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-   -   Stormbreaker a B&C 21DS115 Subwoofer Solution (https://www.avsforum.com/forum/155-diy-speakers-subs/2984850-stormbreaker-b-c-21ds115-subwoofer-solution.html)

Red Five 06-18-2018 08:34 AM

Stormbreaker a B&C 21DS115 Subwoofer Solution
 
9 Attachment(s)
A few months ago I embarked on a journey to find a subwoofer that would meet my 50% music 50% movie listening needs. A high output was another must, since the room in which it will be playing is rather large. I did some homework ran WinISD simulations and decided a B&C 21DS115 was my best option. I added an AT screen to the room, so expansion plans had to be tweaked and the Stormbreaker Cube (or more accurately the Cube XXL) was born. I chose the name of Stormbreaker since it is a dual purpose implement, hammer and axe. Stormbreaker is rather powerful, but remember, aim for the head.

New Cube version, see this link for details - https://www.avsforum.com/forum/155-d...l#post57111406

~10cuft internal volume, ~18hz tune.


https://www.avsforum.com/forum/attac...1&d=1542511583




https://www.avsforum.com/forum/attac...8&d=1542293741




https://www.avsforum.com/forum/attac...6&d=1542293741



Original cabinet, internal volume is ~11 cu ft with an ~18hz tune.


https://www.avsforum.com/forum/attac...1&d=1529509712


https://www.avsforum.com/forum/attac...1&d=1529509712


https://www.avsforum.com/forum/attac...1&d=1529509712


https://www.avsforum.com/forum/attac...1&d=1529509712


https://www.avsforum.com/forum/attac...1&d=1529509712


https://www.avsforum.com/forum/attac...1&d=1529509712


Blue - Original enclosure SPL 1m 1700 watts 2nd order high pass filter 17hz.

Red - Cube enclosure SPL 1m 1700 watts 2nd order high pass filter 17hz.

https://www.avsforum.com/forum/attac...8&d=1542293741


A big thanks goes out to @LTD02 for his design work on this project!

Red Five 06-18-2018 08:35 AM

The list of things
 
Tools:
-Drill
-Impact driver
-Circular saw
-Jigsaw
-Orbital sander
-Tape measure
-Carpenter square
-A long straight edge level is handy for a circular saw guide
-Clamps, lots of clamps (at least 2x 36" clamps and 2x 4" clamps)
-Compass of some sort
-Crimp tool for the disconnects
-50 grit black zirconium sandpaper for the orbital (it will save a lot of time on panels and bracing that do not line up perfectly)
-60 grit sanding sponge (good for sanding inside the baffle cutout edge)
-80 grit aluminum oxide sandpaper for the orbital (great for finishing up vinyl drywall putty and taking material off at a slower rate)
-Wood file
-Knife
-Putty Knife
-Scissors
-Things that are not too large and weigh a lot
-Safety glasses
-Dust mask

Parts list:
-B&C 21DS115
-Two sheets of 3/4x49x97" MDF
-3 or 4 2x4" for bracing (there are many ways of doing this) also they are used behind the baffle to make sure that 21" driver does not go anywhere
-Neutrik NL4MPR Speakon Connector 4 Pole Round Chassis Mount
-2x Neutrik NL4FX speakON SPX Series 4-Pole Cable Connector
-Gold 12-10 AWG 0.187" Female Disconnect 5 Pair (Neutrik terminal)
-1/4" (12-10) Nylon Insulated Female Disconnect Crimp Terminal Yellow 50 Pcs (for the sub terminal)
-Parts Express Speaker Gasketing Tape 1/8" x 1/2" x 50 ft. Roll
-12awg OFC speaker cable
-Acry-Tech DuraTex black 1 gallon
-number 7 2" screws
-number 9 3 1/2" screws
-3 or 4 tubes of Loctite Premium (I used the 375, but 3x is another good solution)
-Mattress foam (I used a twin from Walmart, but discovered later the same thing can be found at Meijer for have the price)
-I tried two different spray glues on the foam with poor results, just put some PL on the foam, it will not go anywhere
-Rust-Oleum 2in1 black matte spray paint for inside the port
-Vinyl drywall putty


If I find more things lying around when I cleanup my work area I will add them to the list!

Red Five 06-18-2018 08:46 AM

6 Attachment(s)
Two full sheets of MDF barely fit in a Dodge Caravan.



Unfortunately I messed up cutting the hole for the subwoofer in the baffle and it will require a take two.

SpinMonster 06-18-2018 11:58 AM

Is the cuttout for the driver off center? What was wrong with it?

Red Five 06-18-2018 12:27 PM

Quote:

Originally Posted by SpinMonster (Post 56361098)
Is the cuttout for the driver off center? What was wrong with it?


The diameter of the hole came out too large using a jigsaw and a makeshift compass. I was off enough 4 flange holes were half over of the edge of the baffle. Two of my friends that have the wood working experience looked at it and said not salvageable.



I ordered a compass that can make a 20 inch hole, that should take away some margin of error. Also a buddy said he could route it out if I made a smaller diameter rough cut first with the jigsaw. I will cut the hole at 19 inches then check the fit and go from there.

Craig S King 06-18-2018 01:44 PM

Cancel your order on the 20" compass.


Find a scrap piece of MDF that's at least 11" long. Drill 2 holes in it, one at one end. Then measure 10" to the other end, or whatever you need the baffle cutout to be, then drill a second hole. Locate the center of your baffle, I use the "X" method, and then screw the scrap piece to the center. Put a pencil through the second hole and spin the fixture around to draw a circle.


Takes 10 minutes and is essentially free.

Red Five 06-18-2018 05:19 PM

How much clearance would grill fabric need from the sub? The plan is to remove some of the toddler market appeal.



Blasting toys from the vents adds another layer to the demo experience. You can literally feel the Ninja Turtles coming at you.

Trimlock 06-18-2018 09:42 PM

Quote:

Originally Posted by Red Five (Post 56362636)
How much clearance would grill fabric need from the sub? The plan is to remove some of the toddler market appeal.



Blasting toys from the vents adds another layer to the demo experience. You can literally feel the Ninja Turtles coming at you.



Enough so the excursion doesn’t hit it.


Sent from my iPhone using Tapatalk

Samps 06-19-2018 07:12 AM

3/4 inch should be enough. That's almost 20mm.

Red Five 06-19-2018 07:32 AM

I have not worked with MDF much. How far in should these be mounted? https://www.parts-express.com/parts-...-pair--260-367

Craig S King 06-19-2018 08:32 AM

From reading the product details from PE, it says both parts need .5in deep hole. The female part needs a 9/16dia hole, and the male part needs a 7/16dia

Red Five 06-19-2018 09:12 AM

My apologies for the poor wording, how far in from the edge of the cabinet? Would running that large of a hole in the side panel be a bad idea?

mumbles60 06-19-2018 10:14 AM

Quote:

Originally Posted by Red Five (Post 56365090)
My apologies for the poor wording, how far in from the edge of the cabinet? Would running that large of a hole in the side panel be a bad idea?

Where you place them will depend on how much coverage you want from the grill... if you want the whole front covered, then they would go near the edges. Since you have doubled the front baffle, a 1/2 inch deep hole is not a concern.

Craig S King 06-19-2018 10:21 AM

Quote:

Originally Posted by mumbles60 (Post 56365464)
Where you place them will depend on how much coverage you want from the grill... if you want the whole front covered, then they would go near the edges. Since you have doubled the front baffle, a 1/2 inch deep hole is not a concern.


I agree with what he said. A .5" deep hole in a 1.5" thick baffle would be fine.


And for the actual size of the grill, personally, I would build a rectangular frame, 29"x39" and chamfer or round the outside edges for the speaker cover. I would build it out of scrap MDF. This would leave a perfect 1" reveal around the grill, but still completely cover the subwoofer. I think that would give it a very professional finish.

Red Five 06-29-2018 08:15 PM

Progress update
 
13 Attachment(s)
I finished the port assembly more sanding than I had hoped for. 3x 16th inch errors make a mess somewhere else in the cabinet. The back panel is a little long, I will have to sand that down. The baffle cutout went so well I could not be happier! A few seconds of filing the driver fit into the outside baffle sheet tightly and no gaps on the inside sheet.



I picked up this jigsaw on Amazon - https://www.amazon.com/BLACK-DECKER-...+decker+jigsaw


The variable speed control is more fine grained than I anticipated and made precise cutting a breeze. I had the curve control set at three.



I am hoping to get the bracing and baffle in this weekend :)

Red Five 07-01-2018 04:52 PM

6 Attachment(s)
Sanding took awhile today. I had to bring the front port down about 3/16th of an inch on one side and the back panel was an 1/8th of an inch too tall. The 2x4 bracing is all installed, minus the two braces that go on the top panel. The baffles are now glued together and curing. Newbie notes - PL goes fast and cab of this size goes through #7 2 in. screws at high rate. Luckily I had another large box of screws lying around from a fence project.

Trimlock 07-01-2018 05:59 PM

Nice use of 2x4’s!


Sent from my iPhone using Tapatalk

Red Five 07-01-2018 07:30 PM


eng-399 07-01-2018 09:36 PM

This might of been said but let the pl dry and then use a putty knife to scrape it off your box. That will save you a ton of time.

Red Five 07-02-2018 05:03 AM

1 Attachment(s)
I tried sanding the PL for a few moments and realized nothing was happening. I used my pocket knife at shallow angle, did a nice job of cleaning it up.

Red Five 07-07-2018 04:32 PM

6 Attachment(s)
Sanding the panels/bracing took a lot longer than I had anticipated. Making a Menards run to get more aggressive sandpaper was definitely worth it. The 80 grit is good for smoothing things off, not so good for taking off 3/16 of an inch of material. I tested the fit of the baffle which went fairly well last night and had a buddy come over today to help with mounting the baffle. Once again the fence project left me with some more screws, the baffle will not be going anywhere :). I had some spray glue lying around from a different project, but the adhesion is not that good. What specific glue usually works best for the foam?

Red Five 07-21-2018 11:16 AM

Build update
 
7 Attachment(s)
First impressions:


I ran a single point no angle measurement with my Yamaha A3070 (after much tweaking with the gains on the iNuke and the Aphex 124A). I must say I am very pleased with the results! It digs deep and effortlessly and produces the LFE better than I thought it would, since it is a pro driver. The response is quick, it does not miss anything even with double bass pedals pulsing in metal tracks!



I do not have measurement capabilities, a UMIK-1 is on the wish list. I will see if there is someone in the area that has a mic and experience with REW. A friend with a Cap1400 v2 wants to do a head to head comparison against the Stormbreaker :)

Craig S King 07-22-2018 07:58 AM

Great progress, and very well documented!



Although now I find myself tossing around the idea of a ported 21" for my music-only setup... :D

Red Five 07-22-2018 09:56 AM

I still have to make the grill for it. There are a couple things I am still thinking about. If I want to make the grill cover the vents and how that will work fastening it on the lower part of the cab. Also curious if the fasteners will hold if I put gasket tape on the back of the grill frame to reduce the chance of vibration.



My next goal is to go through my invoices and put a detailed part list in post #2 :) I needed more than one quart of Duratex to get the finish I wanted. I would suggest a gallon right away on this beast. It added six days to the project waiting for the second quart...

Red Five 07-22-2018 10:00 AM

The 21DS115 would do awesome for a music sub! Even with the lower tune YPAO had to lower the mid bass range because the sub really picks up steam. Play around with it in WinISD, probably does not require this big of a cab if tuned around 30Hz.

Red Five 07-24-2018 07:40 AM

@Last Mile brought EOT over last night. First time I was able to push the sub out of its comfort zone. The suspension will get noticeably loud when pressed. This was also the first time air could be felt leaving the port, air velocity has not been on the radar up to this point. I dropped the MV -1.5db and all was well once again. Still, not bad at all for a pro driver that also has great midbass!

Craig S King 07-24-2018 03:31 PM

Any more pictures of the 21" monster in it's resting place in your HT?

Red Five 07-24-2018 03:47 PM

I will get some more. I am debating one more coat of Duratex on the front. I flipped the sub on its face the following day after I did the Duratex and the Duratex grabbed the table on which it rested. That will get fixed but I can take a few with whoopscident!

Red Five 07-24-2018 05:38 PM

6 Attachment(s)
Pictures as requested! Off topic that power strip is great for turning on the amps.

smcmillan2 07-24-2018 05:52 PM

Quote:

Originally Posted by Red Five (Post 56539000)
Pictures as requested! Off topic that power strip is great for turning on the amps.

LOL! "Hi, my name is Bill, I discovered AVS Forum and now my subwoofer is larger than my TV."

I bet that thing pounds!


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