That's half the fun of this stuff. Screwing around with trying wring that last vestige your system is capable of.
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I have no complaints about this sub, puts most 12" and 15" subs to shame!
Ron
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There is deeper bass available, but it is about 20db less the efficiency of the D123 as a whole.
Ron
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When multiple subs are used each sub need not be all that high performance. In fact I use smaller 12" divers to make the subs smaller, and lower power amps. Judicious choice of RANDOM locations can make them virtually invisible in almost any room, so I don't think that your appearance issue is really a concern. In my theater only one sub is visible all the rest are invisible. The surround speakers are far more obvious than the subs.
And you don't have to be a "rich audiophile" to get the very best sound. But you do have to be willing to make the sound a priority and do things right. In fact, it's not all that expensive to do things right, it's usually cheaper, it's just not what many people want to do. Sound really isn't the highest priority.
For example spending large sums on electronics is a waste of money, but then when you do spend all that money the last thing that you want to do is hide it. I buy the lowest cost electronics and hide it - spend the money where it counts - on the speakers and the room.
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But it is practical to design a sub using a smaller woofer in a bandpass design that goes down to 25 Hz. It has a 25-50 Hz capability, matches up ideally to the closed box 50 Hz Summas, and has enough output over this very small bandwidth to keep up with the high efficiency woofers in the main channels. It probably does have a lower MAX_SPL but it will still do 110 dB SPL in a small room at 35 Hz. Total volume of this approach is far below that of making each source go down to 25 Hz.
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I know it's a loaded question and that there are trade-offs to consider in every decision. But you must agree that since the mains carry so much bass, their placement and the perfomance that results is is an important aspect, maybe even more so than the subs. In your proposed configuration, the most troublesome room modes for most people will fall in frequency ranges covered by the mains, not the subs. Would you place midbass cabinets randomly around the room, same as you suggest for subs?
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So basically the room has 1 source 25-35 Hz, three sources 35-50 Hz, and four or five sources 50-120 Hz. Sure it would be great to have 5 sources 25-120 Hz, but thats not feasible. What I have is not only feasible and low cost but only one of these sources is even visible.
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Best imaging comes from speakers that are placed symmetrically, as I'm sure you'd agree. But you've suggested running your mains down to 50Hz, so two octaves of the modal range are covered by them and only one octave by the subs. Since you prefer the modal range to be covered with speakers that are placed asymmetrically, how do you deal with that? After all, the worst modes in most average listening rooms are above 50Hz.
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So if two sources are forced into symetrical locations then put the others at random locations NOT more symmetrical ones. Its not that complicated is it?
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In the modal (bass) region things like distances to the sources crossover frequencies and the like have little to no real meaning. And talking about 100 Hz (the upper limit of my multiple sub implimentation) as being "run up through the upper bass to lower midrange" is ridiculous. In the modal region the complexity of multiple subs is Exactly what one wants.
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There are two issues here. One is the use of dense interference to smooth room modes. The other is of integration with mains, considering crossover points and slopes and distance between subs and mains.
Dense interference can be accomplished at 100Hz using closer spacing than is required for dense interference at 35Hz because of the wavelengths involved. I'm saying I think probably it is worthwhile to have closer-spaced overlapping midwoofers for modal smoothing, and further spaced subs. The further subs might be arranged symmetrically as Welti suggests, or randomly as you suggest. But the nearby overlapping midwoofers should probably be symmetrical, to provide better imaging. They're the transition drivers, used up to the end of the modal range. They would work something like a traditional line array, but used only up to the Schroeder frequency.
I think I understand your concept, its strengths and weaknesses. How about you? Do you understand what I am saying?
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Below 100 Hz "integration with the mains" is irrelavent - it is insignificant. Thus, to me, your "issues" are simply not relavent. And your argument for symmetric placement is weak because it will always yield a higher spatial and frequency variance than a random or partially random placement will and there are no "integration" issues.
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And my room is very well damped at these frequencies to boot. There are no distinctly measureable modes.
You talk to me like I'm an amatuer who's guessing at what might sound good - and your going to set me straight. I've studied this problem in intensive detail for about 30 years - I hope that I've learned something along the way.
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The only other way I could interpret your comments is that you suggest blending subs only up to 100Hz, in which case modes above that point cannot benefit from smoothing via dense interference. In that case, I say the same thing. A couple of sound sources spaced a few feet away from one another and overlapped in the midbass, up to the Schroeder frequency, will help smooth the modes without any localization problems. They're far enough apart to provide smoothing but close enough together to sound like one acoustic source.
What I visualize is a sort of purposely "unfocused" sound field in the modal region that gradually transitions to a focused uniformly directional point source around the Schroeder frequency. I'm using the word "unfocused" in only an illustrative sense, because what I really mean is distributed sound sources at low frequency that gradually become less distributed as frequency rises, becoming a point source at or about the Schroeder frequency. I think what I'm describing does this perfectly, because it addresses modal behavior at very low frequencies as well as higher up, where there are competing priorities of modal smoothing and preventing localization of the subs. The way this is done is by using relatively closely-spaced overlapping woofers to blend just under the Schroeder frequency and subs placed further away using lower crossover points.
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