Building new sub/mid box

[maxwedge]

Hi guys,
I'm gonna be building a pair of new box's to house some new speakers and could use some advice on tuning. Let me throw out what I've been thinking and see what you think.

The speakers are: 1-2242H (18") and 1-2202H (mid 12") in the same box. The target CF or the 18 I'm shooting for is 10 cu ft. It looks like I'll be tunning this to 25hz as this seems to be what JBL suggests for a sub app with this transducer. All that is perfectly understandably for me. Where I'm lost is with the 12.

My original plan was to take the 18 to 250hz-300hz and stick the 12 in a 1.75 cu ft sealed dogbox. But now as I'm learning about this new 18 (in a sub app), is that they recommend an 80hz-150hz crossover.

So what I'm wondering is should the 12 be in a ported box, now that the crossover is lower than my original plan? Or leave it sealed?

You can find the driver parameters here: http://www.jblpro.com/pub/technote/thiele.pdf

A 2380/2445 combo goes on top of this.

Thanks

[4313B]

Try to keep the 2202 sealed.

What frequency are you crossing the 2445/2380 at?

Are you going to use active filters?

[maxwedge]

Ok, sealed it is. Is 1.75 cu ft ok? Nothing is built yet and I have BB6P on the way but I figure you you guys have all the answers memorized, .

2380 at 1200hz but I can do anything. I have 3 of the latest Rane active crossovers. 1 stereo 3 way and 2-stereo 2 way's. They have 24db/octive slopes and delays to aline the drivers.

[4313B]

1.6 to 1.8 is fine. That size enclosure for a 2202H is basically an infinite baffle.

[maxwedge]

Thank's, I post some pic's as I put them together.

[Hofmannhp]

So what I'm wondering is should the 12 be in a ported box, now that the crossover is lower than my original plan? Or leave it sealed?

Hi Wedge,

you do the same project at the same time like I do..
I use the 2240H with 30Hz Fres and a 2202 in a dogybox.

At this time I'm in the mesurement phase with a B&K test set.
I tuned up the port for the 220l box and let the dogybox with about 25l sealed......why?
For my opinion the CF needs (as your idea) 250 to 300 Hz and about 1kHz for the 2395 with a 2441 driver. In this time I use for the tests a 2397 with this 2441.
The 2202, when coupled at 250 Hz doesn't need a ported chamber, cause I don't need to lift up his sub level. This part is for the 2240. Without network the 2202 is able to drive down to 90Hz, as I figured out with the test set. This may show you that its ok with a sealed dogybox.
The port for the 2240 measures W = 560mm x H = 60mm and a D = about 120mm.
This tuning gives me a box resonance frequency in the diagram of 34Hz.....and it's ok. The passive network I figured out with "Microcap" it works fine.
I will try to put some pics in the forum to show what I mean.

keep in touch....

HP

[Hofmannhp]

This tuning gives me a box resonance frequency in the diagram of 34Hz.....and it's ok. The passive network I figured out with "Microcap" it works fine.
I will try to put some pics in the forum to show what I mean.

Here's the first pic....

[Hofmannhp]

it's me again......

the small plate left of the 2202 is provided for the mounting of a 2402 hf driver.
I used the doublelayer baffle to handle the poblem with the non frontmounting posibility of the 2402. They will be mounted in the outside layer of the baffle, so I can screw the little platte off , where the 2402 is mounted.

HP

and here you see another pic with the inside stabilizers...with holes for the usage of the whole volume of the box and maximum stability.

[Hofmannhp]

it's me again......


and here you see another pic with the inside stabilizers...with holes for the usage of the whole volume of the box and maximum stability. [/B][/QUOTE]

HP

[maxwedge]

Cool , you're a little ahead of me but I hope to be cutting out the main pannels on thursday. I've spent about a 1 1/2 weeks working on drawings. I'm going to center my 12 over the 18 and use round (4"??) ports to tune it to 25hz.
I don't really need (would be nice though) an UHF driver as my 2445/2380 combo sounds preatty good.

Yeah, I didn't really think the 2202 needed a port even if crossed over at 100hz. Just wanted to be sure. I've always just followed charts for porting before, but now I want try and learn this stuff.

Scott

[maxwedge]

But christmas is over and too much $ spent! Oh well. It's hard cutting true and making mirrored pieces with a skill saw.
Broke ground (wood??) today and got the baffles and backs cut out. And , no one carries 1" stuff around here so I have to be glueing pieces together. Would have had the holes cut out if it wasn't for that.

[maxwedge]

As building progresses, I've been playing around with BB6P. I've attached a graph of 3 drivers: red=2242H, green=2202H and yellow=E-120. What bothers me is the curve for the 2202. It seems to drop off quick in the hi freq. I was going to cross it over at 1200 but by the looks of this graph it needs to be lower.


One thing though....I haven't yet figured out how I should set up the 'responce tab' under driver properties. I've been leaving it alone. Could that be part of the problem.
The dog box size is 20.5"/15.5"/9.5" closed with typ fill.

Anyone got an idea?

[maxwedge]

here it is

[4313B]

Originally posted by maxwedge
What bothers me is the curve for the 2202. It seems to drop off quick in the hi freq. I was going to cross it over at 1200 but by the looks of this graph it needs to be lower.

You might want to read about the "Graph Features", "Driver Acoustic Response", and "On-Axis Piston Band Response". It is true that the off-axis response of the 2202H starts to roll off around ~550 Hz and is ~ 3 dB down at ~ 1.2 kHz. The highest recommended crossover frequency is 1.2 kHz. You can play around with the crossover frequencies with your adjustable active filters

2202

I'll try to scan in the 2202H Product Sheet at some point and send it to Don to put in the Library.

[4313B]

Originally posted by Giskard
Try to keep the 2202 sealed.

BTW, now that you have BB6P you might want to plug in the JBL recommendation for a ported enclosure for the 2202H - 17.4" x 14.2" x 12.3" with a 4.2" diameter hole cut in a 3/4" baffle (1.5 cubic feet tuned to 80 Hz).