Bandpass enclosure build
 

I'm on a small budget so buying new sub won't happen now. I'll need to make do with what I have. I noticed on WinISD that speakers with a low EBP can be "encouraged" to play deeper in a bandpass box. As ported is likely not a good option for this woofer (EBP of 55) I'm consider the possibility of building a bandpass box.

The version of WinISD that I'm using doesn't chart woofer excursion, so I want to be sure that I don't put this in too big of a box and blow the thing apart. It's a single 10"
I'm currently planning on a 1.2 cubic foot sealed chamber and .6 cubic foot vented chamber tuned to 44 Hz . . . but I've been known to plan my boxes too big in the past.
Is there a general rule of thumb for chamber size ratios? Or any guidelines for tuning frequencies or any of that jazz?

Here are some of the specs if that's helpful:
Qes: .62
Qms: 5.39
Qts: .55
Vas: 30.8 L
Fs 34.08 Hz

Thanks any information is helpful as I want to learn how to make this judgment calls on my own in the future.

Ryan

are you sure the sealed partition is 1.2 cubes?? maybe its just me but usually with 4th orders, the vented partition is the larger of the two

i'm no genius at bandpasses though

i was thinking the same thing.... would swap sides with the planning for that enclosure.... dont quote me on it but i think you would have better results the other way around

Interesting observation . . . now that you mention it, I think that I have seen the same thing. However, in WinISD, when I flip those two around the frequency response looks like a mountain peak - Yes, it would scream at 40Hz, but it looks like a very uneven response. In this graph, the box is 1.2 cubes & .6 cubes. Tuning freq. is 44Hz. The blue is with the small chamber ported, and the green is the large chamber ported.
Attachment 5738
:dunno:

Part of why I'm looking for some helpful advice.

If you can wait until the weekend, I'll work on it for you.
Please give me the "long" list of your T/S.

A 4th order usually has the larger sealed section. You would also be surprised how small the port can be for the smaller section. I built a guy a box with 2 rockford 12's in the bed of his regular cab truck. I "snorkled" the port in to the back of the cab. Its been a few years, but I think remember that the tube was only 6" id. That truck hit so hard and deep it would kill small roadside animals!

That would be awesome, and greatly appreciated!

The list isn't that much longer. I'm missing a few but here is what I have:
Clif Designs CD10W
Qts: 0.55
Qes: 0.62
Qms: 5.39
Vas: 30.8L
Fs: 34.08Hz
SPL: 84.8 dB
Re: 3.2 ohm
Z: 4 ohm
LeVC: 3.10 mH @ 1kHz
Xmax: (The only information that I could find said 31mm Linear Peak to Peak . . . I'm guessing that would likely mean the Xmax is 15.5mm :dunno: ?)
Bl: ???
Sd: ???

Is that enough or do I need to search the web for more?
Thanks,
Ryan
300 WRMS

So in the instance when I have seen the sealed section as the smaller section is that when the box has essentially been designed to be a "one note fart box" as the green line in my previous post looks like?

The p.c. that I use is in the garage, so I have no internet hook up to it. I will try to save the graph that it spits out to a floppy and reload it so I can display it here. If not I will describe it as best I can.

That green line isn't the worst I have seen. From 32-60hz is dramatically increased over the blue line. But isn't 32-60hz really the only place we want the sub to excel (especially with a peak around 40)?

I agree with your 32 - 60 (and for that reason I really like the blue graph). I agree that I would love to have the sub excel at 40hzish, yet, I don't want it be a one note honking machine. I want it to be musical as I have a few songs that have incredible rolling bass from 35hz - 50hz and for music like that, I wouldn't want any more than a 3db difference between 30 - 60 hz. The green graph has a 10 db difference across it's playable range.

Oh yeah, and the only difference between the 2 graphs is which chamber is ported. So I'm working with nearly the exact same box size (port lengths differ so those displacements change). My vote is for blue - even though it's entire response line is below the 0 gain line - I prefer a flatter response.

On other question. How does a bandpass effect the over-all power handling? This thing is 300WRMS, I have an amp that can give it up to 500. I'm just wondering if I should be quite conservative with my gains, or if I can be free to feed it a bit more power. I think 300WRMS might be a bit under-rated - It has a pretty big magnet for that rating - 110oz. Yet I know the magnet is no guarantee that the voice coil can handle it.

Thanks for your responses. I appreciate it greatly.

Ryan

If you give me the chamber sizes and tuning frequency, would my winISD be able to replicate the graph that your software produces? Or is WinISD missing something? I know its missing things like driver excursion, but I was under the impression that it would graph fairly accurately with the chamber sizes and tuning frequencies.

Thanks again