[Jack D.]

Hi,

I'm unclear of all the benefits of the CD Waveguide.

For instance, If I have a single chair, positioned in the

sweet spot, and I don't care how the system sounds while I'm

not sitting in said chair, do I still want the Waveguide?

If so, why?

[Bob Wilcox]

Jack

I have a single listening chair and rarely move around the room when I listen.

I find that the image from my RM-40s fills the center a bit better and tonal balance has improved stability. Before if I moved my head around at the listening position, I could hear some tonal balance shift as the mix from the midrange and tweeter changed with my ear position. To achieve the best FST tweeter/midrange blend it was neccessary to remove the front plate of the tweeters as described in another thread.

Overall, the speakers have a more relaxed presentation while retaining the ability to adjust their personaility through tuning. The panoramic imaging on a disc such as Roger Waters Amused To Death is enhanced.

Bob

[ctviggen]

I think because it corrects for lobing, which can occur both on and off axis.  Here's one explanation of the phenomenon:
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This occurs because dispersion is dependent on the length of the wavelength relative to the radiator. If the wavelength is long relative to the size of the radiator, there will be good dispersion. Therefore, as the frequency the driver reproduces increases, its wavelength decreases until it is too short and then the driver will begin to "beam" the high-frequency sound. With a tweeter, beaming usually occurs at frequencies beyond our perception; however, with a midrange, the poor dispersion will be noticeable. And speakers with beaming problems will create "sweet spots" in the room.

"We call this lobing," continues Paul. "For instance, you have a speaker with two drivers and a tweeter in the center, and these two drivers interact together at some frequency. If it happens to be a frequency that is proportional to the distance the drivers are apart, lobing occurs. Plotted on a circular curve, lobes have weird shapes -- flowers, butterflies -- you get very exotic interference patterns between two sources."

Lobes occur off-axis and are large fluctuations in frequency response that cause poor sound for anyone not listening on-axis. When one sits off-axis he may be listening to the interference of lobing. This explains why my dad's speakers sounded best only when he sat in his La-Z-Boy -- everywhere else in the room was off-axis, and lobes were interfering with the speaker's sound.
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From http://www.soundstage.com/gettingtechnical/gettingtechnical200312.htm

So, even if you sit in the sweet spot, you're subject to some amount of lobing/beaming.  The wave guide (or more accurately, diffraction slot as suggested by csero) reduces these effects.

[Jack D.]

Thanks Guys,

Brian or John, care to elaborate?