7 x RE Audio XXX 18" subs, Infinite Baffle Sub, Ultimate IB build - Page 5

Here's a pic of the baffle wall...2" laminated OSB and MDF. I didn't take any pictures of the bracing but 2x6s run straight back from doubled 2x6 wall braces, in other words perpendicular to the wall.



25% refers to width & height of the wall. For an 8'x8' wall, there would be 4 drivers, 2' up from the floor, 2' down from the ceiling and 2' from each sidewall. In a perfect world, that placement defeats width and height modes.

One 10kQ is not enough for 8 subs (even a real one, you'd still be at only 1200w per sub).
I'm telling you dude, I tried it already (not a box sim, rather in the real-world), a 10kQ is not enough power for 4 LMS's (Even a real-deal one). It IS enough power for 4 XXX in an IB. As per above.
A pair of LMS's will require a K20, FP14k, K10 or a iTech 8k (in that order, at MINIMUM). Anything less, would be less than ideal results (in the real world with realistic music, not some theoretical box sim).
You will regret it in hindsight if you don't give it the power it requires, just telling it like it is. (Will it work? Yes. Will it be all that it can be? No.)

You haven't changed my mind at all (because I have already tried that amp with that driver in a 22" sealed config) and I'm sticking to what I have already said.

Also keep in mind the 10kQ is -3db at 7hz, and the 14k is -3 at 1.8hz

That driver layout may be better than the flat line. For reasonable validation, find and download the "Room Response Calculator" or something similar. RRC only does 2 drivers but, since you setup is symmetrical, you can input just one side...one driver against the floor and the one above/beside it. The other side should yield the same response on the room centerline. Your engineer should be able to come up with a design taking advantage of the fairly stiff concrete wall...maybe use it as one flat in an I-beam with the baffle wall.

I already gave my suggestions in post #93 and in earlier posts for the LMS drivers. A 1500w amp channel will not mechanically damage a XXX in free air. I repeat you do not need a hpf, your electronics will already provide a mild one below 10Hz. IMHO content below 10Hz is not what people break drivers with anyway it is 10-25Hz where the content is usually a good 10-15dB hotter.

The LMS drivers are D2 coils so they are either a single 4 ohm or single 1 ohm load. They are not going to present a 2ohm mono load. So 4 on a 4 channel amp will provide a 4ohm mono load to each channel.

What coil config did you get for the xxx's? D4 or D2? If D2 you will end up with each driver being 4 ohm mono or 1 ohm mono. If D4 you can wire for single 2 ohm or single 8 ohm per driver.

Also the difference between 2100w per driver and 4200w per driver is 3dB at maximum and likely to be less in reality due to the last 3dB always being the most non linear both mechanically and thermally.

Ricci is right. You can have 1x16-ohm, 2x8-o, 4x4-o, 4x1-o or 2x2-o as a load. But you cannot have 4x2-o's.

Two 10kQ's could power 8 subs reasonably well. But a single would push the amp to the max, you'd be asking the power supply to provide almost 10000watts into a quad 2-ohm load.

You always need more power than what the sub is rated for, otherwise you are redlining the engine (all the time), you want it to coast along a 2000rpm not 10,000rpm

Those are peak ratings BTW, not 10,000watts RMS. The circuit breaker cannot defy physics. Most 120v-30amp breakers can do just over 3kW RMS long-term power. Divide that by 4 and multiply by 90%, and that is roughly how much RMS power per driver you get.

You will not find a more powerful amp for ~$800

That's a thing of beauty. If you don't mind my asking a scatter shot question, how is the stereo imaging on that beast? I'd expect astonishing fidelity in every respect - the only thing I see that I wonder about is the absence of a point source... or do the horns keep the sound focused? I ask because I just put away my horns for dome tweeters and I find that stereo imaging has improved, but that the sound stage also moved back a bit, and that some music sounds a bit less 'live'... but at the same time small, delicate sounds are sharper, easier to pinpoint and more ethereal.

Imaging is the best I've ever had...including other horns, domes, ribbons, ESL and dynamic planars. I chalk precise imaging up to very low diffraction.

For the LCRs alone, the "ethereal" part is not like a cone & dome system. Rather than being a point source/wide polars, they radiate more a spherical section. Because the LCRs do not fully illuminate room surfaces, spaciousness and listener envelopment is provided by (8) wide dispersion surrounds. In other words, the LCRs are crystal clear and very dynamic but "dry" without surrounds. For simple stereo I prefer wide dispersion monopoles or dipoles.

some posts should be carved in stone.

I bet the delivery guy loves you.

Man, you move quick! Glad to hear the eagles have landed.

How about giving us a pic for the ages… 4 LMS-U’s with 4 RE XXX together… Living in harmonly. That would be a site! Maybe the second most impressive thing I’ve seen recently. Right behind this of course:

They are hardcore, huh? You can see how much of a pleasure it was for me to install them in a 20 inch high crawlspace. Glad they showed up in good shape. With the way they are packaged, It would take serious effort to damage them.

This may be a bit off topic but is the overall diameter of the LMS and XXX the same. I have a hole cutout for the LMS but was wondering if I could fit the xxx just as well?

TC lists the cut-out at 16.83" and the RE XXX is listed at 17.375"

I really have to stay off this forum, after looking at the pics of the XXX 18 again I couldn't help myself and ordered one

Woah! Yeah, I've nearly gone there too but unfortunately I have this thing about drivers in multiples of two. I can't just have one!

Can't wait to see what you do with it.

I normally always order multiples as well but this is just for curiosity and to compare, if I like it then multiples will be ordered. Besides the fact that it just looks so cool I want to own one

What do you think of a 9cuft sealed enclosure for this beast? I only have that and a 4.5cuft sealed available for it right now, no time to build a new enclosure until after X-mas.

Exactly. I would get one just to look at but.... then I'd hate just looking at it after a while and want it to work for what I paid.

9cuft is a very good size but how much power do you plan to give it? 2,000w in 9cuft is perfect.

I will feed it a healthy 2000 watts and see was up!

I don't have any modeling software on this comp so I appreciate the quick expertise on power and size

I am tired of all this crap. Im gonna pull the trigger one two more soon as I finish the new LCR's. You guys stink, and really I have a thing about drivers in 4's now.


4.5 isnt enough for this guy, 9 cuft will be perfect as scott already stated. Never heard the deep bass like these guys do.

4.5cuft can work with some extra power and probably some heavy handed signal shaping. Josh Ricci is doing this right now with four dual-opposed XXX18's in his HT room.

Beast, more XXX18's eh? Ahahah! My plan worked! Sucker, erm, I mean congratulations!!

Now I must know more about these new LCR's, mister.

Right now im rocking the av123 LS6's and they sound awesome!!! I do want to use them for a dedicated 2 channel setup though, so they wont be in the theater long...I think.

New LCR's are going to be td12x's with the SEOS12 and dna-360's havent gotten anywhere on box design yet, as I want to originally try them out in the old advent boxes if I can get them to fit somehow.

If we don't push you towards more subs then we would be neglecting our duties as a true basshead brotherhood

Ive never really needed a "push" just more a nudge. Even a reminder, haha. "Oh ya! I forgot I was going to order two more 18's this week." Lol