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#1646881 - 03/03/04 01:48 PM Approaching plaster walls ?
david5858 Offline
Member

Registered: 12/05/01
Posts: 17
Loc: ,,UNITED STATES
Ethan,
I've just finished reading your Top Ten Small Room
Acoustic Improvements article, http://www.ethanwiner.com/eq_vibe.html
and I'm ready to give it a go, yet there are 2 concerns about my room that I want to mention to see if you would have me proceed with any variation to what the article suggests.
The room is 14 x 10 with a 9 ft ceiling.
It will be the control room.
The 2 concerns are . . .
1. plaster walls
2. wall to wall, cut pile carpeting
Thanks again Ethan,
David
_________________________
david5858

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#1646882 - 03/03/04 02:42 PM Re: Approaching plaster walls ?
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
David,

I usually prefer a reflective floor and absorbent ceiling, but carpet is okay if it's thick enough. The issue is avoiding recurring reflections between those two parallel surfaces. Carpet is thin and so absorbs only higher frequencies, which lets the lower frequencies continue to rattle around. So if you instead put thick dense absorbers on the ceiling you can solve that problem effectively and to a much lower frequency.

Plaster walls are fine, and any problems caused by reflections there can be treated with some amount of absorption in a few key places.

Have a look at the Acoustics FAQ, second in the list on my Articles page:

http://www.ethanwiner.com/articles.html

In particular, see the sidebar "Hard floor, soft ceiling" for more opinions and advice about carpet in studios and control rooms.

--Ethan

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#1646883 - 03/04/04 06:02 AM Re: Approaching plaster walls ?
david5858 Offline
Member

Registered: 12/05/01
Posts: 17
Loc: ,,UNITED STATES
Thanks Ethan,
As you suggested, I looked at your FAQ article and for simplicities sake I’m thinking of installing bass traps in the control room as shown in figure 3a of that article using either 2 or 4 inch thick #705 FRK. This would be in addition to the thick dense absorbers for the ceiling that you mentioned earlier if they would still be necessary as well as absorption in other key areas that you also mentioned.
Several questions come up… ,
1. My ceilings are 9 ft. Can I go with 8 ft fiberglass bass trap panels as shown in fig. 3a?
2. If so, should the 1 ft. space that’s leftover be at the ceiling or at the floor, or a little of each?
3. Is this cross corner bass trap panel to be mounted on 1/8” or ¼” plywood as shown in your “build a better bass trap “article?
4. Should I use 2 inch #705 FRK or 4 inch?
5. And finally (if there is such a thing)
I have two windows in this room, each of which is within 11 inches of a corner.
This will effectively prevent the panels near those windows from joining the walls at equal distances from there respective corners. The best I could do would be to have those panels join the walls at the 11 inch mark next to the window casing, and go cross corner to the other side to a point roughly 21 inches from the corner on that side.
Would this give the same absorption as the ideal way it is shown in fig 3a?
Again, the room is 14x10x9 and if it matters. . . the 2 windows are on the wall behind the listener.
Thanks again, David
_________________________
david5858

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#1646884 - 03/04/04 11:45 AM Re: Approaching plaster walls ?
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
David,

> My ceilings are 9 ft. Can I go with 8 ft fiberglass bass trap panels as shown in fig. 3a? <

Yes. You can center the panels vertically so there are equal gaps above and below.

> Is this cross corner bass trap panel to be mounted on 1/8” or ¼” plywood <

No, those are two different designs that work on entirely different principles. Rigid fiberglass works fine all by itself. Wood panel traps need rigid fiberglass inside, but that's not the primary absorption mechanism.

> Should I use 2 inch #705 FRK or 4 inch? <

Four inches is better.

> The best I could do would be to have those panels join the walls at the 11 inch mark next to the window casing <

Not a problem. It doesn't have to be exactly 45 degrees. As long as they're basically straddling the room corners they'll work fine.

--Ethan

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Moderator:  Ethan Winer