Need some advice. 2 fi q 18's

**vrmarkii** · **07-27-08, 08:37 PM**

A while back I bought a q18 with the intention of building a sonotube for it. Before getting the chance to build upgradeitus struck and I ordered another one. But I dont have room for 2 sonotubes of this size. So rather than build the sonotubes I decided to build a box in the front stage area under my screen. I'm limited to around 32 cubic feet or approximately 450 liters per driver. I'd like a little feed back or suggestions on where to go with this. Would I be better off just going with my original plan or go ahead and biuld the new box for 2 drivers?
Here is a screenshot of the 2 different subs in winisd the green plot is for a 700liter sonotube tuned to 13.6hz and the grey is the 32cubic foot dual sub enclosure also tuned to 13.6hz. I'll be using an ep2500 for an amp.
Thanks in advance, Ryan

**mrogowski** · **07-28-08, 08:47 PM**

Ryan, go with your second plan. Trust me, with two drivers and room gain, you would notice little difference between that and your original build.

**Mike P.** · **07-28-08, 09:30 PM**

I agree with Mark. If a box in the front stage area better suits your needs then go for it. Low end output will not be a problem!

**SteveCallas** · **07-28-08, 11:54 PM**

If you go 450 liters per driver, I'm not so sure I would tune in the 13hz range. I'd take a look at something like 16hz. Not much point in more extension if it is rolled off. Should turn out pretty nice.

**vrmarkii** · **07-29-08, 08:18 PM**

Thanks for the replies. This is my first HT sub build. I've built them years ago for cars but didnt really get into the details. So alot of this is pretty new to me.
Will it be possible to get a flat frequency response from 5-100hz with the box tuned to 16-17hz?
Is it possible to see what my room gain will be like before building?
I've modled a few more enclosures in WinISD. 4 900 liter enclosures tuned to 14-15-16 and 17hz and one 1400 liter enclosure tuned to 13.6hz. I may be able to squeeze 2 2'x3'x4' boxes into the front stage area. But will it be worth the extra space?

Both of the 18's are dual 2ohm drivers. Whats the best way to wire these? It looks like I'm stuck with either 2 or 8 ohms bridged. Or 4 ohms x2 unless I'm missing something. Any suggestions?
Thanks again

**mrogowski** · **07-31-08, 11:34 PM**

Don't get too hung up on the curves a piece of software gives you. Remember, you are arguing over a hertz or two. The largest size edges just that much closer to infinite baffle, and on a personal note, that would be the pinnacle of low end. If you can do it, do it. If not, don't sweat it.

Regarding wiring, match the drivers to the safe output of your amp. If it is stable to 2 Ohms, do it.

Best,
Mark

**vrmarkii** · **08-01-08, 12:28 AM**

Thanks Anything I do is going to be better than the 200 watt 10 I have now. I do believe I'm in for a shock

My ep2500 came today, my other Q18 should be here monday, and I have a parts express order showing up tomarow. I still have to pick up some more mdf and the sonotube for the ports router bits etc. hopefully I'll get started this weekend. Pics to follow.

**vrmarkii** · **08-01-08, 02:04 AM**

Thought I might get some feed back on my box design. Dimentions are 25.5 tall x 36 deep x 96 long. 4 internal braces with 2 8" x 30 5/8" ports placed on the sides 2 3/4" front baffles. Roughly 40ft^3 13.6 hz.

**vrmarkii** · **08-02-08, 06:13 PM**

Here are a few more pics of my design after tweaking it alittle. If anything looks out of whack please let me know.

**Mike P.** · **08-02-08, 09:44 PM**

Looks good as far as I can tell.

**vrmarkii** · **08-05-08, 12:35 AM**

Well went out to the garage this weekend to get to work and noticed something. The widest I can cut on my table saw is 26 1/2". And I dont trust the dude at home depot so I had to do some redesigning first.

Had to shrink the box down to 25 1/2" x 26 1/2" x 96" so I'm back to what I origianally planned. With dimentions I went back to the garrage and managed to get most of my cuts made.

I'll pick up some more mdf tomarrow and start glueing it together. Anybody have a source for a cheap 1"-1 1 /2" corner round bit?

**thxgoon** · **08-06-08, 02:47 PM**

Looking good! With all of that sofware I thought you might CNC the thing

**Mike P.** · **08-06-08, 03:09 PM**

Nice looking bracing!

Quote:

Anybody have a source for a cheap 1"-1 1 /2" corner round bit?

The cheapest I've seen is here:

http://www.routermania.com/product.c...7&cookietest=1

**vrmarkii** · **08-06-08, 06:59 PM**

I would but the largest capacity machine we have at work is 20x40. Plus I think upper management might get ****** about the mdf dust in the coolant sumps.

Thanks not too bad for a jig saw and router. I started glueing stuff together but didnt get real far... Need more clamps. After I set up all the brace's in there I realized I went way overkill with the braces so the 2 port end supports arent going to be used. I'll snap a couple more pics tonight.

**Mike P.** · **08-06-08, 07:47 PM**

The plans don't look like overkill. We'll see when you post the pics.

**tenzip** · **08-07-08, 02:39 AM**

Quote:

vrmarkii wrote:

After I set up all the brace's in there I realized I went way overkill with the braces so the 2 port end supports arent going to be used. I'll snap a couple more pics tonight.

Quote:

Mike P. wrote:

The plans don't look like overkill. We'll see when you post the pics.

I think I see what you're saying, the two port end supports don't really have any structural value, just hold the end of the port tube. I'm not sure how important that might be?

Maybe having them there to provide something to use as a flare would be worth keeping them.

**vrmarkii** · **08-09-08, 03:25 PM**

What I ended up doing was moving the braces inward to eliminate the port support braces. I'm just going to use an mdf ring on either end to add more material for the port end radius. Progress has been slow to say the least. I only have 6 clamps and would rather just take my time then spend more money on harbour freight clamps. Besides UPS somehow managed to loose my other sub

. So I got an extra week or so of time to kill.
All the internal braces should be glued in today and I should be able to get the front on tomarow. Has any one had problems with cutting part of the radius into the sono tube itself? I built this so I could flush trim the holes to the sonotube ports. And If I go with a 1 1/4" radius i'll be cutting 1/2" into the sonstube.
You can kinda see what I did here with the braces. I cant find the power cord for my cammera charger so no new pics for now.

**SteveCallas** · **08-09-08, 04:06 PM**

You definitely don't want to cut into the sonotube itself. Simply add more MDF rings to create some of the port length from just MDF.

**vrmarkii** · **08-09-08, 04:36 PM**

Hmm what about going to a 3/4" Radius would that be large enough? This is what I had planned to do.

**collo** · **08-09-08, 06:52 PM**

Like Steve said, you can do your flare entirely from MDF....

Linky

**vrmarkii** · **08-13-08, 01:52 AM**

Those are pretty nice looking collo

. I took your guys advice and got off my **** and made a circle jig for my router. After making the first cut I've been kicking myself for ever touching the jigsaw. Ohwell It'll all be on the inside anyway.
So Quite a bit more progress since the last pictures. I'm just waiting on the 1 1/4" corner radius cutter. Once I get the radius on the inside of the port tubes I can put the top on, flush trim the edges, get the final front baffle on, and get it prepped.
Anyway here's the pics.

**Mike P.** · **08-13-08, 03:51 AM**

It looks well built. Definitely one of the biggest subs I've seen. I can imagine what it'll be like to move around!

**collo** · **08-13-08, 04:27 AM**

Nice job!

A bit of damping material on the faces that are furthest apart wouldn't hurt.

**SteveCallas** · **08-13-08, 07:23 PM**

Looks great

Quote:

Anything I do is going to be better than the 200 watt 10 I have now. I do believe I'm in for a shock

Yeah, I'd say so, just a little bit

**vrmarkii** · **08-13-08, 07:39 PM**

Thanks guys.
Mike its not bad to move around now. But there is still a full sheet to be added. Deffinately have to have some help to get it in to place. But hopefully I wont have to move it for a long time.
Collo I was thinking about that. Would just using r13 work? The widest unsupported section is about 18.5" where the driver cutouts are.I might add another brace behind the driver so it bolts through 1.5" of mdf, and have a 3/4" front baffle with the drivers flush mounted. Right now my plan was to just bolt them through 3/4" of material and have them flush mounted in the front baffle. I really want this cabinet to be dead solid, no noises. But I dont want to sacrafice internal volume if I dont have to.

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