critical listening - i hear something i don't like


i need some help. I've been around this high end audio and theater thing for a while...but am just finally getting MY system close to the point where i really want to listen to it. I just upgraded a few components and actually (finally)hear 'air' in a movie i was watching this past week. The entire front collection of speakers dissappeared. WOW!.. getting very close to something good.. okay..enough background...

Here's what i need help with. In between these episodes of marvelous listening, when the movie track gets loud, the sound appears incoherent. There are three things i'm guessing i could attribute this to: 1.) the amp speaker relationship - either the speakers can't take the signal output by the amp, or the amp can't keep up with the signal. 2.) my room really does need some anti-reflective treatments - I have stuff in the corners.. but the side walls are bare (rectangular,sealed room, carpeted floor) 3.) the digital cable between DVD and PrePro may need some more thought

Any thoughts on where to focus my efforts? i explicitly didn't include a system description because i don't want to get into equipment conversations yet. If this thread gets interesting, i'll do that next

thanx in advance
objective1
Sean...thanx much.. i've read a bunch of your other posts as i've been flopping around the forum over the past few years.. and based on what i've read in the past (both here and elsewhere) your responses seem right on the money. What you suggest, is what i suspected... thanx for the confirmation. Room treatment and amp changout where the next things on the list. Followed by moving to something like wilsons when the budget allows.
Spend your $100 on a few good books about room acoustics and the rest on buying the supplies that you'll need to treat the room. Room treatment not only benefits system linearity, the sonic presentation will become more enjoyable.

There is something that should be said here that many folks may not realize. That is, an acoustically treated room that was not designed from the ground up will only be QUIETER than an untreated room in terms of total spl. Having said that, you may find yourself listening at louder levels in a treated room than an untreated room. That's because the presentation is both more enjoyable and linear in amplitude over a wider bandwidth. As such, max spl and average listening spl are not the same thing.

Outside of the speaker / room interphase, you probably don't have enough power to drive the Request's with authority. You are talking about a speaker that is rated at 87 dB's with 1 watt in and a 4 ohm load. Don't be fooled by ML's "bogus" rating of 90 dB's as it was spec'd with 2 watts of drive fed into the speakers ( 2.83 volts @ 4 ohms is two watts, not one ). If you do the math, you need gobs more power. Yes, i did say GOBS more power. Even if you did have the power available, you are using a speaker that is displacement limited and not suited for high volume listening sessions. Most E-stat's were never intended to reproduce sustained spl's.

If you do some checking, i think that you'll find that people that purchase "panel" type speakers end up changing musical tastes in a relatively short period of time. That is, music that has a high average power level ( rock, hard blues, etc... ) doesn't sound as good to them as it used to. Sure, the music still sounds phenomenally crisp and detailed, but it lacks the "drive" that gives that type of music its' energy. As such, they start listening to music that caters to the presentation / spl levels that these type of speakers work best with. That's why you'll probably hear more acoustic, jazz, classical, etc.. type music coming out of these speakers than "rock" or high spl HT presentations. This is true even though the owner may have been quite a bit more of a "rocker" when they initially purchased this type of speaker. Acoustic, jazz and classical are all basically transient in nature, which better suits the limited displacement capabilities of a panel speaker.

While you have a dynamic woofer to take some of the strain off of the panels in terms of excursion / displacement limitations, you're still running out of power. Combine the two distortions ( amplifier smear and speaker break-up ) with the effects of an untreated room and i don't doubt that you're running into problems. My guess is that most of the people that frequent this forum and others like it are in very much the same boat, but may not even realize it. Then again, we all use our systems differently and expect different things out of them, so high spl linearity and cohesiveness may not matter to many of them. Sean
>
Let me run this up the pole and see if anyone salutes it.

It's hitting a major room peak resonance point. The room shakes, which shakes the rack, which shakes the CD player, causing it to go into extreme error correction/concealment, which drains the power supplies, which now throws the clocks off. And for a brief milli-second the sound goes to he!! in a hand basket...

If your rack is at the midpoint of any wall, or in a corner, it stands a good chance of being excited even more, as they are the points of highest pressurization.

Dave
actually... if my spl meter is accurate... i don't listen above 100 db.. that's really loud in my little room
thanx for all of this... here are some details.. but i feel i have a little more work to do

room dimensions 13'6" x 19' x 8'

ml 334 and proceed BPA 3 driving requests, theater i and scripts. and a descent sub source is a krell dvd standard through a krell hts 7.1

transparent audio ultra xl's throughout

i don't bleed my ear drums, but i would say i listen loud...probably close to 110 db

either way... i'm thinking the 100$ room analysis by ASC would be the next step... then i'll see if the ml334 is just falling behind trying to drive the requests
Just so it may make more sense, my last post was written immediately in order after Objective1's response to my first post. I don't feel rewriting it to better fit what has come subsequently.
Responders are the the ones who are "postulating" in my post. Sorry for the ambiguity.

A more powerful conclusion will result in discovering first hand the cause to your problem instead of relying on present or past responses. I would be surprised if lack room treatment is not partly or totally the cause because the room's sonic affect increases with volume and a "poorer" room commonly results in what you described. Because you are addressing the room already, you can soon eliminate it as a confound or, hopefully, eliminate the problem.
First, I should say with so little information, my comment may not apply--but it well could. Almost any system can "outplay" the room. As you turn it up the energy held in the room is too great relative to the direct sound--the result is a loss of coherency. When we design rooms, we need to know how load a person will play their system and the room must be designed to properly relieve that energy--I say properly, because it can't just be leaked--it has to be disappated appropriately. My guess is that you are simply outplaying the room (by the way this occurs and is actually much easier to detect on 2 channel systems). High SPLs for HT require much pressure release. THX specifies rooms above 110db (that's really loud in my opinion). I don't listen to movies that loud--but many of our clients do, and we have to design the room with that in mind.
Sounds like too much room reverb. Get a copy of F. Alton Everest's Master Handbook of Acoustics and do an RT60 analysis of your room. (It's easy, trust me.) This will tell you what frequencies are problematic and will help you determine what type of absorptive material will work best, and where to put it, to smooth out the response.
In defense of Ohala, you can't comment intelligently on this type of question with out details. For instance, room dimensions, speaker placement, speaker type, amp type, decible level when sound starts to distort, etc. Here is a WAG, you are overdriving speakers to sound pressure levels neither your room nor your speakers were designed to handle.
np.. no tears here... :-) just looking for some objective help... trying to focus my plans
i was hoping some haphazard audiogon postulating would bring someone with experience out of the woodwork... to comment intelligently on the problem. Sounds like i should do some external reading and not work this here. :-(
Incoherence at high volume in an untreated room?..you don't say...

Since you're dealing with that already, I guess you'll soon come to a better conclusion than you would from haphazard audiogon postulating anyhow. Hope your efforts are the fix you're looking for.
that's something i should be working on anyway... i've done the first stage of treatment...and that made a significant difference. I have floor to ceiling bass traps in all corners... i actually had to turn down the gain on my sub
that actually was my first guess.. i recently updated my pre/pro from a proceed AVP to a Krell HTS 7.1 dynamics changed significantly

looking for more opinions... thanx for yours
You don't mention your equipment, but I would guess that you are experiencing deficiencies in your amp where the sonics become constipated, congested, and/or restricted on loud and/or complex and/or otherwise demanding passages.

Another reason why amp selection is so critical.

-IMO