Anyone in Sav, Ga area to help with sub box? (2 Viewers)

[Robert_J]

You're gonna make my head explode! Maybe one day I'll buy more 18s to make an IB but it's definitely not feasible right now. Hmm alright well do you know of a easy to follow build thread on a single 18 transmission line? If it offers that much more power per watt or efficiency over regular ported and sealed then I'll just get over how they look.
Thanks for the help yet again.
I guess it should be noted that I bought the older version of the FI Q, I heard it requires a bigger box than the new ones

A TL sub will be massive. If you wanted the best bang for the buck, a THT would be it - http://www.billfitzmaurice.com/THT.html They don't need much power at all to reach levels of 120db in their passband. Here's a little example -
The best example of efficiency is this autotuba video. Read the description. This is an 8" sub with under 20 watts of power going to it. The Autotuba is another BFM design.

 

[mulalleybs]

Robert J to the rescue! Well it sounds like an 18 would make the box too large to got through a door lol not to mention you have to buy the design

 

[schan1269]

The only thing I don't like about DIYsubwoofer dot org...
Granted subwoofer vs full range speaker is a tad different...
When did the laws of physics change and ported handles more power than sealed?

 

[schan1269]

Thought I'd throw this out there...
The ultimate expression of TL speaker design.
http://www.bowers-wilkins.com/Speakers/Home_Audio/Nautilus/Overview.html

 

[mulalleybs]

So Robert, could you post a build for a sealed sub using the same height as the a360. obviously depth and width will change, bout would like depth to stay close to the a360 just so I can put the dub close to it.

 

[schan1269]

Wait a minute, you are going to build a box so that you can ignore proper sub placement?

 

[mulalleybs]

Wait a minute, you are going to build a box so that you can ignore proper sub placement?

in a corner right?

 

[schan1269]

Not necessarily. In one of my HT(I have a total of 4, 3 here and 1 in the cottage in CO), the sub is 1/3 down the left wall. In another it is in the middle of the back wall.
But, you do have a slightly different desire, you want maximum bass...
I prefer linear bass. My SACD/DVD-A room, the 5 speakers and sub take precedence over everything else in there.
The 5 speakers are four Infinity Crescendo 3007 and a "cobbled together" box of bits from a broken 3006 for the center and a M&K sub.
The "center speaker" is an RTA TV stand that I enclosed the top section for the drivers. The rear panel was replaced by MDF. So essentially, the center speaker IS the TV stand.

 

[Robert_J]

There's optimum placement for a flat response, optimum placement for SPL and then there's a bunch of compromised locations because your sub won't fit in either of those places.
The corner usually provides the loudest location and it is usually the easiest for EQ for a flat response. Until you get a sub (any sub) in your room and test with proper equipment you won't know. 99% of sub owners just put it in the room, set it up to go boom and leave it.

So Robert, could you post a build for a sealed sub using the same height as the a360. obviously depth and width will change, bout would like depth to stay close to the a360 just so I can put the dub close to it.

http://www.subwoofer-builder.com/freesoft.htm Build it as big as you can while still fitting through the door. Ignore the part of the software concerning the port.

 

[Robert_J]

The only thing I don't like about DIYsubwoofer dot org...
Granted subwoofer vs full range speaker is a tad different...
When did the laws of physics change and ported handles more power than sealed?

The writer may have thought that was in the sub's passband. Either way, I pretty much ignore the power handling ratings for sub drivers. In the home theater, 99% of the time they will reach full excursion before they hit their max power rating. And it they are hitting full excursion then it's probably too loud.
My dual 15's are complete overkill. Calibrated, and at full receiver volume they are just loafing along. But at least I know they are well in their operating range and producing as little distortion as possible.

 

[mulalleybs]

There's optimum placement for a flat response, optimum placement for SPL and then there's a bunch of compromised locations because your sub won't fit in either of those places.
The corner usually provides the loudest location and it is usually the easiest for EQ for a flat response. Until you get a sub (any sub) in your room and test with proper equipment you won't know. 99% of sub owners just put it in the room, set it up to go boom and leave it.
http://www.subwoofer-builder.com/freesoft.htm Build it as big as you can while still fitting through the door. Ignore the part of the software concerning the port.

How big of a sealed box do you think would be sufficient? I have dimensions for just over 9 feet right now that I like.

 

[Robert_J]

Is that 9 CF gross or net? Did you double baffle the box in the design? You will need to because that driver will be like a jack hammer and if the mounting screws don't have enough material to bit into, they will work themselves out.
The Qts for the Q18 is .46. Not matter what size box you put it in, the Qtc of the driver/enclosure combination will never be lower than .46. The smaller the box, the higher the Qtc and you don't want it higher than .707. The sweet spot is between .500 and .707 (I lean towards .500). Based on all of that, 9cf is great if that is as big as you can go. After building it, go to Wal-Mart and buy 6 or 7 cheap pillows to stuff into the box. The sub will act as if it were in a larger enclosure.

 

[mulalleybs]

Is that 9 CF gross or net? Did you double baffle the box in the design? You will need to because that driver will be like a jack hammer and if the mounting screws don't have enough material to bit into, they will work themselves out.
The Qts for the Q18 is .46. Not matter what size box you put it in, the Qtc of the driver/enclosure combination will never be lower than .46. The smaller the box, the higher the Qtc and you don't want it higher than .707. The sweet spot is between .500 and .707 (I lean towards .500). Based on all of that, 9cf is great if that is as big as you can go. After building it, go to Wal-Mart and buy 6 or 7 cheap pillows to stuff into the box. The sub will act as if it were in a larger enclosure.

the box with what I typed in was 42x24x20 I could probably go larger I just don't know what number I should stay between (and I have no idea if that included bracing. probably not lol), but the width and depth can be made a little wider if need be. Are those numbers with the older FI Q or the newer one? I've read that the older one needs a larger enclosure than the newer thats why I ask.
Those numbers were just what I plugged into boxnotes to see what 8-9 feet could take in dimensions. its 9.36 CF internal volume, but I see no mention of bracing or anything on this. With 3/4 mdf and double front thickness.

 

[Robert_J]

I'm using the current Q T/S parameters as a guide. I don't have easy access to the older ones.
Bracing isn't included. If you go with the dowel or scrap lumber strips as braces, it won't take up more than 10%. Then the pillows will then let the driver perform as if it were back at 9.36 CF.
42x24x20 is a good size as you can use handy panels (24x48) to minimize large cuts. Or you can go to Home Depot or Lowes and have them do all of the panel cutting. That will leave it up to you to cut the hole for the driver.

 

[mulalleybs]

If thats the case I'll just do 42x24x24 and then I'll use 1x2s for bracing. Whats the best kind of glue/screws to get?

 

[Robert_J]

The proper way to make the box is glue only if you have enough clamps. Otherwise, the screws hold the box together until the clue dries. You can leave them in or as some people do, remove them and fill in the holes.
Standard wood screws 1.5" long and drill small pilot holes so the wood doesn't split. Tight-Bond II wood glue is everyone's favorite.

 

[mulalleybs]

sounds good, is there anything else I should know?

 

[Robert_J]

If you are going to cut some wood and want to stay on the cheap, use a saw board and a circular saw - http://www.popularmechanics.com/home/reviews/4283497
Other than that, it's gluing and screwing. Ask a question when you need to. I'll be checking in a few times over the weekend.
When you are ready for finishing it (paint, etc.) just come back and I'll give you may standard method.

 

[mulalleybs]

Found the specs on the v1 sub; i was kind of disappointed to find out it wasnt the v2 which is 1500 watts rms, but considering this is still better than the SSD and I got it for cheaper it's not all that big a deal.
DUAL 1 | DUAL 2
Fs: 32.4 Hz | 32.1 Hz
Re: 0.7 Ohms/coil | 1.4 Ohms/coil
Qms: 9.31 | 9.37
Qes: .48 | .48
Qts: .46 | .46
Mms: 341g | 347g
Cms: 0.73mm/N | 0.73mm/N
Sd: 1210cm^2 | 1210cm^2
Vas: 149.7 l | 149.7 l
Spl: 92.0dB 1W/1m | 91.9dB 1W/1m
Bl: 13.9 N/A | 19.65 N/A
Xmax: 28mm
Rms: 1000W
Sealed box: 4-8 cuft
Ported box: 6-10 cuft @ 28Hz
Displacement: 0.24cuft

 

[Robert_J]

Unless you live in a concrete bunker, you will never come close to using the full potential of that sub. Most houses can't handle that type of stress from a sub.