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I do have to take a small exception to your three graphs in the above post, although I suppose you copied them from elsewhere and had no control.
The vertical scaling is quite inconsistent between the three graphs, and makes it difficult to draw meaningful conclusions......
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Yeah, three different owners running their measurements in three different months. Not ideal, but just a very generic representation of what can be achieved at various tuning points with different drivers.
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it would "seem" that the only one that is coupling to the room properly is the first example given in the 18" Avalanche
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Well the coupling area with an LLT will begin around 25-30hz and extend down to just below the tune - below that, the 4th order rolloff comes into play and there will be a dropoff. Flat output definitely won't go on for ever. Considering the third sub's tuning is coming in around the high 16hz area I believe, the extension to ~13hz is pretty impressive. If you were to take a ported sub that measured very flat to 18hz anechoically, like an Axiom EP1500, you would not get such results without heavy EQ in room.
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Hopefully this will save you from answering so many questions
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HOPEFULLY
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Excellent explanation. Very factual, scientific, and based upon repeatable results if the "formula" is followed
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Thanks. A logical and factual explanation of the
real benefits was one of my top goals, as there are people with no clue as to how such a design really works saying things about it that are completely wrong and backwards - it's not a knock, but they just don't fully grasp the design intent. For people who have enough interest to want to understand why this design works and why it came about, hopefully this will shed some light.
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A little cheat sheet you could put out as a starting point for people thinking about building one of these might give them an idea of what they are getting into
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Yeah, I might just list my main designs for popular drivers so it could be a one stop source.