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Discussion Starter · #1 ·
I started a thread in the Subwoofer area asking for advice as to which under $500 sub(s) would give me the best performance for my basement HT (see picture for space / layout). I was advised that due to the large volume of space I need to fill (5405 cu.ft.), DIY would probably be the best option for me given my budget constraints. It was also recommended to look into an IB sub installation if possible.




The following possibilities come to mind...


1) IB sub installation using cold room (580 cu.ft. - vented to outside)

2) IB sub installation using stair cavity (154 cu.ft. - possible to open into cold room for more volume)

3) Use the PJ screen stage as a sub box (72 cu.ft.)

4) Build a custom sub for A/V rack location (sonotube?) and build A/V rack into PJ screen stage.


Please let me know what you guys think would be a good solution for this space. I was initially keen on doing an IB install but I'm now leaning towards using the PJ screen stage as a sub box (option 3) as it would probably give me the best sub placement and I won't have to cut holes in any of my walls (could be an issue later when selling the house, etc.)
 

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Just finished reading your thread in the Subwoofer section ( http://www.avsforum.com/avs-vb/showthread.php?t=1172271 ) and wanted to throw in another recommendation to try an IB if possible. Looking at your drawing it doesn't look like an IB would be the most practical but I'm still going to recommend it
If you do go IB I think you should focus on either the FiCar IB318 or AE IB15 as these drivers are reasonably priced and designed specifically for IB use with a Qts right around .707. If you can save up a bit there's a reduced price on the AE IB15's if you buy four ($500 for 4 vs $150 each so you save $100). For power the Behringer EP2500 is the budget king these days giving a true 2000W into 4 ohms bridged mono for $280 shipped.


I just finished up an IB build using 4 of the AE IB15's along with a Behringer EP2500 and I'm still just blown away by the SQ and output. I do not run a high-pass filter and haven't broken anything (yet) even playing Bass I Love You (strong 7hz tone) at insane levels. See below for what I did with $800





Also if you get serious about doing an IB you should stop by the Cult of the Infinitely Baffled and get a thread going: http://ibsubwoofers.proboards.com/in...board=projects



The first step to determine if an IB would make sense would be to measure the potential locations where the IB could be installed. There are 2 ways to do this, if the locations are near the ground you can place your current sub in that spot and take measurements at your listening positions. If the locations are not near the ground you can place your current sub at your listening position and take measurements from each potential location. If you find the FR looks nasty at all of the places you could install the IB than it's not going to work out. If the FR looks good then it may be worth looking into further.


What are you currently running as mains anyway? If they can play down to 60hz or so the side wall placement may not be too bad...
 

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The area at the foot of the stairs loaded into the cold room would make the most sense for an IB setup. A simple manifold covered with a DIY grille will get the job done. No need for a large power amp as you won't be able to use that kind of power unless your goal is burning up the voice coils.
 

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Quote:
1) IB sub installation using cold room (580 cu.ft. - vented to outside)


3) Use the PJ screen stage as a sub box (72 cu.ft.)

#1 and #3 are both doable....the only issue with the IB is that hopfully the placement by the foot of the stairs is okay for great in room response. You need to place a decent sub there to find out.


#3 I like the best even though I have an IB myself, 4 sealed subs would be great too.


btw, are you saying your budget is $500 Max?
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by lennon_68 /forum/post/17040506


The first step to determine if an IB would make sense would be to measure the potential locations where the IB could be installed. There are 2 ways to do this, if the locations are near the ground you can place your current sub in that spot and take measurements at your listening positions. If the locations are not near the ground you can place your current sub at your listening position and take measurements from each potential location. If you find the FR looks nasty at all of the places you could install the IB than it's not going to work out. If the FR looks good then it may be worth looking into further.

The existing sub I have is just a budget 8" 200W sub and it doesn't really play that low or loud hence the need for the upgrade. I'm not sure that placing this sub in the possible locations would give me a good indication of what I could expect with multiple 15" drivers installed in the same location. Also, I do not presently own any equipment able to measure the frequency response.


This whole discussion started with just a simple sub upgrade and now I'm thinking I might be getting in a little over my head with having to deal with room modes, frequency responses and equalization. Even though an IB sub would probably provide the best performance, could I get pretty decent performance out of say a couple of 15" forward facing drivers built into the PJ screen stage. It just seems like that would be a lot simpler of a build for my first HT setup. I'm not ruling out an IB sub, I would just like to know how much difference there would be SQ wise between these two options. If I could get solid bass response down to 20Hz, I think that would be good enough for my needs.

Quote:
Originally Posted by lennon_68 /forum/post/17040506


What are you currently running as mains anyway? If they can play down to 60hz or so the side wall placement may not be too bad...

I'm just running some Athena surround speakers so my mains are just front and left bookshelf speakers (play down to about 100Hz). I am planning on purchasing two towers for my mains and then move these bookshelfs to become rear surrounds at a later date to upgrade from a 5.1 to a 7.1 setup.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by penngray /forum/post/17040675


#1 and #3 are both doable....the only issue with the IB is that hopfully the placement by the foot of the stairs is okay for great in room response. You need to place a decent sub there to find out.


#3 I like the best even though I have an IB myself, 4 sealed subs would be great too.


btw, are you saying your budget is $500 Max?

I suppose I could go above $500 but then I would be thinking about either waiting a little longer on doing the sub build or making the sub build doable in several stages (ie: Stage 1 - purchase amp and one or two drivers, Stage 2 - Add more drivers). I'm also not considering building materials as part of the cost (just amp, drivers and filters if required).


How many drivers and what size do you figure I would need to make the PJ screen stage into a good sub box? If I went this route, would I completely seal the stage or port it?
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by mayhem13 /forum/post/17040569


The area at the foot of the stairs loaded into the cold room would make the most sense for an IB setup. A simple manifold covered with a DIY grille will get the job done. No need for a large power amp as you won't be able to use that kind of power unless your goal is burning up the voice coils.

Would you suggest that the manifold goes into the cold room or comes out of the cold room? Depending on the size of the drivers, coming out of the cold room could be an issue with adequate room at the bottom of the stairs. Also, should the drivers face the listening position (couch) or is it fine to have them firing 90° to the listening position?
 

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Quote:
Originally Posted by elerium /forum/post/17040746


...now I'm thinking I might be getting in a little over my head....

Not at all. There are some on here that deal with flat bass down to very low frequencies, and others that just want, as you do, to augment the sound tracks with some suitable level of bass to get a better effect. Don't fret that you can't dial everything in to the nth degree. With your budget, you want to think in terms of the most bang for the buck, and the IB approach would probably do that for you, and without needing to get into detailed cabinet construction.
 

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Quote:
Originally Posted by elerium /forum/post/17040801


I suppose I could go above $500 but then I would be thinking about either waiting a little longer on doing the sub build or making the sub build doable in several stages (ie: Stage 1 - purchase amp and one or two drivers, Stage 2 - Add more drivers). I'm also not considering building materials as part of the cost (just amp, drivers and filters if required).


How many drivers and what size do you figure I would need to make the PJ screen stage into a good sub box? If I went this route, would I completely seal the stage or port it?

if you want to keep things simple, throw 2 Exodus DPL15s in your stage, run them in parallel for a 4 ohm load and power with an EP2000


F3 about 20hz, more SPL than you'll use and close enough to budget.
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by zero the hero /forum/post/17041105


if you want to keep things simple, throw 2 Exodus DPL15s in your stage, run them in parallel for a 4 ohm load and power with an EP2000


F3 about 20hz, more SPL than you'll use and close enough to budget.

That link to the Exodus DPL15s had minimal information about how to use these drivers. If I were to go this route would I just seal the entire stage, cut a couple of holes in the front and mount these drivers or is there more to it than that? Do I need to include port holes in the stage enclosure? Should I be looking at installing baffles or structural re-enforcement inside the stage? Does the shape of the stage matter?
 

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If you want more info Kevin Haskins is the owner of that site/company and posts here often. No ports, 72 cf is basically IB. I'd make sure there are no leaks or vibrations and make sure the baffle is thick enough to support the drivers. You can plug the TS specs into any box program and get sample curves. Two of those drivers in 72cf look like this:

 

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Discussion Starter · #12 ·

Quote:
Originally Posted by zero the hero /forum/post/17041435


If you want more info Kevin Haskins is the owner of that site/company and posts here often. No ports, 72 cf is basically IB. I'd make sure there are no leaks or vibrations and make sure the baffle is thick enough to support the drivers. You can plug the TS specs into any box program and get sample curves. Two of those drivers in 72cf look like this:

Thanks for running that simulation. That response curve looks pretty great to me and I would definitely be happy with that as an end result (I know that room modes are going to mess it up though). Based on the concept of IB, I'm guessing that the more volume the better (or at least deeper) performance I can get. I could seal the columns on either side of the stage in with the stage to increase the volume (gain another 30 cu.ft.) but this would create a fairly irregular shape. Does the shape of the space matter or is just the more volume the better?


EDIT: Also, if I install two drivers on the front of the stage, should they be spaced symmetrically or not (with respect to the listening position)? I seem to recall reading somewhere that you get better performance from dual subs when they are not space symmetrically apart.
 

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more space will not significantly alter the curve - don't bother. As far as placement, that's a very complex question and really based on individual rooms. Further apart will give you a better chance at a smoother response, but there are always room modes; no getting around that. Buy a receiver with Audyssey MultEq XT someday, or go the manual route with a mic and a parametric EQ like a Behringer BFD. There are always improvements to be made - get the bass now and worry about EQ when the bug bites again.


Oh - the shape doesn't really matter. You may get some standing waves inside a large enclosure, but stuff a good amount of polyfill in the deep ends to combat that.
 

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Lots of space and a funky shaped room, so my recommendation would be multiple sub enclosures that you can move around to get the best sound at the listening position.


Maybe go to this site:

http://home.comcast.net/~jhidley/


He has a link to an Excel file showing some sub drivers he's got available. There are some 12" TC Sounds units on there. And there are also some $125 12" Peerless units as well.


Two of those and one amp would be nice and pretty easy to build.




Coming from what you have now, you might not need anything crazy to be real happy. It might be more important to get 3 cheaper sub drivers versus 1 or 2 better ones simply so you have more placement options. Like 2 enclosures up front and one behind the seating area.


Something like this maybe:

http://www.parts-express.com/pe/show...number=295-470


Or this:

http://www.parts-express.com/pe/show...number=295-560



You won't need massive power to drive 3 of those and placement issues may be more important than 1 really nice subwoofer.



Just some more options I would consider.
 

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Discussion Starter · #17 ·

Quote:
Originally Posted by mayhem13 /forum/post/17042208


Look again. That's pretty much a huge waste of 72cuft with an F3 of 43hz.

I'm not that familiar with the terminology but I'm guessing that F3 is referring to the 3db down point and that showed up at 20Hz with the Exodus DPL-15s. This seems consistent as the 3db down point with the AE IB15s is 17Hz which is a definite improvement. Please fill me in if that is not what F3 is referring to and what F3 is all about. I'm just a beginner here trying to piece it all together.
 

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Quote:
Originally Posted by elerium /forum/post/17042543


I'm not that familiar with the terminology but I'm guessing that F3 is referring to the 3db down point and that showed up at 20Hz with the Exodus DPL-15s. This seems consistent as the 3db down point with the AE IB15s is 17Hz which is a definite improvement. Please fill me in if that is not what F3 is referring to and what F3 is all about. I'm just a beginner here trying to piece it all together.

No, you're right. Mayhem must have misread the graph and I didn't even go back and look before I took the reins and ran with it
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by lennon_68 /forum/post/17042666


No, you're right. Mayhem must have misread the graph and I didn't even go back and look before I took the reins and ran with it

Thanks for running the AE IB15s through the software simulator anyway as they appear to have a bit better performance than the Exodus DPL15s. I still don't have a good sense as to how much better a true IB install would be (ie: using the cold room) compared to using the stage. Is there any chance you could run the simulator using the cold room as the sealed box so I can see the difference?


If there isn't a substantial improvement using the cold room over using the stage area, I will go with the stage area for a few reasons:


1) The subs will be firing towards the listening position which I am led to believe is better than firing at 90 deg to the listening position.


EDIT: 1b) Being able to place the subs in two different positions spaced far enough apart should also help flatten the bass response in the room. Again, I'm not 100% sure about this but it seems consistent with what I've been reading.


2) My "mains" are currently just bookshelf speakers with not much low end. These speakers will be set to small on the AVR and I expect that it would be better to have the subs in the same vicinity as these speakers for music listening. I'm not 100% sure this a valid point but it seems to make sense to me.


3) Not having to cut holes in walls is a good thing as it won't be too easy to talk the wife into letting me take the reciprocating saw to the finished walls.
 

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Quote:
Originally Posted by elerium /forum/post/17042751


Thanks for running the AE IB15s through the software simulator anyway as they appear to have a bit better performance than the Exodus DPL15s. I still don't have a good sense as to how much better a true IB install would be (ie: using the cold room) compared to using the stage. Is there any chance you could run the simulator using the cold room as the sealed box so I can see the difference?


If there isn't a substantial improvement using the cold room over using the stage area, I will go with the stage area for a few reasons:


1) The subs will be firing towards the listening position which I am led to believe is better than firing at 90 deg to the listening position.


EDIT: 1b) Being able to place the subs in two different positions spaced far enough apart should also help flatten the bass response in the room. Again, I'm not 100% sure about this but it seems consistent with what I've been reading.


2) My "mains" are currently just bookshelf speakers with not much low end. These speakers will be set to small on the AVR and I expect that it would be better to have the subs in the same vicinity as these speakers for music listening. I'm not 100% sure this a valid point but it seems to make sense to me.


3) Not having to cut holes in walls is a good thing as it won't be too easy to talk the wife into letting me take the reciprocating saw to the finished walls.

I just ran it and there's not a very large difference just comparing the FR. Also comparing the AE IB15 to the Exodus Audio DPL-15 there's not a large difference between the two. The Exodus has a bit more xmax and therefore can handle a bit more power but the AE has a bit lower extension.


Regarding your points above I completely agree with all three. Number 2 will be very important if you decide to try the crossover a bit higher than the standard 80hz. I have "tower" speakers up front - MTM's with 6.5" woofers - but prefer the sound with the crossover up higher at 120hz. If you have the sub on the side of the room that won't work but up front below the screen that would work just fine.
 
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