As far as multiple subs go, I would never buy several expensive subs. But I would say, based on the work that I have done and my own experience, that I would much rather have several cheap subs than one expensive one. For a long time I used three $100 subs - worked very well. I did get an improvement by upgrading the subs quality, but it was not a tremendous improvement, noticable, but nothing earth shatering. The biggest improvement comes from the second sub with a little more from the third and diminishing returns from there.

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.

Its not practical to get every speaker in a two or three channel setup to go that last octave. I use a 15" for its high efficiency and directivity not for its LF capability, although that is a plus. But a cabinet to 25-30 Hz for a large high efficiency woofer is not practical.

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.

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?

The mains must be placed at the best non-modal location relative to the room boundaries for the best direct field response, i.e. best image. This may or may not result in the best locations for the LF modal region frequencies. To this I add two smaller subs - one above the mid line of the room and another as far away from the mains as possible. These subs cover 35-120 Hz yielding about five speakers (center channel if used) at near random loactions covering the range from about 35 Hz and up. So where the mains are placed is basically irrelavent for the LF modal issues. I now add a single VLF sub to cover the 25-50 Hz region that the Summas can't reach. So only the frequencies from 25-35 Hz are not covered by several drivers, but at these frequencies the wavelengths are so long that it isn't possible to get multiple uncorrelated drivers anyways. This configuration yields the best LF response that I have ever obtained in a small room.

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.

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.

The modal region in my room is only up to about 100 Hz. 120 Hz max., most definately not 200 Hz. I would define Bass as anything in the modal region and "mid" as anything from the bass to about 500 - 1 kHz where our hearing perception starts to change. So to me, only bass is a modal concern. And, as usual, you don't appear to have read my response. Since I have five sources in the bass region above 50 Hz, its pretty much irrelavent where they are put. You are confusing what I claim. With enough subs, placement doesn't matter, symmetrical, asymmetrical, whatever, the differences are negligable. But for a finite number of four or less, placement is a factor and non-symmetrical is better. That doesn't mean that each and every source must be randommly placed only that a tendency for a random placement will tend to yield a better LF response. Categorizing everything I say into absolutes is not the way to an understanding of my position. Its not that black and white.

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?

• Computer Simulation of Room Acoustics