Anyone here built a double chamber reflex sub?

[zobsky]

If so:
1. Details ?
2. Did you compare it to the equivalent single reflex subwoofer?
3. Regardless, how did you like the results?

FWIW, Here's a VERY ROUGH proposal I drew up for a slot ported DBR sub of about 5 cu.ft. net tuned to about 22 Hz for an RSS390HO 15" driver . I know the slot ports are a bit too skinny and should probably be split up further along their axes, but as I said, this is a rough design


Thanks

[duanebro]

Re: Anyone here built a double chamber reflex sub?

Do you have the modeled fr?

[isaeagle4031]

Re: Anyone here built a double chamber reflex sub?

Ive done a couple. One used the ROT of 1/3 2/3 volumes of each chamber. Interesting results, but not necessarily any better than a properly designed ported box.

[zobsky]

Re: Anyone here built a double chamber reflex sub?

Do you have the modeled fr?

Not near my home computer right now in order to upload the winisd models, ...but i posted several modeled graphs on this thread: http://techtalk.parts-express.com/sh...gnments-please

Thanks

[zobsky]

Re: Anyone here built a double chamber reflex sub?

Ive done a couple. One used the ROT of 1/3 2/3 volumes of each chamber. Interesting results, but not necessarily any better than a properly designed ported box.

Interesting ?

[isaeagle4031]

Re: Anyone here built a double chamber reflex sub?

Yeah, it was used in a van. It hit the lower register very hard but having 2 peaks could make it a bit harder to tune. Great for dub step, not so much for pop music.

[zobsky]

Re: Anyone here built a double chamber reflex sub?

This morning, I decided that since I haven't been able to find a lot of documented builds of DCR subwoofers, such a sub needed to be built and the results documented, for better or worse. I spent the afternoon refining the dimensions and the sketchup model. I couldn't attache the win isd model but basically its a 5 cu ft slot loaded double chamber reflex tuned to 22 Hz via four 5 x 1.5 " slot ports . Port dividers not shown in the sketch.

I've started glue up and should have something to report in a day or two. After starting the build and looking at the size of the enclosure, I half wish I had built a TH instead, .. (but been there done that already, so what's the fun).

[isaeagle4031]

Re: Anyone here built a double chamber reflex sub?

What you've got there is more of a dual chambered 6th order bp. Either way you will have 2 tuning freqs.

[zobsky]

Re: Anyone here built a double chamber reflex sub?

Hi,
How does this become a 6th order BP. The driver will be in the left most ( larger chamber )? Unless the holey brace in the smaller chamber is the source of the confusion

[zobsky]

Re: Anyone here built a double chamber reflex sub?

[rpb]

Re: Anyone here built a double chamber reflex sub?

Looks like a bandpass to me as well.

I saw a design years ago where the woofer was on the outside of the box. The chamber directly behind the woofer was ported into a lower chamber, and the lower chamber was ported to the outside of the box. I think it was called a double chamber reflex.

[zobsky]

Re: Anyone here built a double chamber reflex sub?

Looks like a bandpass to me as well.

I saw a design years ago where the woofer was on the outside of the box. The chamber directly behind the woofer was ported into a lower chamber, and the lower chamber was ported to the outside of the box. I think it was called a double chamber reflex.

Hi
Perhaps that would be the "fostex style" dcr
http://www.fostexinternational.com/d...3e_enclrev.pdf

Maybe that's the type of Dcr that Mjk spreadsheets can calculate ( I'm away from my main computer at the moment)

[isaeagle4031]

Re: Anyone here built a double chamber reflex sub?

Yeah the brace is what threw me. So what is your chamber volumes and tuning for each?

[zobsky]

Re: Anyone here built a double chamber reflex sub?

5 cu ft split into 2 chambers in the ratio 2:1

Tuning is around 22 Hz. Note that I split up the 12" x 1.5" wide slot port (accounted for in WinISD by designing with 4 ports instead of 2) via a divider to
1. slightly reduce the port area resulting in a slight reduction in the port length.
2. brace the slot port.
3. reduce the port aspect ratio from 12:1.5 to 5:1.5

I'll double check my volume calculations tomorrow before sealing the cabinet in case I need to balance anything out

[HareBrained]

Re: Anyone here built a double chamber reflex sub?

I built a DCR for my computer speakers. I choose that enclosure because a DCR can provide lower tuning while controlling the excursion. It's great for full-range drivers that have low xmax. For a sub, I have yet to want to listen to one that needed more xmax. I tend to prefer sealed subs anyway.

Still an interesting project. Do you have a standard reflex enclosure to compare it to?