Danny's Weblog
Mounting speakers in walls
Many years ago I was interested in hi-fi and learned all about speaker design: impedance curves, crossover networks, resonance, etc.
The big problem with speakers has always been reflections. Whether from the internal surfaces of the speaker itself, or the surroundings, the reflections cause undesired resonance, impedance anomalies, etc.
I was vaguely musing about this a few weeks ago and it occurred to me that many of these problems are alleviated by mounting speakers in the wall and allowing the rear of the speakers to remain open into a large, relatively non-reflecting room. (Not my original idea!)
Today I Googled for that idea and was unable to find it. In particular, when I looked for wall-mounted speaker info, the manufacturers made no recommendations that I could find for making sure that the speakers were mounted in a repeatable way – that is that ensures that the required specifications for frequency response etc can possibly be met.
Likewise, some happytalk pages about installing wall-mount speakers (aimed at people moving into a new house) made no mention of verifying that the response of the speakers would be adequate, and gave the impression that they could be covered (concealed) with various fabrics at the whim of the homeowner. (Ie, the effect on frequency response of high-frequency losses in the fabric – or anything else – was ignored.)
Many commercial speakers (in cabinets) sound rotten even after (presumably) someone verifying the design. What is the chance that speakers will have any fidelity at all after installation by a *builder*? This reminds me of the way humanity has lost manned spaceflight capability; I suppose it's hardly as important, but it's just as significant, that what was once *common knowledge* about acoustic design has disappeared from the culture.
Incidentally, in Googling for the idea above, I was curious what solutions had been found for maintaining phase coherence between high and low frequencies if the high-frequency radiators are mounted separately from the low-frequency (allowing the high-frequency radiators to be swivelled inwards for a larger "sweet spot"). I was expecting digital delay lines and whatnot... but no....
This guy sounds like he knows more than I ever did, so I guess I can't say audio knowledge has disappeared from the culture *entirely*: [http://www.helsinki.fi/~ssyreeni/dsound/dsound-a-03] (it's a long article about sound synthesis, and discusses eg "matrixing subchannel coefficients" *before* the "Advanced Topics" section).
On the other hand, it seems to me that three decades ago a lot of the webpages one sees advertising audio would have been viewed as preposterously ill-educated by most audio consumers.
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