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Discussion Starter · #1 ·
Hi all,

I now have my new AVM-20 tweaked and sounding really good. Finally, 5.1 at last. I'm using an all Mirage setup: OM-7 fronts, OM-C3 Center, & OM-R2 surrounds. Also a Mirage BPS-150 sub. ANthem MCA-5 amp by the way.


Now, when it was just a 2-channel and sub system with an Adcom 2 ch preamp, it sounded good. Now it's very bright in the 2K to 8K range. I have hardwood floors and thin curtains. So where should I start?


A rug covering the floor between sofa and Fronts?

Wall treatments?

Or Heavier window treatments?


I'm also only using the RCA inputs/outputs on the preamp-amp connections. Should I move to Balanced IC's first or last?


Any help you guys could provide is greatly appreciated...

Alan
 

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I would start with the rug. That will help with first reflections from the floor and also with a very general damping of the liveliness in the room.

If you tell us how your windows and system sit in the room, maybe we can offer some ideas.
 

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Discussion Starter · #3 ·
I'll try and draw it:


--..D..--.w.-.w.-----

|..............TV...Sub.|..---------------fp=fireplace

|.........L............R...|------------------D = Front door

||..........................W-----------------W = window

|fp.........................|----------------- DW are doorways without doors

||........................Rack-----------------C=chair

|......C.............F. A.|

|_.............S..O....._|

..|S=========S|

..|........................|

..|........................|

.DW.....................|

..|.......................DW

..|........................|

..|........................|

..|_____W_W____|




Now for some dimensions to put it in scale:

Overall Length: 30 ft


Width 15 then down to 14ft


Front Wall to sofa (my seat): 15 ft


Front wall to surrounds: 15 ft


Dist between L and R mains: 5.5 ft


dist from front wall to L and R mains 2.5 ft


This room was two rooms years ago. The previous owner ripped out the wall and made one big room. Also, some of the old wall remains along the ceiling bisecting the room and providing the mounting surface for the surrounds on the walls. However, this also hangs down from the ceiling about one foot.


Which all makes for a very Hot room. And very hard to draw on a forum.


All suggestions are welcome.
 

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XLR connections are not terribly expensive. Though you don't really need them for short connections. A good rug will do wonders for cutting down the echos. Maybe some wall panels for first reflections as well if needed. Though that right wall looks a little crooked in your rendition there.
 

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Hi Alan,


I agree that a carpet is the first thing you need. Then wall treatment - 1-inch absorption to start. The carpet is unlikely to fully correct your reverberation problems, but it should help some.


XLR connectors are last, in my opinion. Yes, RCA unbalanced connections are susceptible to noise, but this typically happen on runs of more than a dozen feet or so.


Regards,

Terry
 

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Ok now we can see the rabbit.

I would suggest eithertreating the windows or going for a live end/dead end set up, which I have found very effective for both ease of doing and improvement.

Some treatments to the wall behind the screen/mains would do it. Posibly a large panel os acoustic foam preferably the egg box type (convoluted its called here) possibly 2 sheets side by side which you could cover in an open weave fabric for a better look, hessian is good.

This will improve reverb in the room, clear the bottom end to some extent and be a general good thing.

After that you're probably looking at bass traps and room lenses.
 

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Discussion Starter · #7 ·
dave c:


What exactly is a live end/dead end set up? Could you elaborate a little? Or, maybe point me to some links?


Also, do any of you guys who have offered suggestions so far have any experience with Mirage OM speakers? I was just wondering how the front wall treatments will effect their imaging and overall sound? Are these panels meant to deaden or just merely tame my room?


Oddly enough, I've owned the Om-7's and the sub for a couple of years now. The move away from my Adcom GFP-555II pre-amp to the Anthem Ht pre-amp has been ear-opening. They never seemed VERY bright. Actually, I guess my old dull adcom was my "room treatment" for the past few years.
 

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Dead end/live end is a way of controlling/limiting the liveliness of a room without making it completely dead.

The idea is that you treat one end, usually the front" behind the speakers and the screen with absorbant treatments.

It might, or might not, be neccessary to cover the whole wall. But, as sheets of acoustic foam, at least here in Oz, come in 2.00mx1.40m sheets, I would suggest trying a sheet behind the speakers to see if it makes a difference. A friendly foam seller might lend you a sheet on the basis you might buy 2!! Or at least let you return one if you don't want it. In my experience, this can be a very simple way to help a room.

Just hang'prop it behind the speakers and try them out. If you room is very wide, use the sheets landscape rather than portrait. Its not really rocket science, so just get them in there and hear if it moves the sound in the right direction.

I have recently done this in my very lively living room and the differences were huge.

The price here for a sheet of convoluted foam is about $160 Australian which is around $100 US.

The foam can be covered with an open weave fabric for decorating purposes. You might care to try putting over any electrical outlets in that wall as well as it may provide some damping from mechanical vibration to the cables.

Just treating one wall this way will reduce the amount of sound ricocheting around and give a cleaner, leaner, drier sound.
 

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[Dave C and I posted our replies simultaneously]


"Live End - Dead End" was a design idea for audio control rooms developed by Don Davis in the late 70's. It was very popular during the 80's. It consists of making the front of the room relatively dead (with absorption), and leaving the back relatively live with hard surfaces.


It was a really good idea for stereo listening rooms, in my opinion, because the absorption toward the front killed early reflections to make the sound stage clean, while the liveness in back due to rear reflections created nice ambiance.


However, with movie surround sound, the ambiance is already built into the soundtrack - it's in the two (or 3, for 6.1) surround channels. So the live end is not necessarily a good idea.


As for front wall absorption, it reduces reflections from the front which will "smear" the front sound stage and make your front channel imaging indistinct. Side wall absorption, at the mirror points between you and your speakers, is just as important for the same reason. These "early reflections" occur during about the first 15 milliseconds after the direct sound from the speaker. The brain thinks they are one sound, and smooshes them all together. Hence the distorted or indistinct sound localization, because it's trying to average all the directions.


An important side benefit is that absorption placed anywhere in the room will reduce reverberation time. Low reverberation time is essential for accuracy of soundtrack reproduction, as well as for dialog intelligibility.


Some people worry about making a HT room sound too "dead." But rooms which sound dead are generally only dead at mid to high frequencies. Their reverberation is very non-uniform across the sound spectrum.


This is often the result of putting 1-inch absorbers everywhere, and no 3 to 4-inch absorbers for the low end. A room which has a proper balance of absorbers will sound tight and accurate, without sounding dead. We ALWAYS do a complete time-domain acoustical analysis for any mid to high end home theater to determine the amount and type of absorption it needs.


I encountered a terrific multi-use family room the other day which did not sound dead at all, yet it had RT60s (reverberation times) of around 1/4 of a second over all frequencies. Relative to its size, this is as accurate a room as you'd find in the best commercial cinemas!


Hope this helps.


- Terry
 

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Don't forget the ceiling!!!! It's very important and the most overlooked treatment.


One of the most impactful improvements I made was adding an absorbtion panel to the ceiling, at the first reflection points of L, C, & R. This is very important for center channel intelligibility. Made a big difference with two-channel listening too.
 
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