Acoustic treatment help for home theater space - AVS Forum
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post #1 of 15 Old 01-19-2014, 07:12 PM - Thread Starter
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I hope this is the right section, as have been reading as much as I can. Last July I moved into a 'new' home (built in 1938, steel and concrete construction) with a partially finished basement. The finished area is L-shaped, with only 2 small windows, and perfect for a HT. Since the drywall and drop ceiling were already installed, I was hoping to save money and time on the build and optimize what I have to work with - 3 kids and family visiting for Christmas accelerated the timeline for a functional theater.

Although I have read a bit of the introductory information on acoustic treatment and speaker placement, I am a bit overwhelmed and am ‘losing the forest for the trees.’ I am looking for advice on the following:
1. What are the best or immediate acoustic treatments do I need to optimize my 5.1 home theater sound?
2. What are recommended sources for purchasing home acoustic treatments?
3. Should I hire a consultant specific for acoustic treatments and how do I go about finding a reliable one?
4. What is the best method for finding and removing rattling due to bass?

The layout:
- 13' 5" wide x 25' long, but only the ‘front’ 18’ are used for theater, as the rear portion will be a separate seating area and will have a low wall separating the HT.
- Ceiling is 7’, drop ceiling (USG tiles, NRC 0.70), with steel I-beams and concrete at approx 8’.
- South wall is drywall over concrete. North and west wall are drywall over cedar beams. East wall (front wall) has a mural on concrete on top half, drywall on bottom half below the 6” ledge) (pictured).
- Front wall will have a black felt curtain along the entire length, behind the screen. It will fill the gap between the wall and the screen (screen is floating, mounted 6” from ledge).
- Pictures on the wall are just there to cover wall outlets (previous owner had a lot of neon lights on walls).

Equipment:
- AVR: Marantz SR6008
- Fronts: Definitive Technology BP-8060ST
- Center: Definitive Technology CS-8060HD
- Rears: Definitive Technology SR-8040BP
- Sub: HSU VTF-15H

The basic layout:
Layoutcompleted_zpscc432494.jpg

View from the rear left:
Front2_zpsec308a07.jpg

View from the rear right:
Front1_zps757631d1.jpg

View from the front:
rear1_zpsf846096a.jpg

View of the ceiling and front wall mural prior to installation:
Ceilinggrid_zps8a121147.jpg

Any help or advice is greatly appreciated.
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post #2 of 15 Old 01-19-2014, 07:45 PM
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There are lots of sources for material. GIK, RealTraps, and off the shelf. Knowing what type to place where is the trick. Cookie cutter approach doesn't work really well. You have to know what sound you are after and how to get it there. Contact BigMouthinDC if you are looking for a consultant.
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The original Pro Theater Layout
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post #3 of 15 Old 01-20-2014, 04:07 AM - Thread Starter
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Quote:
Originally Posted by SierraMikeBravo View Post

There are lots of sources for material. GIK, RealTraps, and off the shelf. Knowing what type to place where is the trick. Cookie cutter approach doesn't work really well. You have to know what sound you are after and how to get it there. Contact BigMouthinDC if you are looking for a consultant.

That is certainly helpful. I know that different items will treat different problems, but I was not thinking of a big picture. Right now the bass feels a little boomy regardless of how I play with the crossovers and levels. The midrange is not as crisp as I am used to in other setup I have heard.

With my layout, I was thinking of getting rid of first reflections with a panel on the north wall using mirror technique and a panel between the rear speakers. I know I need bass traps, but the front corners are not likely useable, so that leaves the southwest corner and maybe some trapping in the small alcove with the radiator. Realistically, I am hoping to keep it within $1,000, if possible.
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post #4 of 15 Old 01-20-2014, 07:13 AM
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I am by no means an expert .I have read many threads some with designers lik Erkstine and Bpain. (I may have spelled thones wrong) I also follow many DYI. I put 1/1/2 inch mineral wool on my entire front wall and 24 inch base traps in the corners then I covered it with a sheer black fabric. I plan on doing pannels on the side walls as well. Mineral wool is really cost effect and has similar propertues to the more expensive fiberglass pannels. I put 3 inches on back wall but you do not have one.
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post #5 of 15 Old 01-20-2014, 08:47 AM
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Quote:
I am by no means an expert .I have read many threads some with designers lik Erkstine and Bpain.

I believe that is Bryan Pape, who works for use.
Quote:
There are lots of sources for material. GIK

Right which we work with all customers from start to finish to come up with the best layout possible. He can contact us here if he would like for us to come up with a plan for him
http://gikacoustics.com/acoustic-advice/
Quote:
View of the ceiling and front wall mural prior to installation:

There are a lot of other things we would want to do with this room but one tip is to fill the whole ceiling with fluffy fiberglass between the drop ceiling and the actual ceiling.

Quote:
I am a bit overwhelmed and am ‘losing the forest for the trees.’
Take a look at some of the following videos to get you up to speed a bit more on room acoustics.
http://gikacoustics.com/educational-videos/
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post #6 of 15 Old 01-20-2014, 08:59 AM
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Here's a DIY thread that might help you, http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-moveable-corner-traps-not-fixed-frames#post_19947420
I have this general suggestion for those wanting to learn about acoustics:
Quote:
A) read this Acoustics/Treatment Reference Guide , via gearslutz, its a easy read in layman terms, starts you off with basics and good foundation with practical discussion. Studio acoustics and Home Theater acoustics.
From that, simple/straight forward advice via Jens Eklund:
Quote:

1. Learn how to make measurements: REW - Room EQ Wizard Home Page

Don’t do anything without measurements.

2. Define your MLP (Master listening position). Confirm with measurements.

3. Identify and treat your modal and SBIR - Speaker Boundary Interference Response related issues and educate yourself about different bass-absorbing techniques.

Other info: SBIR by Bryan Pape

4. Treat areas that otherwise creates early reflections.

5. If the room is big enough, add diffusers

Always base your decisions regarding different treatment, on measurements. Avoid thin porous only absorbers (including wall to wall –carpet, drapes etc.) unless a measurement indicates the need for it.


B) Knowing that for “best” audio/sound in a listening room, these parameters are tackled in prioritized order:

1. Speaker location, 2. Listener position, 3. Acoustic treatments, 4. Electronic correction.

Understand the small room acoustic model you will follow.
Looking at this link, everyone can see visually the various small room models, it's 7 pages from the book "Acoustics and Psychoacoustics Applied"

http://eetimes.com/design/audio-desi...n?pageNumber=0


C) If you have desire for more knowledge:
-read one of many books out there, a great 1st book is "Master Handbook of Acoustics" by F. Alton Everest, a perfect follow-up book is "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" by Floyd Toole.



-shameless plug for Ethan Winers book also, "The Audio Expert".



.. ..



-study Ethan Winers site, http://www.ethanwiner.com/acoustics.html

-Become familiar with the different small room acoustic models for home listening spaces

-This is also a 101 read on Room Acoustics, http://www.crutchfield.com/learn/learningcenter/home/speakers_roomacoustics.html

-SAE Home Acoustics info site has many definitions and explanations http://www.sae.edu/reference_material/audio/pages/fullindex.htm

-There are many other sites on the web, like

........One of the first ones, StudioTips small room acoustics forum http://forum.studiotips.com/index.php,

........Acoustical measurements defined Rives audio http://www.positive-feedback.com/Issue12/rives2.htm,

........RPG Acoustics Library papers http://www.rpginc.com/news/library.htm, etc.

-Be careful of info overload all at once



D) Measurement info/threads:

-online downloadable file with the Sound System Engineering chapter 6 on measurements http://www.focalpress.com/uploadedFiles/Books/Book_Media/Audio/9780240808307.pdf



-Get the hardware side of REW down quickly, this thread by member omegaslast dummy's guide on setting up REW and his blog http://polaraudio.blogspot.com/2012/01/calibration.html easy 101 read with pictures to walk you thru the mechanical of set-up and taking measurements



-Highly recommend Nyal Mellor's site, http://www.acousticfrontiers.com/Aco...surements.html , and a very detailed/helpful white paper http://blog.acousticfrontiers.com/st...ist.%20Rms.pdf

-Room Measurement & Treatment by "fotto" (Floyd)





- Envelope Time Curve - ETC - Impulse gearslutz thread

-Using energy time curve for acoustic analysis: by "mtbdudex" (Mike R)



-http://www.avsforum.com/t/1421599/etc-isd-gap-question  ETC - ISD gap by

-Basic acoustic measurement primer v2.1 (via gearslutz "DanDan")

-http://www.realtraps.com/art_measuring.htm





-http://www.avsforum.com/t/1316623/diy-custom-printed-movie-poster-acoustic-panels-cheap/60#post_20147783 DIY Custom-Printed Movie Poster Acoustic Panels



-first reflection software: http://www.avsforum.com/t/822273/free-software-to-help-determine-your-first-reflection-points/240#post_22619555



-a while back I downloaded this Measurement/calibration sequence from Dennis Erskine.



RoomMeasurementSet-up.zip 4.990234375k . file  

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post #7 of 15 Old 01-22-2014, 07:26 PM - Thread Starter
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Quote:
Originally Posted by mtbdudex View Post

Here's a DIY thread that might help you, http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-moveable-corner-traps-not-fixed-frames#post_19947420
I have this general suggestion for those wanting to learn about acoustics:
Quote:
Originally Posted by myfipie View Post

I believe that is Bryan Pape, who works for use.
Right which we work with all customers from start to finish to come up with the best layout possible. He can contact us here if he would like for us to come up with a plan for him
http://gikacoustics.com/acoustic-advice/
There are a lot of other things we would want to do with this room but one tip is to fill the whole ceiling with fluffy fiberglass between the drop ceiling and the actual ceiling.
Take a look at some of the following videos to get you up to speed a bit more on room acoustics.
http://gikacoustics.com/educational-videos/

Thank you for the multitude of sources. Although I have an idea of what I want to do, I realistically will do better in hiring someone to do, especially after reading more about this plus I do not have enough time to fabricate the bass traps and panels completely from scratch. The one spot that I have no idea what to do with is the little alcove to the side, and also possibly relocating the sub.

Does anyone have a recommendation for a local audio consultant to look at my set up in person, or would an online consultation be adequate?
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post #8 of 15 Old 01-23-2014, 01:52 AM
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Bryan Pape, many here have used him as consultant, and I went to a HT meet Nov-2013 here in SE Michigan that he designed the entire acoustic plan. Great HT sound.
It's as a general plan, so you could DIY or buy from GIK or combo. You and Bryan determine that upfront.
Good luck.
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post #9 of 15 Old 01-24-2014, 01:58 PM - Thread Starter
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Originally Posted by mtbdudex View Post

Bryan Pape, many here have used him as consultant, and I went to a HT meet Nov-2013 here in SE Michigan that he designed the entire acoustic plan. Great HT sound.
It's as a general plan, so you could DIY or buy from GIK or combo. You and Bryan determine that upfront.
Good luck.

Wonderful, I will contact him.

In regards to filling the area above the ceiling, would this be superior to adding absorbers on the walls? Or would this be secondary?
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post #10 of 15 Old 01-25-2014, 03:25 AM
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Soapbox time:
You need to look at the videos Glenn posted, seriously, before you spend any $$$. Get some education.
Sound energy in a room is a good thing, it adds ambiance and spaciousness feeling.
The strategy of a proper acoustics plan is to manage that to maximize the potential of your speakers in your room.
Give a man a fish and you feed him for 1 meal, teach a man to fish and he's set for lifetime.
Education is your ally.

Since your room has ceiling tiles, focus on the walls first.


Via my iPhone 5s using Tapatalk
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post #11 of 15 Old 01-26-2014, 07:22 PM - Thread Starter
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Thanks for all of the great advice and leads to the videos. The videos gave me a better idea of what to do and in what order: bass trap, absorbers for first reflection, then diffusers, to put it simply. I also have to continue to move my front speakers around for better listening position, as they are bipolar speakers and involve a bit of trial and error to determine placement. Although the education is certainly helpful, this is something that I don't think I will be expert enough to be able to do without more expert advice.

It seems like corner bass traps are the more common bass traps used. I will have a velvet curtain along the front wall, behind the screen and speakers, so corner traps may not have the correct appearance. Is it possible to use bass traps outside of the corner to achieve the same effect, or am I stuck with modifying my curtains to allow for the bass traps?

Also, are people using diffusers for HT? It seems like you cover the usual reflection points with absorbers, and then throw in a few diffuser.
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post #12 of 15 Old 01-26-2014, 08:05 PM
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First thing I would do is cover the back 128" of the south wall with broadband absorption to mimic the lack of wall on the opposite side and restore some symmetry to the surround field. Next would be absorption across the front wall, to keep surround information from reflecting off the front (those sounds should come from the surround field, not from the same direction as your front soundstage). Finally, I would put absorption or diffusion across the middle 6-8' of the back wall.

BTW, that's an awfully huge gap you have between your front speakers and surrounds with absolutely nothing bridging that gap. The diagram shows your surrounds placed at the incorrect location AND place asymmetrically to the centre line of your set-up. IF you want to stick with a 5.1 set-up, your surrounds would be better off lined up with the back row of seats.

However, since you already have 7.1 receiver, I would encourage you to go with 7.1 set-up: side speakers in-line with the front row and rear speakers spread out on the back wall. It will give you excellent wrap-around envelopment and rear-vs-side directionality in the surround field.

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post #13 of 15 Old 02-11-2014, 10:07 AM - Thread Starter
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I have an additional question regarding bass traps, because the front wall will be a long velvet curtain behind the screen (about 7" clearance) . I know that traditional bass traps are triangular and go in the corners, but can you effectively have flat bass traps, like along the front wall behind my curtain? I am going back to the designer about curving the curtains along the side to hide a bass trap, but it may not be an option.

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Originally Posted by sdurani View Post

First thing I would do is cover the back 128" of the south wall with broadband absorption to mimic the lack of wall on the opposite side and restore some symmetry to the surround field. Next would be absorption across the front wall, to keep surround information from reflecting off the front (those sounds should come from the surround field, not from the same direction as your front soundstage). Finally, I would put absorption or diffusion across the middle 6-8' of the back wall.

BTW, that's an awfully huge gap you have between your front speakers and surrounds with absolutely nothing bridging that gap. The diagram shows your surrounds placed at the incorrect location AND place asymmetrically to the centre line of your set-up. IF you want to stick with a 5.1 set-up, your surrounds would be better off lined up with the back row of seats.

However, since you already have 7.1 receiver, I would encourage you to go with 7.1 set-up: side speakers in-line with the front row and rear speakers spread out on the back wall. It will give you excellent wrap-around envelopment and rear-vs-side directionality in the surround field.

Very big thank you for the recommendations. I was planning on moving the rears to more symmetrical positions (they were originally placed by the home theater installers). I also have the room wired for 7.1 for when I decided on additional speakers (and have more money), but will adding the two side speakers in any way reduce the output from the front speakers? The reason I ask is that I would need to use a smaller pair of speakers as my side speakers (ie bookshelf size) and they would be much smaller than my front floor standing speakers. I have not seen an answer by searching, but I am not sure if I am searching for the right question.
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post #14 of 15 Old 02-11-2014, 11:46 AM
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Originally Posted by Spazdoc View Post

I know that traditional bass traps are triangular and go in the corners, but can you effectively have flat bass traps, like along the front wall behind my curtain?
Sure. Rather than corner traps, I would make the front wall a giant bass trap. Take advantage of all that surface area.
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I also have the room wired for 7.1 for when I decided on additional speakers (and have more money), but will adding the two side speakers in any way reduce the output from the front speakers?
Keep in mind that 7.1 adds speakers behind you ("surround-back" connection on your receiver), whereas the surround speakers are intended to go along your sides ("surround" connection on your receiver). As long as you understand that your current surround speakers are at the incorrect location.

As to your question, adding another pair of speakers won't reduce the outputs of your fronts. Besides, when you recalibrate, all the speaker levels will be reset to give the same relative output from all speakers.

Sanjay
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post #15 of 15 Old 02-11-2014, 11:53 AM
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