Acoustical Treatments Master Thread - Page 53

I completely agree. Using pink noise, a timbre difference can be noted among my three identical front speakers but it is MUCH smaller than it was when I had the so-called matched and dedicated center speaker from the same company. Position in the room and relationship to other objects will affect any speakers but it always is best to start out with a match. BTW, I could further reduce the discrepancy with Meridian MRC but the change was small.

Kal

klipsch towers on left and right.
left goes shii
right goes shewww

High frequency reflection is not the same for both speakers. Could it be the large pain of glass - you bet!

How does it sound with movies/music?

Sounds very good. No obvious distortion. Just annoying.

BTW - I did decide to go with the false wall approach that you show in your theater. Right now, I am trying to figure how I will bring the AC outlets to the front of the wall. Kind of tough if you bring the wall out 4" or more.

I'm planning a remodel (mostly a change of furniture and surface treatments, i.e. change the color scheme of my GOM, carpet, and furniture) of my HT this fall/winter and wanted to get some feedback on if my acoustical treatments need to be readdressed. My room is used primarily for HD HT and HDTV, with minor usage for high resolution audio such as SACD/DVD-A.

I have attached a Visio of the current room which measures approximately 18' 5" x 24' 6" with 8', acoustical drop tile ceilings. Above the ceiling tiles, the ceiling joists are filled with 9" of rolled OC insulation.

I have a 110" Stewart GH RS on the front 18' 5" wall, and my primary seating position is about 11-12' away. The front wall is currently treated with 1" OC 703 from floor to ceiling. The side walls are treated similarly, except only the bottom 48" is treated, the top 48" or so is left untreated drywall. At the rear of the room a wet bar area is going to be built which is not shown in the Visio diagram, but there are no treatments currently on the rear wall.

The room is located in the basement, so behind all the walls is poured concrete. The external walls are standard 2x4 stud construction although they are staggered 1/2" away from the concrete. R13 insulation fills the void between the poured concrete and the inside of the drywall. The drywall is double layer/GG 5/8". The interior equipment closet at the rear left corner of the room is standard 2x4 with a single layer of 5/8" drywall with a Middle Atlantic Slim5 rack flush mounted with the wall as shown (a smoked plexiglass door covers the equipment). The floor is poured concrete with heavy padding and cut pile carpet.

L/C/R speakers are M&K S150 THX Ultra, SR/SL/SBR/SBL are M&K SS150 THX Ultra in tripole configuration. Subs are a pair of M&K MX350's controlled by a Velodyne SMS-1.

Any suggestions are appreciated.

Nice speakers; I have the same myself.

How does the system sound now? The best recommendation would be that you get some acoustical testing software and microphone and run some tests.

Thanks. I really like M&K speakers and it continues to surprise me that they don't get talked about much here on AVS despite their use in movie/music studio monitoring and mastering.

I think my room sounds great now (better than it ever has), but the nature of this hobby is the endless pursuit of audio/video perfection. As much as we all like to think we've hit the nail on the head with our own HT, there's always room for improvement. Regardless of how many comparisons you do with other HT's/demo rooms/etc it's hard to say one is better than another unless there is an obvious problem due to our poor auditory memory. Plus you have all the other enthusiasts here commenting on their own rooms/HT's so it makes one wonder if there's more to be done.

While my room was built with HT in mind, there are some design/construction shortcomings and compromises. Your advice to have the room tested is a good one and I know that I should probably go ahead and do it, but I was just wondering if there were any glaring deficiencies that could be corrected prior to going that route in order to realize a more detailed assessment of my room's areas for improvement.

I know what you mean, but I posted a thread on upgrading them and drew out a slew of M&K owners advising against it. I'm guessing that we're a smug bunch not needing approval from anyone else to know what we've got.


Making changes to a room that "sounds great now" without acoustical measurements would be like . If it sounds that good already, there may be a tweak that would improve it, but you're more likely to go backwards.

Do you know my wife or something?

Seriously, I guess I need to qualify where I'm at now before I decide to make any changes.

How do you know it sounds great?
The reason I say that is our hearing mechanisms are very good at adapting to "bad stuff" (the result is fatigue). I can't tell you the number of times we've been in "this room sounds great" but after we calibrate the comment is "I had no idea it was so bad."

I would strongly advise having a pro do some extensive measurements to see where you are at. These initial plots can target areas for improvement (if any) and give you something to compare once changes are made.

Dennis Erskine:


My mother says in the same breath "I don't know why you spend so much time thinking about acoustics. My living room sounds great. BTW, thanks for the new DVD player. I really like the subtitles button. When I can't understand what they're saying I can just rewind and read it."

You're right, as I mentioned my assessment of my HT is entirely based upon my limited experience with my previous environments and comparisons with other rooms (albiet admittedly via ear/auditory memory - also admittedly faulty at best ). I know my room is not perfect, possiblty not even ideal, hence my post here and interest in improving my situation. My area of expertise has nothing to do with this hobby or interest.

I'm all for having a "pro" come in and do measurements, I'm just wondering if there are any basics or otherwise glaring omissions I've missed prior to going through that exercise so that I can make it more meaningful be alleviating flagrent issues and focus more on "fine tuning".

If however, the proper starting point is simply starting with whatever you have whether it be a raw room or a room treated in any way, then that would be an appreciated suggestion as well.

Recommendations for the NW suberbs /North Shore of Chicago would be appreciated as well.

Monty Williams

You might enjoy having a look at this: Sencore 10 Steps to Optimized Sound

Here's some starts:

LF/RF too far apart for imaging and sound stage
LR/RF too close to side and front walls (SBIR)
One of two subwoofers are mis-located
Rear surrounds have timbre mismatches
Where is the center channel with respect to the screen?
Center channel too close to front wall

Thanks Bob,

There's some good info there - some of which I've already considered and implemented, but some which I haven't. I think the responses to my initial and follow up posts confirm that if I want to quantify my efforts then I need to establish a baseline with what I have now.

However, I must point out that I can't recall a thread on this forum where someone had their room measured in raw form, incorporated the recommendations, and then remeasured after the the suggested corrections were made. I'm sure there have been some, but if anyone can point them out I'd be very appreciative.

I've been entertaining the idea of THX, Alpha, or the like, certification for about a year now, and I am most interested in pursuing it this fall/winter.

Okay, what do I need to do to get more detailed information from you, i.e. let's talk about consultation. PM or email would probably most appropriate at this point I'm assuming.

However, I must quickly ask for clarification on one point though - Why would the rear surrounds have "timbre mismatches" when they are the exact same speaker as the side surrounds and all the tweeters are the same/timbre matched according to M&K?

Again, if it is appropriate to contact you via email/PM or via telephone please let me know. I'd like to get my remodel going this fall.

Monty Williams:


If the side surrounds are the same as the fronts, right down to the model number, then ignoring reflections and broken drivers/cones, they're as good a timbre match as you're going to get.

If the side surrounds have the same size drivers/cones as the fronts, but the speaker cabinets are different, or the configuration of the drivers (e.g. two midrange vs one midrange) is different, then there's a strong chance they are not timbre matched.

To try it yourself, throw in a copy of Mission To Mars and go to chapter 11. The sound of one man's voice is paned slowly through all speakers. With my setup it's easy to hear a difference between the fronts and the rears. I have three identical fronts, right down to the model number (no horizontal center).

Monty Williams:


Alpha Certification example:
Building the Music Vault - part 1, part 2, and part 3.

AVS thread: ---k---'s Upgrades, Treatments & fun w/ ETF -- not the whole 9 yards, but it was the first one I thought of.

All four surrounds are exactly the same, same model, same part number etc. The onle difference is the orientation each is facing so that the phase is correct. The surrounds are M&K's recommended match for the S150 L/C/R's (as well as the subs) I'm using. There is no mismatch, at least according to M&K, within my speaker system.

Obviously placement and room acoustics affect it afeter the fact, hence the purpose of my posts.

Monty Williams:


I meant are your four surrounds the same as your three fronts.


I think this means the answer is no. The surrounds are different from the fronts.

To tell if they are timbre matched, try Mission To Mars.

Timbre mismatch is due to the close proximity of the left rear surround to the side wall as contrasted to the distance of the right rear surround from any side boundry.

We can do a THX Certified Home Theater. Alpha Certification is Terry's domain.

Monty,

> I can't recall a thread on this forum where someone had their room measured in raw form, incorporated the recommendations, and then remeasured after the the suggested corrections were made. <<br />
Here you go:

http://www.audioholics.com/productre...ealtrapsp1.php

It's written as a review, but it has exactly what you're asking for.

--Ethan

From step 2 "Front L & R Main Speakers

Form an equilateral triangle with the center of the listening area

Locate at least 3 feet from walls

Position about 1/4 of room width from side walls & 1/4 of room length from front wall"

Realistically, how many of us have the room to do this, or perhaps should I say the desire to do this? In my 24' long room, according to this I need to place my fronts 6' out from the front wall. Therefore my AT screen needs to be 7' from the front wall. My 24' room is now effectively 19' long. Are there solutions to this ideal situation that won't eat up 1/4 of my room? e.g front wall treatments.

Thanks,

Todd

Remember the title "OPTIMIZED sound" (in their opinion). It says nothing about real world rooms or practical solutions. Unfortunately, there is no one perfect way to set up every speaker in every room.

Basic rules of thumb:

- Maintain symmetry left to right in front of you.
- Dont' put any speaker or any seat right up against a wall
- Place the seating first and let it guide the rest of the setup
- The equilateral triangle is a decent starting point but be willing to move from there.
- Be willing to treat the walls if the speakers (front) need to be placed close to the walls because you bought too big a screen or you have a very long narrow room.
- Set your speakers to small and let the sub handle the bottom. This lets you move the sub for best response without messing up imaging. The best place for your mains is almost never the best place for bass response.

Pretty much everything else is unique to a specific situation.

Bryan

I've never seen a theater where LCR are that far from the front wall. Mostly, they are a few feet out or mounted ON the wall. Mine are like that, but I've treated the front wall with 2" J-M Linacoustic and am planning to add bass traps there as well.

If your mains are crossed over with the sub(s) at 80Hz, the mains would be about 3.5' from the front wall. Since this isn't a practical solution in most cases, the front wall needs to be treated with a combination of absorption and diffusion to diminish boundary effects.

WHAT would you suggest I use to attach 2' x 2' "accent" panels built of 1-1/2" Knauff board to my walls which are also made of GOM-covered Knauff panels. Does Velcro work? How about some kind of spike strips? Where can I buy them?

You can buy spike strips cheaply at Home Depot. Also, take a look at the various models of RotoFast fasteners at http://www.rotofast.com A little pricey but elegant and effective.

Kal

THANKS for the quick reply!

When you say spike strips, are you speaking of the mending plates they sell in the lumber/truss section or something else?

I'd never seen these Rotofast jobs -- I'm (essentially) attaching one panel TO another, so only the double one would work. That's why I was looking into the spikes or velcro.

Yup.

Kal