Hello Doublej,
Thanks for joining in, and for telling us about not one... but THREE speakers that you'd really really want to see.
I'll come back to the wall-and/or-corner friendly speaker in a few paragraphs - I'll have a lot to say about that one.
The behind-the-couch speaker is a totally new concept to me. I've never thought about that placement option before. I take it you have in mind the couch being a few inches out from the wall, and the speakers are between the couch and the wall? If so, I'm envisioning a wide, shallow box with probably most of the drivers facing up (maybe a woofer down lower that's too wide to fit on the shallow top of the enclosure). We'd need to pack a lot of output into a format that's just a few inches deep. On-axis response would be pretty much irrelevant, as we'd be listening to the speakers' reverberant energy only since we wouldn't have line-of-sight to the drivers. But the power response (summed omnidirectional response) would matter a great deal. Then there's the effect of the couch itself - if it's a cloth couch it would be highly absorptive, but if it's leather it would be reflective at mid and high frequencies and absorptive at low frequencies. We'd probably want to protect the drivers from stuff falling onto them off the back of the couch, so grilles of some type would more than likely make sense. But I don't see any insurmountable obstacles - only some interesting challenges.
Next is the kitchen cabinet loudspeaker pair that doesn't give you a hole-in-the-middle even though they're 12-15 feet apart. Okay, first let's look what I'd do to avoid a hole-in-the-middle. Two words: Toe-in. (Or, is that one word??) The way to avoid hole-in-the-middle with two widely-spaced speakers is to toe them in severely. And in my opinion such speakers should be designed from the outset to be toed in. This means they should have a radiation pattern that is as uniform as is practical across a wide horizontal arc. If you don't mind building a kit, Madisound has already designed this speaker. It's called the "Loki", and uses a Seas coaxial driver. The coaxial format gives very good pattern uniformity over a wide horizontal arc (something like 110 degrees in this case, if I recall correctly). Like any speaker they'll have more output on-axis than off-axis, but the output falls off fairly smoothly as you move off-axis so these speakers are very good candidates for an application like this. Toe 'em in a good 45 to 60 degrees or so. I currently use the Seas coaxials in speakers of my own design in my home theater system. This is a product I'm not planning to market mainly because I can't begin to compete with Madisound's kit price; they hadn't come out with the kit yet when I designed mine, so at the time I had high hopes.
Here's the Loki:
http://www.madisound.com/catalog/product_info.php?cPath=35_40_275&products_id=1688Just for fun, here's a link to a picture of my Seas-coaxial-based speaker, which I showed alongside the big Jazz Modules at the Lone Star Audio Fest in Dallas last May.
http://www.positive-feedback.com/Issue31/lonestar.htm scroll down about 1/4 of the way
I call my little coaxial speaker the "Leela". If you're not a Futurama fan, click on this link to understand why:
http://ng.netgate.net/~mette/fandom/costumes/leela/LeelaOrig2.jpgFinally, let's look at the wall-and/or-corner friendly speaker. In my opinion, a design that is going to reflect midrange or treble energy off of a very nearby wall or corner is a mistake (bass energy usually can't help but be reflected off nearby room boundaries). Research has consistently shown that early-arriving reflections are detrimental to perceived sound quality (this was even shown in research published by the designer of an omnidirectional system). However - and this is where omnis and bipolars and other polydirectionals shine - an abundance of late-arriving reverberant energy is usually perceived as timbral richness and lushness. So a polydirectional located some distance from the walls works very well.
In my experience (and I've just recently completed some experiments in this regard), polydirectionals aren't the best choice for a speaker that's going to go up against the wall or in a corner, unless geometrically there won't be additional early-arriving reflected energy.
Corner placement is even more demanding. Energy that normally would have gone wide to the sides is now funnelled early into the listening area via the intersecting walls, and this tends to color the sound in undesirable ways. The answer in my opinion is a speaker whose radiation pattern is no more than 90 degrees wide, down to as low a frequency as the speaker's physical dimensions will allow (directional control requires larger and larger size as we go down lower and lower in frequency - this is why bass horns are huge while treble horns are small).
In my opinion there's a speaker on the market that's a significant upgrade over the Klipschorn. It's called the Seven Pi, and uses a much simpler but very effective bass system along with higher quality parts than the Klipsch uses. It's available in several versions; more information can be found at
www.pispeakers.com.
Now if you're looking for a speaker that is either wall-or-corner friendly, then it's got to have the controlled radiation pattern that corner placement calls for along with a bass system whose tuning can be changed dramatically so that instead of becoming boomy with corner placement, it just goes deeper. I'm already producing that speaker - actually, two of them. Both my Jazz Modules and my floorstanding version of Stormbringer (which uses essentially the same enclosure) have bass systems that can be tuned from 37 Hz all the way down to 21 Hz by changing the length of the port, and the speaker is -9 dB at 21 Hz with the latter tuning. Corner loading gives a theoretical +9 dB boost. I haven't had the opportunity to test the theory because I don't have a room with two usable corners, but it ought to work. I know they can work well very near corners, tuned to the mid 20's.
Another speaker that works well with corner loading is the Audio Note An-E series. In fact, I stole my rear-porting configuration directly from them; I just added the user-variable tuning feature (mine uses a modular flared port that can be removed and the port length changed).
Of course, maybe for one reason or another (looks, size, cost) my speakers wouldn't work for somone who's looking for a wall-and/or corner friendly speaker. Perhaps I should make a downscaled version?
So anyway out of your three suggestions, I see two that I can add to the list of what would be feasible: The behind-the-couch speaker, and a scaled-down version of what I'm already doing in my current speakers. The kitchen-cabinet speaker, imho, is already being offered in a Madisound kit, or if you don't want to do a kit, then look into a coaxial by KEF or Tannoy or Gradient.
Once again, thanks for your rich suggestions, Doublej!
Duke
