BMD Alpha 21" Devastator Build - Page 4 - AVS Forum | Home Theater Discussions And Reviews
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post #91 of 102 Old 04-12-2020, 08:30 AM
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Originally Posted by Jk7.2 View Post
Yes. I think it might be the best and simplest option.

I’ll go make a couple test pieces. One just routed and painted, one sanded to 320 first.

Chris
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post #92 of 102 Old 04-12-2020, 06:31 PM - Thread Starter
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I remembered this weekend re: some plastics work I did ~20 years ago. We used wet-dry sand paper, and then to get rid of the frosted look, we used a polishing compound on a buffer wheel. I actually have one still on one side of my grinder wheel in the garage that I used for polishing chrome, etc. I plan to play with some of these options once I get my plastics later this week. If you are near a Harbor Freight it may be worth taking a look at trying some of these. The main thing is to use plenty of compound, which works as the abrasive part of the process. I used some Dremel bits about a year ago with a tube of compound, and was able to restore a horribly scratched up plastic display on one of my kids devices.

https://www.harborfreight.com/search?q=buffing%20wheel
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post #93 of 102 Old 04-12-2020, 06:43 PM
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BMD Alpha 21" Devastator Build

Quote:
Originally Posted by pyrobuilder View Post
I remembered this weekend re: some plastics work I did ~20 years ago. We used wet-dry sand paper, and then to get rid of the frosted look, we used a polishing compound on a buffer wheel. I actually have one still on one side of my grinder wheel in the garage that I used for polishing chrome, etc. I plan to play with some of these options once I get my plastics later this week. If you are near a Harbor Freight it may be worth taking a look at trying some of these. The main thing is to use plenty of compound, which works as the abrasive part of the process. I used some Dremel bits about a year ago with a tube of compound, and was able to restore a horribly scratched up plastic display on one of my kids devices.

https://www.harborfreight.com/search?q=buffing%20wheel

Buffing it occurred to me as well. If I had a big wheel set up, definitely the way to go.
All I’ve got is the dremel stuff though.

If it works great for you, I might amazon a wheel. Don’t feel like going to hf currently.

The 4” for a drill in the HF link looks perfect.

Chris

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post #94 of 102 Old 04-24-2020, 07:33 AM - Thread Starter
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The Lexan came in and I was finally able to finish my first Alpha this last week!

Here are a few pics installing the Lexan. I'm glad I added a window, but it shows every speck of dust, etc... But seeing the driver on this beast in action through the window is unreal!



I had to use some temporary screws to screw into the aluminum bar at the bottom of the Lexan, until I can get to the hardware store and get some short black screws to match.

Also I wasted some gasket tape, and should have drilled the pilot holes before installing the gasket tape. Doing it the other way around embedded wood shavings into the tape, which you could have picked out and been fine, but it looked really bad being behind clear Lexan. (EVERYTHING SHOWS).

Here is a pic of the final cabinet after I convinced my brother and a few other guys to help me "carry", push, kick, shove the thing upstairs. It actually moved fine on a dolly, but is SUPER heavy.



I've got a Crown XLS DriveCore 2 2502 coming that I plan to use longterm to drive it. For now I used a 1502, and bridged it worked pretty well, no clipping, and plenty loud at about halfway in my temporary space while the theater room is being built. It sounds really good, and after tweaking the MiniDSP and watching a few movies already with it I am very happy to have pulled the trigger on these. Still a lot of tuning to do, and a few touchups on some screws, install a pillow, and some Duratex spots on the top need touchup, but very happy with the outcome.
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post #95 of 102 Old 04-24-2020, 07:41 AM
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Man these do look good with the window. Very nice job. Glad you are enjoying it. Once you have the second up and running the game will change again. Unless your an extreme bass head like we all are, you’ll never drive these too hard.
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post #96 of 102 Old 05-07-2020, 06:42 PM
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Quote:
Originally Posted by Red Five View Post
Talking to Chris the BMDs could use some mid bass help. Plan old Devastators would be good for that or add a couple Minis.
@Red Five Why do you think the Alpha’s lack the slam of the other Dev’s, is it the cab or the NSW?
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post #97 of 102 Old 05-07-2020, 06:47 PM
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Originally Posted by redliner140 View Post
Why do you think the Alpha’s lack the slam of the other Dev’s, is it the cab or the NSW?
The BMDs resonator has a fundamental frequency in the mid 50s. It is dropping quickly past 80Hz. The shorter resonators are more efficient past 50Hz or so, they have a lot more output. Rooms can reduce output a lot past 50Hz. If you look at @johnson636 MLP measurements of his Minis they are less than flat at the MLP in the mid bass range. It depends a lot on the room.

This is the way...
Stormbreaker | WI HT Meet Thread | The Devastator Index | Dual Mini Devastator Build
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post #98 of 102 Old 05-07-2020, 08:07 PM
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Quote:
Originally Posted by redliner140 View Post
@Red Five Why do you think the Alpha’s lack the slam of the other Dev’s, is it the cab or the NSW?

As John stated, just a lower tune on the qw.
I can attest that the nsw is fully capable, my other driver is in a submaximus v3 and has plenty of chest slam. Just depends on enclosure design.

Chris
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post #99 of 102 Old 05-07-2020, 09:04 PM
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If you can fit a bit more than a full marty, consider adding some Finalizers instead. Will do the low end just as well as the full marty, and have the 48” Devastator qw up top.

Chris
@pyrobuilder


I just finished my Finalizer V2 DF and I can tell you that it is way better than a Full Marty [my driver is on the 2x2 side so they lay down] .... they have the same footprint....and yes I have both boxes..


Juju

Sub List: 1- Red Five Mini V1 Devastator 18" w/PA460, 1- Red Five Devastator LFE 21", 1- Red Five Devastator 21" Finalizer V2 DF , 1- BOSS platform [The Hideaway Theater], 2- 18" "Full Marty" tuned to 17Hz w/RSS460HO
Wish List: Anthology http://www.speakerdesignworks.com/Anthology_1.html


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post #100 of 102 Old 05-08-2020, 05:36 AM - Thread Starter
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@pyrobuilder


I just finished my Finalizer V2 DF and I can tell you that it is way better than a Full Marty [my driver is on the 2x2 side so they lay down] .... they have the same footprint....and yes I have both boxes..


Juju

Thanks for the feedback, I really appreciate it! I am to the point that by mid-next week I'm going to start framing out the inner shell of the theater room, but right now I'm wrapping up the layout. I think I'll adjust the false walls a bit more to accommodate some Finalizers, I was debating on something like this anyways, so might as well make sure I have room for either, and no limit myself to one or another.

As an update, I finally got my Crown 2502, and so far have loved the BMD Alpha in my family room. It shakes everything, which is a bit scary, and I don't feel I can turn it up as much as I want, for fear of destroying the house, or blowing out a window. I also don't want to push it too much until I get the MiniDSP tuned more to make sure I protect the Driver. It is a quick and dirty setting right now.
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post #101 of 102 Old 05-17-2020, 04:13 PM
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Quote:
Originally Posted by Red Five View Post
Talking to Chris the BMDs could use some mid bass help. Plan old Devastators would be good for that or add a couple Minis.
Quote:
Originally Posted by a77cj7 View Post
As John stated, just a lower tune on the qw.
I can attest that the nsw is fully capable, my other driver is in a submaximus v3 and has plenty of chest slam. Just depends on enclosure design.

Chris
@a77cj7 Which driver are you using in the v3? How’s the v3 compared to the Dev’s in output and sound signature? Looking to build something with a lot of chest slam and can get low. In addition to being a Bass Head, I’m also an audiophile, so it also needs to have good sound quality. Ported is also an option.
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post #102 of 102 Old 05-17-2020, 04:38 PM
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Quote:
Originally Posted by redliner140 View Post
@a77cj7 Which driver are you using in the v3? How’s the v3 compared to the Dev’s in output and sound signature? Looking to build something with a lot of chest slam and can get low. In addition to being a Bass Head, I’m also an audiophile, so it also needs to have good sound quality. Ported is also an option.

I’m using a nsw6021.
The v3 has more output than any of my dev’s, with slightly more low end than the Alpha. It is also far larger than the dev’s, so you could match output to occupied volume with a few 21” Devastators. If you want chest slam, the 40” or 48” Devastator designs do it well.
I prefer the sound signature to direct radiator designs.

Chris
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