Room acoustics
Sep 27, 2004 at 10:19 PM Thread Starter Post #1 of 36

gerG

Headphoneus Supremus
Joined
Jun 22, 2001
Posts
2,374
Likes
10
Location
Arizona/Michigan
Room acoustics is a popular topic on head-fi. I believe that it is of special interest to dedicated headphone listeners who are transitioning to speakers, or listeners (like me) who walk the fence between headphones and speakers. The reason I make this statement is that we get used to listening to music with minimal reflections, especially in the midrange and lf range. Speaking for myself, I find that the more I listen to headphones, the less tolerant I am of room reflections on my speaker systems.

I thought that I would start a general room acoustics thread as a collection point for ideas, successes, failures, links, and educational discussion. I am no expert at this, but I can at least share my mistakes as I go along. I am working on a room right now, so here is the story so far. Sorry about the format, but space limits mean crunching as much as possible. The link is a 1.5 meg pdf file.

gerG


Livingroom update
 
Sep 28, 2004 at 1:15 PM Post #2 of 36

jefemeister

Headphoneus Supremus
Joined
Sep 7, 2003
Posts
2,807
Likes
11
I bought a pair of ASC Tube Traps awhile ago and couldn't be happier with the results. But at $700 a pair, they are a little pricy. I've seen articles on how to make your own, I'll try to find and post them later tonight. Here's my thread from awhile ago on the subject:
http://www6.head-fi.org/forums/showthread.php?t=57894

BTW, your link above is broken
 
Sep 28, 2004 at 1:22 PM Post #3 of 36

NetRunner

100+ Head-Fier
Joined
Jan 17, 2003
Posts
141
Likes
10
Good topic.. Just recently when your Behringer DEQ2496 thread surfaced I got interested in it. For room eq purposes mainly. I had been thinking about some parametric (Behringer included) eqs before too.
I have to see if it's any help on room nodes, though that is not adviced. Treble seems to need a little lifting too because of slight over abundance of absorbting materials. (Though, Rat shack meter isn't too accurate, to say for sure, if that really is the case..)
 
Sep 28, 2004 at 1:31 PM Post #4 of 36

spwal

500+ Head-Fier
Joined
Oct 22, 2003
Posts
630
Likes
10
dude,

there are SO many other things to worry about besides room acoustics unless you are living in a marble church or something.

but really, just put a couple cushions up against the wall and hang some fleeces on your torchiere lamps, angle your speakers properly and you will be fine.

spending 700 bucks on acoustic damping is pretty insane, at any level.

if you have a garage and want to have fun and carpet the ceilings, thats your business, but for the rest of the living room listening public, creating a couple odd angles at the first reflection point and breaking up the corner of the rooms with hanging fleeces or jackets is good enough.

sean

this isnt my advice, this is the uber high end shop owners advice to me. Im not qualified to talk about room acoustics.
 
Sep 28, 2004 at 1:38 PM Post #5 of 36

jefemeister

Headphoneus Supremus
Joined
Sep 7, 2003
Posts
2,807
Likes
11
Quote:

Originally Posted by spwal
if you have a garage and want to have fun and carpet the ceilings, thats your business, but for the rest of the living room listening public, creating a couple odd angles at the first reflection point and breaking up the corner of the rooms with hanging fleeces or jackets is good enough.


and when's the last time that anyone on this forum did something just "good enough"?
biggrin.gif
But seriously, acoustics are essential and while the things you suggest are definitely the first place to start, a properly treated room in worth its weight in gold. I'm not sure how uber your uber high-end dealer is.
 
Sep 28, 2004 at 2:57 PM Post #6 of 36

NetRunner

100+ Head-Fier
Joined
Jan 17, 2003
Posts
141
Likes
10
spwal: Eh.. Most people I know think that the room acoustics have the biggest effect on sound besides the speakers themselves! So at least I might put that much in acoustics.. *Though, there isn't much room place anything...*

I have a room node of >10dB at 60Hz (well.. the response is pretty much a roller coaster all the way) and highs are -10 dB down above 11kHz.
 
Sep 28, 2004 at 3:56 PM Post #7 of 36

gerG

Headphoneus Supremus
Joined
Jun 22, 2001
Posts
2,374
Likes
10
Location
Arizona/Michigan
Is the link still broken? It works for me, but maybe it is just being polite.

I absolutely believe that the room is the most critical component. Chasing upgrades beyond mid-fi in an average room is pretty pointless for me. This became abundantly clear when I set up an outdoor system. The lack of boundary effects did astonishing things for the image and realism. I want that effect indoors now. I am perfectly willing to spend more on the room than the speakers, because the room is more important than the speakers. What good are transducers that are +/- 1 db across the spectrum if the room turns them into +/- 10 db shoutmeisters?

That said, I have no intention to go out and just buy some of the standard noise control solutions on the market (many of which I believe to misapplication of theory). Part of this is about learning. For whatever reason, I have a passion for acoustics, and I want to understand my own environment better. It was a genuine revelation when I discovered that I could calculate internal dimensions of a room, or car, or headphone, from a simple response plot. I need to do a lot more reading on the subject, but the discovery process is a lot more fun.

I had another thought for muting some of the LF wave bounces. Difficult to treat at the walls, since that is a pressure boundary (same for the corners). Real bass traps work by converting the pressure to velocity, then imposing a loss mechanism. However, there is a velocity boundary in the middle of the room (vertical plane for the side walls, horizontal for the floor/ceiling), so I am thinking of ways to work on that. Should work in theory, could be ugly in practice. More tricks to try.


gerG
 
Sep 28, 2004 at 5:37 PM Post #9 of 36

ooheadsoo

Headphoneus Supremus
Joined
Dec 11, 2002
Posts
4,835
Likes
11
Well, here's my DIY panel thread again. If I were to do it again, I'd step up to the 6pcf stuff. http://www6.head-fi.org/forums/showthread.php?t=78414

Here's what you need to make your own ASC type tube traps: http://www.knauffiberglass.com/index...rodDetail&ID=1
You might consider stuffing the tubes with fiberglass as well to increase absorption. Decorate to taste. Here are some examples:
!cid_image001.jpg

!cid_image002.jpg


On the otherhand, what would arguably be even better in performance than the fiberglass tube traps but tough to make attractive would be Jon Risch's SQ&D traps (simple quick and dirty.) Just buy some bales of fiberglass from your local hardware store and stack 3 bales in each corner. Decorate as needed.
 
Sep 28, 2004 at 5:46 PM Post #10 of 36

gerG

Headphoneus Supremus
Joined
Jun 22, 2001
Posts
2,374
Likes
10
Location
Arizona/Michigan
jefe, it just broke on me as well (sort of random). Try downloading the link target, that seems to be more reliable. I have been having a lot of trouble lately launching pdf files from my browser.

ooheadsoo, are those diy line arrays? I would love to try that, but it is an expensive experiment.


gerG
 
Sep 28, 2004 at 6:14 PM Post #12 of 36

ooheadsoo

Headphoneus Supremus
Joined
Dec 11, 2002
Posts
4,835
Likes
11
The bottom picture is for the tube bass traps in the front corners of the room
smily_headphones1.gif
Of course, line arrays would be nice too, but they won't be under $100
wink.gif
Those are GR Research's Alpha line arrays. You can buy them in kit form or completed.
 
Sep 28, 2004 at 7:00 PM Post #13 of 36

gerG

Headphoneus Supremus
Joined
Jun 22, 2001
Posts
2,374
Likes
10
Location
Arizona/Michigan
Good links guys, keep them coming.

Here is the asc site: asc tubetraps

What I have in mind will use a similar principle (using perforated boundary to convert pressure to velocity) but cover more area. The ASC traps look like they will work, but only treating the corners will not be enough. The reflections in question are off a large part of the boundary, so I need area coverage where the pressure effects are at.

One of the problems with the traps is that they also chew up some of the primary signal. It would be better to leave the primary intact, and just cancel the bounce. I had some fun a few months back by using an extra subwoofer against a back wall (different room). I fed it an out of phase signal, with a time delay equivalent to the transit time across the room. It worked like a charm! I have a wrinkle on this approach to try as well.

Dang I wish I could stay at home and play with this stuff.


gerG
 
Sep 28, 2004 at 7:11 PM Post #14 of 36

CSMR

1000+ Head-Fier
Joined
Mar 24, 2004
Posts
1,162
Likes
11
Quote:

Originally Posted by gerG
Speaking for myself, I find that the more I listen to headphones, the less tolerant I am of room reflections on my speaker systems.


Quote:

Originally Posted by GerG
This became abundantly clear when I set up an outdoor system. The lack of boundary effects did astonishing things for the image and realism.


Is that what is best, lack of reflections? That's certainly not the case for instruments. On the violin rooms that are too small give a very hard sound (sometimes they are damped but it's pretty useless IMO); very large rooms can give an echo and a dry sound; rooms with odd angles, big objects or anything that will give strange reflections sound harsh. That's what I think I find from experience. With speakers though I suppose the effect of room acoustics in the recording location will already be recorded, so is that why it's best to totally minimize reflections?
 
Sep 28, 2004 at 7:23 PM Post #15 of 36

ooheadsoo

Headphoneus Supremus
Joined
Dec 11, 2002
Posts
4,835
Likes
11
It's a totally different reason why you want to do it for speakers compared to for instruments, though the reason why the unwanted sound effects occur are the same. gerG linked a good paper on some reasons why things occur the way they do and why it is important which I'll just link to for convenience here:

http://www.infinitysystems.com/homea...kers_rooms.pdf

Actually, I don't think anyone thinks that reflections should be 100% absorbed. No speaker designer designs his speakers for anechoic chambers
tongue.gif

Here are some broader acoustics articles written in plain english:
http://ethanwiner.com/acoustics.html
http://www.realtraps.com/articles.htm
http://ethanwiner.com/articles.html
 

Users who are viewing this thread

Top