Aleph 5 + Dunlavy 4

"What is the theorectical benefit of toe-in ? image and directional treble ?"

Yes, the speakers are extremely directional and have very narrow and well-controlled dispersion characteristics. That's one of the reason why they can be placed fairly close to the room's boundaries without encountering severely adverse effects. Direct toe-in helps the speakers achieve the amazing focus that makes them very special.

I became interested in this thread, because I encountered a similar problem when I first setup my SC-IV's. I placed them in a manner very similar to yours, in a room almost the same size and shape, and had virtually no bass even though I was driving them with a KSA-150. It took me almost a week to open the owner's manual (audiophile pride, you know) and set them up per the manufacturer's instructions. The transformation in the sound was truly spectacular. Since then, I've setup literally dozens of pairs of Dunlavy's, and all of them sounded best with long wall placement.

If there's absolutely no way for you to utilize the long wall, I'd suggest placing your seat directly against the back wall with the speakers moved half-way into the room, as a starting point.

Best Wishes,
Felix
www.audioannex.com

Sorry to sort of go off the subject, but I really think the speaker cable needs to be changed. I think you need cables that has more emphasis in "speed" rather than "guts". Sorry if I sound like I don't know what I am talking about. Just think, "low gauge" and "low capacitence".

Felix: By mirror imaged, i was referring to the design of each individual speaker as a vertical array, not from side to side. The drivers below the tweeter are a mirror image of the drivers above the tweeter, etc...

As far as the controlled dispersion pattern goes, much of this has to do with the MTM type driver layout and the "acoustic blanket" ( damping material around the high / mid drivers ) that Dunlavy makes use of. All MTM arrays will demonstrate limited vertical dispersion. How limited the vertical dispersion is will have to do with the spacing between the drivers and quantity of drivers used in such an array.

My experience with toe-in on a speaker of this nature is that it DRASTICALLY limits the size / width of the soundstage while producing a much "hotter" high end and tonally forward presentation. Increased toe-in will also limit side-wall reflections, so it would provide better performance in non-long wall installations. While the center image is increased with toe-in, a certain amount of air / space between instruments is also lost due to increased focusing of the signal into a smaller area. In such a situation, sitting further back ( beyond the distance of creating an equilateral "V" with the speakers ) will produce an increased sensation of the performers being front and center rather than if the speakers were not toe'd in and you were sitting in an equilateral triangle. Obviously, personal preference will dictate what works best for you in your system but the experience of those like Felix who have quite a bit of experience with a product of this type should not be disregarded. Even if we do have different personal preferences : ) Sean
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"By mirror imaged, i was referring to the design of each individual speaker as a vertical array, not from side to side. The drivers below the tweeter are a mirror image of the drivers above the tweeter, etc..."

Fair enough, but that's not what mirror-imaged means.

"My experience with toe-in on a speaker of this nature is that it DRASTICALLY limits the size / width of the soundstage while producing a much "hotter" high end and tonally forward presentation. While the center image is increased with toe-in, a certain amount of air / space between instruments is also lost due to increased focusing of the signal into a smaller area. In such a situation, sitting further back ( beyond the distance of creating an equilateral "V" with the speakers ) will produce an increased sensation of the performers being front and center rather than if the speakers were not toe'd in and you were sitting in an equilateral triangle."

AFAIK, you've never setup a pair of SC-IV's. The constraints you describe are somewhat ambitious given the actual performance of the product.

"Obviously, personal preference will dictate what works best for you in your system but the experience of those like Felix who have quite a bit of experience with a product of this type should not be disregarded. Even if we do have different personal preferences : )"

I appreciate that, Sean, but this really isn't an issue of personal preference unless one has a strong desire to live with a distinct lack of bass and focus, basically negating the fundamental design goals of the speakers. There's a very good reason as to why the owner's manual goes into detail illustrating specific placement options.

Best Wishes,
Felix
www.audioannex.com

I have worked with one set of the original SC IV's ( not the re-designed "A" models ) a while back, another set of speakers* that are very similar in design but FAR more advanced and "tweaky" and several "good sized" speakers using MTM designs. As such, that experience is what i based my comments on.

Based on the experience mentioned above, I will only add that if one can't place the speakers along the long wall and minimize the amount of "clutter" between the speakers so that they can directly "communicate" from side to side, measurable toe-in will probably be a necessity. MTM speakers are designed to "spray" the sound out horizontally and if the speakers can't "blend in the middle" due to obstructions, one must force the situation by aiming them inwards to the point that the signals are forced to blend together.

Having said that, I'm sure that Felix' experience with the Dunlavy's that he owns is 100% accurate. I'm also quite sure that John Dunlavy knew his product well enough to know how they work best and included his thoughts in the speaker manual. The only variables to the two above situations are that room acoustics do differ, along with the constraints of various installations. This is not to mention that one can enjoy / prefer slightly different presentations from someone else using the same speakers. As such, one WILL have to experiment ( to a much greater extent ) with speaker placement when using a "less than conventional" speaker design in order to find out what works best for them in their room. I don't know of any speaker made that can be placed in one given set of positions, regardless of room layout or size, and obtain universally repeatable performance. Some basic suggestions may provide pretty consistent results, but there will always be exceptions to the rule due to the above mentioned variables. In other words, one size does NOT fit all. Sean
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* A custom built set of speakers using similar driver layout using as good or better quality drivers, far more advanced individual cabinetry for each driver, better quality internal wiring, no passive crossover components and active quad-amplification.