20Hz-30Hz in small room?

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5ergo

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Ive talked to a few guys that should know about room acustics and they all said that you cant reproduce that low in small room even if you have bass traps.

But there was one guy that wrote an interesting article about it and said that its possible with proper bass traps.
here: http://www.ethanwiner.com/acoustics.html#big waves

Now i want to ask you guys as well about it.
What i have i mind is my 9.85 x 13.1 feet room with high (9.85 feet) ceiling.I will buy a sub that can actually reproduce 20Hz well. And no my setup is not for mixing but for fun, so no "dont use sub" advices please ;)
I will use a sub for movies and listen music without it...

So what do you say?
 
You can absolutely reproduce 20-30Hz in a room that size. What you can't and won't get is modal issues that low. In fact, in a smaller room, you'll not have direct axial modes down that low providing any reinforcement/cancellations at those frequencies. Now, you can still potentially have some tangentials and obliques that low.

Bass absorbtion and control will still help though. To say that you can't reproduce lower than the axial modal frequencies of the room is simply incorrect. My room for example is 17x21x8. I'm flat within +/-5db down to about 17Hz even though the dimensions (if you believe the premise) should not support lower than 22Hz.
 
5ergo said:
What i have i mind is my 9.85 x 13.1 feet room with high (9.85 feet) ceiling.I will buy a sub that can actually reproduce 20Hz well.
Click to expand...

Yep, shouldn't have a problem. When you shop for a sub, be sure you are really getting 20Hz--the specs might say 20Hz, but it might be way way down. Now just about any driver I've ever seen specs on is down some that low, but it's a question of how much. It's best if the manufacturer publishes a response curve so you can compare.

For music it's less demanding as you can be happy with 40Hz.

Don't be afraid to mix with a sub in a treated room, as long as you have the sub properly calibrated. Then just turn it up when you watch movies :)
 
> What i have i mind is my 9.85 x 13.1 feet room with high (9.85 feet) ceiling. I will buy a sub that can actually reproduce 20Hz well. <

You already got the correct answers, confirming what I wrote in my Acoustics FAQ. But please understand that a room that size and shape (square) will have serious bass problems throughout the mid to upper bass range, and a subwoofer will not help that. So you'll still need as many bass traps as you can manage.

--Ethan
 
Hey Ethan, if a bass trap absorbs low frequencies, and broad band absorbers absorb mid and high frequencies, why don't they call them--broadband "traps" :confused: :D
fitZ
 
Broadband?...is that like the GoGo's or the Bangles?
 
Ok thanks for this!

Which sub?
http://www.svsubwoofers.com/subs_pb12_plus_response.htm
This one, only ill have the cylinder version.People say its quite sick :)
I have in mind crossover to be low (like 50Hz).

"Don't be afraid to mix with a sub in a treated room, as long as you have the sub properly calibrated. "

No mixing, just playback for fun.

"But please understand that a room that size and shape (square) will have serious bass problems throughout the mid to upper bass range, and a subwoofer will not help that"

Well its more like a rectangle (4x3meters).And yes i will damp it. In fact i thought i could simply put a large, "fat" blanket on the whole wall behind speakers.

Picture of my room:
http://freeweb.siol.net/loreni23/mojanova.jpg

Ill first measure FR of a room via PC and mic. Which (free) app do you guys suggest?
 
5ergo said:
Well its more like a rectangle (4x3meters).And yes i will damp it. In fact i thought i could simply put a large, "fat" blanket on the whole wall behind speakers.
Click to expand...

Sergo,

I large fat blanket will not do one thing to help you with low frequency sound issues - at best you might help with some high mid to hig reflections.

You need to begin studiying how to handle low frequencies.

DO a search here - or a google search - you'll find lots of information out there on the subject.

Rod
 
yes i know but i also have mid bass issues, so bass traps + blanket for overall bass.
 
If you do soft, scrim faced, bass absorbers, they'll do the midbass and lower mids just fine.
 
Like this blue and violet foam here?
https://photobucket.com/albums/v342/RINGO-4-LIFE/?action=view&current=HOME-STUDIO-118.jpg

I found this pic searching this forum and i learned about a few things.
Im going to put this foam on my wall behing speakers and lots of bass traps on corners and a few on side walls, ceiling and that would probably be it.

But it aint going to be quite right, cause side walls will be mostly dry in front side of my room and vice versa.
 
Keep in mind that there are no instruments that get anywhere near 30Hz, unless you have a pipe organ in your den. If you get down to 60, you're probably good to go.

And Ethan is the best resource for home studio acoustics.
 
If you're looking to save money and reach deeper, 6" of 703 fiberglass will do a superior job IMO. As long as you don't mind a little DIY, it's tough to beat.
 
Hate to disagree but here are the specs for 6" of 703
125_250__500__1k__2k__4k
1.19 1.21 1.13 1.05 1.04 1.04

...and that's mounted flat on a wall.

6" of OC 1240 is as follows:

125_250__500__1k__2k__4k
1.31 1.14 1.11 1.09 1.06 1.07

Straddling a corner with 6" so you have a 12" or so airspace behind it will yield significant benefit down into the 50's.

Will more thickness help? Sure. But don't discount what 6" of 703 or 705 can do for you.
 
Hey, bpape,

Where did you get those specs? I've been involved in a lot of specing of acoustic test facilities, and my understanding of the physics is that you need a 1/4 wavelength of material to get adequate absorption to get a free field. In our anechoic chamber we're using two foot wedges and it's only rated down to 100 Hz.
 
Thanks but im not a DIY guy really so ill probably buy Eathans stuff, though i doubt ill gain much 20-30Hz with bass traps.

Yes i need that low, dvds go even below 20Hz...

So you say its better to use bass traps instead of foam on wall behind speakers?
 
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