RL-p15 LLT Sonosubs

[Geoff St. Germain]

Well, in addition to the 3.5 cu ft ported box tuned to 24 Hz, I decided to build a couple of LLT sonosubs for the two RL-p15 drivers I bought from Mike. These guys are 260 L (9.2 cu ft) tuned to 14 Hz. I started on them about a week an a half ago and right now they're finished sitting in my living room. I'm still working on getting REW up and running so that I can do some equalization with them, but so far they are RIDICULOUS. I set up the smaller box first and it is nice and compact and does give out tremendous bass, but these things are just ridiculous. Anyway, here are some progress shots.

Here I am with the sonotube (Easy Pour). It's 20" diameter and the tube was cut to around 54". The total height of the sonosubs came out to around 5'2". The pieces for the end caps are on the ground under the tube. (The tube isn't cut to length here, it's still cut in half as it came from the supply place where it was sold in 12 ft lengths)



Here's the port beside the enclosure tube, also made from a sonotube. The port is 6" in diameter and a little over 3' long. The port ends have a 3/4" radius flare.



Here you can see the flare in the top cap.



The bottom caps are test assembled before finishing.



I lined the tubes with fiberglass insulation. It was listed as some kind of acoustic batting, but I only went with it cause it was the cheapest stuff they had and I didn't know of any difference. I was honestly surprised at how dead the interior of the tube became after getting it in there, like a black hole for sound. I separated each pad into two so that the insulation was half as thick.



Here's one of the top caps with some of the finish applied. I used a texturized truck bedliner spray.



Here's a bottom cap with the mirror being test fitted. I saw this on a couple of other sonosubs and thought it was pretty neat. I'll also be putting in some blue led lighting in the bottom at some point for effect.



I have such a ridiculous amount of this insulation that I decided to line the port even though I didn't think it was necessary.



Here's the carpet being put on. This is a marine carpet that I was able to get at a local custom auto interior shop at cost. After mentioning what it was for a subwoofer the guy was pretty interested so I think that played a part.





I'll be hoping to get some finished pictures of the subs in my room next week and hopefully an initial FR measurement once I get this software figured out. I don't think REW likes my Mac very much. I'll have to try it on my XP laptop.

[WillyD]

Sweet!

[SteveCallas]

Nice work, but I gotta ask, is it ridiculous? There might be some potential for an audible port resonance with the length being more than 36", but if you don't hear anything, nothing to worry about. If you do, trim the ports back a bit.

[Geoff St. Germain]

Ridiculous! Seriously, the sub 20 Hz bass is pretty amazing and adds a new nuance to movies (more like in the theater). I watched the new Transformers trailer on with these subs and it's a lot different than when I watched it before, that's for sure. The port resonance should be around 182 Hz for the length of the port I've used. I haven't heard anything yet, but I haven't driven them hard at all.

Anyway, I grabbed a shot of them in the room. I'm driving them with a Crown XTi2000 so I'm getting up to about 800 W to each driver.

[Geoff St. Germain]

The long extension cord spread across the room arose because apparently I have a grounding problem with the outlets on the side of the room where the subs are. I got some mean 60 Hz hum when I tried plugging the amp in on that side and running the RCA from my AVR to the Crown. Nasty stuff. I have more stuff to figure out now. I was only using the outlets for that lamp before and I know that the plug by the AVR is fine. Time to break out the receptacle tester and do all the outlets in the house now.

[WillyD]

Great job, they look good all finished up and in place.

[Bob_99]

Yes, very nice job. If I may ask, how do you cut a tube like that and get a straight cut?

Thanks.

Bob

[SteveCallas]

Geoff wrote:

I got some mean 60 Hz hum when I tried plugging the amp in on that side and running the RCA from my AVR to the Crown. Nasty stuff

My pro amps were getting 60hz hum as well, I use cheater plugs to get rid of it.

[Geoff St. Germain]

Bob_99 wrote:

Yes, very nice job. If I may ask, how do you cut a tube like that and get a straight cut?

Thanks.

Bob

That actually took a little though. What I ended up doing was measuring up from the good ends and marking at the required height. Then I taped together about 10 sheets of paper to get one long piece that I could wrap around the tube, then it was simply a matter of lining it up as well as possible and then marking. After that I used a jigsaw with a fine tooth blade and it cut really nicely. I used a drill to make the starting holes.

[Sonnie]

You did a marvelous job Geoff... I know you are enjoying those babies.

[SteveCallas]

They do look pretty sweet in that room

[Geoff St. Germain]

Sonnie wrote:

You did a marvelous job Geoff... I know you are enjoying those babies.

I am very much enjoying them.

Thanks for the kind words guys!

[Geoff St. Germain]

Ok, so I can't get REW to work with either my XP laptop or my Mac. My Mac's in/outputs aren't supported by REW it seems and the laptop has no line out and I no longer have an external sound card for it. As a result I've tried a manual FR measurement. I've included the calibration file for my Galaxy CM-140 that Sonnie has provided (thanks). Anyway, here's my first try. It's actually pretty surprising to me how loud 75 dB is and I didn't get that loud because I'm in a duplex at the moment. Anyway, here's the plot.



Now for some things I need to do. First, I want to take the measurements at higher output since the low end is difficult to measure above the background noise in the house which is in the 35 dB range. The part below 16 Hz can be ignored as what you see is simply the correction values added with a zero measurement as it wasn't measuring above the background below 16 Hz. Probably the whole measurement would benefit from a higher signal to noise ratio. I'll also be measuring up to about 150 Hz or so. The subs are crossed to the mains at 80 Hz currently. I'm thinking that the large wide dip centered at around 65 Hz may have something to do with the crossover.

Does anyone else have any suggestions for things to change for future measurements? Other suggestions in general?

[SteveCallas]

From what I have noticed, including my own testing, manually playing sine waves, recording the output, and applying corrections is more prone to error and not as precise as doing an automatic sweep with RoomEQ....and it takes a lot longer too If you could borrow a friend's soundcard or have a friend bring a computer over that has one, I think you'd be better off.

[Egil]

Very nice twins you've built there

[wig]

Man are those things sweet! I'm sure they made all the difference in the world.

[Geoff St. Germain]

I think I may have the Windows version of REQ running properly on my Mac now so hopefully I'll get some time this weekend to take some measurements.

Thanks for the compliments!