[polarbare]

Hello all - well, I've finally decided to update the system, and after putting in a reasonable investment in electronics and speakers, I'm now left with room acoustics. Unfortunately, I live in an apartment (can't quite find the right house where I want it...), so space becomes a premium (with all of my crap  ).

I'm mainly going to be doing bass trapping, and was wondering how much you have to have at a minimum before it becomes effective. The main living area is 14' x 24' x 9' tall. Because of sliding glass doors leading to the patio, the system is oriented across the short axis of the room. I can only add bass traps to 3 corners of the room, as one corner has a door that leads to the garage. I would post pics, but the place is a disaster  Will trapping only three corner floor to ceiling be worthwhile? I am debating the GIK tricorners vs 244 panels straddling the corners (mainly because of the cost differential to be honest).

P.S. What software do you recommend for being able to show the room layout (walls, openings, furniture, crap)?

[drummermitchell]

The guys say more bass trapping the better.I also don't have an ideal(size wise+it's a living room)
and I have just a bit of gear .
I purchase 4 Gik tritraps and stacked them in the front corners.
Before using 2 subs with my TT,I could only turn her up so much,I'd get low feedback thru the subs.
When I installed the tri's,I could use both subs and turn her up(no feedback)and the bottom is a lot more defined.
I also have one corner(too much stuff)I can't use.I did order 2 more tri's for the other corner,
should be hear next week so I'll have 3 corners double stacked.
I was quite surprized how much they cleaned up the music,even with lots of stuff in the room.
If I can hear a major improvement in my room,I'm sure you will with yours.
I'm also sure if I had less stuff in there,it would improve bigtime,mine is 11X15(HUGE) .

[Nyal Mellor]

I know others will probably disagree but I would focus on using treatment for early reflection and reverberation time control (the ceiling being a good place where you can put a lot without it becoming visually intrusive). These selfsame treatments can also provide useful bass trapping if used in 3" or 4" depths.

You need quite a few bass traps to make a worthwhile difference (although every little helps). Getting good bass is very speaker and listener position related. Put them somewhere bad (like having your listening position in the center of a room) and you are going to be chasing your tail with bass trapping.

[polarbare]

I know others will probably disagree but I would focus on using treatment for early reflection and reverberation time control (the ceiling being a good place where you can put a lot without it becoming visually intrusive). These selfsame treatments can also provide useful bass trapping if used in 3" or 4" depths.

You need quite a few bass traps to make a worthwhile difference (although every little helps). Getting good bass is very speaker and listener position related. Put them somewhere bad (like having your listening position in the center of a room) and you are going to be chasing your tail with bass trapping.

The ceiling might be a bit problematic as I don't want to mess it up and get charged when I move out. One early reflection will be where the sliding glass door is - putting a real trap there is problematic, but I can put up some heavy drapes to help take care of that (thanks - wasn't really thinking about early reflections at this time, but that one seems simple enough). The only other early reflection I can address would be there rear wall - there is a painting there, but I could take a high resolution photo of it and have GIK make and art panel. The coffee table is a bit problematic, given it's also the table I eat at (hey, I'm a bachelor ). Maybe a thick blanket I can put on it when listening to two channel, but the rest of the time just leave off.

As far as the number of traps, I would be using 6 of the Gik tritraps - not sure how I could squeeze more in here currently. The other thing is, I am looking for a house, so I don't want to go too crazy at this time.

[drphoto]

Uhhh are you talking about bass trapping to improve sound, or to avoid complaints from your neighbors?

What are your speakers? Subs?

OB subs are less prone to 'room shaking', but still providing an satisfying experience for the listener, at least in my limited experience. But any significant bass will still leak out of the room. This pretty much the only reason I'm glad I my own place, now that the idea of property as an investment has been shot to hell.

I'm a convert to the idea that multiple subs can smooth out bass response. Doesn't mean there isn't a need for traps, but can perhaps reduce the number needed.

[polarbare]

Uhhh are you talking about bass trapping to improve sound, or to avoid complaints from your neighbors?

What are your speakers? Subs?

OB subs are less prone to 'room shaking', but still providing an satisfying experience for the listener, at least in my limited experience. But any significant bass will still leak out of the room. This pretty much the only reason I'm glad I my own place, now that the idea of property as an investment has been shot to hell.

I'm a convert to the idea that multiple subs can smooth out bass response. Doesn't mean there isn't a need for traps, but can perhaps reduce the number needed.

Improve sound - I'll be listening during the day, when everyone else is at work. Speakers are going to be Salk HT2-TL's (still being built), subs are a pair of Rythmic F15SE's.

[oneinthepipe]

You can install panels on stands for locations where portability is important, such as in front of a sliding door.

Regarding the ceiling, you could build a rack, either from wood or metal, similar to the rack that Richard Vandersteen built, that rises straight vertically against the sides of the listening room with a horizontal bar connecting the two sides.  The rack or frame would look something like an upside down U without the rounded top but with crossbars on the bottom legs for stabilization.  Richard Vandersteen's rack is made from square tubing with holes and has pins for easier assembly and disassembly.  You could attach ceiling treatments to the top and reflection point treatments to the sides.  The rack can be moved forward and backward for fine tuning, and you would not need to worry about damage to the side walls or ceiling. Here is a link to the Vandersteen room at RMAF.  http://spintricity.com/58/public/Vol1-10#/58/4536/oct-2009/rmaf-2009---audio-alternative-audio-research-shunyata-research-vandersteen-audio

[James Tanner]

Hello all - well, I've finally decided to update the system, and after putting in a reasonable investment in electronics and speakers, I'm now left with room acoustics. Unfortunately, I live in an apartment (can't quite find the right house where I want it...), so space becomes a premium (with all of my crap  ).

I'm mainly going to be doing bass trapping, and was wondering how much you have to have at a minimum before it becomes effective. The main living area is 14' x 24' x 9' tall. Because of sliding glass doors leading to the patio, the system is oriented across the short axis of the room. I can only add bass traps to 3 corners of the room, as one corner has a door that leads to the garage. I would post pics, but the place is a disaster  Will trapping only three corner floor to ceiling be worthwhile? I am debating the GIK tricorners vs 244 panels straddling the corners (mainly because of the cost differential to be honest).

P.S. What software do you recommend for being able to show the room layout (walls, openings, furniture, crap)?

Hi polarbare,

The formula for figuring out how thick the absorber has to be is:


AbsorberThickness Formula:

1130/ (4 x First Null frequency)

Example:

For 250 Hz absorption:

1130 / (4 x 250)  = 1.13 ft thick.


james tanner
Bryston

[Levi]

Lots of good information here.  I could not agree more, room acoustics is very important in having a good sound.

Brian helped me with my room.  If you contact Brian (Bpape), he has a software you can download for your laptop.  He is the moderator at Hometheatershack.  If he is not too busy, you can ask him to analyze the data you gathered.  Perhaps, you can send him a picture of your room to go along with your data.  He will then recommend how many panels to use in key locations.

--Levi

Hello all - well, I've finally decided to update the system, and after putting in a reasonable investment in electronics and speakers, I'm now left with room acoustics. Unfortunately, I live in an apartment (can't quite find the right house where I want it...), so space becomes a premium (with all of my crap  ).

I'm mainly going to be doing bass trapping, and was wondering how much you have to have at a minimum before it becomes effective. The main living area is 14' x 24' x 9' tall. Because of sliding glass doors leading to the patio, the system is oriented across the short axis of the room. I can only add bass traps to 3 corners of the room, as one corner has a door that leads to the garage. I would post pics, but the place is a disaster  Will trapping only three corner floor to ceiling be worthwhile? I am debating the GIK tricorners vs 244 panels straddling the corners (mainly because of the cost differential to be honest).

P.S. What software do you recommend for being able to show the room layout (walls, openings, furniture, crap)?

[jtwrace]

Hi polarbare,

The formula for figuring out how thick the absorber has to be is:


AbsorberThickness Formula:

1130/ (4 x First Null frequency)

Example:

For 250 Hz absorption:

1130 / (4 x 250)  = 1.13 ft thick.


james tanner
Bryston

Never saw that before...is that a standard?  GIK approved?  Bryan?

[bpape]

That formula finds the quarter wavelength of the given frequency which is the 'optimal' thickness.  Treatments MUCH thinner than that will have an impact at 250Hz or lower.

Bryan

[jtwrace]

That formula finds the quarter wavelength of the given frequency which is the 'optimal' thickness.  Treatments MUCH thinner than that will have an impact at 250Hz or lower.

Bryan

Thanks!   

[Ethan Winer]

For 250 Hz absorption:

1130 / (4 x 250)  = 1.13 ft thick.

That seems a bit over-spec'd.

100 percent absorption is not strictly needed. You can avoid the worst of the comb filtering due to early reflections with rigid fiberglass 2 inches thick, though 4 inches thick is a little better. Even if a material absorbs only 20 percent, a null that's infinitely deep is reduced to 19 dB deep. Double that to 40 percent and then the null is only 13 dB deep. At frequencies where the absorber is 50 percent effective the null is only 11 dB deep. By comparison, 703 rigid fiberglass that's 2 inches thick absorbs 86 percent at 250 Hz reducing a null to around -4 dB.

--Ethan

[Jeffrey Hedback]

Going back to the OP, I do suggest that trapping the three available corners (floor to ceiling or 8'...likely same difference) is very worth doing.

Check out Google SketchUp which you can use to create a 3D version of your room...leanring curve for basic shapes is not too steep.  Or, DoubleCAD if you want to create a 2D plan view (it's free but if you don't have previous CAD experience, I'd stay with SketchUp).

If you do post drawings, all the great opinions offered thus far will be focused on your room rather than generalizations.  I think that would be most helpful.

[polarbare]

Thanks for all the info guys. It seems like I will still be able to get some benefit from even (relatively) limited treatments - I've done a fair bit of reading before posting, but throughout it all, I knew I wasn't going to be able to do everything suggested given room constraints.

Edit - thanks for the sketch up tip.

I will likely go with REW to see what effects I am having.

Edit2 - grrr, sketchup doesn't work with windows 2000