rooms and sound levels


Any of you folks know whether a room has a specific sound level that, if gone over will cause a decrease in the clarity of sound? I find that my system seems to blare over a specified level depending on the cd played. Anyone write an article about this subject? I'm building bass traps at the moment, but the blare seems to be noticable in the mid and trebble, which is why I pose the question. It sounds clear below a certain level with no hint of distortion. Would a diffuser be of value? Has anyone had experience/benefit from the monster surge protector/ conditioner, which retails at about $300. The small 8 or 10 plug wonders?
arp
Hello, Yes, you can overdrive a room. If at any point things are rattling or walls are shaking you are overdriving the room. Its a distortion afterall, don't we have enough distortions without adding more? From, not treatment the room (woouw-wuoow, boom-boom) and adding insult to injury of overdriving the room these are things we can and should control.

Preemptive damage control... yes, I still have things that rattle in my room! Though the walls don't shake.
Bob
Arp:

More info is needed. Does this happens at the same SPL?

A system component listing can provide a better base to comment on.

Does it happen when there is also bass present in the music played?

Your phrase "It sounds clear below a certain level with no hint of distortion" makes me think it is not inherent to the CD source.

Does the same happens while playing other sources like radio from your tuner (if any)?

What is the volume setting in your preamp when this happens?
You need bass traps in the corners. I have some homemade ones using Corning 703, 4" thick, 18" wide and they remove exactly what you speak of. They actually impact the mids and highs much more noiticibly than the lows. Sometimes I remove them because I like the added airiness but I definitely can't turn the stereo up as much as I can with the traps.

I used to have the same problem with my TT so it is the room, not your CDs.

Arthur
I find that my system seems to blare over a specified level depending on the cd played.

1) Depending on RT60 and how the reverberation decays - yes this will have an influence on how loud you can go. Our hearing is absolutely remarkable - we can stand extremely high transients from an acoustic drum set (typically 115 db SPL) as long as they are indeed transients (brief). The RMS or time average energy level may be quite low becuase the drum hits are brief.

2) A lot of rock music is compressed for crap consumer systems and so it sounds bad (loud) very easily because the RMS or averge energy level has been deliberately engineered to be very high. (This is almost ALWAYS done with drums...so you may not be able to stand a recording nearly as loud as you could comfortably stand SPL's from a real acoustic set) So for starters you need to avoid CD's that have the audio "squashed" or "compressed" (which means ALMOST ALL modern pop/rock CD's...if you can find old 80's stuff it is generally much better than what is churned out today )

3) Most consumer systems compress quite badly above 100 db SPL - flattening transients and making the RMS energy higher - a dull blaring sound is what you typically get...distortion goes rapidly up....most owners think "WOW my stereo plays so very loud" but in fact it is not loud at all....it is all just distortion! (Assuming you need 10 db SPL "headroom" then you may need to consider pro drivers or horns if you want to go much above 100 db SPL on transients or much above 90 db SPL average or continuous listening level without the music starting to sound stressed/strained). Nevertheless you will be limted to good quality CD's without compression see 2) above.
You can definitely overdrive a room. Unfortunately it's not a simple answer or magic bullet that will tell you when and how. Taking relatively advanced measurements and looking at decay times will show you what happens, but usually it's caused by a few frequencies that are ringing or loading and not decaying properly. What those frequencies are depend on the room, speaker placement, listener location, acoustics, etc. In general this is a very common and can be difficult problem in smaller rooms, which from a design point of view means that to overcome the problem in small rooms usually means shorter RT times.