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#301474 - 04/12/10 01:16 AM Acoustic panels hurt QS8 and second row?
htnut
Unregistered


I'm thinking of putting acoustic panels at my first reflection points, but am worried they might negatively affect surround QS8's since they rely on reflection. Should I still bother?

Also, if I have a second row of seats which is elevated then won't I have a second reflection point (don't know if that is the right term)? Should I add a second set of panels for the second row or just treat the front row? If I add a panel for the second reflection point wouldn't I have to have it elevated (in relation to the panel for the first reflection point) as well?

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#301479 - 04/12/10 01:58 AM Re: Acoustic panels hurt QS8 and second row? [Re: ]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10634
Dr. Toole's findings and review of the literature relating to side-wall reflections have been discussed here previously. This is covered at several points in his book "Sound Reproduction". For example, at pp.503-504 he states: "The matter of side-wall reflections of L, C,and R loudspeakers warrants some discussion because of the widespread belief that these reflections should be eliminated as a matter of ritual. The ritual had its origins in recording control rooms-listening in stereo-encouraged by alarmist cautions about comb filtering(see Chapter 9)or degraded speech intelligibility(see Chapter 10)or masking of other reflections within recordings(Olive and Toole, 1989). When examined, none of these turn out to be problems."

The importance of first reflections in creating spaciousness is emphasized and providing an area of blank wall at least 4 feet long "at the locations of the first lateral reflections" is recommended(p.504).
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Enjoy the music, not the equipment.



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#301494 - 04/12/10 07:18 AM Re: Acoustic panels hurt QS8 and second row? [Re: JohnK]
htnut
Unregistered


Huh. That goes against what I've been reading about room treatments thus far. Many people have reported positive results after adding panels/treatments, though. Perhaps their room was overly reflective to begin with?

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#301507 - 04/12/10 10:45 AM Re: Acoustic panels hurt QS8 and second row? [Re: ]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13576
Loc: Iowa
My ceiling and wall first reflection panels have had no affect on my QS8's performance. They have helped tighten and improve the front soundstage by reducing the echo or clapping problems.
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M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
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#301551 - 04/12/10 02:11 PM Re: Acoustic panels hurt QS8 and second row? [Re: SirQuack]
grunt Offline
connoisseur

Registered: 12/04/06
Posts: 3569
Loc: Nirvana
I imagine a lot of it is room, equipment and ear dependent.

In my apartment there was a wall about 3 feet from my right M80 and nothing to create a direct reflection for my left M80. I put a large stack of pillows against the right wall to simulate a panel at the first reflection point and felt the soundstage sounded narrower and less realistic. I switched and through up a piece of plywood about 3 feet from my left M80 instead and it balanced out the soundstage and made it sound wider and more realistic.

I also found with my QS8s in my apartment and now my house that having curtains 360 degrees around the room deadened much of the surround sound ambience though in some cases it does make discrete sound effects more precisely directional. I found that the loss of ambience far outweighed more directional rear sound effects. So in my apartment I would just leave the rear and side backs, behind the listening position, open to enhance the reflected sound. In my house I didn’t even buy curtains for the back and back sides of the room.

So IMO where the panels are located will determine what if any effect they will have on your QS8s. If they are up front to catch the first reflections off your main I don’t imagine they will have any appreciable effect on your QS8s.

But personally unless you have a specific problems you are trying to address I think treatments are a waste of time and money and may actually be detrimental to “good” sound reproduction.
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3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1

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#301645 - 04/13/10 12:46 AM Re: Acoustic panels hurt QS8 and second row? [Re: grunt]
htnut
Unregistered


Thanks everyone, I think curiosity is just getting the better of me. I'm somewhat blessed with an irregular room with lots of stuff & furniture, so I may not need a lot of tweaking. I still may try bass traps though...

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#301687 - 04/13/10 11:10 AM Re: Acoustic panels hurt QS8 and second row? [Re: ]
Riker Offline
devotee

Registered: 10/16/06
Posts: 375
Loc: Ottawa, Ontario
I installed some AST panels a few months ago in my basement HT room. To me, it improved the overall room sound considerably. BUT, I did not put any panels at the first reflection points or at the rear of the room where it would absorb the surround sound. My panels are 2ft x 4ft by 2" thick and positioned about 2 feet above the main speakers, therefore, not eliminating first reflection. The result for me was just enough "control" of the room to make my music sound focused but still have a wide sound stage.
_________________________
Acoustic Zen Adagio, Veritas center, Axiom EP500, QS8s, Anthem AVM20, MC20,Adcom GFA7400

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#301695 - 04/13/10 11:41 AM Re: Acoustic panels hurt QS8 and second row? [Re: Riker]
htnut
Unregistered


Interesting...you put the panels on the "front" wall behind the speakers (ie. same wall as your display/screen)? I've read opposite opinions on whether or not to treat/deaden the front wall. When you think about it, treating the front wall alone shouldn't affect the spaciousness or soundstage, it should in fact (as Riker says) focus things.

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#301708 - 04/13/10 12:14 PM Re: Acoustic panels hurt QS8 and second row? [Re: ]
Riker Offline
devotee

Registered: 10/16/06
Posts: 375
Loc: Ottawa, Ontario
My room is a dual purpose room with one part being the HT section and the other is the computer section. I had 6 panels to install so I put 3 on the wall where the speakers and tv are, so behind the main speakers and about 2 feet above the tweeter. Two of them on are the side wall of the right main speaker, again same height, and the last one is on the left hand side wall where the computer station is so it is 14 feet away from my left speaker. None in the back wall.

All in all, sounds very good to me, I'm happy and would recommend those panels if asked about them.

Riker
_________________________
Acoustic Zen Adagio, Veritas center, Axiom EP500, QS8s, Anthem AVM20, MC20,Adcom GFA7400

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#301808 - 04/13/10 10:45 PM Re: Acoustic panels hurt QS8 and second row? [Re: ]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10634
Nut, as I quoted him, Dr. Toole explains why first order reflections should be promoted(not suppressed)by bare side walls in front of the speakers, but among the treatments he does suggest(p.507)is absorbing material on the center portion of the front wall behind the speakers
_________________________
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Enjoy the music, not the equipment.



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