Site Links
Howdy, Stranger!
It looks like you're new here. If you want to get involved, click one of these buttons!
Quick Links
Categories
In this Discussion
2 woofers in a sealed box VS 1 loaded in a PR box- thoughts?
i.e. Using the CSS LDW7s, and with ability to use a EQ; comps of f3, f6, f10, and distortion (within driver excursion limits).
Box volumes look to be similar for these set-ups.
Looking at VituixCAD / Enclosure / Info it shows that 2 sealed have a slight advantage at f3 (which doesn't seem correct to me w/o EQ?), and I am wondering if with a bit of EQ on the dual sealed drivers targeting either f6 and/or f10 levels of the single PR levels is doable within reasonable driver excursion? My 1 and ½ cents is that the sealed dual driver box would get somewhat close on an f6 or f10 level, with less distortion. Any help with looking at this would be appreciated. Thx
Comments
If you have plenty of power on tap I bet EQed dual sealed will stomp all over a vented/pr setup.
It'll have less smearing/group delay as well in the lower frequencies.
Two subs sharing the same sealed chamber?
I did a quick sim in winISD using .5 ohm series resistance, 25 liter boxes and the Dayton DSA215-PR with 6 grams added mass. The SPL graph is at 5.5 mm of excursion for both and the excursion graph is with both at equal spl (about 98.5). The F10's are almost the same and the dual sealed has enough headroom to be equalized to match the PR setup everywhere except right around 40 Hz. Personally I think the dual sealed looks great as is but increasing the series R to 1 ohm gives an F3 of 50 and a .3 Db of bump at 107 Hz which might be even better.
JamesMC > thanks for running these
Playing around with paring with a 6.5 in. coaxial (open back / baffle for the coax), and dual woofers in same chamber. Possibly adding a coil for the lower (or back mounted?) woofer as a ½ way. Initially thinking using a 1st order HP on the mid of the coax (at fs or 2x fs) and bringing the woofer(s) in accordingly.
Sealed between the two woofers, push/pull or both open to the same chamber? I've been playing around with unibox 408, want me to run them through it?
It's probably been discussed previously, but those LDW7s bare an uncanny resemblance to the Rival woofers.
You are a step ahead of me - haven’t gotten to positioning. Just noodling 2 sealed vs 1 with PR.
If you can run it - great. Thx
Both are 15L/.53ft³.
First graph is 2 drive units in parallel, compound. I think this is what we want. Since they are in parallel, it calculated power at 60w.
Second graph is single driver w/30watts.
Not good enough at passive radiator to attempt.
Vented in the same 15L/.53ft³. Wow.
Free bass?
The port.
Best.
Invention.
Ever.
So yes, although my main system has a pair woofers in a sealed box, I’m well aware that it’s about the same as a single ported woofer, in terms of deep bass output.
A single ported will be cheaper than a pair of sealed boxes.
A pair of woofers, ported for a low tuning for deep extension and EQ’ed/limited, can be optimised for smaller box, lower group delay and deep and smooth in-room response.
A pair will have more output than a pair in sealed boxes.
Excursion w/2in the same sealed chamber @60watts and @30watts. Not sure how much room there is to eq. I can play around with a smaller box and see what happens.
xx
Are these woofers going to be used for music or HT?
It does make a difference in how you want them configured if you are going passive on the XO's.
It would be primarily music.
I've pre-wired for a potential sub in main room, but need to get it ok'ed by the boss. Thinking of making a little 'plant table' for the corner. My 8in sealed / EQ'd in my current speaker is good on its own.
OK - I am really liking this config offered by Kornbread - the roll-off looks excellent for music and you can turn on/off the sub for LFE in HT use:
In-room might be different as you have a lot of open space behind your mains . . . worth testing in some temporary boxes, me thinx.
IF I can get the sub in the room, F3 60 (with the nice closed box 6dB roll) works. I was hoping for mid 40s (with a bit of EQ), as I've been spoiled by ~sealed box rolloff, and in-room mid 30's with my 8 in woofer builds.
PEQ for the win, buddy!
Looking at WinISD Max SPL graph the dual sealed beats out the single vented design (flat 32hz tune) until ~vented F6 around 45hz. EQing will help make that happen and the extra headroom above that should help with distortion. That and the fact that down in that region the room starts to do it's thing. So I am still pretty convinced the dual sealed will not only sound better and more controlled, but also sound like it can dig deeper since it is beating out the ported output below ~27hz. So low notes should carry a little bit of that deep breathyness.
But that's just my interpretation. If I've overlooked something definately let me know.
Looking back more objectively, I'm probably biased in terms of my room/placement. From your photos your room seems more open/central in placement. You may need the extra bottom end output of the port to overcome that. Comes down to your experience in your room to know.
W/o a separate sub support, 8 in driver(s) both single and (as in my previous speaker build) push-pull, in 3ways sealed get me into the mid 30s, and without the port / PR prone one note fall off. If I had my druthers, which I do with DSP, I’d target a 10dB roll-off (somewhere btwn sealed 6dB and ported 12dB) as ultimate.
Software is great but some times it's time to build some test boxes and listen.
I have built many systems after modeling. The ony way to tell if they work is to build them. Don't get me wrong, 99 % of the time it works out as planned. But, they may not sound very good. It's science AND art...
I build a lot of test boxes.
Just as a note, sealed enclosures naturally roll off at a rate of 12 dB/octave and ported enclosures roll off at a rate of 24 dB/octave. You can off course realize something in between those two with a ported box by decreasing the volume and/or changing the port tuning. This all assumes no EQ/DSP manipulation of the FR curve.
Yes, thanks. Sometimes Maths is a second language...ha
