Need help planning a DIY sub.

okiepolkie

I need some help from some of you DIY’ers here on the forum(and others if you would be so kind to help).

One of the HT’s I’ve been contracted to construct needs a DIY subwoofer.

I’m attaching a few images of what I have to work with. If you need more info, just let me know.

The room is approximately 22x14x8.

The owner has suggested putting the subwoofer in the top of his component cabinet. The cabinet is approximately 4 feet wide, 2 feet deep, and 7 feet tall. I can take a picture and post it if that would help. The cabinet is made of ¾” plywood. In this location, the subwoofer would be at the back of the room facing the front stage.

The following components will be placed in the cabinet.

Rotel RSX 1056
Denon DVD1910
Belkin PF31 Line Conditioner
HD cable box
generic VCR

The other option would use an infinite baffle subwoofer using the side attic space as the enclosure. This would put the subwoofer towards the front of the.

The sub will be powered with the standard PE 240 or 250 watt plate amp.

I’m considering using one of the following drivers:

Ascend Audio Atlas 12
Adire Audio Shiva 12
Dayton DV310-8-8 12" sub

I'm leaning towards the Atlas 12, but I don't know if the 240 watt amp will be enough for it. If it is infinite baffle, I think it would be fine, but I don't know if it would work for the vented enclosure.


If I place the sub in the component rack, will it cause too many vibrations? It can be surrounded by 2-3 layers of mdf if it would help.

Please give me any suggestions and/or opinions for this setup.

okiepolkie

Pic 2

tryrrthg

If it were me I'd go IB. Get two atlas 15's. the plate amp will be plenty of power for them in an IB. Someone over at the HT forum DIY area is using two atlas 15's and only 150 watts with great results.

okiepolkie

Pic 3

okiepolkie

Pic 4

okiepolkie

Forgot to mention that the budget is only $300. I rearranged a lot of other items to get it to that point, so I don't think I can get any more.

tryrrthg

Originally posted by okiepolkie
Forgot to mention that the budget is only $300. I rearranged a lot of other items to get it to that point, so I don't think I can get any more.

Two of the IB sub drivers from parts express will help with the budget a bit. I would not put the sub up in that cabinet.

unc2701

My $0.02:

_something_ will rattle. I had to put more nails in my ceiling when I got my sub... if anything at all is loose in the cabinet, you'll regret it...

goingganzo

i mean never put a sub in a cabinet it will rattle it like no other. i say go with the ib the bass is so much better and get a sub with the xbl motor. the aa drivers are top notch and chad is a great guy to work with he has great hours and will take the time to anser any questons you have. i was getting some strange stuff trying to moddle the ava 18 and chat gave me the right anser. if i rember right my -3db opint is 14hz

Dennis Gardner

I love my dual Shiva ported box. It is basically 2 5 cubic foot boxes tuned to17hz powered by a 200 watt plate amp. It will push the drivers to bottom out at the lowest of frequencies with this amp.

If an IB is what you really want, split 4 of the acoustic elegance IB15 woofers with someone here on the forum. They are $100 when purchased in 4s. this is half off, and the best deal in IBs.

Acoustic Elegance IB15 Deal!!

ohskigod

hey dennis,


do you have plans for that sub? how did you wire the voice coils. i might be building another sub (have a shiva and an unused Dayton DVC, which has nearly identical T/S paramenters.)

Dennis Gardner

I used the EBS (Extended Bass Shelf) design that is 142 liters for each sub. This puts a 4 inch port 19 inches long to get a 17hz tuning.

You may have to contact Adire Audio to get the plans emailed to you as the old plans from their site aren't on the new one that I can see. I adjusted the plan to fit into the bottom of a hide-a-bed couch. This gives me 10 cubic foot (2-5 ft. boxes in the single enclosure)of bass box that rumbles the wifes **** as we watch movies. She actually asks girlfriends to try the couch just to see their reaction!

This wiring options are here:DVC Wiring

I use my subs @ 8 ohms with a 200 watt plate amp. They are wired in series, then I paralleled the drivers to achieve the 8 ohm nominal impedance.

okiepolkie

I think we'll go with the Atlas 12 or 15 and use it as an infinite baffle with one of the 140watt plate amps from PE. It will be on the right wall(looking from the back) at the front using the attic as the enclosure.


Should we go with the 12 or 15? I believe either one will be sufficient. If nobody votes heavily for the 15, then I'll just use the funds somewhere else in the theater.

Dennis Gardner

In all honesty, a single 15" IB will only give the output of a good 10" box sub, a 12"IB is like an 8" box, etc. Very deep bass, but very little output levels. Clean as hell, not boomy, but not very loud. It takes displacement to create much volume in an IB.

The advantage with an IB is that it takes very little power to power it, but because there is no back pressure caused by a box, it takes very little power to overpower it.

Buy the most displacement you can for your $$$.

This is a good read to explain my claims:The Cult

AsSiMiLaTeD

I didn't read all the posts, but looked at the pictures...

Don't put a sub in that cabinet...REALLY bad idea. I'm sure someone else has said it...but just in case...

okiepolkie

Okay, so if the the IB won't yield the HT impact I'm looking for, what woofer would go best with the 240 watt amp in a large, sealed enclosure? I am still going to place it outside the room with just the port and woofer going into the room.

Will the 240 amp be able to power the 15".

Dennis Gardner

The Atlas 15 in a ported box tuned to 21 or 19 hz will give the flattest response and should match well with the plate amp you are looking at.

Take a look at these graphs:Atlas 15 graphs

A box built on the other side of a wall with port and driver coming through the back of the wall will work just fine. Take a box sub and place it next to where your proposed hole will be and run some bass notes to ensure that you get good response at the seating area. A couple of feet (sometimes inches) either way can make a difference. Just set your sub against the wall and let it fly.

tryrrthg

The Atlas 15" is supposed work well in the Adire Audio reference designs for the Tempest sub. It looks like they don't have the plans available on the web site anymore. I have them on my hard drive somewhere if you want them just shoot me a PM with your email address.

The EBS design is 340 liters tuned to 15.8hz with two 4" flared vents.

The more popular design is a bit smaller at 214 liters tuned to 15.4hz with two 3" flared vents.

both are supposed to work well with the Atlas driver.

okiepolkie

The 15" driver is really calling, but I think the 12" Atlas will work better between the studs.

Does anyone have any good enclosures to go with the 12". I have at least two feet behind the wall to work with and at least two feet from the floor up(maybe more) and 14-16" between the studs.

It will still be driven with the 240 watt plate amp.

I'd like to at least be able to get to 20 Hz, but that is not the most important feature.

I don't have any modeling software yet, so I might talk to someone at Ascendant to see what they recommend for that particular location, but help here would be greatly appreciated.

okiepolkie

I went back and re-searched DIY subs and found gatemplin's picture of an
IB sub.

If this has the potential to yield good results, then I can try something similar to this, or just build my enclosure on the other side of the wall and have 5 inch deep hole to account for the wall.

With all of this, the 15" Atlas will be feasible.

I also have a good carpenter that can construct a good enclosure, so I just have to come up with the parts.

So now I'm back to going with the 15", unless someone thinks this will be a bad idea.

Dennis Gardner

You can try build the box for an IB just as he did and leave it open to add another sub when $$$ allow. The added sub will add 3db instantly and help spread out power handling.

A box will add the 3 db over the IB for a single driver for less money (wood, port and materials), but more work on your part. Here is a link to a pdf file for the Tempest that will work great for the Atlas as well.Tempest ported designs

DG

okiepolkie

After talking with Dennis over the phone, I've decided to go with a single 15" Atlas with the standard 250 watt plate amp from PE and I'm going with a 30' subwoofer cable from Bluejeans .
I ordered the amp last night and the sub today at lunch. Shipping on the sub was about $15, so everything together looks like it will be around the $300-$340 range on price after we are completely done.

I'm using the IB design with the attic above the room as the enclosure. The ceiling is black, so a small, black grille in the ceiling won't stand out.

Chad, at Ascendant, said the 250 watts are overkill for IB, but it will work well when the owner decides to get another 15 Atlas. He was really nice to talk to and apologized about the lack of info on the website. The influx of orders has been keeping him busy for a while, so he hasn't had time to follow through with some updates and additions.

Since it is going in the attic, I worried about dust and other things damaging the electronics. To remedy this, I'm going to build a frame to put over the whole setup, then place 20"x20" air filters on all sides to keep it cleaner.

I'll post pics along the way.

Thanks for all the suggestions and help.

tryrrthg

Originally posted by okiepolkie
Since it is going in the attic, I worried about dust and other things damaging the electronics. To remedy this, I'm going to build a frame to put over the whole setup, then place 20"x20" air filters on all sides to keep it cleaner.

I wouldn't do that. It will likely alter performance in some way.

okiepolkie

I was thinking of the cheapest fiberglass filter that barely stops dog hair, and restricts a minimal amount of air flow.
If there are better ways, I'm open to them. I just know the components will be exposed to the elements a little more in that type of location. I thought about grille putting grille cloth around the frame, but I didn't think it was going to be able to "filter" much out.

tryrrthg

I'd post your concern over at the Cult of the Infinitely Baffled and see what the experts have to say about it. There are a LOT of people who mount IB's in their attic and don't have any problems. I would think it would be fine without a filter of some sort. Just go up and clean it every few months.

Dennis Gardner

Attic = Car trunk. Most drivers are built for it. The plate amp might not be built for the extreme summer heat of the south though if that is in your plan. Protection from the elements is ok as long as air flow isn't changed drastically. Filters won't hurt your sound, unless they buzz in their frame.

okiepolkie

I got the amp and sub on Thursday(Fedex finally brought the sub, but not my center channel).

The amp is much heavier than I expected.

The sub is massive. If this one doesn't provide good bass, I don't know what will(as long as I set it up correctly).

Hope to be done by the weekend and I'll post pics by next week.