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8x 18" LMS 5400 Ultras Sealed to 27 Cube 15hz Ported Build

69K views 623 replies 86 participants last post by  kblackburn101 
#1 · (Edited)


This is a continuation of the discussion in this thread. There was some further discussion here as well. My current low end setup, chronicled here, consists of 8x LMS Ultra 5400s in sealed enclosures with 4x FP14000 powering them, pictured below. Kind of absurd to upgrade, but that's what this project is about. I feel the sealed enclosures I built left a lot on the table under 40hz that I can pick up by going with a vented alignment. A full build gallery is available here.

The outer dimensions of the new enclosures measure 48" long, 46" high, and 30" deep. Ports will be oriented on the sides as I will be stacking these. These dimensions were chosen mainly to fit in the current space that I have, stacked two high.

I've got two of these built, and I consider it a great success. It output as modeled, though the tuning ended up around 14.7hz, with an effective port length of about 55". I'm going to pick up some more lumber once the roads here are dry. The output from these down low is just so much greater than the sealed boxes. It would take four of them to equal one of these at 15hz. The bass from the ported boxes also feels like it has more impact. You feel it a great deal more in your chest. To make up for the lack of ULF I decided to get some Crowson transducers for my couch, which also add a great deal of tactile feel. Since this setup is on a slab, the ULF from the subs basically does nothing aside from causing my walls to flex an doors to bounce around. I can listen at lower bass levels now with more feel while having more headroom in reserve. Watching previous demo scenes and listening to various bass heavy music so far have me convinced this was the right move.

Since completing all four of these, I am incredibly happy with the results. EQ'd the same the bass is far more visceral and I have a lot more headroom where I needed it.

Bracing was accomplished with strips of left over ply from the build. Handy since it was almost all cut to size already. The boxes are painted with Duratex. Holes filled with spackle.

Sketchup file: download
Cut list: download

Original setup. The new enclosures will be stacked in the same place as the old.


Here is the project half-way through. Can't wait to finish. I can't describe how imposing these are, they still look kind of like toys in the picture, but those are 8' ceilings.


Modeled at 6200w with 13.5hz 3rd order butterworth highpass. I ended up using a 14hz 4th order filter. Very similar results.

Compared to the sealed subs with 8000w input and 11hz 3rd order filter (I have massive room gain in this area, filter prevents over excursion below 7hz). Both of these signal levels push the subs to almost identical excursion levels.



Excursion:


Port Velocity:



Enclosure:

It weighs about 400lbs with the drivers in it. This was built from maple ply, which was excessive, but the selection was poor when I went out to get the lumber for this. The second was built out of some not-so-good 6 ply soft wood sort of like arauco, but worse. It warped really bad and made my life miserable. Thankfully I have a lot of clamps. I found some nice Baltic Birch for $40/sheet that I'll be using for the last two.














Results, as modeled. Huge gains. It's hard to move these things. This was back-to-back with a sealed enclosure in the same location. No changes otherwise. This measurement was taken with a faulty mic. Apparently I shocked it one too many times or something and it was rolling off way sooner than expected. The gains are the same, but the slope is all wrong.



impedance



And in room results. There's a null at 80hz where the mic is placed. What's crazy is I still have headroom.



And full system results with XT32


3 Sweeps to determine compression... I can't measure louder with the umik1.

100db to 126db. Interesting how the walls react
Unstacked


Stacked


THD @ reference level. Mic is compressing/clipping


THD @ OMGWTF level. I think I might be am definitely reaching the ceiling of the mic's limits. I'm afraid to test louder for fear of damaging something in my house.

 
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#452 ·
I don't have any "befores"... but I should be able to remove the corner pieces from the front wall easy enough and remeasure without. (Stand by).


Here is just my mains by themselves, to give a different perspective on the effect of the absorption on the bass decay.


This was the 110db sweep I did a week ago.


Well... I think I found the bass culprit.


Looks like it could be my new mains that is adding the extra upper-bass, the Quad UM's seem to be adding lots of 60 to 80hz.

I will look at EQ'ing them downwards slightly if that is the case.


 
#453 ·
Ok here we go.


Everything kept exactly the same.


Removed all of this (~17 cubic feet):





Red without, Blue With.


With Corner Bass Traps:








Without Corner Bass Traps:



 
#456 ·
Hey not'...


I'm thinking of getting into a couple Crawsons, and powering them with the inuke 1000 DSP. Since you have the same set up I'm sure you would know.......doesn't the inuke roll off at 20hz? Is there some work around or does it not matter?
 
#457 ·

Quote:
Originally Posted by SeekingNirvana  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/400_100#post_24645116


Hey not'...


I'm thinking of getting into a couple Crawsons, and powering them with the inuke 1000 DSP. Since you have the same set up I'm sure you would know.......doesn't the inuke roll off at 20hz? Is there some work around or does it not matter?

Not noticable. Do it.
 
#458 ·
Yea I think I will do it....I get a feeling the wife is going to get me a Oppo 103D for my birthday, i'm asking for it so I can run the Crawsons off of the sub out. I haven't even finished building my dual Ultra's....and I'm already looking for more.


Did you set the gain or volume (what ever it's called, since it doesn't actually make noise) of the Crawsons and just leave it, or does it vary with the MV?


When you say it's not noticeable, is it because the 20hz feeling is so intense? Can you feel 10.....5hz?
 
#459 ·

Quote:
Originally Posted by SeekingNirvana  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/400_100#post_24645846


Yea I think I will do it....I get a feeling the wife is going to get me a Oppo 103D for my birthday, i'm asking for it so I can run the Crawsons off of the sub out. I haven't even finished building my dual Ultra's....and I'm already looking for more.


Did you set the gain or volume (what ever it's called, since it doesn't actually make noise) of the Crawsons and just leave it, or does it vary with the MV?


When you say it's not noticeable, is it because the 20hz feeling is so intense? Can you feel 10.....5hz?

You can feel all the way down to dc, it's pretty intense. If there's rolloff, I don't notice. I'm also EQ'd slightly with the dynamic EQ so there's more action at lower levels without it getting too crazy as the mv raises.
 
#461 ·

Quote:
Originally Posted by SpinMonster  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/400_100#post_24645961


Rob, was there any difference in crossover when you ported the subs other than the subsonic cross?  What is the cross freq/slope?

I cross at 80hz in multichannel mode (movies) and 90hz in 2 channel mode (music). No change. Whatever slope my receiver users...
 
#462 ·
standard slopes for receivers are 2nd order highpass (meant to be put on top of sealed speakers with natural 2nd order rolloff) for the mains and 4th order lowpass for the subs. so the net effect is 4th order acoustic crossover. reality though varies...quite a bit!
 
#463 ·
So when you say 2nd order that is 12db right? 12db per octave....and a octave is half the frequency?


So.....where ever it starts to roll off let's say 30hz.....then by the time it has dropped to 15hz it's down 12db?


1st order is 6 db per octave

2nd order is 12db

3rd order is 18

So on and so on multiples of 6?


What is the highest order? 6th=36db...
 
#464 ·

Quote:
Originally Posted by LTD02  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/450#post_24649811


standard slopes for receivers are 2nd order highpass (meant to be put on top of sealed speakers with natural 2nd order rolloff) for the mains and 4th order lowpass for the subs. so the net effect is 4th order acoustic crossover. reality though varies...quite a bit!
 

I agree but he has theater mains with big bass and is not likely rolling off at 80hz.  He could likely use 4th order electrical at 80 or 90. As it stands I doubt there is much missing in his system but the better power handing with more filtering from the mains may make for more detail in the mid-bass. JBL lists his 4722 mains as being +/- 3db down to 30hz. I'm sitting here thinking that many enthusiasts would consider his 4722's as being great quality deep bass.....haha

 

http://www.jblpro.com/www/products/cinema-market/screenarray-systems-2-way/4722_4722n#.U1tULvldWa8
 
#468 ·

Quote:
Originally Posted by SeekingNirvana  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/450#post_24649862


So when you say 2nd order that is 12db right? 12db per octave....and a octave is half the frequency?


So.....where ever it starts to roll off let's say 30hz.....then by the time it has dropped to 15hz it's down 12db?


1st order is 6 db per octave

2nd order is 12db

3rd order is 18

So on and so on multiples of 6?


What is the highest order? 6th=36db...

Thanks for clearing that up for me
 
#469 ·

Quote:
Originally Posted by SeekingNirvana  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/450#post_24645116


Hey not'...


I'm thinking of getting into a couple Crawsons, and powering them with the inuke 1000 DSP. Since you have the same set up I'm sure you would know.......doesn't the inuke roll off at 20hz? Is there some work around or does it not matter?

I'm using the 3000dsp which I think is a better match, Randall at Crowson told me that they can take up to 500 watts and are an 8 ohm load and the 3000 puts out just under 500 watts per channel in 8 ohm stereo. I've clipped the inuke many times with no harm done to the Crowson.
 
#470 ·

Quote:
Originally Posted by carp  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/400_100#post_24651286


I'm using the 3000dsp which I think is a better match, Randall at Crowson told me that they can take up to 500 watts and are an 8 ohm load and the 3000 puts out just under 500 watts per channel in 8 ohm stereo. I've clipped the inuke many times with no harm done to the Crowson.

I'm running them at 4 ohms bridged off the nu1000dsp, which translates to 500 per transducer. I run them hard. I've overheated them before testing, but haven't seen any real issues in movies.
 
#471 ·

Quote:
Originally Posted by notnyt  /t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/450#post_24651542


I'm running them at 4 ohms bridged off the nu1000dsp, which translates to 500 per transducer. I run them hard. I've overheated them before testing, but haven't seen any real issues in movies.


Duh...didn't think of that...


That would have saved me having to run another set of speaker wires (my amps are in the room next to me) when I get my 2nd Crowson...oh well.
 
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