J15L

[DJPhatman]

A quick question: why wait until this point in the build to install the driver spacer to the baffle? Would it not have been easier to install the spacer and test-fit the driver with the baffle not installed in the cab?

If you do it's difficult to attach the horn braces to the baffle.

I was expecting the "IITP" hammer to ricochet off my head, but that makes sense to me now.

I'm really curious how much "better" the J15 is over a J12... here comes my favorite, Chris' SPL Chart widget!:

[ncgrove]

A quick question: why wait until this point in the build to install the driver spacer to the baffle? Would it not have been easier to install the spacer and test-fit the driver with the baffle not installed in the cab?

If you do it's difficult to attach the horn braces to the baffle.

I was expecting the "IITP" hammer to ricochet off my head, but that makes sense to me now.

I'm really curious how much "better" the J15 is over a J12... here comes my favorite, Chris' SPL Chart widget!:

I'm not sure, because I've never heard a J12, but I'd bet the octave and a half between 100Hz and 300Hz is pretty significant. The low end extension is a bonus too.

I prefer the sound of the DR250 over the J15. I suspect the reason is the increased sensitivity in the 90Hz-200Hz range. I have no data to confirm this, though. In any case, if you fiddle with the vertical axis on the chart, the difference between the J12 and J15 becomes more apparent:

[AntonZ]

I'm really curious how much "better" the J15 is over a J12... here comes my favorite, Chris' SPL Chart widget!:

Now I really want to build a J12L (or two). Go no further, please. I'm busy enough as it is
Anyone who has had a J12 and J15 side to side please do chime in.

[DaveK]

Anyone who has had a J12 and J15 side to side please do chime in.

Been there, done that, posted it in the Reviews area a while back. This is a very subjective area, but I preferred the tone of the J15 to the J12. YMMV.

[ncgrove]

Completely subjective, indeed. My J10 sounds like it's a whole lot easier to move around than my J15.

I pretty much finished up the dirtiest and least desirable part of the build process: Wood filling and sanding. First I sawed off the extra horn panel that's been sticking out for a while. Just used the standard circular saw and sled. I then hit the sides with a 1/8" roundover bit and got busy with the Bondo. I filled in all the staple holes, nail holes, screw holes, and anywhere the wood was dinged up. Then it was an hour or so of sanding. If you don't have an orbital sander, get one. I'd say it's a must for these boxes. Then I shot some flat black spray paint wherever I could see Bondo or PL. I'm not sure if the spray primer over Bondo and PL is necessary for good Duratex adhesion. Bill has said it's not.... Leland said might as well because it only takes a minute or two, and won't hurt. I had a can laying around, so I said might as well also. Here's what it looks like now:



I think the tiger stripes are pretty cool looking. It's kind of tempting to spray a clear coat on it and call it a day. However, I'll be a good citizen and roll on Duratex. I'm thinking it's gonna look pretty sharp.

That is two paint cans you see in the middle of the picture, holding down the foam hemisphere that I just glued in. Sometime tomorrow I'll be able to brush some Duratex over the phase plug assembly. I'm trying to get as much Duratex on inside the horn before putting in the melded array supports. It's a pain to reach down past them to paint the horn.

[ncgrove]

Got a whole lot of work done. Rolled Duratex and installed all of the goodies like handles, crossover, piezo array, polyfill, and mattress topper. Here's how it looked before driver installation:





Then I wired up the driver and jack plates and it was all ready to button up. I signed my work with red Sharpie marker, of course:



Then it was a whole lot of time with the screwdriver putting the back on nice and tight. Here's what it looks like all put together:





And there it is. The first published account of a J15L being built. I hope yall have enjoyed the thread. I'm going to give it a go at a show this evening. I'll let everyone know how it goes.

-Nathan

[DJPhatman]

Nathan, excellent build and thread. Would you also mind getting a weight of the cab, all up? Breathlessly awaiting the gig review.

[Charles Jenkinson]

Great stuff Nathan. More than slightly jealous. I see there's a diffuser to put into the array..., also I remember someone say that an undamped patch behind the driver was a no no when they ran their jack - maybe there's not much space there hey? I'm also wondering how people run their wiring to the back of the array - little plywood conduit/duct or what have you, but that's my concern. Looking forward to first impressions! Once again, well done!

[Grant Bunter]

Nathan,


Thanks for posting your build, I've enjoyed watching the progress and seeing the final result

[Tom Smit]

, also I remember someone say that an undamped patch behind the driver was a no no when they ran their jack - maybe there's not much space there hey?

I think he left a little area open directly behind the magnet so that it could have some air space. It looks like there is a small patch of cream-coloured topper in the bottom right of that particular area, mixed in with the white topper.

[Bill Fitzmaurice]

Got a whole lot of work done. Rolled Duratex and installed all of the goodies like handles, crossover, piezo array, polyfill, and mattress topper. Here's how it looked before driver installation:

Remove the foam from the ports, you don't want it in there.

[ncgrove]

Do you mean the foam pieces in front of the ports to the throat chamber? They are small scrap pieces, about 1/2" wide, so there is at least 2" of clearance between the foam and the port. Do the ports need the full 3" clearance of the duct extension to be effective?

After I posted the previous pictures, I took the cab outside to the back yard with the little Lepai amp and cranked some tunes. Holy crap! The J15 series plans should come with a warning. They aren't kiddie toys. I'm pretty sure I pissed off the whole neighborhood with a mere 10 Watts (downhill, with the wind to the Lepai's back). Wow. I can't tell if the J15L sounds any different than the regular J15. The J15 sounded good, and the J15L sounds good.

What's really good about the J15L is the "L". We played our show in the parking lot of an oilfield supply company (The Offshore Technology Conference is here in Houston right now. Lots of parties.) They happened to have an industrial scale in their warehouse, so I got to put it on the scale. Drum roll........ it came in at 37 pounds! As a reference, my amp rack weighs 34 pounds. When are the Amp Rack Lite plans coming out? Here's the picture of the rig all set up:



I thought the bass rig sounded great. I set the limiter at a little shy of 40V, and I only noticed it flickering once or twice. Everyone else in the band didn't know what in the world I was bringing in at first, and then they were all surprised that they could hear it so well. Did I mention that moving the cab around was a piece of cake? Fellow forum member Bryce was running sound and had a couple of his T48s, and a pair of DR250s running. I definitely was liking the T48 authority. I typically keep the bass EQ knob on my rig at about "3" (the above picture is from before I turned it down), so the extra bass frequency authority from the subs was nice.

In all it was a good show: Didn't have to rehearse, Didn't have to set up, Free food and beers, Got paid, Minimal take down. That's a success as far as I'm concerned!

I unloaded the Jeep this morning and hauled my gear upstairs. The J15L is DEFINITELY lighter than the standard J15. Check this out:



The coveted 2xJ15 stack! You can really see the difference between the two models. I think the J15L looks WAY cooler.

Thanks for all the kind words about the build thread. If any videos from the show get posted, I'll be sure to throw them on here.

-Nathan

[Bill Fitzmaurice]

Do you mean the foam pieces in front of the ports to the throat chamber?

I see foam near the entrances to the ports. There shouldn't be any foam actually in the ports or within an inch of the port entrances. I can't tell from the picture angle if that's the case.

[ncgrove]

Do you mean the foam pieces in front of the ports to the throat chamber?

I see foam near the entrances to the ports. There shouldn't be any foam actually in the ports or within an inch of the port entrances. I can't tell from the picture angle if that's the case.

Ahhh I see. There is not a very good perspective in the picture, so concern is warranted. The throat chambers are empty, I'm pretty sure there's sufficient clearance in on the driver side of the ports. Anyway, it's not something I'm worried about enough to open the box up and check. Thanks for the discerning eye, Bill.

[miked]

Epic build thread and fantastic finished products, Nathan! I really enjoyed watching your progress and am happy that the cab exceeded your expectations!

On a different note: As a fellow bass player, I'd love to hear my rig through that Jack Lite. After not particularly digging the sound of several commerical cabs, I built a 15/6/1 fEARful (Greenboy design from the Talkbass.com forums). I built a 3-way cab, but I leave the tweeter almost attenuated almost all the way down all the time. Should've built a 2-way cab.

Maybe one of these days I'll drive down to Houston and we can hang out.