[klh]

I have a room that is 20x14x8 and it will be a dedicated home theater / multichannel audio room. The fronts and surrounds will be floor standing monopole speakers, and although I don't have one yet, I plan on getting a projector and screen. I want to treat the room, and I'm starting from scratch (bare room). Ultimately I'd like to keep the cost <$1,000. I am into DIY things, so I'd prefer to make the treatments myself, but ulitimately I'm after good sound, so other options and recommedations would be appreciated.

Ethan, I've checked out your websites, articles and forum (as well as your business website) and have been impressed with all.  I understand the theory you've presented... I'm just looking for ways to implement them.

I've also checked out 8th Nerve and have also been impressed with that.

Fellas, I'm looking for as close to an ideal room acoustics set up as I can possibly get while staying within the previously mentioned price constraint... what are your recommendations?

[jgubman]

Other than the dimensions, what's the room like? Typical painted drywall on a raised wood floor or something different?

How much and what kind of furniture do you plan on having?

You can start by making some of Ethan's panels and/or the various John Risch treatments:
http://www.geocities.com/jonrisch/a.htm

You'll almost certainly want some bass traps:
http://ic.net/~jtgale/diy2.htm
http://teresaudio.com/haven/traps/traps.html

[klh]

The room has wall to wall carpet and sheetrock walls and ceilings.

Thanks for the links... Chris' tube traps were particularly interesting... have you or anyone else made them?

[klh]

The room is a dedicated home theater so basically there is a couch, a 27" TV (ultimately there will be a projector and screen), and the audio electronics/speakers, etc.

[Ethan Winer]

K,

> I'd like to keep the cost <$1,000 ... I'm looking for as close to an ideal room acoustics set up as I can possibly get <

A thousand dollars won't get you "ideal" acoustics, but you can certainly make a big improvement over the bare room you have now. 24x14x8 is a nice size, but that also means you have a fair amount of total volume, which in turn means you need a fair amount of treatment - especially bass traps.

> I've checked out your websites ... I'm just looking for ways to implement them. <

Well, you basically have three choices: build, buy, or some combination of both. With that budget I think you'll do best to buy the bass traps, which are difficult to make, and build your own mid/high absortion panels from rigid fiberglass.

--Ethan

[jgubman]

K,
no, I haven't made the tube traps. I'd love to, but I just can't find a source for the fiberglass (ok, I haven't really looked that hard). Let us know if you build them and they work out. Looks like a fairly easy project to complete.

By all accounts Ethan's traps are very effective. My brother-in-law recently ordered a "room kit". I'm waiting to hear how they work out, if they're as good as I expect them to be, I'll probably get a few of Ethan's mini's.


Anyways, for a good coverage, you'd probably want 2 - 4 bass traps in the rear and maybe front corners, kill early reflections w/ 2x4 rigid fiberglass panels and get the upper room corners w/ either micro traps or 8th nerver "corners".

I'd think that would be a good place to start.

[_scotty_]

jgubman, you might consider buying this book it can probably answer most of your questions regarding acoustics and your home theatre.
Handbook for Sound Engineers, The New Audio Cyclopedia. here is a link to comments about the book,  http://www.windwire.com/wireless/asinsearch_0240804546.html

OwensCorning type 703 semirigid fiberglass can be purchased from building contractor suppliers. It isn't cheap but it is effective. A good bass trap can be made by standing a sheet up in a corner. If you put a 2ft. wide floor to ceiling panel in the corner and a 4ft. wide panel in front of it you can have even greater effectiveness at low frequencies due to the air space between the panels. Good luck with your project.

[spectralman]

I have made the Jon Risch tube traps in the past.  They work very well.  I put them in all four corners, stacked 2 to a corner.

[klh]

Ethan,

I re-read your info on "Acoustic Treatment and Design for Recording Studios and Listening Rooms" and have a question pertaining to the floors and ceiling. You recommend a reflective floor and an absorptive ceiling which helps excentuate ambiance in a studio when recording acoustic instruments. Does that extend to a purely listening environment? It seems to me that it creates a prime first reflection off the floor which would thus color the sound. If I'm wrong, please correct me, and if you have another recommendatin, please let me know.

Lastly, you have made it clear in other posts that you don't care for the LEDE design. Isn't the reflective floor/absorptive ceiling a pseudo LEDE room flipped on end? How is this different?

[klh]

Ethan...

A few more questions. In the previously mentioned article, you also said 705-FRK can be mounted in the corners (wall to wall and wall to ceiling), yet it seems that most people here use 703. It seems to me, the 4" 705 would be better, just more costly. Is that true? And, in your opionion, is it worth the extra cost? Using either seems more practical than your better bass traps because they aren't necessarily permamently attached to the walls. How much better are your permanent low and high bass traps than the more portable cross corner fiberglass panels? Also, what would you recommend using for the primary reflections if one wanted a non-permanent form of treatment? How do you think it would sound if one built a portable version of your mid/high absortion panels and then placed them in appropriate locations on the ceiling and the front, back and side walls to take care of the primary reflections and then packed in as many cross corner traps as possible to take care of the mid to low fequencies? My guess is that the permanent "better bass traps" (low bass, high bass and mid/high frequency units) would be... better, but the more practical nature of the alternative would be more realistic.

[klh]

Sorry Ethan, but a couple more questions. One of the previous posts recommended the following website...

http://teresaudio.com/haven/traps/traps.html

I like what he has built. Obviously it is a different implementation but it is still relatively similar to the theory that your cross corner traps are based on. Would you please comment on how that design is either equal to, better, or inferior to your design? I would think the cross corner traps are probably more effective as they can also be placed at the wall to ceiling corner, but what about what he did tto take care or the primary reflections... how effective do you think his use of "diffraction" and absorption is in those locations?

Thanks.

[Ethan Winer]

K,

> One of the previous posts recommended the following website ... Would you please comment on how that design is either ... <

The effectiveness of a corner-mounted absorber made from fiberglass is basically dependant on the amount of fiberglass. There's no magic to a tube shape, and the designs I see around the 'net are frankly pretty silly when they instruct sealing the trap air tight. You can't seal porous material like rigid fiberglass!

So when comparing a round chunk of rigid fiberglass with a flat panel of the same material, with both placed in corners, which is better depends on the amount of fiberglass (volume) and the total size (width and height). Both designs will surely help, but neither will equal the high absorption at low frequencies of a MiniTrap.

--Ethan

[klh]

That's pretty funny. Thanks Ethan.

[klh]

Sorry, Ethan, but I think you might of missed the last two posts on the first page. Would you please address those, too. Thanks.

[Ethan Winer]

K,

> You recommend a reflective floor and an absorptive ceiling ... Does that extend to a purely listening environment? It seems to me that it creates a prime first reflection off the floor which would thus color the sound. <

In recording studio control rooms there's usually a big console in the way, but I still recommend that for regular listening rooms too. However, you are correct about a first reflection off the floor. The options are:

* Put down some throw rugs in the reflection path. This will be my choice if I ever get around to replacing the carpet in my home theater with a wood floor.

* Have the floor be carpeted and also add substantial absorption on the ceiling that works to lower frequencies. You risk making the room too dead, but less treatment elsewhere in the room can balance that.

* Live with it. After targetting the first reflections off both side walls and the ceiling, only the floor reflection remains which is not as bad as having all four reflections present.

> you don't care for the LEDE design. Isn't the reflective floor/absorptive ceiling a pseudo LEDE room flipped on end? <

I don't favor or diss any particular design, and I don't consider myself qualified as a room designer anyway. But it seems to me that making the entire front of a room dead sounding serves no useful purpose. Absorption is best spread around a room evenly, and placed only where needed to solve a particular problem. For example, serious absorption in the corners for bass trapping, and optionally thinner panels at the first reflection points. Large areas of bare parallel surfaces can then be treated with absorber panels in a checkerboard pattern, or some other pattern that is visually acceptable to others living in the house.

> most people here use 703. It seems to me, the 4" 705 would be better, just more costly. <

I can't say if it's worth the extra cost to you, but 705 is definitely better than 703 at 125 Hz and below. Just yesterday I updated my Acoustics FAQ and changed "I think" to "I'm sure" because just last week I tested this in a real lab. This particular question has been the source of some raging debates among some pro acousticians lately, and now it's no longer in question.

> Using either seems more practical than your better bass traps because they aren't necessarily permamently attached to the walls. How much better are your permanent low and high bass traps than the more portable cross corner fiberglass panels? <

MiniTraps are 2-4 times more absorbent than an equivalent thickness of rigid fiberglass at low frequencies, depending on which frequencies. I'm confused by your comment that raw fiberglass is somehow more portable than a MiniTrap. A MiniTrap is exactly as portable as something you'd make yourself, only it works better and is sturdier. One of the problems with DIY panels is figuring how to cover them attractively, and coming up with a way to mount them without major damage to the walls. At the minimum, MiniTraps can be stacked in corners, leaned against the walls, propped up on boxes, and generally placed anywhere temporarily if you prefer. But having a metal frame is a huge advantage because fabric-wrapped fiberglass is very fragile around the edges, and gets pretty ratty looking quickly if handled and moved around a lot.

> what would you recommend using for the primary reflections if one wanted a non-permanent form of treatment? <

A pair of MicroTraps, one on each side wall. Stick a tiny nail or picture hook in the wall, and hang the MicroTrap just like a picture. Easy, clean, fast, minimal wall damage.

> How do you think it would sound if one built a portable version of your mid/high absortion panels <

Early reflections are mainly a mid/high frequency issue, so even cheap acoustic foam an inch thick will do in a pinch. The advantage of MicroTraps, and moreso with MiniTraps, at those locations is the absorption is extended to lower frequencies. As you probably know, besides scrambling imaging, early reflections also cause comb filtering in the frequency response. That one-inch thick foam will help the imaging, but it can't reduce the comb filtering except at 1 KHz and above. By using a more substantial absorber both problems are effectively solved down to a much lower frequency.

--Ethan

[klh]

Thank you for the thorough reply  

And, I'm sorry for not being more clear in previous posts.

I was comparing your panel bass traps (with the wooden face) to 703 and/or 705. You've stated previously (if memory serves me right) that the wooden low bass absorber does so down to about 100 Hz. I was asking about how 705 absorbs... but since then I've gone through several other posts in this forum and found several answers to that and many other questions.

What I'm mostly interested in now is how these types of absorption devices ultimately affect the sound. Anyone can interpret and estimate the effect on sound based on numbers, but, as far as I'm concerned, all that really matters is what we hear. Data is important, but it doesn't replace the actual experience of listening to music in rooms with these devices, and you have that experience.

Essentially what I'm wondering is whether the cumulative effect (or total sound) in a room that has 705 mounted in the corners (ALL wall to wall and wall to ceiling corners) and 703 both covering the primary reflections and checkered elsewhere sounds less than, equal to, or better than a room filled with all three of your low bass, high bass and mid/treble panels permanently built into the walls.

I wasn't referring to your Mini and Micro Traps, but that comparison is just as important. I think it's easy to say you prefer the mini and micros to the other two... you wouldn't sell them if that wasn't true! But, I also think that if even though the 705/703 combo is less efficient than the mini/micro trap combo, using more of the 705/703s would in the end either even out or at least be close.

As for the previously mentioned comparison of your wooden panel traps to raw 705 or 703, that is difficult to make. Your experience with both is extremely valuable.

One last thing... in reading through the posts in this forum, I get the impression you think raw 703 and 705 sounds better in smaller rooms, whereas the wooden panels/traps are better in larger rooms? Is that correct? If it is, at what volume do you make the transition. If I'm wrong, please expain why.

Thanks and sorry for being difficult!

[Ethan Winer]

K,

> What I'm mostly interested in now is how these types of absorption devices ultimately affect the sound ... Data is important, but it doesn't replace the actual experience of listening to music <

Data is more important than you're giving it credit for. Anything we can hear can be measured, and with greater predicability and repeatability than even very careful listening. For example, we can readily measure distortion as low as 0.01 percent, but 0.01 percent means the distortion components are 80 dB below the music. Can you really hear that? Could any human tell the difference between 0.01 and 0.03 percent distortion? I really doubt it. Likewise we can measure frequency response errors of a tiny fraction of a dB, but I'd be hard pressed to hear a change of 1/4 dB in any source material at any frequency.

> what I'm wondering is whether ... 705 mounted in the corners ... and 703 ... sounds less than, equal to, or better than a room filled with all three of your low bass, high bass and mid/treble panels <

Rigid fiberglass absorbs mid and high frequencies, and panel traps reflect mid and high frequencies. So if you use panel traps, even with the mid-high absorbers as shown in my article, you'll get less mid/high absorption than an equivalent surface area covered with rigid fiberglass. This is one huge feature of the traps I sell - they absorb more bass than panel traps and over a wider range, but without killing all the mids and highs as do foam and rigid fiberglass.

So if the only two choices are rigid fiberglass and panel traps, I can't give you an answer as to which is "best" and either approach can give very good results if you're careful not to overdo the fiberglass.

> even though the 705/703 combo is less efficient than the mini/micro trap combo, using more of the 705/703s would in the end either even out or at least be close. <

Yes, with perhaps twice as much rigid fiberglass you could approach the low frequency absorption of MiniTraps. But then you'll have too much absorption at mid and high frequencies. Again, I see this all the time with rooms treated with foam or fiberglass. If you put in the right amount to get the mids and highs right, the bass is still a big problem. If you add more to improve the bass further, the room becomes too dead.

> at what volume do you make the transition <

I've used both panel traps and fiberglass in large and small rooms, and either can work well. Fiberglass works well in corners, but not so well flat on the wall. Panel traps work very well flat on the walls. Since a large room has proportionally more flat wall surface area than corner area, panel traps make sense there because treating only the corners doesn't cover enough of the surfaces.

I'm not trying to be evasive, but I can't give you a fixed "crossover" point. So I'll just guess and say a wall longer than 15 feet will benefit from panel traps or MiniTraps on the wall. This is in addition to fiberglass or MiniTraps in the corners, or panel traps on the walls near the corners.

--Ethan

[John Casler]

I don't favor or diss any particular design, and I don't consider myself qualified as a room designer anyway. But it seems to me that making the entire front of a room dead sounding serves no useful purpose. Absorption is best spread around a room evenly, and placed only where needed to solve a particular problem. For example, serious absorption in the corners for bass trapping, and optionally thinner panels at the first reflection points. Large areas of bare parallel surfaces can then be treated with absorber panels in a checkerboard pattern, or some other pattern that is visually acceptable to others living in the house.

Hi Ethan,

I think the idea of the LEDE room is to reduce most "room generated" reflection (more in the mids and highs) while not affecting the reinforcement of the major room boundaries, in the Dead End.

The Live End then does allow diffusion and reflection (but many including myself do treat the Live End a bit too) so as to not reduce the "air" the ear/brain perceives from highly diffused sound coming from the rear.

And of course Bass Traps and corner treatment is used in both the LE and the DE to decompose bass artifacts and corner generated problems.

[Ethan Winer]

John,

> I think the idea of the LEDE room is to reduce most "room generated" reflection <

I'm not a studio or HT designer, but my good friend and expert Wes Lachot says the current trend - at least with recording studios that cater to rock and rollers - is to make the front of the control room as live as possible. Angled walls and an angled ceiling then direct all first reflections away from the listening position, instead of relying on absorption. The rear of the control room is equally live, using diffusion to avoid slap echo and comb filtering off the rear wall. Substantial bass trapping in the corners and an absorbent cloud over the center of the room complete the treatment.

Wes' own control room is designed like this, and it sounds truly awesome. Anyone who fancies themselves as being "into audio" would love to have a listening room that sounds as good as Wes' control room!

--Ethan

[capo]

Ethan,

That  new recording studio trend makes a lot of sense to me.  What do you think about diffusion on the front wall, since my front walls are mostly not angled?