My DIY subwoofer project

[Rudy81]

Mike, thanks for your help this evening. BTW, I modeled the AV-15X tonight and with two drivers I can see the extra SPL but only at the higher frequencies. The two drivers seem to be the same as one 18" near 20Hz and less SPL below 20. Is that what you show?

[michael hurd]

In comparison, here is a pair of Acoustic Elegance AV15X in the same 15 cubic feet net, 15 hz tuned enclosure with 1500 W PIN. The overall shape of the response will work better considering room gain. Ideally, you won't require a double baffle, although I would probably glue rings around where the driver or driver(s) mount. This will give you a bit more enclosure volume, as that large port is going to gobble it back up.

The rest of the wood that you would use for the doubled baffle can go into making braces, and an inside port flange.

[michael hurd]

Downloaded the .wdr file for the Gen II Maelstrom. It appears that the parameters are different enough, to give a bit more low end. I still would recommend the pair of 15" AE drivers over a single driver, given the same enclosure volume constraints. It also appears that the old Gen I Maelstrom file I have didn't have any entry for the Le tab... so it wouldn't have as much high end as shown on the graph.

Gen II in green, 1500w PIN.

[CECAA850]

What about 2 of the 15" version of THESE ?

[Rudy81]

What about 2 of the 15" version of THESE ?

Works for me. I'm not hung up on one brand or another. I would like the best bang for the buck in the build. I'm still trying to understand the benefits of 2 15's vs. 1 18.

[CECAA850]

What about 2 of the 15" version of THESE ?

Works for me. I'm not hung up on one brand or another. I would like the best bang for the buck in the build. I'm still trying to understand the benefits of 2 15's vs. 1 18.

LFE is about moving air. One 18" driver covers about 254 sq. in. Two 15" drivers cover about 353 sq. in. If x-max is the same. the two 15" drivers move a lot more air.

[Rudy81]

Moving air....excellent. I guess that is what Mike was trying to tell me. I will have to go back to the drawing board.

[CECAA850]

If you're starting over anyways, you might look into an opposing driver configuration. It will virtually eliminate any cabinet movement.

[Rudy81]

If you're starting over anyways, you might look into an opposing driver configuration. It will virtually eliminate any cabinet movement.

I have considered that option. However, doesn't that limit location placement of the sub so that one side with a driver is not too close to a wall or another large object, like a La Scala?

[Jay481985]

My apologies for not seeing this sooner. Try not to bend the ports at all. I remember every bend causes a 1/4 or so flow restriction. If you could try and have the ports angled, it would do so much better.

As with the dual opposing drivers, if the cabinet is built well it will be fine.

Also I noticed you want a 15 hertz tune. Is this for music or movies as honestly my subwoofer is tuned to 18 hertz and I am glad for it since I cannot really hear anything lower than 25 hertz in honest no bs assessment. Feeling is a bit different but the house starts to shake violently when i play it where i start to feel 25 hertz waves.

Also just fyi I am at an atc school of late

[Rudy81]

Jay, that's awesome! Best of luck.

I spent some time on the phone with Mike and he got me 'straightened out' on bending the port. This will be purely for LFE. I have dual RSW-15's on my mains for 2 channel listening....and it is sweet!

If need be I can tune higher.

[Jay481985]

So you are building a LLT subwoofer?

http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/1820-llt-explained.html

I suggest a sonotube design since the port can be accomodated easier than a box design.

Have you thought of infinite baffle?

[Rudy81]

It wont really qualify as an LLT but close. I started out looking at IB subs. Unfortunately the room may not lend itself to an IB. The other issue is temp control with a big hole in the ceiling.

[Jay481985]

I still suggest doing a sonotube method though

[Rudy81]

Sonotubes would end up being fairly tall, which is a limitation if I am going to place it in the front of my room. I really had hoped for the IB solution since it offers so many advantages. I then started thinking about the issues during Texas summers and the temperature differential between my media room and the attic. The build would certainly have been much easier. I had planned on 4 opposing 18" drivers.

[Jay481985]

Is the subwoofer in optimum position?I am just saying that the front of the room may not be optimum and you won't find out until after the fact and with sonotubes you can order fat stubby ones if you don't mind those.

[Jay481985]

Oh I reread this whole thread and apoligies for making you restate certain facts like me asking what this subwoofer was for movies or music. [:$]

Also there are some things to know about ports. If you make the port to the exact same size as winisd tells you, you will actually go a bit deeper than the tuning and lose some more spl. This is caused by the fact that once the air from the port is expelled from the port it still acts like it came out of the port for a little distance.

Also did you think about stuffing your subwoofer. This will make it go a bit deeper without having to increase the size of the box. Just make sure there is a path to the sub and port.

Did you factor in the room gain? I remember Dr Who gave me the formula. I suggest pming him and giving him your room dimensions and he should be able to give you a number back to put into winisd to see room gain. (When I had my subwoofer in the dorm the 1/2 space f3 was 25 hertz or so at 119 db but I remember that with room gain in my tiny room it turned into an f3 of 15 hertz or so at 125 dbAlso remember the graph is perfect for a subwoofer that has little resistance. The hotter it gets the more resistant it will have and the more likely it will not look like the graph. I forgot the name but I remember beringher had a device to basically tune the subwoofer as well, I digress that to Michael Hurd as I can't for the life of me remember the name

[Rudy81]

Jay, all good considerations. My goal is to locate the sub in the front of the room. I can move it around some, but with several large speakers, seats etc, even in a large room things get limiting. While we chat on this issue I am re-visiting a DIY SPUD option. The box design is already a given. I just need to get some possible position dimensions and see if I could work it in. That may actually be the way to go.

[Jay481985]

the spud is a great design. Do they still offer the diy model anymore?

[Rudy81]

No, they stopped making the kit. But.....