of the 1/4 wavelength rule for acoustic centers. I'll take a look at that. Once I am certain that everything is well broken in I'll need to try some measurements and adjust from there. I just bought a mic, but sadly I have no idea how to properly measure. Time for more research!
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Old 23rd February 2018, 08:11 PM   #15
Quattrofish is offline Quattrofish  United States
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I'm not going to say that I measured properly, but I measured.

And I measured. And I shifted the speakers then measured again. And again.

My mic is properly calibrated from Cross Spectrum, but I don't have a boom mic so had to set it on a tripod on the couch. It was above the top of the rear cushions, exactly where my ear is when listening, but I realize it isn't ideal.

Anyway, the upper frequency results varied quite a bit depending on subtle tweaks. My guess is most of that is bad mic set up. The big bump at 60hz and trough at 80hz, however, were consistent. They are also quite audible, especially when playing music featuring double (stand-up) bass. Lots of resonance. I tried to test treat the nearby corner with couch cushions. It helped the 80hz trough, though not by much, and didn't touch the 60hz bump.

Any thoughts?
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Old 23rd February 2018, 08:39 PM   #16
planet10 is offline planet10  Canada
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Quote:
The big bump at 60hz and trough at 80hz,
Certainly room issues. 8 ft ceiling?

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Old 23rd February 2018, 08:59 PM   #17
Quattrofish is offline Quattrofish  United States
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Quote:
Originally Posted by planet10 View Post
Certainly room issues. 8 ft ceiling?

dave
Yup.

8'2", actually, but...yeah.

The room is 22' x 10'. I listen across the short axis. My position is about 7 feet from the side wall.

I doubt that stacked couch cushions (6' high, 1' thick) are ideal for low-frequency dampening, but I would have thought that they'd help more than they did. The lack of significant impact suggests that it isn't the corner so much as the room in general.

I'm glad I didn't go for that MTM we first discussed, with two 12pw. They would have resonated my house to pieces.

I'm also glad that I had as many hours on the 12pw as I did, because I almost blew them out of the cabinets the first time I measured. WAY too much current. No nasty noises then, or now, so I may have gotten away with it. Whew!
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Old 23rd February 2018, 09:52 PM   #18
planet10 is offline planet10  Canada
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Alpair 7.3eN/12pw WAW build
98” > 138.4 Hz > /2 = 79.2 Hz

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Old 23rd February 2018, 10:12 PM   #19
wcwc is offline wcwc  United States
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The A7/12pw combo puts the A7 about 34" off the ground. I would need to set it on a 12" high fireplace mantle. So would the 12pw work OK with a shorter enclosure (assuming the same footprint)? If it would work, I would expect less extension from the enclosure.
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Old 23rd February 2018, 10:55 PM   #20
planet10 is offline planet10  Canada
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Quote:
The A7/12pw combo puts the A7 about 34" off the ground
Without a base under the A12pw cabinet, about 32.5” (823mm). A bass easily adds 3-4”.

There is a variation of the design that trades height for despth so that they could be stand mounted:

Click the image to open in full size.

Planset subscription would inclde me doing smaller volume boxes as well. Plansets are always growing :^)

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