Alpair 7.3 bezel covers on or off? - diyAudio
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Old 24th February 2015, 10:06 AM   #1
Jpaul is offline Jpaul  United States
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Default Alpair 7.3 bezel covers on or off?

Hello all,
My Alpair 7.3 drivers arrived today, and as far as I can tell visually, they are in perfect condition. The driver run-in/break-in will begin today, in accordance with Mark's written instructions. The Pencil 7.3 build will begin soon.

The 7.3 Pencil drawing does not include details of the front baffle driver opening dimensions, but the Alpair 7.3 driver dimension drawings give all the details necessary for machining the hole in the front baffle for the driver, with or without the bezel cover. All the MA speaker enclosure drawings that I've seen have each option i.e., with and without bezel cover.

So my question is this; what is the purpose of the cover? I see that Mark recommends leaving it on, but makes no reference to it's intended purpose. Is it aesthetic or functional? Any arguments pro or con? FWIW, the driver looks pleasing to me without a cover.

TIA,
John
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Old 24th February 2015, 01:31 PM   #2
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Quote:
Originally Posted by Jpaul View Post
Hello all,
My Alpair 7.3 drivers arrived today, and as far as I can tell visually, they are in perfect condition. The driver run-in/break-in will begin today, in accordance with Mark's written instructions. The Pencil 7.3 build will begin soon.

The 7.3 Pencil drawing does not include details of the front baffle driver opening dimensions, but the Alpair 7.3 driver dimension drawings give all the details necessary for machining the hole in the front baffle for the driver, with or without the bezel cover. All the MA speaker enclosure drawings that I've seen have each option i.e., with and without bezel cover.

So my question is this; what is the purpose of the cover? I see that Mark recommends leaving it on, but makes no reference to it's intended purpose. Is it aesthetic or functional? Any arguments pro or con? FWIW, the driver looks pleasing to me without a cover.

TIA,
John
Hi John,
Its worth doing a search as there's allot of comment/advice on this topic. As the design-engineer of this driver, the adhered cover increases rigidity and chassis damping. But not everyone wants to go the extra mile, preferring to leave the cover off to make the driver easier to recess into the front baffle.

Thanks
Mark
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Old 24th February 2015, 05:23 PM   #3
Jpaul is offline Jpaul  United States
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Quote:
Originally Posted by markaudio View Post
..., the adhered cover increases rigidity and chassis damping...
Thanks
Mark
Thanks so much for responding Mark,
So the bezel covers are meant to be adhered to the driver frame before or after the drivers are screwed in place?
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Old 24th February 2015, 06:45 PM   #4
AndrewR is offline AndrewR  United Kingdom
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Glue before fitting the drivers, making sure the bezel and frame holes line up before the glue sets. Needless to say, be extremely cautious about not dripping or getting glue onto the cone/surround. At least use the cardboard piece in the box to cover the cone/surround while applying the four tiny amounts around the frame. Spread before snapping the frame in place so it doesn't randomly ooze to the cone's surround.

Andrew
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Old 24th February 2015, 08:13 PM   #5
Jpaul is offline Jpaul  United States
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Thanks Andrew, what did you use for the adhesive?
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Old 24th February 2015, 08:17 PM   #6
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2 part epoxy is the recommended glue.

We do notnormally use the bezel covers but i have done this once or twice and this glue works well. Be careful.

dave
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Old 24th February 2015, 10:12 PM   #7
Jpaul is offline Jpaul  United States
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Thanks Dave
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Old 24th February 2015, 11:14 PM   #8
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Hello Jp,
This jpeg will help you. Note the gluing positions on the front face of the Alp7 driver.

1 - Use a 2 part epoxy adhesive suitable for plastic composites (ABS). (Bostick, 3M and similar are usually available in small tubes for home repairs.

2- Find a cocktail stick or anything similar. Have it ready for mixing.

3 - Apply the A bond, then the B bond aside each other on the driver's face. Take care to keep the glue volumes the same (see pic)

4 - Using the cocktail stick, mix the 2 bonds. Keep the mixed glue toward the centre of the face (no need to spread it out).

6 - Align the cover over the face (logos at 12 noon and 6 o-clock, blue/red connectors at 3 and 9 o-clock. Eye-ball the holes for close alignment.

7 - Firmly press down and immediately slide the cover to get adjust the holes to align. (A small flat blade screw driver levered in a hole can help to get the alignment just right.

8 - Allow hardening time as per glue makers recommendations.

Have fun

Thanks
Mark

Last edited by markaudio; 24th February 2015 at 11:17 PM.
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Old 24th February 2015, 11:50 PM   #9
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Quote:
Originally Posted by markaudio View Post
3 - Apply the A bond, then the B bond aside each other on the driver's face. Take care to keep the glue volumes the same (see pic)
I mix it on a piece of scrap cardboard.I am a klutz and this helps avoid disaster.

dave
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Old 25th February 2015, 12:09 AM   #10
Jpaul is offline Jpaul  United States
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Quote:
Originally Posted by markaudio View Post
Hello Jp,
This jpeg will help you. Note the gluing positions on the front face of the Alp7 driver.

1 - Use a 2 part epoxy adhesive suitable for plastic composites (ABS). (Bostick, 3M and similar are usually available in small tubes for home repairs.

2- Find a cocktail stick or anything similar. Have it ready for mixing.

3 - Apply the A bond, then the B bond aside each other on the driver's face. Take care to keep the glue volumes the same (see pic)

4 - Using the cocktail stick, mix the 2 bonds. Keep the mixed glue toward the centre of the face (no need to spread it out).

6 - Align the cover over the face (logos at 12 noon and 6 o-clock, blue/red connectors at 3 and 9 o-clock. Eye-ball the holes for close alignment.

7 - Firmly press down and immediately slide the cover to get adjust the holes to align. (A small flat blade screw driver levered in a hole can help to get the alignment just right.

8 - Allow hardening time as per glue makers recommendations.

Have fun

Thanks
Mark
Thank you Mark for the step by step instructions...is 18mm plywood considered a thick or thin baffle
Quote:
Originally Posted by planet10 View Post
I mix it on a piece of scrap cardboard.I am a klutz and this helps avoid disaster.

dave
Thanks Dave, that made me laugh...I can already see the glue dripping on the cone with my not so steady hands.
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