otherwise with respect to what? Are you saying your graphs will be different? If so, of course they will be different [slightly]----I'm modeling a speaker that I have, not the one you are likely investigating. I was merely showing the overall type of frequency response and cone excursion that you will achieve using this type of enclosure. Naturally, different drivers, different volumes, different tunings will all yield changes to the graphs.
If you mean something else, then by all means, I'm all ears [and eyes].....
I don't see the reduction in excursion as sufficient reason to go DCR. I see the main use as being to avoid pipe resonance in a long, thin enclosure, such as tall, slim floorstanders (high WAF).
There's nothing to prevent you altering the enclosure chamber ratios and port sizes, I've done it myself, but I have yet to find a combination that outperforms a similar size conventional ported enclosure by enough of a margin to be useful. Hoffman's Iron Law applies here as everywhere else.
There's an spl graph that IMO shows a much flatter frequency response, between the ranges the woofer will be playing. The dip is also very significant because that's near where the sub will be cut off anyways.
excursion reduction is not a factor in either instance. This enclosure just appears to be the more efficient, and I have yet to hear one with my own hears. Why not build one?
^^ enclosures are the same size, everything is same. Same power, all three are modeled for 2 drivers.
There's an spl graph that IMO shows a much flatter frequency response, between the ranges the woofer will be playing. The dip is also very significant because that's near where the sub will be cut off anyways.
excursion reduction is not a factor in either instance. This enclosure just appears to be the more efficient, and I have yet to hear one with my own hears. Why not build one?
Well yes, we were modeling two completely different drivers in very different tuning scenarios. If you implement a LPF right where the dip is, then yes it becomes insignificant. I had thought you were going to implement this setup with a LPF in a more "traditional" location in the 100Hz region.
Is that a simulation using the 12W7 you had mentioned before? It appears that the increase in sensitivity occurs mainly right before the higher-tuned port resonance; otherwise it is on-par with the blue graph, which I presume is the 31Hz tuned ported box.
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That's just trading a pipe resonance for a dual chamber resonance. A pipe resonance is much easier to tame by using a bit of stuffing at the beginning of the line (where it doesn't affect the fundamental resonance much) whereas a dual chamber resonance can only be tamed by stuffing the port (which will aggressively attack the fundamental).
You stated before that you want wide bandwidth, your simulated response shows only about 1 octave of passband. That's fine though, if that's what you want, it just doesn't match your previously stated goals.
Anyway, what you are doing here is using resonances spaced very closely together to get a narrow band of gain. There's nothing wrong with that either but there's ways to get this done a lot easier than this complex box with 2 chambers and 3 ports.
In fact, I'm simulating something VERY similar (using closely spaced resonances to achieve some narrow bandwidth gain) but I'm using a MUCH simpler box. It's a simple folded transmission line with about 220 cm total length.
An externally hosted image should be here but it was not working when we last tested it.
Same effect but with more bandwidth, much easier to build, much easier to modify after the fact if desired.
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BTW, once you put that your simulated response in car it's going to be anything but flat, it's going to boom like crazy around 35 - 40 hz. That's fine if that's what you want but don't think it's going to be anything close to flat.
Are you even gonna build this? I like helping/discussing, but so many times it's just pipe-dreams that never even get off the ground and lots of time wasted. A lot of times I wonder why very few actually post pictures of finished results. 😕
what software did you use to model that?
I realize cabin gain changes everything, but I though it was below 40... I have a huge car not a tiny hatchback.
also could you describe the setup in that graph? the only way I could get near 140 was in a smaller box tuned to 45 hertz, insanely peaky
by means of wide bandwidth I thought an octave was pretty wide when compared to an "efficient" ported enclosure.
this tl intrigues me though...
I realize cabin gain changes everything, but I though it was below 40... I have a huge car not a tiny hatchback.
also could you describe the setup in that graph? the only way I could get near 140 was in a smaller box tuned to 45 hertz, insanely peaky
by means of wide bandwidth I thought an octave was pretty wide when compared to an "efficient" ported enclosure.
this tl intrigues me though...
I don't understand the second resonance in your enclosure. I thought it was a long folded port. ... how does the concept provide the efficiency posted above?
Hornresp.
It's shown in .5 pi space as opposed to your 2 pi graph, that accounts for most of the difference. Usually you don't model in .5 pi space but since this is going in a car it's kind of appropriate.
Look at the red line in the graph you posted. It's flat up past 200 hz. (Not including inductance or any real world issues like that.) And it will continue to be flat as high as the driver can play. That's wide, flat bandwidth. In that case there's only a single peak from the box resonance down at tuning, that's all the box contributes. But when combined with the driver output you get your wide, flat bandwidth.
Impedance peaks provide very narrow bandwidth peaks. This is true in all cases. But if you cluster a bunch of impedance peaks together, spaced close to each other the net result is relatively flat gain across as much as 3 octaves, that's how horns work.
A simple ported box has the one peak at it's fundamental tuning frequency (and others higher up that WinISD doesn't calculate and we can ignore for now). Your double chamber box has 2 peaks spaced close enough together to flatten out the dip between them. If you move those peaks further apart you will see a dip in the middle, same as a 6th order bandpass.
If it's the 140 db thing that's got you excited, don't be. Your drivers and box will do the same thing if modeled in .5 pi space.
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An externally hosted image should be here but it was not working when we last tested it.
That's the same thing but in 2 pi.
This is 2 Kicker L7 12 inch subs in about 375 liters with 1250 watts.
@oscars yea I'm going to build this, my current box is so bad I often leave the subs off 😱. its still too chilly up here in Canada, and I'll mostly be building this outside so I gotta wait a bit. I'll be sure to post pics though.
@just a guy, you have great information. I am not building anything for spl. yea the 140 looks great, but I didn't buy w7's for an spl car. I'm not that much of a newb...
im interested because a lot of people on here are constantly talking about tl's and folded horns, (which are very similar no?). I was always under the impression I would never get one in my trunk. especially not two...
abc will give me the flat response up to 60ish hertz, which is all I need from the sub. it can't move an inch and play that many frequencies...
now, yes I am also interested in getting all the efficiency I can out of whichever enclosure. is that fair?
thanks for the input, you guys are really helping me. I think like a lot of other guys on here I'm only used to ported and sealed, and these enclosures are foreign territory. they just sound so promising.
let me play around with hornresp.
@just a guy, you have great information. I am not building anything for spl. yea the 140 looks great, but I didn't buy w7's for an spl car. I'm not that much of a newb...
im interested because a lot of people on here are constantly talking about tl's and folded horns, (which are very similar no?). I was always under the impression I would never get one in my trunk. especially not two...
abc will give me the flat response up to 60ish hertz, which is all I need from the sub. it can't move an inch and play that many frequencies...
now, yes I am also interested in getting all the efficiency I can out of whichever enclosure. is that fair?
thanks for the input, you guys are really helping me. I think like a lot of other guys on here I'm only used to ported and sealed, and these enclosures are foreign territory. they just sound so promising.
let me play around with hornresp.
Well... I'm not a newb either but spl is the primary goal of my current project. (Within the restraints of a $500 budget.) There's nothing wrong with spl being a primary goal.
All alignments are similar and all alignments are different. Think of it this way - you have a driver and a baffle. You can fold up that baffle like origami into any shape you can dream of but no matter what you do it's still just a driver and a folded up baffle.
There is no magic and no free lunch. You can create and use impedance peaks but to create strong resonant peaks you need lots of interior volume. That means that I can design a horn, a tl, a ported box all in the same overall dimensions but they will all be ~ equally loud.
Horns are generally louder because they are usually much much larger than other alignments that cover the same bandwidth. That doesn't mean you can't design an undersized horn - it just won't be any better than any other alignment of the same size.
(At some point the enclosure geometry enters into the equation as well and dictates how large an enclosure can be before it's misaligned but that's beyond the scope of this discussion.)
For my current project I've simmed ported, tl, tapped horn and front loaded horn. Both types of horn are just not comfortable with the space I have available. The ported box won't give me the upper resonance (at 100 hz) that I want to pull up the efficiency to counter inductance effects and cabin gain, and so I've settled on a transmission line.
If your current plan meets your goals and you like it, go ahead and build it. There's no reason no to. IMO there are easier ways to get the same response with a much less complicated box but in the end we pick our own compromises and learn from the results.
Good luck, and the offer still stands. If everything goes well I'll have my car done enough to listen to within about a month if you end up in my area and want to see/hear it. (I don't even have the car yet and I'm not sure it will pass safety but that's the planned timeline at this point.)
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