Glass Behind Speakers: What Type of Acoustic Treatment Should I Use?

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Q I own Paradigm Monitor 11 speakers and an 80-watt powered subwoofer. The speakers are set up in my living room 6 feet out from a sliding glass door. What type of acoustic treatment product should I put up behind the speakers to improve their sound? Should it be foam or something more solid? —Jon Cotton / via e-mail

A Reflected sound bouncing off the walls, floor, and ceiling of your room can negatively affect sound quality. What you need to be most concerned with is early reflections, or the sound that bounces off surfaces closest to the speaker—typically the side walls in most stereo and home theater setups.

While reflected sound off a front wall can create problems, in this case your speakers are positioned 6 feet out into the listening room—far enough that early reflections off surfaces behind them shouldn’t be an issue.

Another factor here is that you are using a subwoofer to handle bass duties. The low bass frequencies conveyed by subs radiate equally in all directions. Mid and high frequencies, on the other hand, are more directional, primarily radiating forward from your speakers. This is the most important range you can hope to treat for.

The upshot here is that, given your current speaker layout, applying acoustic treatments to the front wall of the room isn’t exactly crucial (though you may want to consider putting something absorptive like curtains over the glass doors to absorb any sound that ping-pongs off the back wall of your room). Your best investment will be to install acoustic panels or other treatments on the side walls of your room where early reflections from your speakers are most likely to be an issue.

jasonbf's picture

I own monitor 11s, v6...They were originally intended for HT, but the room proved too small (12x13)...So, I managed to accommodate them in my music room (14x17)...Not easy, since I tend to like soft and fuzzy for music...The monitors, however, tend to be vivid and somewhat bright (that titanium tweeter!!)...Frankly, I found floor and wall coverings to be of limited benefit...Besides changing out one piece of hardware, what did work best was the use of cable matching to flavor the sound...Consider cables the equivalent of herbs and spices in cooking...The monitors remain somewhat vivid and bright (their basic nature), but are now musically listenable, especially at lower volume...