Thinking inside the box

[Bassick]

This if for bbeljefe, what you are describing is a ABC band box. I've did my research on that type of enclosure. What I'm purposing is something different, this has never been done (if it has I havn't seen it). This concept works for sealed and ported or any kind of enclosure. At the core the concept is simple: "Increasing the cubic feet as the frequency lowers". And as everybody knows, "increasing the enclosure size decreases the port tuning for a giving port diameter and length".

 

[Bassick]

The extra chamber is not ported out its closed off, click on this attachment. View attachment 26544551

 

[bbeljefe]

Yeah I get what you're saying, which is why I said that I don't think it will make any noticeable difference in Fb, save the obvious difference making the box bigger would accomplish.

I just don't see how porting into a sealed box is going to help anything but I could be wrong. In my way of thinking, you can't expect the sound waves to travel into an empty chamber at one frequency and then back out through the same hole as another frequency. In fact, what it looks like to me is a whole bunch of standing waves inside a ported box... and standing waves are one of the things we spend countless hours trying to eliminate when designing enclosures.

But hey, I'm not Amar Bose so by all means, build it and test it. ;-)

 

[cfox10 10+ year member]

Like above... It would seem you would get cancelation across frequencies and standing waves. Just don't see how this would work.

 

[Buck 5,000+ posts]

We are all on the same page at least, lol.

 

[gumby688 10+ year member]

If the inside port is ported into a sealed chamber wouldn't it still just act like a sealed too me that looks like it would just be a singled ported box but I am not a audiowiz or anything.

 

[Bassick]

Thanks guys for all the input, I understand the problem with the standing waves. I kind of sort of disagree about it tho. I still plan to experiment with this, who knows maybe some other idea may come from it. Thanks guys.

 

[Bassick]

oh yes, I forgot to post my system

Head Unit: Alpine CDE 147-BT

X-Over: Kicker Front Row ZXDSP1

Sub Amp: Brutus BRX1100.1 D

Subwoofer: 2 Brutus BRZ15D4

Mid Bass & Mid Range Amp: Brutus BRX320.4

Mid Range Drivers: Door: 2 ATL5768CX (5x7)

Rear Deck: 2 HF8SQ-i4(8" square)

Highs Amp: Brutus BRX160.2

Tweeters: Pyramid TW47

 

[bbeljefe]

Definitely do some experimentation and post up pics and video of the results.

 

[ahardy17 10+ year member]

seems like each port on those inner chambers would have to get progressively smaller with respect to the chamber size too, to provide a higher tuning frequency for each of them. I can't see it working the other way around. I'm interested in the idea but calculating the reactions between all the ports is extraordinarily involved; you would probably have the best luck starting with just one additional chamber to see how it behaves so you can figure how to effectively tune it in the hopes of stretching a more even response, then add the third chamber in later. You could do an MIT thesis on such on a project. I'm sure there is a way to determine the behavior of 2 ports in such a setup, it's just a matter of whether or not the second (and third) port and chamber combination would behave predictably with the only resistance being the sealed volume of the smallest chamber. I say you must become the pioneer of this concept and enlighten the rest of us!

 

[psych0ticnemes1 5,000+ posts]

I don't understand a lick of how this could work, but major kudos to you for trying something different. I'm a huge fan of trying different things and being somewhat unique. I stayed away from SPL competitions for so long thinking, why build a fart cannon? But what if you stumble across a design that allows you to quadruple output or something? It intrigues me more than just grabbing massive subwoofers and throwing gobs of power at them.

Good luck.

 

[Bassick]

ahardy17, You seem to grasp the fundamental of this theory of mine. I appreciate your reply (highly motivational). I don't know your background but could you give me some expert advise as for as the predictability of the ports, if not do you know anybody that can, again thanks

 

[bbeljefe]

The ports and additional chambers are going to behave like braces in any other cabinet. They'll have little to no measurable affect and will have even less audible affect.

In a sealed box all you have is the front of the cone to make noise. In a ported enclosure, most people can't hear an audible tonal difference between, say, 35 Hz tuning and 38 Hz tuning.

I predict that adding chambers and ports to a sealed box will yield less than .5 Hz difference in the Fb of the box, relative to the change that simply making the box larger would cause.

In simple terms, you're trying to see if three interconnected 2' boxes will hold more than one 6' box. And the answer is, it won't.

What you will accomplish though is only two of three things a DCBR accomplishes and that's lower driver excursion as a result of the added port resistance and consequently, slightly higher power handling capability. But, less excursion is only desirable if you have a driver with low xmax and with the technologies we have today in the audio world, a driver with low xmax that needs help with power handling isn't worth the time and trouble of making a complicated enclosure for. Especially when you know for a fact that that complicated enclosure won't provide any acoustical gain. Not to mention, the increase in power handling would be negligible because you're not really moving much more air at all across the coil, since no fresh air can enter a closed system.

And please don't get me wrong... I applaud your thinking into it. I just don't see any appreciable benefit from what you're proposing.

 

[Side Show 10+ year member]

i'd say you'll get a lot of port noise