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Do acoustic treatments make rooms lifeless and dead?

post #1 of 13
Thread Starter 
I had planned pretty standard treatments for my dediacted room up to a couple of weeks ago:

2 inches of 703 equivalent on front wall
1 inch of linacoustics equivalent on side walls up to just over ear height
First reflection points treated
2-4 inches on rear wall up to ear height (Denis Erskine general advice I think but am open to correction) or to full height on rear wall (Bryan Pape general advice I think...)
Corner triangle bass traps
No definite plan for soffit treatments as advice for soffit bass traps is conflicting.

Then I was going to do an REW test - then add or take away acoustic treatments as needed. Fairly standard stuff.

All was well until about a week or two ago when it was suggested to me that acoustic treatments in the standard manner ie like the above plan make rooms that are too dead, lifeless and "unpleasant to sit in", and the best approach is to design a room with a normal reverb time and only if necessary, then add some side wall diffusion."

I don't have any strong opinion on this as I'm just at the point where I need to decide on acoustic treatments so I dont have any prior experience, and I know the vast majority on here use very similar treatments but I'd be interested in opinions on this alternative view.
post #2 of 13
I'll wait and see what armin says on your strategy.

For the life of me though, I can't understand the practice of 1" linacoustic wrapped on the side walls floor thru 42" or 44" or whatever has been stated, ear height. That applies then a EQ on high freq only, why do you want to do that?

Sent from my 32GB iPhone4 using Tapatalk
post #3 of 13
IMO your treatment plan does not sound excessive.

I think most of your suggested plan are common "blanket" suggestions for "small" room acoustics.

I would however recommend thicker reflection point treatement(2" linacoustic or similar) and spacing treatments off rigid boundaries 2-4".

What size is your room? That makes a huge difference as to what options will work.

Completely diffusing a room will be X$$Pensive and difficult. I'm not aware of any DIY HTs which were completely diffused and validated successes.
post #4 of 13
I agree with Nick that your treatments sound pretty standard except many folks say not to treat the rear wall. I left mine untreated for a bit more life. A side note-- when I was working in the corner near my front walll in heavily treated area, I actually lost my balance and perception. You can over treat a room to the point that your senses don't like it...
post #5 of 13
A friend of mine's HT has 2" of acoustic panels hanging on the wall AROUND all 3 walls (left, right, and back), and I don't like it at all 'cos the room sounds "dead" to me. So, yes, one can overly deaden a room to make it lifeless.
post #6 of 13
I was planning on doing what the OP suggested.
I've reached the point of doing the acoustic part of my HT Room and have not done anything in over 9 months. I just don't know what I should do.

What would be recommended first step or basic steps to do when taking into account the acoustic paneling in a HT Room?

post #7 of 13
Originally Posted by Fatshaft View Post
What would be recommended first step or basic steps to do when taking into account the acoustic paneling in a HT Room?


Start with lots of reading.


post #8 of 13

WOW! Thanks so much for that link...
post #9 of 13

A lot of people refer to rooms being "overtreated" and therefore sounding "dead" / "lifeless" / "uncomfortable" / whatever you want to call it. This is obviously not an easy thing for people to describe as they don't know how to quantize this into something measurable and definable. Let me attempt to quantize this into something that is measurable and definable.

RT60 - a calculation of a rooms "reverb" over time is a useful measurement if you own a literal theater - a large auditorium - a stage - etc. But these measurements are quite useless for small rooms. We can also look at frequency response graphs - but these don't really give us a useful metric either. A "dead" room can look quite similar to a "live" room in frequency response. As we're all aware, turning up the tweeters / compensating with EQ doesn't make the room sound more "live" - it just makes the highs louder, which doesn't solve our problem either.

The answer lies in the time domain. We use Waterfall graphs quite often in our articles as they give a fundamental picture of how we hear. The waterfall graphs show frequency response over time. Here's an example:

Now the problem in a "dead" room - like I've said above - is not that the treble is simply quiet, but that it is completely overdampened. Unlike the example above, the waterfall graph of a dead room would be really short, instead of ringing past half a second. This means the sound doesn't travel around in the room as much as it does in a typical space (and of course, our ears are more used to what we usually hear everywhere). But I believe it is a step further than that. Some rooms can sound quite dead in the sense that the higher frequencies are damped quite a bit, but don't sound wholly uncomfortable. This is why quantizing these problems are important to me - why do some "dead" rooms sound good and fine, but others uncomfortable?

In my experience, all the very "dead" / "lifeless" rooms I've been in and tested all showed similar results in one area: the high end was dampened much more than the bass. So this isn't really suggesting that absorption makes a room uncomfortable, but that a very uneven balance of decay times from low to high frequencies is uncomfortable - and would explain why some rooms that sound more "dead" don't always sound bad at all.

So in essence, treating the room with a LOT of thin absorption doesn't really seem like the best route to treating the room. This is the fundamental reason why foam isn't usually suggested by many people, and is why we don't only manufacture thin absorbers. We suggest bass traps often to avoid things like the room being overtly dead, making sure we can get as much low frequency action wherever possible. When we get in our test room to try different set ups - thats what we aim for: even decay times, from low to high frequencies.

I'm writing an article on decay times currently, hopefully it will be up on the site soon! I do hope that has cleared up some understanding for now. OP, if your room doesn't have carpet I'd say your plan sounds pretty good. 1" of Linacoustic is thin though and might unnecessarily over absorb the high frequencies. I would suggest maybe doing twice as thick, but half the surface area of your side wall plan.
post #10 of 13
Great post!
post #11 of 13
Thread Starter 
Thanks for all the replies. Alexander, your article on decay times would be very welcome, even an unfinished version by PM would be great as I have to move ahead within the next two weeks or I'm at a standstill.

My room is 23 ft long x 16.5 wide. I have a build thread on avforums.com in UK, as it is more local to me (in Rep of Ireland) for advice on local materials, etc. A google search for "rock flix 10 year anniversary build" will get to the build thread if anyone is interested. It's a fabric frame build using GPowers framing method, Sandman's frame design, Desert Sunset stage, FOSI Star ceiling.

I'm coming around to the idea of tacking room treatments up, measuring the room, then slowly taking the treatments down and re-measuring. Then letting xt-32 EQ take over.

Alexander, would a 0.3 to 0.4 second decay time be a reasonable target for a room that is not too dead but not full of echoes? Bear in mind I'm a complete novice at this and I've just got those times from the builder of a room in UK that is known on the forum to be a spectacular sounding room.
post #12 of 13
IMO decay balance is the key here while taming you bass resonance issues.

If you end up with 400ms or 500ms it should be balanced as well as possible across the FR.

Try not to focus on a number so much as you want to tame early high gain reflections, modal ringing, and maintain a reasonable decay balance. Your "number may be a little higher or lower just depending....
post #13 of 13
The only problem with using decay times in a small room is that they will be drastically different from one location to the next, even in the listening area. It most often should be used as a take it with a grain of salt kinda check. They are much more important in large rooms. You could break it down into band limited time domains to get a better feel if you wished, but same rule applies. I'll put it in other terms. When I do a full on audio calibration, I will check this only as a "let's see what it yields" look see. On another note, treating a room is part art and part science. The treatment does address physical issues associated with sound wave and boundary interaction. However, we are also after sculpting the sound. Shaping it. Which means, I will need to know what "sound" environment I am after and how to get there. Cookie cutter approaches usually kill high frequencies. This is what gives a room it's sparkle, spaciousness and often envelopment, so Alexander is absolutely correct. Products exist from multiple companies that preserve or diffuse the high frequencies while addressing the more problematic mid bass. Some products work better, or much better, than others, so it's up to the buyer to do their homework.
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