Alpair 7.3 microtower - diyAudio
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Old 25th November 2014, 09:56 AM   #1
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Default Alpair 7.3 microtower

I'm hoping for some help. This is my first delve into the world of wide range speakers so please forgive the ignorant questions. I have a couple of diy builds under my belt and want to try something different and not involving a crossover...

I like the size and attributes that are described of the CHR-70 microtower and I think they will suit my purposes well. However, I see that the Alpair 7.3 is considered superior to the CHR-70 and as such I'm really interested in knowing if anyone has built or modelled an Alpair 7.3 microtower bipole (preferably in a castle configuration).

I have seen the Alpair 7.3 HT design by 11opas (with feedback from Dave, P-10 and Scott). These look wonderful but I am after a different aesthetic which leads me to my questions. Given it is ML-TL can you change the cross section profile if you keep the height constant. I am thinking a square such as the microtower or a curved cabinet similar to the Mirage Omni 550 with either a flat or backward sloping top.

Is there a tried and tested design out there which I have been unable to dig up that I could be pointed to?

If greater minds than me are willing to present plans or advise I will build and provide a build log for everyone's enjoyment.

I'm up for the more complex woodworking challenge of curved cabinets but want to make sure the effort will be rewarded with the best possible sound!

Any help or advice would be gratefully received.

Thank you, Andrew
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Old 25th November 2014, 06:08 PM   #2
chrisb is offline chrisb  Canada
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IINM, Dave has modeled a variant of the microtower for A7.3 - I could very well even have a set of drawings somewhere in my e-mail archives - there must be 5 or 6 times as many designs as I've yet had time to build.

As the questions of adjusting enclosure dimensions, - with an MLTL, you can alter the aspect ratio of Wx D that make up the CSA, but not the line length, driver location and terminus location/dimensions.

Today seems to be great opportunity for me to chatter on about this design - I've built a total of 3 pairs now, and much prefer the Castle version with second driver mounted on top & up-firing.

If you're up for a curved enclosure such as the Omni, calculating the exact CSA might be easier than actually constructing them. I've tried a couple over the years, and CCM curves cost money (and time) - whether you use rubber ply and vacuum bagging, or KerfCore, etc
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Old 25th November 2014, 06:18 PM   #3
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Hi Chris, thanks for the feedback. You have confirmed my thinking on CSA vs length for the ML-TL. The question that follows would be the effect on changing baffle width on performance.

For example if I recreated 11opas' design in a curved design I could maintain the baffle width, volume, length and CSA fairly easily. However if I went for the traditional micro tower design with a square CSA then the baffle width will increase. Being a dipole with an up firing driver I think this will have less impact than in a single driver cabinet but will it affect room placement and performance etc...

Thanks again
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Old 25th November 2014, 06:23 PM   #4
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ps I'm planning on using a translam technique for the curved cabinet build which means a fair bit of work to design but then a CNC machine will cut all the layers creating a relatively straightforward build. It is however a fairly inefficient use of material but will provide consistent results.
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Old 25th November 2014, 06:39 PM   #5
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Quote:
Originally Posted by chrisb View Post
IINM, Dave has modeled a variant of the microtower for A7.3
Besides driver cutout details, vent is 2in diameter x 1.875in long

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Old 25th November 2014, 06:42 PM   #6
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Originally Posted by Crankyajc View Post
if I went for the traditional micro tower design with a square CSA then the baffle width will increase.
The microTower cross-section is already square.

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Old 25th November 2014, 07:05 PM   #7
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Thanks Dave, so just confirming if the port dimensions you quote above are used then the 7.3s can just drop in to the standard micro tower cabinets (driver cutouts excepted)? The plans you knocked up for 11opas were marginally taller, had a larger front firing port and a larger volume.

Sorry for the newbie questions
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Old 25th November 2014, 07:16 PM   #8
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But they did have a similar CSA
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Old 25th November 2014, 07:19 PM   #9
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Quote:
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so just confirming if the port dimensions you quote above are used then the 7.3s can just drop in to the standard micro tower cabinets (driver cutouts excepted)?
Yes. for a pair of A7.3 in microTower.

Quote:
The plans you knocked up for 11opas
You'll have to remind what that enclosure is. Link?

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Old 25th November 2014, 07:49 PM   #10
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Here it is http://www.diyaudio.com/forums/marka...-7-3-ht-3.html
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