Need to match output of my Q-18 LLT with something else.

[epicentyr]

I am in a situation where when I moved my theater downstairs the only place that I can put my Sono sub is totally dead. I loose almost all the sound to my stairs and into another room. The only alternative that I have is to change to dual subs, 1 on each side of my center channel. The area is 30"wide 30"tall and 18" front to back for each sub. I am thinking dual 15" forward firing speaker and port. I already have the EP 2500 amp so I am just looking for a solution for the subs and boxes. Hopefully they can be tuned to around 15-16hz my llt was 14.5 and sounded great.

The Sono sub used to bow the slider doors in my living room but now all i get is amp clipping and loud bangs because I am pushing it too hard.

Please help a bass head.

[Mike P.]

The driver you choose will have to work in a box with a net volume of 7 cubic feet, as that is the space available from the measurements you posted.

[mgboy]

The Mach5 IXL-15.2.2 models quite nicely with 6-7 ft^3 tuned in the mid/upper teens, IMO. You can throw 5-700 watts into each of them easy, just have a subsonic filter. Two of those would get you roughly 115db down to 15 Hz.. if I'm thinking correctly this morning.

[epicentyr]

Those Mach5 subs sure do put function before form. Thems is uuugly.

With such short dimensions I am thinking that I will need to do a rectangular port instead of a quickrete tube port?

If I create a box with a certain volume and a port with a certain length and crossectional area... Does the shape of the box even matter? I thought the inside opening of a port needed to be at least 1 port diameter away from the nearest wall.

[epicentyr]

The Mach 5 18" looks to recommend 7cuft ported for a 19hz tune will this put out more spl than the dual 15. Dual 18's would be pretty sweet.

[Geoff St. Germain]

Assuming the 15s have the same or similar Xmax then dual 15s will produce more SPL than a single 18.

[mgboy]

The IXL-15.2..2's have a 22mm xmas, same as their bigger brother the IXL-18. I'm not sure how much more volume the IXL-18's want than the 15's but I'd rather have a lower tune with two 15's than higher tuned 18's. I like subsonics though... I'm not sure how they compare to the Q18..

[epicentyr]

What about using PRs I have never had the opportunity to work with them. Do they allow for smaller boxes compared to sealed or ported? 15" forward facing with 2PR facing left and right would look like a killer setup. Similar to Mike Cason's avatar only 1/2 height. that would allow me to have 6 drivers?

[epicentyr]

Am I running into diminishing returns when I see the AV123 15" pair for $999. Those would be great with my rocket850's and bigfoot.

[Geoff St. Germain]

There are commercial offerings that are getting into the price range of DIY options of similar output, but I think that DIY still has the advantage. It definitely has the advantage that you can custom build the enclosure to suit the space available for it. Also, when you start getting into the less budget oriented DIY solutions the cost savings becomes significant. Looking at Ilkka's tests, the 18" LMS 5400 with 2 18" PRs was the best performing subwoofer in ultra-low bass by a considerable margin. At the time that setup probably cost less than $2K. Though not available anymore, the proposed 18" from DIY Cable will probably at least be in the neighbourhood of the LMS if not exceeding it and the target price is $2K with two 18" PRs based on the same top assembly and a suitable Face Audio amplifier.

PRs allow using drivers that would require ports that would either be too big for the enclosure or so long that there would be problems with port resonances. The boxes can be smaller than the same setup in a ported design due to the fact that the PRs generally take up less volume inside the box than the port. Some of this may be offset due to additional bracing requirements as PRs generally have a lot of moving mass (up to a couple of kilograms in some cases).

[epicentyr]

What sub manufactures offer matching PRs? SoundSplinter? ♦

[Geoff St. Germain]

The only "matching" PRs that I'm aware of currently available are the Peerless 10" and 12" and the Dayton ones from PE. The DIYCable Sicko-18 will have matching PRs. I know that there are going to be 18" PRs to go with the DIYCable Maelstrom-X but I'm not sure if they will have matching cones.

[SteveCallas]

epicentyr wrote:

I am in a situation where when I moved my theater downstairs the only place that I can put my Sono sub is totally dead. I loose almost all the sound to my stairs and into another room. The only alternative that I have is to change to dual subs, 1 on each side of my center channel. The area is 30"wide 30"tall and 18" front to back for each sub. I am thinking dual 15" forward firing speaker and port. I already have the EP 2500 amp so I am just looking for a solution for the subs and boxes. Hopefully they can be tuned to around 15-16hz my llt was 14.5 and sounded great.

The Sono sub used to bow the slider doors in my living room but now all i get is amp clipping and loud bangs because I am pushing it too hard.

Please help a bass head.

Very sorry to hear that.

With those box dimensions, a couple SDX15s tuned in the 19hz range look like it would work really well - only issue I see is needing a highpass filter centered around 14hz. I'm guessing effective volume will end up around 190 liters, so I'm liking a 6" diameter port that is 26" long for each sub.

What will become of the Q18 LLT? Is there absolutely no other place you can move it to? How about behind the listening position?

[epicentyr]

Theater.pdf
I hope this worked. The sono is basically firing upstairs. I hope that the proposed location will get some room gain.

[epicentyr]

I am running into ~$1000 for this diy setup with 2- 15" drivers. Can I expect much better performance from DIY vs Dual MFW-15? I will probably end up finishing the DIY solution in April so the delay in ordering the MFWs is not an issue. WOW I just saw they pushed the ETA till July. Ouch. +1 for DIY.

[SteveCallas]

Yes, you can expect much better performance from DIY than any commercial solution for the $ spent once you break the $300 plane or so. Not a knock against AV123, but they are still a distance behind SVS in terms of subwoofer performance per dollar, and the new SVS Ultra 13 is in the same performance range of a single ported TC2k 15" for example. But, it costs twice as much. Building a second sub doesn't cost as much as the first, so if one wanted, they can get nearly twice the performance of a top notch commercial option while still saving a few $. It all depends on whether one is up to the task of building their own sub.

No way to move the Q18 LLT into that front left corner near the end of the couch?

[epicentyr]

Thanks Steve,
I was already heading down that road. I may be able to get a couple of extra ft^3 than I had originally thought by making the cabinet deeper. The LLT cannot go in that perfect front corner b/c that is the door to my master bedroom. The people who built the house in the '70s should have known that someone was going to need a place to put an enormous subwoofer That would have been a perfect location.

I am really lucky b/c i have a 48x96 $100,000 CNC cat my factory that I use for projects If anyone is local to Grand Rapids Mi I am willing to barter for time on the machine

Thanks for everyones help. I will start a new thread in a couple of weeks when I get time to work on this project. I am just finishing my bar that will house 2 stingrays in the glass top. Don't worry I'll Post pics when it is complete.