Would you consider this trend, or feature, between speakers in the same product line to be typical throughout the industry?
It certainly is true for B&W. Many other speaker makes and product lines seem to have an identifiable sound, but I couldn't speculate how widespread this is. Even within a company as large as B&W, and their well-known sound features or flaws (depending on your preference), there seems to be big differences between the sound characteristics of their 600 and CM series and the much higher priced and much better sounding (and measuring) 800 series. To me, it's almost as if the 800 series are made by a different company.
Are there any rules or guidelines about speaker size vs. room size? I keep reading about bass extension in small to medium rooms and large speaker placement problems in small rooms.
None that I have enough confidence in to repeat to others
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How bass sounds in a room isn't a simple matter of a speaker's size and it's bass extension as measured under optimum conditions. Just the same, many people do choose to use larger size and more amp power to attempt to solve problems. Brute force can work, but it costs money and it won't necessarily solve the problem.
You have to think about reflections off of walls, ceiling, and floor, and the locations of the listener and the speaker or sub woofer relative to those reflecting surfaces. How this behaves varies with the wavelength and the room dimensions. This is a complex topic and I won't attempt to try and explain here. Read this for starters, read this:
http://en.wikipedia.org/wiki/Loudspeaker. Scroll down to the paragraphs on Listening Environment, Placement, and Directivity to get a feel of the complexity. Here is one short paragraph under Placement:
"In a typical rectangular listening room, the hard, parallel surfaces of the walls, floor and ceiling cause primary
acoustic resonance nodes in each of the three dimensions: left-right, up-down and forward-backward. Furthermore, there are more complex resonance modes involving three, four, five and even all six boundary surfaces combining to create
standing waves. Low frequencies excite these modes the most, since long wavelengths are not much affected by furniture compositions or placement. The mode spacing is critical, especially in small and medium size rooms like recording studios, home theaters and broadcast studios. The proximity of the loudspeakers to room boundaries affects how strongly the resonances are excited as well as affecting the relative strength at each frequency. The location of the listener is critical, too, as a position near a boundary can have a great effect on the perceived balance of frequencies. This is because standing wave patterns are most easily heard in these locations and at lower frequencies, below the
Schroeder frequency – typically around 200–300 Hz, depending on room size."
If you listen to some bass heavy music, and simply walk around the room you'll find locations where the bass seems louder, and other locations where it is lacking. A simple solution to puny bass is to move the speakers or the listening position. Of course, in many homes this isn't always possible.
This is the problem that room EQ software such as REW, Audyssey, or YPAO try to solve. Its a great idea, but they have had variable success. Different people love or hate the results. Stay tuned as the software improves.
