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Discussion Starter #1
I just thought this might be interesting for some people. Hopefully, I've got the graphs done properly?

Sealed "eD 19Ov.2" in a 4.5 cu3 very stuffed with pollyfill. Corner of my room.

And here is a ported "eD 190V.2" in a 13 cu3 tuned to 18hz, no pollyfill. Same corner in my room.




Notice any similarities?

No EQ at all yet. The BFD isn't even hooked up.
 

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Discussion Starter #3
Yep. The sealed enclosure is nice, but I won't be using it in the future.

Is it just me, or do both enclosure seem to have similar peaks and dips? Is that the room in action?

Both have a dip at 22hz, peak at 40hz, slacking off at 50hz, dip at 65hz...
 

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Discussion Starter #7

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No manufacturer dare sell a proper LLT subwoofer, the market is just too small, I guess. Think about shipping and handling.. Storage... :s
...or proper engineering. :hide:
 

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What do you mean by this? LLT isn't 'proper engineerig'?
Nope :innocent:

Engineering is about achieving better performance while minimizing compromise...not ignoring or belittling the compromises made.

Let's just say that professional subwoofer engineers (at least the ones I know) would be taking a very different approach if given the opportunity to design with larger cabinets.
 

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Mike will you expand on what these compromises are IYO? There are always compromises.

If home audio mfger's could build these larger enclosures (which they can't for practical reasons) they would use them to get more overall output probably with multiple drivers or hornloading and not that much more extension and also charge crazy prices. It also matters what subwoofer engineer's you know. If they are pro audio oriented of course they would do things differently. I don't think we can really speculate on hypothetical's though. They are not going to start designing 600L enclosures.
 

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they would use them to get more overall output probably with multiple drivers or hornloading and not that much more extension and also charge crazy prices.
And that's the crux of my point...

Things like the cabinet size, tuning point, hornloaded or not, number of drivers, etc... are all merely tools to help the designer achieve performance goals. They are not absolutes on performance.

If a larger enclosure is to be used, then the driver design should change.

Throwing a driver designed for a smaller enclosure into a larger enclosure does not guarantee performance advantages - unless all you care about is a single frequency response measured from the listening position. Tuning below Fs results in undamped bass. A larger enclosure tuned lower moves port and cabinet resonances lower, which tend to get triggered more easily by increased distortion (even if a lower xover point is used). There is no increase in sensitivity, so there is no reduction in thermal non-linearity (the main advantage to having a larger enclosure). Cone-excursion increases in the audible passband which results in more IMD, THD, and power compression.

And all this so the frequency response goes lower than the bandwidth of the source material (except for a few sound effects where any semblance of accurate reproduction is totally meaningless). The main reason commercial subwoofers don't dig crazy insane low is because their products have to sound better than the competition in A/B comparisons....when your source material doesn't dig to 1Hz, it makes no sense to make your subwoofer sacrifice performance in the 40-80Hz octave to achieve extra extension. All the theory and know-how is there to achieve 1Hz extension, but nobody does it because it has no audible correlation....just like a 4000dB noise floor has no audible correlation.

Btw, I'm not saying that LLT can't be an optimum design choice for a given set of parameters, but it is certainly no magic formula to good performance.

Also, I don't believe "flat after room gain" results in perceptually accurate bass response, but that's a debate for choosing the design goal, not judging final performance.
 

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I agree with you for the most part Mike. I thought that you were saying that EBS was always a bad design choice. Like you said it depends on the whole design and the goals for that design. The cab size, amp power, driver/s, room, everything should be taken into consideration. Slapping random long throw 15" driver in giant ported box tuned to <16hz with big amp does not = success. You do accept that there will be higher distortion in a certain bass range depending on tuning and that the port and cabinet resonance will be closer to the sw's operating range. I would argue that while you may lose a bit of your upper bass sensitivity, you do gain sensitivity on the low end and extend usable output range. Also there are literally hundreds of movies out now with intentional bass below 16hz and sometimes below 10hz. Once you've got what you personally feel like is more than enough 30-120hz for your needs, it can be rewarding and fun:1eye: to go after that bass.
 

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Like me going from a ~6.2 cuft sealed enclosure,which according to specs, graphs and manuf. is ideal to a ported enclosure of ~12cuft which is same as above for vented.
This is to hopefully keep the linearity and add dB across 15Hz-65Hz.
It will be designed to my room's response though after REW.
 
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