Rrrrolla

iTrader: (3)

At the tuning frequency, a driver moves very little, and yet it produces an increased output. This is because at tuning, the driver's output is "assised" by the port's output. This would translate into an increased power handling since you can then throw more power at the sub at those frequencies which it is most efficient without hitting the drivers xmax. The problem of course is high power being thrown at the driver at a frequency below tuning. The driver is completely unloaded and might as well be sitting on the bench at frequencies below tuning. An abc box is beautiful, since you can get a frequency response similar to a sealed system (no big bumps like a regular vented system) only with about 10db of gain. If you get the tuning frequencies low enough, it will sound outstanding in conjunction with most cars transfer function. I've built a few, and they sound great!

maltesechicken

I've heard nothing but good things about them when built properly. I would love to try it.

I love the Math side of building a box, so calculating the the final volumes (minus port displacements and driver displacements) and keeping the chambers at 2/3 and 1/3 at the end is part of the challenge that I enjoy, and I'll be able to do well on my own.

My difficulty comes in deciding what size box and what tuning frequency would be best for this driver. So given the theile small of this, what size box, tuned to what would you recommend?
Clif Designs CD10W
Qes:0.63
Qms:5.39
Qts:0.55
Vas:30.8L
Fs:34hz
Re:3.2
xmax:15mm
RMS: 300

Rrrrolla

iTrader: (3)

I think the qts is too high. might want to find a good vented box driver instead. I honestly dont know what it would sound like. I always THOUGHT that the Q of the system basically represented the drivers "stiffness" in free-air kinda thing. For vented boxes, you dont want it to be too loose or it will bottom out easy on notes below tuning. But for sealed, it can be a little more efficient to have the driver move easily, and it will not bottom out especially if its in a small sealed box as the box pressure acts like a spring. I could be totally wrong though, this is just how I figured it went.

Anyways, I dont believe this would be a good choice for a vented enclosure of any type, especially a large one like an abc box.

Dukk

That quote from the other page is correct - the driver moves less so it should have more mechanical power handling. Woofers have changed though - this current trend of heavy cones with massive magnets 'buggers up' the Qts value so you can't really go by the rule of >0.40. Now more than ever you kind of have to know the driver you are using and what it will do when the enclosure volume goes up.

With WinISD you can plot cone excursion and theoretical power handling. See what you come up with. Most drivers can handle about 15% more movement than Xmax before things get.....interesting..

Without looking at software I would say that you are gonna top out at about 1.5cuft for volume. That's going to make you vents longer and that can get tricky.

maltesechicken

I'm guessing you mean <0.40
I haven't found that feature yet, and I thought that I've explored every part of WinISD. Is there a new version of it or is that in WinISD Pro?

At any rate, I won't use this sub for a dual chamber enclosure.
I do hope to build an ABC box what 10" subs would you recommend?

The amp I'd power them with is a stereo amp: 300WRMS x 2 @ 2ohm, so dual 4ohm subs would be ideal - and I would likely build a 3 cubic foot box for them. Any suggestions?

Thanks.

maltesechicken

I believe you are right as this is how I understood how free-air subs work
If I can't port the box, the sub is useless.
I'm thinking that I will build a 2 cubic foot box, tuned to 32-34hz for this, and if I blow it, so be it. This is really just an in-between sub until I can get a pair of quality 10's that are suited for a ported set-up

maltesechicken

Alright, looking to do this sometime soon . . .
I've got the subs:
Pioneer TS-W257D4
Qts: 0.54
Qms: 12.94
Qes: 0.57
Vas: 18.1 (l)
Fs: 39.7
Re: 1.5 ohm (parallel)
Z: 2 ohm (parallel)
Le: 1.07
BL: 9.64
Xmax: 11.5 mm
350 WRMS - I'll be giving them 300WRMS each.

So now I need to chose a tuning frequency . . . if this was just ported, I would go with 32Hz, but Aperiodic Bi-Chamber is new territory, so I don't know which frequency to "pick"

With the speakers in a 3 cu ft box, below are the frequency responses:
Top: 30Hz
Middle: 32Hz
Bottom: 35Hz

Dukk? BigRedGuy? Which would you choose?

Thanks

snobro1808

Roll with the second diagram or the first, Its* up to you

Dukk

Really? First rule of venting is to not tune below FS which pretty much eliminates an ABC unless you want the ultimate bonk-monster. If you still want to try it, go with the 35hz.

maltesechicken

Arg. I was afraid of that.
So even if I were to just port the box I should tune it to 40Hz? I don't like the freq. response of 40hz
Perhaps I'll try and sell them and look for a pair of drivers with a low QTS and low Fs.