# Bookshelf speakers backing



## harrym (Jan 30, 2010)

With Klipsch bookshelf speakers setting in 12-inch deep solid wood built-in shelves, would some sort of baffle cover the wall behind them? They are rear-ported, and the wall behind them [back of the shelf unit] is 1/2-inch wood nailed to the wall studs. I have considered carpeting or egg-crate foam. Would either help, or is something else recommended?


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## bpape (Sep 14, 2006)

Something thicker would be preferable. Carpet and foam will do little to nothing in the range where you'll have problems in that cavity. If there will be a covering on the shelving in front of the speakers, I'd actually recommend filling the entire cavity with absorption to minimize the problems.

Bryan


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## MatrixDweller (Jul 24, 2007)

Who ever coined the term "bookshelf" speaker ought to be shot.


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## tonyvdb (Sep 5, 2007)

MatrixDweller said:


> Who ever coined the term "bookshelf" speaker ought to be shot.


I agree, the bookshelf is the worst place to put a speaker.


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## harrym (Jan 30, 2010)

Each space in the bookshelves that houses my speakers is 13Hx24Wx12D. There is 5" of open space behind my speakers. For maximum clarity in dialogue, would making a sound trap 4" thick for the space behind the speakers help? I am considering a frame filled with fiberglass insulation and covered with speaker cloth. That would leave 1" of free space behind the rear-ported Klipsch speakers. Any suggestions?


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## Prof. (Oct 20, 2006)

Rear ported speakers in a bookshelf situation is not good..:thumbsdown:

The Manufacturers generally recommend a minimum clearance for the rear ports..and I think filling the space with fibreglass is going to muffle the sound..
I would be more inclined to fill in the space at the sides and top of the speaker, and leave the back wall clear..
Whatever you do, it's going to be a compromise with speakers in bookshelves..


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## bpape (Sep 14, 2006)

A lot depends on the situation. IF you're using a sub and crossing over the LCR's to the sub, then the port is effectively out of play as it will be tuned much lower than the 80Hz xover.

Filling the cavity is essential to killing resonances from the enclosed space. 

Bryan


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## Prof. (Oct 20, 2006)

That's a good point...I hadn't considered the sub!

So harrym..If you're using a sub, then fill er up!!


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## MatrixDweller (Jul 24, 2007)

I'm assuing from your description that you either have RB-10's or Synergy B2's or maybe even WB-14's. In any case I would suspect that you might require a higher crossover frequency on your sub than 80Hz to start with any of those speakers. The B2's might be OK at 80Hz though. The other two might require x-over's at >= 100Hz.

Best material for filling the enclosure would be rigid fiberglass or rockboard. The fluffy stuff won't work as well and will be harder to work with. You can get the better insulation from HVAC supply stores or contractors.


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## harrym (Jan 30, 2010)

No, they are the Klipsch RS/CX-4 system, with the KSW-10 subwoofer on order. I have some of the speaker cabinet insulation from Radio Shack [don't remember the name and it's no longer listed] that I planned to use. It's a loose fiberglass batt, yellow in color, probably 2" thick when allowed to decompress.


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