Room Acoustics

LenWhite

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Feb 11, 2011
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systems.audiogon.com
Like others on this forum my music room was designed by Rives Audio and for the most part I've really liked how it quieted the room and added focus and articulation. But like others I've made changes, most notably by eliminating the absorber panels at the sidewall early reflection points, adding diffusion at the front wall and front side walls, and changing speaker positions a number of times. I think the changes I made have improved the dynamics and soundstage body.

I've added a ceiling hung projector and powered projection screen since the design was implemented in 2010 which necessitated removing a 10'L X 3'W Owens Corning 703 fiberglass absorber frame hung from the rear media room hallway. But the major Rives design changes are still in place. They incorporated absorber panels: (6) Owens Corning 703 fiberglass panels (2’W X 4’L X 2”D) in the left side wall upper decorator media room setback area, (12) Owens Corning 703 fiberglass panels (2’w X 4’l X 2”d) in the two kitchen upper decorator setback areas; and (4) ceiling hung 6’ X 6' RPG BAD Diffusor "Clouds" in the media room.

I used a Sarasota, Florida firm about a year ago to measure the room audio frequency response, but was told the readings didn't match what he was hearing. Ultimately I changed the speaker and diffusion positioning he recommended - for the better I think. Perhaps the audio measurements didn't correlate because the room is L-shaped and part of an open SE Florida floor plan.

I'm pretty satisfied with the current sound but a bit frustrated with the audio frequency measurement failure. I would also like to change the front wall/front side wall RPG BAD rectangular panels to something more decorative. I'm considering something diffusive like the RPG Skylines mounted on the left side wall, and some type of floor standing support for the center front wall and directly in front of a right side wall insulated glass french doors. But given the expense and not really knowing if that would improve the frequency response I'm hesitant. Narrative and pictures of my current setup can be viewed at http://www.whatsbestforum.com/album.php?albumid=46.

I'd very much appreciate knowledgeable input.
 

ddk

Well-Known Member
May 18, 2013
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Utah
Like others on this forum my music room was designed by Rives Audio and for the most part I've really liked how it quieted the room and added focus and articulation. But like others I've made changes, most notably by eliminating the absorber panels at the sidewall early reflection points, adding diffusion at the front wall and front side walls, and changing speaker positions a number of times. I think the changes I made have improved the dynamics and soundstage body.

I've added a ceiling hung projector and powered projection screen since the design was implemented in 2010 which necessitated removing a 10'L X 3'W Owens Corning 703 fiberglass absorber frame hung from the rear media room hallway. But the major Rives design changes are still in place. They incorporated absorber panels: (6) Owens Corning 703 fiberglass panels (2’W X 4’L X 2”D) in the left side wall upper decorator media room setback area, (12) Owens Corning 703 fiberglass panels (2’w X 4’l X 2”d) in the two kitchen upper decorator setback areas; and (4) ceiling hung 6’ X 6' RPG BAD Diffusor "Clouds" in the media room.

I used a Sarasota, Florida firm about a year ago to measure the room audio frequency response, but was told the readings didn't match what he was hearing. Ultimately I changed the speaker and diffusion positioning he recommended - for the better I think. Perhaps the audio measurements didn't correlate because the room is L-shaped and part of an open SE Florida floor plan.

I'm pretty satisfied with the current sound but a bit frustrated with the audio frequency measurement failure. I would also like to change the front wall/front side wall RPG BAD rectangular panels to something more decorative. I'm considering something diffusive like the RPG Skylines mounted on the left side wall, and some type of floor standing support for the center front wall and directly in front of a right side wall insulated glass french doors. But given the expense and not really knowing if that would improve the frequency response I'm hesitant. Narrative and pictures of my current setup can be viewed at http://www.whatsbestforum.com/album.php?albumid=46.

I'd very much appreciate knowledgeable input.


You need to clarify why you want to change things around when you're happy with the sound. What is it in the measurements that needs addressing? Not being happy with the looks is easy to fix, just takes money.

david
 

LenWhite

Well-Known Member
Feb 11, 2011
424
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375
Florida
systems.audiogon.com
You need to clarify why you want to change things around when you're happy with the sound. What is it in the measurements that needs addressing? Not being happy with the looks is easy to fix, just takes money.

david

As I stated in my post, I'm pretty satisfied with the sound. But a bit frustrated not knowing if accurate audio frequency measurement would have highlighted changes that could have improved the sound further. I don't have the audio expertise to precisely pinpoint spikes and nulls in the room nor the tolerance for learning how to use audio frequency measuring equipment.
 

ddk

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May 18, 2013
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As I stated in my post, I'm pretty satisfied with the sound. But a bit frustrated not knowing if accurate audio frequency measurement would have highlighted changes that could have improved the sound further. I don't have the audio expertise to precisely pinpoint spikes and nulls in the room nor the tolerance for learning how to use audio frequency measuring equipment.

You're also asking about making random changes. Learning to use the equipment is very easy, the art is to understand the measurement and knowing what to do afterwards. In your case it seems like you're worried about something that isn't giving you any problems. I'm trying to understand what you're asking for here. You're not supplying any measurements, no one knows how where taken and by whom. You seem to have no sound issues either, so what kind of feedback are you looking for?

david
 
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Bruce B

WBF Founding Member, Pro Audio Production Member
Apr 25, 2010
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As I stated in my post, I'm pretty satisfied with the sound. But a bit frustrated not knowing if accurate audio frequency measurement would have highlighted changes that could have improved the sound further. I don't have the audio expertise to precisely pinpoint spikes and nulls in the room nor the tolerance for learning how to use audio frequency measuring equipment.

Rives should have done that for you. Otherwise, hiring a "good" acoustician, is worth all the money,time and tweaks in the world!
 

LenWhite

Well-Known Member
Feb 11, 2011
424
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375
Florida
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Rives should have done that for you. Otherwise, hiring a "good" acoustician, is worth all the money,time and tweaks in the world!

I haven't been able to find any in Florida so far!
 

LenWhite

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Feb 11, 2011
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Florida
systems.audiogon.com

GaryProtein

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Jul 25, 2012
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I guess there are no gods.
 

ddk

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May 18, 2013
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I guess there are no gods.

Hold your judgement, there's not enough information to judge anything or anyone! I still don't know what Len's question is. His sound is good but he's unhappy that the measurement didn't his sound? He still wants to change things around, why?
 

microstrip

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May 30, 2010
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Len,

What type of measurements are you referring to?

I have often said that sound measurements of rooms are an excellent diagnostic tool for those who understand them, but not a target by it self.
 

Dale Pitcher

Industry Expert
Mar 11, 2014
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0
Torrington, WY & Boseman, MT
Alternate View of Room Acoustic Issues

Over the years, I have designed a number of rooms for several clients. At one time, I was building rooms prefab in 10' sections and shipping them complete, and then flying out to oversee final construction. I have done six "signature" rooms with ceilings configured some what like an inverted boat keel. One client south of Indianapolis spent over $200,000 on his room - but that was primarily due to his dressing out the room with Rosewood and a lot of other fancy stuff.

I have usually charged $5000 to $10,000 per room for the room design. Most of the cost was AutoCAD work, with the output of DXF files to CNC machine the ceiling arc trusses out of 1.5" LVL.

I've been involved in the audio industry for over 40 years, and I've worked a great deal with acoustics during that time - mostly for clients and a few stores. My own listening room for a number of years had 16" thick walls, a ceiling structure of constrained layers that was than suspended on felt and Sorbothane (I would not use the Sorbothane in hindsight) and a 4" thick floor suspended on 3" Cork. The floor was floated away from the walls, so there was no vibration conduction.

I stopped doing the prefab rooms a long time ago. They just took up too much time and space. I've done a few AutoCAD room designs in the last couple of years. I'll bring up some of the features of these rooms in a later post if there is interest.

My time is tied up in other ventures, and I probably won't do much more AutoCad work for room design. I have nothing to sell here. Some very good companies are in place to do this work. Everything I offer here is free, so long as people will expand and refine these concepts if they find they work, or report back to the forum that they don't work, along with their reasoning.

My views on many issues of how to deal with room resonant modes and damping may be different - that may be because they are wrong. My approach is minimalist. #1: Design the room dimensions correctly (almost everyone does that right). #2) Do not use fiberglass anywhere, only wool. #3: Never use elastomers. There are other things, of course. If people are interested, we'll get to that.

One product that I actually put in limited production (a few hundred were made) is fairly easy to build. A major acoustical room treatment manufacturer offered to buy the technology from me, but I declined. This was for two reasons: 1) I wanted all the credit for it (dumb), and 2) I didn't know well enough how the system worked. I almost always had to set up the system - end clients could usually not get it to work as well. This is because the math on this was never completed. Perhaps someone on this forum can combine their math abilities with an understanding of resonances and really make it work. If that happens, make it free to anyone that wants to use it.

It may be that someone else has come up with this idea and refined it. In that case - never mind.

I believe that many room tuning systems do not eliminate problems - they minimize the primary modes, and re-radiate many other lessor modes at different frequencies. What if you could largely eliminate a mode with very little effect at other frequencies, that would be ideal.

Basically here is the core idea. Use enclosures (we used aluminum cylinders - 6", 8", 10" covered with 1/4" F-13 acoustical felt of different diameter and height. Fill them with a reactive mass, such as sand. Our rough finding was that the size of the cylinder corresponded to frequency, the actual mass contained within - to the magnitude of the resonant mode.

Here is an easy way to try this. Remove bass traps from room. Get 4 50 pound bags of sand. Start by placing one bag behind each speaker - 2' from rear wall, 1' from side wall. See what this does - move it around a bit. Then place another one a little further from the back wall, and a little further in from the side wall. You will hear a difference - for better or worse. If its' better, play around with it. If its' a lot worse, wait for further posts.

Cylinders can be made from SonoTube - usually available from Home Depot type stores. Acoustical wool felt from Sutherland Felt (Online): Item 713-4, F-13 Wool Felt, 72" Wide @ $40/lineal yard.

A lot of rooms ended up with 4 cylinders: 2@8" Diameter - 28" High, 2@10" Diameter - 18" High.

Keep me posted if you want further information.

Regards,

Dale Pitcher
 
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microstrip

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(...) Cylinders can be made from SonoTube - usually available from Home Depot type stores. Acoustical wool felt from Sutherland Felt (Online): Item 713-4, F-13 Wool Felt, 72" Wide @ $40/lineal yard.

A lot of rooms ended up with 4 cylinders: 2@8" Diameter - 28" High, 2@10" Diameter - 18" High.

Keep me posted if you want further information.

Regards,

Dale Pitcher

Thanks for a very different and interesting post. Can you tell us what is the thickness of the 713-4, F-13 Wool Felt?
 

LenWhite

Well-Known Member
Feb 11, 2011
424
72
375
Florida
systems.audiogon.com
Hold your judgement, there's not enough information to judge anything or anyone! I still don't know what Len's question is. His sound is good but he's unhappy that the measurement didn't his sound? He still wants to change things around, why?

Totally not true! Did you really read the post? I said nothing about changing anything except for cosmetic reasons.
 

LenWhite

Well-Known Member
Feb 11, 2011
424
72
375
Florida
systems.audiogon.com
Len,

What type of measurements are you referring to?

I have often said that sound measurements of rooms are an excellent diagnostic tool for those who understand them, but not a target by it self.

Measurements that would show specifically where audio spikes and nulls are occurring in the room. Presumably I could then adjust the acoustics to ameliorate and further improve the sound.
 

ddk

Well-Known Member
May 18, 2013
6,261
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995
Utah
Totally not true! Did you really read the post? I said nothing about changing anything except for cosmetic reasons.

That's what I thought initially but the conversation went a different direction, sorry for the misunderstanding.
david
 

microstrip

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May 30, 2010
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Measurements that would show specifically where audio spikes and nulls are occurring in the room. Presumably I could then adjust the acoustics to ameliorate and further improve the sound.

Can we assume that you are just referring to frequency response around the listening position? I have seen people ruining listening spaces just placing speakers and seats for the flattest measured response in the listening position.
 

LenWhite

Well-Known Member
Feb 11, 2011
424
72
375
Florida
systems.audiogon.com
Can we assume that you are just referring to frequency response around the listening position? I have seen people ruining listening spaces just placing speakers and seats for the flattest measured response in the listening position.

As I said in my original post I'm pretty pleased with the existing sound considering the limitations of the room. I did express disappointment regarding what I consider a failed audio frequency response measurement, really more frustration I failed to ensure I was maximizing my investment in acoustics.

I am interested in improving the room cosmetics however.
 

Nyal Mellor

Industry Expert
Jul 14, 2010
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As I said in my original post I'm pretty pleased with the existing sound considering the limitations of the room. I did express disappointment regarding what I consider a failed audio frequency response measurement, really more frustration I failed to ensure I was maximizing my investment in acoustics.

I am interested in improving the room cosmetics however.

There are ways to do room acoustic measurement and analysis remotely. I offer a remote service as do others. You either take the measurements and send to the consultant for analysis, or he/she takes over your computer and does them for you. Details on my room acoustic analysis page.

I strongly believe in the value of acoustic measurements and have developed a process for reviewing a set of measurements and comparing to targets. You may or may not have read the paper I wrote entitled Acoustical Measurement Standards for High End Audio.

I've worked with DallasJustice who is on this forum extensively, he is in Dallas I am just north of San Francisco. All the work was done remotely, even including integration of multiple subwoofers.
 

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