Hardwood floor or carpet in Home Theater Room

[Jabez Scratch]

I am building a home and my great room will be about 20' x 17'. We're thinking of putting in oak hardwood flooring, but may go w/ carpet (40 ounce carpet if that makes any difference). Acoustically speaking, is it better to go with carpeting? My brother has hardwood floors in his main TV room and it produces a displeasing echo. I should note that he does not use external speakers, i.e., he uses the TV's speakers.

I have a 5.1 surround system (w/ the possible expansion to 7.1 in the future).

Thanks.

[Olorin]

I think you've answered your own question. My intuition tells me

you're right, but there are a lot of factors that aren't covered by the

rest of your post, such as room layout, shape, how much furniture and

what kind, what will be on the walls, etc.

[dragonfyr]

Boy, this is not as simple as most will expect it to be.

But lets take a look at just the acoustical effects of the carpet, ignoring all of the other substantial factors.

Yes, the carpet will provide some reduction of the reflections of some frequencies, but it will not do so in as well behaved a manner as expected, and it is difficult to qualify the effect without either much more specific information or, better yet, actual measurement of a sample followed by performance tuning based on after install measurements.

So, in order to give you an idea of the realities that are involved , allow me to mention a few variables.

First, we will assume a single layer of carpet 3/8 of an inch thick for our example. For the purposes of calculation we will assume the carpet to be totally absorptive (which it is not in actuality!), and we will assume no padding for the sake of simplicity. I will then give you a rough idea of the effect the carpet will have and thereafter raise a few of the real variables that make such a prediction so prone to error and variability.

First, the absorptive qualities of a substance are not determined in the real world by the orthogonal thickness (perpendicular distance from under surface to the top of the material). Rather, much more acoustic energy is incident upon the surface at an angle. And for our example I will simplistically assume a 45 degree angle. (I hope you can already see that we realistically have to deal with a wider range of incident angles!)

For 3/8" carpet, the length of travel at 45 deg would be .53033 inches.

This corresponds to a quarter wavelength of a frequency of 6,365 Hz.

Thus we could very simplistically say that the carpet would attenuate the frequencies above 6,365 Hz and have essentially no effect on lower frequencies.

The real world will tell you otherwise, as the carpet is not entirely absorptive and it will have a reflective coefficient as well. Thus not all the energy will be absorbed. Depending upon the warp, weave, distributed density, and other various attributes of the carpet, etc., it will not provide a linear response above this frequency either!

Combine this with variables such as a pad, which will also have a distinctly different absorptive and reflective behavior over the full range of audio frequencies and you will have added a very non-linear acoustical treatment.

It will aid in attenuating some of the reflection. It will not however provide a linear correction.

Will it be better? Hmmm. It will be different! Will it be optimal? Probably not! And here in lies the real challenge. In order for a room to be tuned optimally, the reflective and absorptive characteristics of a material need to be known. And as a result there are myriad databases of the measured real world frequency dependent characteristics for different materials across the frequency spectrum. Thus, knowing the values of these material characteristics allows one to plug them into a powerful modeling program such as EASE to provide a beginning predictive model. (also these tools allow you to optimize speaker placement, orientation, and MANY other variable too numerous to address in this space. Auralization tools can even allow you to literally hear the difference in the model for any given listening position based on the the various adjustments.

After a satisfactory model is prepared and the system installed, the fun of tuning the actual result begins. And that is when you can run around taking measurements and verifying both the well behaved aspects as well as identifying and correcting the lest well behaved aspects.

Thus, in this example which has taken about 5 minutes, I hope that you can see that simply hanging or laying rugs and carpet, and other assorted treatments do not simply achieve what many hope they achieve. In this example, the primary critical mid-range frequencies have not been addressed. Intelligibility has not been substantially improved, but the average person will notice a difference and it may seem pleasing and rewarding.

And far be it to be my intent to dissuade anyone from attempting to address the characteristics of an acoustical space! I am simply trying g to point out that it is not a good idea to simply run to a website and buy allot of random expensive whiz bang solutions and slap them into the room and assume the problems are solved! Will it sound different! I think one could reasonably say yes! But will it indeed be an improvement...that is another question, and one that without a greater awareness is most likely to result in an answer that is not as beneficial as one might hope!

But do not become too dismayed! As there is another real option which I hope we can present in the not to distant future. And in the meantime, we can try to assist with more specific questions, given that we acknowledge some fundamental constraints. There are options! And real solutions! But it pays to understand the limitations!

[TBrennan]

The hardwood looks better and is easier to keep clean. All three of my rigs are in rooms with oak floors and sound fine. As has been mentioned much depends on furnishings, drapes, size and shape of the room and so on.

I'd go with wood floors and then use an area rug, drapes and such to calm things down if needed.

[sfogg]

If you are strictly talking about the home theater aspect then carpet, no doubt.

It will cut down on reflections compared to wood. Both sound *and* light reflections. The less light you have reflecting around your room the better your picture will look.

With a direct view CRT (bright) in my old room if the light was reflecting off our hardwoods(or walls) at the right angles it would seriously wash out the picture. This will be worse the larger the picture. Even at night while watching in the dark reflections from the TV/screen off the floor can be distracting too. Moreso the bigger you go for screen size.

But of course hardwoods look nicer.... IMO

Shawn

[TBrennan]

Note that horn speakers with their controlled directivity can have less willy-nilly reflections than direct-radiators do. In my DIY horn rigs I dialed the systems in by using horns with the best pattern for the room, I experimented with horns with horizontal patterns as narrow as 60 degrees and as wide as 130 and from 40 to 60 vertically.

Though I've no idea of how much of the spectrum of the RBs in question is controlled and how well. But I would guess that the mids and highs are pretty focused with little splash either horizontally or vertically.

Mind that most of the info and notions out there on reflections concern direct-radiators, horns work differently.

[steelie]

This i a great question. I'm in the process of doing a complete remodel in one of my rooms to accommodate a 2-channel rig. HT will be part of the deal but it's not my primary concern. Regardless, I've spoken with a few different acoustical consultants and all have suggested going with hard wood floors.

I think the idea is that hard wood floors can be controlled with area rugs and that there are better ways to provide a room with acoustical treatments than simply laying down carpet.

[sfogg]

Tom,

That is certainly true to a point but there will still be plenty of

reflections off the back wall, side walls... then the

ceiling/floor...etc...etc. Sketch out what even a 20 degree horizontal

coverage will do in a room with a back wall in it and there will be

reflections.

And some horns hold their patterns much tighter then others. I've been

playing around with 805s and they are a much tighter focused horn then

511s even though the specs for dispersion pattern isn't that much

different between them. If I walk up next to a playing 805B there is a

point where I get out of its coverage and the sound literally jumps to

the back of the room. The first time it happened I thought my surrounds

were playing it was such a strong change. But it was that the

reflection from the rear wall was stronger then the direct sound from

the horn I was standing 2' away from. With the 511s that doesn't happen

when I move up next to them in the same position. And this is in a

heavily treated room.

Shawn

[dragonfyr]

In the smaller listening rooms there is plenty of acoustic energy radiated from the cabinets, diffraction, and the general Q of the horns in both the horizontal and vertical axes.

And even with corner placement, there are plenty of early reflections to be dealt with.

The concept you mention is sound (gee, a pun!), but the real versus ideal nature of the speakers still leaves quite a bit to address.

That being said, the situation with the fully horn loaded higher Q speakers is indeed much superior to the traditionally loaded low Q speakers. So the problem is reduced, but not eliminated.

Good point! Nice to see someone is thinking in terms of Q and controlled acoustic radiation! Both Tom and Shawn make some very valid points for consideration in ANY acoustic space!

[DrWho]

I vote for hardwood floors....worst case scenario you can always throw

down a large area rug after the fact. I believe wood floors will be

worth more when you sell the house too. But as far as sound, there's

just something about having wood in the room and I'll never go back

(seems to be prevalent through every room I've heard). As far as

reflections go, strategically placed throw rugs get rid of that glare

and can even add to the aesthetics of the room.

That said, the absolute best HT's I've ever heard were carpetted (the

THX Ultra2 demo room at klipsch and then some other guys I know). In

the end I really don't think it's that big of a concern because it's

but one piece in the grand puzzle (ie, I have heard that khorns need a

rather plush carpetted floor due to a few reflections in the midrange,

things like that).

So how dedicated of a home theatre is this and what kind of speakers

are you using and what is your budget on the room? If it's not too late

I would recommend angling all your walls a bit to help minimize

parallel surfaces.

[TBrennan]

Shawn---Yeah, horns do funny things and multicells can have odd fingering effects. So how do you like the 805s?

I used to use 1005s with 288Ks and loved them.

[sfogg]

Tom,

"-Yeah, horns do funny things and multicells can have odd fingering effects. So how do you like the 805s?"

I have only been using the 805 on the center channel with a

288-8K. I like how consistant it is from all over the room and it

has very nice mids but the combo is rolling off *hard* at 6k. So much

so that it is down at least 12dB or more by 10kHz. Very rolled off IOW.

My 902s still have output up to 20kHz on the 511s. OTOH because it is

so rolled off I don't think it is getting up high enough to have the

'fingering' as the cells dispersion isn't really narrowing yet. At

least I haven't noticed if it is and I was trying to hear it. If I had

the adapter I'd try a 902 on the 805 but don't have that part.

I have (3) 288s but one is missing a diaphragm. I have one on order

from Great Plains and after I get that I'll see if it makes any

difference on the top end. The other two both have Altec aluminum

diaphragms in them and they both roll off the same way so I assume it

is just the way it is. When I get a chance I'm going to try Triamping

them running JBL 2404Hs for the top end. Just need to find some time to

run the extra wiring and make the cables I need and such.

One thing is for sure.... Altec multi-cells are just hard core cool looking!

Shawn

[TBrennan]

Shawn----I think the multi-cells act much like CD horns in that the frequency response on axis pretty much tracks the power response of the driver. So a roll-off is to expected. EQ may be in order.

My 288s on 1005s were strong up to about 15K with EQ. I also used various tweeters coming in at 10K first order instead of EQ. Used Fostexes and also 902s with no horns attatched. The 902s "naked" sounded pretty good and the internal horn of the throat probably loaded the diaphragm well enough at high frequencies. Give it a shot, it may not be flat but will add some sparkle.

Altec multis are the coolest looking horns for sure followed by that huge 3' wide JBL lens job.

[sfogg]

Tom,

"My 288s on 1005s were strong up to about 15K with EQ."

How much boost were you adding? I tried 6dB (as high as it goes)

through the Lexicon and it made very little difference. I could do more

in the external crossover (or put a first order high pass on it up very

high to act like EQ) but I'll most likely try the tweeter first. I have

the drivers/tweeters/crossovers... just need to wire it all up.

"The 902s "naked" sounded pretty good and the internal horn of the

throat probably loaded the diaphragm well enough at high frequencies.

Give it a shot, it may not be flat but will add some sparkle."

And there certainly wouldn't be much power going into it just handling

the high end. I'll have to give that a listen. Did Altec ever make any

small tweeter horns for the 1" drivers? I have a pair of Mantary's out

of Model 14s but I think they are CD horns so the 902 would likely need

some EQ with that if I used it as a tweeter. The JBLs would fit the

system easier too.

Shawn

[TBrennan]

Shawn---I don't recall how much EQ I used other than it was quite a bit. All that stuff is gone now.

Around 1990 Altec did make a tweeter based on the 902 with a small horn, the MR-902-16HF. I've seen them on ebay and they are in the late Altec catalogs on the Audio Heritage site.

[picky]

Wow, that multi-cell is a beaut!

I wanted to point out one aspect which may not have been mentioned here as to why to consider carpet over wood floor: Visual reflection from the screen. If your seats are set fairly far back from the screen, a glaring reflection of the screen light off a shinny floor can be a huge visual distraction, just as a light-colored ceiling can.

We have a concrete floor in our basement with vinyl resilient floor tile. Our seats are close enough to the screen where visual reflection from the floor is not an issue. However, ceiling reflection was an issue for a while. Now, with the installation of our melamine foam, flat black suspended ceiling, not only are their no noticeable acoustic reflections (not even from the floor), but there are no visual reflections and the picture looks absolutely stunning. The melamine is 2-1/4" thick and made to provide a 90% absorption factor across a wide range of frequencies. I never believed this type of ceiling could make such a difference, but it certainly did in our theater.

[oldtimer]

You will probably get a more "live" sound from hardwood than carpet. I have had both in my speaker room (living room with tv) and while different, both sounded pretty good. I am thinking there was maybe more of a studio sound with the carpet. From an economic point of view, if the room will have high or even normal traffic, carpet needs to be replaced at least every 5 to 10 years, collects a mountain of dust which stays there until you replace it, and will look bad for a while until you decide to replace it. Hardwood will stay clean with ease and pay for itself after 10 years or so compared to carpet. Also think on this: musical stages are never carpeted, they are always hardwood.

-------------------------------------------------------------

stated views are that of the writer only. your mileage may vary. writer has no financial connection with hardwood flooring manufacturers at the time of this post, but may in the future.

[Jabez Scratch]

Thanks for the input so far. It's very helpful. I suppose the hardwood serves more as a reflective surface. We are planning on laying area rugs and there will be furniture and a gas fireplace on the side wall. IF we do go w/ carpeting, it will be relatively thick (40 ounce).