40th Birthday present

[Forcefed2002]

I would be eternally grateful if one of yall that's handy with the software to model this for me so I know exactly what I'm dealing with tuning wise.

Also, any input about the location of the subs to the floor & their relation to the tuning of the chamber. It's closed on 3 sides (except for the little slits I added to the feet in earlier portion of thread.

2 12JLw3v3 in common with double baffle.

All dimension ar I.D.

3/4 mdf everywhere.

4ohms drivers bridged.

Please help a newb understand And See How Far Off The 31hz Tuning May be

P.s. If I've omitted required specs just let me know

 

[Forcefed2002]

Sadly you sort of pigeon holed yourself with that box into not having any options for pointing sub/port in a different direction or moving it around the cabin. Often just repositioning the sub/box can make a more dramatic difference than small variations in volume or tuning.... that said, you could try to shrink the volume of the box a bit to test higher tuning... it would be about the easiest way.
Also you may have miscalculated port length or are getting some loading along a wall or other hard surface that's making it tune lower than you aimed for.

In an effort to narrow down the options Ive included specs in hopes I can get a definitive answer on the box tuning freq.

Also, I feel you about pigeon holing myself.

You'd think with a cargo Astro, mounting location and option would be no proplem. However, I have to have all the room in the rear. The fact that the rear of the box protrudes further than the seats is really more than I was initially wanting to give up. My only option would be to invert the box firing woofers up. And if that's what needs to happen I guess I'll cross that bridge then. But I was fond of the idea of the security from theft of downfiring...u know, at least they wouldn't be visible.

 

[hispls 5,000+ posts]

OK, If your measurements are internal I'm getting 3.9 cubic feet tuned @ 25hz.

Hate to say it but those subs model really flat in 6-7 cube tuned at 25hz but not so pretty in 4 cube.

Otherwise, if you could somehow tune it up to 35 to 37hz it isn't quite flat but should be a bit more effective for music giving you a nice boost in output between 40 and 60hz (assuming you listen to actual music played with instruments I like this a lot).

You really can't do much by way of changing position of the box/subs/port in your application so you're pretty well stuck there, though for laughs you could try moving the box around in the cabin, standing it on one end, or whatever just to see how much of a difference it can make in your overall response..... just for something to do if you're interested.

 

[Forcefed2002]

OK, If your measurements are internal I'm getting 3.9 cubic feet tuned @ 25hz.
Hate to say it but those subs model really flat in 6-7 cube tuned at 25hz but not so pretty in 4 cube.

Otherwise, if you could somehow tune it up to 35 to 37hz it isn't quite flat but should be a bit more effective for music giving you a nice boost in output between 40 and 60hz (assuming you listen to actual music played with instruments I like this a lot).

You really can't do much by way of changing position of the box/subs/port in your application so you're pretty well stuck there, though for laughs you could try moving the box around in the cabin, standing it on one end, or whatever just to see how much of a difference it can make in your overall response..... just for something to do if you're interested.

Well that makes alot of sense as to what I'm experiencing output wise. 25hz !! Smh

Obviously I made a mistake.

I too love the 35-37hz suggestion as I am a music listener in the high 30 low/mid 40 area.

Thx soo soo much hispls.

Now the million dollar question.

What do U...suggest I do to achieve that 35/37hz target?

Aside from building a new enclosure.

How do I manipulate the port to achieve your recommendation?

You're been a most valuable asset to me in this build & if you could go a step further in letting me know how to fix this id put you up for forum humanitary of the year.

 

[Forcefed2002]

I noticed hispls, you cut 7" off your port to get you into ur personal sweets pot on your recent build. (Apples/oranges)

Boomingrandpa also mentioned cutting the port down for similiar reasons. (3"inches I think)

I could cut off port length, or slide in another piece of 3/4 mdf down the existing port reducing it's height from 2 5/8 to 1 7/8.

Whatever u thinks best.

But I feel running it through the program you used earlier to model my enclosure is probably the best bet, so I shall wait patiently for the results should you decide to do so today.//content.invisioncic.com/y282845/emoticons/thankyou.gif.5451126d09e870f796f50c3a4dd5acd7.gif

Got the big 3 done today, yay.

 

[hispls 5,000+ posts]

Well that makes alot of sense as to what I'm experiencing output wise. 25hz !! SmhObviously I made a mistake.

I too love the 35-37hz suggestion as I am a music listener in the high 30 low/mid 40 area.

Thx soo soo much hispls.

Now the million dollar question.

What do U...suggest I do to achieve that 35/37hz target?

Aside from building a new enclosure.

How do I manipulate the port to achieve your recommendation?

You're been a most valuable asset to me in this build & if you could go a step further in letting me know how to fix this id put you up for forum humanitary of the year.

The closest thing I can think of to being somewhat neat looking would be to cover up the side the port is on and throw a round port into it. Otherwise carving length off a slot port will be ugly and/or at the very least very tricky.

 

[Forcefed2002]

The closest thing I can think of to being somewhat neat looking would be to cover up the side the port is on and throw a round port into it. Otherwise carving length off a slot port will be ugly and/or at the very least very tricky.

Couldn't I just cut some of the 26.75" port board off from inside the box & no one would be the wiser?

Your round port idea is neat, but if I could just shorten the port internally I feel it would be the easiest (hopefully as effective ) method of achieving my goal.

If this is true, I simply need to know how much of that 26.75 to cut off to reach 35-37hz tuning.

I understand that will also increase net volume, but as we mentioned earlier, buidling a little bigger net than manufacturers spec is a good thing (to an extent)

Or am I missing something here?

 

[hispls 5,000+ posts]

I noticed hispls, you cut 7" off your port to get you into ur personal sweets pot on your recent build. (Apples/oranges)Boomingrandpa also mentioned cutting the port down for similiar reasons. (3"inches I think)

I could cut off port length, or slide in another piece of 3/4 mdf down the existing port reducing it's height from 2 5/8 to 1 7/8.

Whatever u thinks best.

But I feel running it through the program you used earlier to model my enclosure is probably the best bet, so I shall wait patiently for the results should you decide to do so today.//content.invisioncic.com/y282845/emoticons/thankyou.gif.5451126d09e870f796f50c3a4dd5acd7.gif

Got the big 3 done today, yay.

Mine still tunes a little low for my liking (peaking at 41hz with the seats in), and of course mine you can climb into to work the edges smooth after sawzall taking length off the port. .

Shrinking the port tunes lower so that's right out and those subs definitely don't want a smaller box so shrinking the box is probably dead too. Dunno how you're going to cut length off of that port easily/cleanly.

 

[hispls 5,000+ posts]

Couldn't I just cut some of the 26.75" port board off from inside the box & no one would be the wiser?Your round port idea is neat, but if I could just shorten the port internally I feel it would be the easiest (hopefully as effective ) method of achieving my goal.

If this is true, I simply need to know how much of that 26.75 to cut off to reach 35-37hz tuning.

I understand that will also increase net volume, but as we mentioned earlier, buidling a little bigger net than manufacturers spec is a good thing (to an extent)

Or am I missing something here?

If you think you can cut that down inside go for it. You'll be shooting for the port wall 10 or 11 inches instead of 26 and change. Extra volume looks very good for these subs so don't worry about that.

 

[Forcefed2002]

Bingo, that's what I needed, thank you sir.

I'm confident with the tools I have that I'll be able to cut that board (jigsaw through a sub hole) and blend the leftover against the edges with a belt sander.

Will have faith in your #'s and perform the operation tomarrow.

 

[Forcefed2002]

http://www.jlaudio.com/12w3v3-4-car-audio-w3v3-subwoofer-drivers-92154

You can see where I got the initial port specs.

Click specifications then ported enclosure.

But I'll be following your guidance.

 

[hispls 5,000+ posts]

12W3v3-4 - Car Audio - Subwoofer Drivers - W3v3 - JL AudioYou can see where I got the initial port specs.

Click specifications then ported enclosure.

But I'll be following your guidance.

Your port is longer (effectively), and as the box gets larger the same ratio for port area and depth just multiplied up to box volume tunes lower and lower as you go up.

They claim 30hz which is probably right for their box, but IMO that tuning does not model well in such a small box. In twice the airspace it looks great though.

Good luck inside there, and take heart, it's always way easier to add a little more length if you decide you need a little lower tuning again later.

 

[Forcefed2002]

If you think you can cut that down inside go for it. You'll be shooting for the port wall 10 or 11 inches instead of 26 and change. Extra volume looks very good for these subs so don't worry about that.

Can't than u enough.

And so my final question being, that when I cut it down by the amount you suggested, what then is the final tuning number, so that I may speak intelligently about it in the future & so I have a reference to go by with future builds?

Secondly, what software are using to model my enclosure? I d like to become proficient with it.

 

[hispls 5,000+ posts]

Can't than u enough.And so my final question being, that when I cut it down by the amount you suggested, what then is the final tuning number, so that I may speak intelligently about it in the future & so I have a reference to go by with future builds?

Secondly, what software are using to model my enclosure? I d like to become proficient with it.

Should tune around 36-37. Give or take 3 cycles it's hard to hear the difference 5+ and it becomes pretty obvious. I like winISD, it's simple and I've been happy with predicted vs measured output. Not nearly as powerful as Bass Box Pro, but far less finicky.

 

[Forcefed2002]

Should tune around 36-37. Give or take 3 cycles it's hard to hear the difference 5+ and it becomes pretty obvious. I like winISD, it's simple and I've been happy with predicted vs measured output. Not nearly as powerful as Bass Box Pro, but far less finicky.

Ok, here I go, shooting for a 10.5 inch port length.