Dual SoundSplinter RL-p15 D2 LLT Sub Project... (the Behemoth - Revival of old build thread)

[Sonnie Parker]

Here's the first DIY Subwoofer build I did back in 2007. With HTS on the down side I figured I might better grab my info and pics while I can... so you'll see a few of my build threads revived from that site, although it won't have all the user comments, it will have the main build info and pics that are still hosted on my own site.

My IB idea wasted away (actually Rodny took it all from me)... but I'm still wanting to play, so the next idea is a dual 15 LLT design. I believe I can follow through with this because it won't require near as much work as the IB I was planning.

Obviously there is some fun factor to this, which is probably much of the driving force behind the project, but there is also somewhat of an objective I'd like to meet at the same time.

My room is 11.5' wide x 19.5' deep x 8' high.... ~1800ft^3. If you check out my HT construction pages you'll see it is built extremely solid, tight and well sealed.

Currently I have a pair of SVS PB12-Plus/2 subs in the room, both tuned to 16Hz. Initially I had these up front in symmetrical corners, but I had always dealt with a nasty trough in my response around 30-55Hz… here’s what that looked like:

I tinkered with placement and the best I could do is one of the Plus/2's being located in the rear, behind one of my recliners. For the best response I crossover the rear sub at 60Hz and the front sub at 80Hz... and it sounds like I want it to now…

Here it is filtered:

With this one sub being located where it is... it hinders the full use of the recliner, I actually have to pull the recliner out further from the back wall than the other two recliners. At any rate... the sub just doesn't fit back there and I wanna move it back up front and have my pair of Plus/2's symmetrically located in the front corners.

To over compensate I want to build the dual RL-p15 LLT to place behind the recliners across the back wall. I know I'm crazy

... you don't have to remind me. Can I just do it... thanks! This should take care of the initial problem area I have between 30-55Hz with the dual Plus/2’s up front.

I'll use a pair of SoundSplinters:

RL-p15 D2
Qts: 0.333
Qes: 0.363
Qms: 4.032
Fs: 23.426 Hz
Re: 3.66
Ls: 5.236 mH
Lp: 7.277 mH
Rp: 10.46
Dia: 330 m
(% shift): 23.7 %
Vas: 163.0 L
Mms: 290.9 g
Cms: 158.6 u
Bl: 20.76 T*m
n0: 554.4 m
SPL: 89.43 dB
Sd: 0.0806 m^2
Xmag: 27.4 mm
Xmax: 24.6 mm

This will be paired with a Behringer EP2500 which should bring me to about 650 watts per sub at 4ohms each.

To give you an idea of my listening levels... I measured the SPL in the room from my main listening position at the level I normally listen… about 80 on my Maestro M2. Watching WOTW I was peaking at 115db at the beginning of the movie when the machine first comes out of the ground and starts blasting/frying people. I'm not sure exactly what the bass response is in those scenes, but it vibrates and shakes me pretty good… any louder and it’s just too loud. Anyway... that's just to give you an idea of how loud I listen and the levels I'd like to accomplish... or as close to it as I can get.

In speaking with Stevecallas, it appears I’ll need somewhere around 520 liters / 20ft^3 with a 9” diameter port x 33” long. Rough dimensions will be something like 12" high (excluding the downfiring space) x 16.5" deep x 72" wide/long internal measurements. I believe this is tuned to 14Hz? Although we may try to tune it lower. Stevecallas may correct me on this. The idea is to build it so that it downfires and fits behind the three rear recliners causing no issues with the recliners functioning normally.

 

[Sonnie Parker]

Here's a pic of behind the recliners and back wall where the DIY sub will be located...

 

[Sonnie Parker]

I think we have our final dimensions:

This image has been resized. Click this bar to view the full image. The original image is sized %1%2.

I believe I'll go with one solid box and seal off each enclosure.

Figuring about 30 liters per box for the drivers and the bracing, that should give us about 265-270 effective liters per box/driver, which is what I believe we were shooting for.

 

[Sonnie Parker]

Here's a little progress:

If you find anything wrong, it was Rodny's fault...

 

[Sonnie Parker]

Here's a few more shots that Rodny took tonight...

 

[Sonnie Parker]

Here she is all primed and almost ready to paint...

 

[Sonnie Parker]

I sure hope this table holds it up overnight....

More pics tomorrow after it's installed...

 

[Sonnie Parker]

Okay.... finally... it is in and works beautimously!

Here's a few final pics... it was rough getting good pics with the flash...

Sorry, I'm a po-fessional photographer.

And let me just tell ya... it is all that two grown men can do to pick this thing up off the floor even 2 inches. It is ridiculously heavy! But we managed to get it off the trailer and into the room...

With all the chairs removed....

Rodny and Walter of CKR (Montgomery, Alabama)... (UPDATE 2017 - our good friend Walter is now deceased - we sure miss him)

Rodny and me...

With the seats back in place...

Closer up behind the seats...

No doubt we accomplished the goal of providing plenty of room for the recliners to now recline without hitting the sub... worked out very well.

Rodny and Walter both will be quick to tell you... my room needs a rear sub... you just don't even want to listen without one in there. There is no doubt we accomplished the goal of fulfilling that need as well.

So both goals have been accomplished...

First thing we did was set the level of the subs... all to 75db... including the behemoth. We listened for a while just to make sure everything was working, but not too loud. Then we turned off the behemoth and played WOTW at the normal level I listen with only the SVS subs in the front playing. This produced a max SPL of 114.5db during the scenes where the machine was blasting people at the beginning of the movie. I'm not sure exactly what frequency range those blasts are, but they are loud none the less.

Then we turned on the behemoth and replayed those scenes at the same level...

Max SPL hit 122.8 at that same level on the receiver. We were all astounded at how much SPL it added at that same level. Of course I've never felt impact like that ever.... yes not ever!!! Not one sign of strain on the dual RL-p15 behemoth... it's like it was just getting warmed up. No unusual sounds and no port noise that I noticed, not even sitting on the back row... and if you sit back there during WOTW, you better have a porta-pottie beside you...

... it will lift you out of the seat. It is awesome!

I don't think it's so much the extension as it is the sheer in your face pressurized feeling you get in this small well sealed room of only 1800ft^3.

Anyway... I'm one happy little kid at x-mas...

So on to the graphs... nothing too terribly impressive here...

These are all from my main listening position.

SVS PB12-Plus/2's only (unfiltered)...

Dual SS RL-p15 Behemoth only (unfiltered)...

All subs combined and unfiltered... (without the x-over on the rear sub)...

Filtered... and yes... one set of filters (coupled) did the trick...

Personally I think it sounds great as it is now... I've fiddled with the phase a little to where it sounds better with music... and it pounds with movies. I'm just not sure it gets any better than this... words just don't do it justice.

We were able to get the dip at 70Hz pretty much out by setting the receiver x-over to 100Hz and using the CX2310 at 75Hz on the rear sub. But I didn't have the right cables... of all things. The CX does not accommodate TRS, I need XLR. Walter happened to bring a few extras, so I used those temporarily. I'll pick me up what I need and get that hooked back up so that I don't have to boost that area as much as I do without the x-over.

I want to thank everyone who helped me and/or had a suggestion from the thread, especially Stevecallas for helping me figure out all the pertinents of an LLT... and most assuredly Rodny, he put an awful lot of time an effort in this project and treated it like it was his own... and Walter at CKR for allowing us to use the shop. It is all much appreciated!!!!

Now it's time to enjoy!

 

[chrapladm]

And nice to see this build again.

 

[tesseract]

Whoa, that is some serious sub wooferage!