[TRADERXFAN]

This walldamp stuff looks interesting from Acoustic Sciences (http://www.asc-soundproof.com). --This thread made me look around again. I wasn't aware of this before.

take a look at the options they show for different wall designs in the guide...
http://www.asc-soundproof.com/isodamp-architectural-guide.pdf

[JLM]

We're mixing isolation discussion with self-noise. 

Isolation of the structure (double/staggered stud walls, furring strips, isolation pads, etc.) lowers the sound transmission in and out of the room.  Attention to detail (doors, electrical boxes, ductwork, etc.) is critical.  This does not affect how things inside the room sound.

Self-noise issues involve mass, stiffness, and the constrained layering concepts.  As Traderxfan stated you don't want a perfectly stiff/reflective box (where reverberation times are very low and you'd hear the room almost as much as the speakers) and you don't want a perfectively absorptive (anechoic) room either (where there is no reverb and it sounds like you're underwater).  Our ears are conditioned to hearing in "normal" rooms (typical size, shape, construction).

Note that addressing these two issues can benefit one while making the other worse.  For example the mass/stiffness of the interior wall is reduced when you go to double/staggered stud walls because there is drywall on only one side of the studs, thereby reducing mass by nearly half and stiffness even more.

Having a separate room is primary, then size/shape of the room.  Isolation is usually the next most important issue as most of us live with others or experience a variety of outdoor noises.  You can achieve great results more by paying attention to the details then by throwing piles of money at the 'problem'.  Just furnish the room in typical styles (unless you're a minimalist Scandinavian  ).  Bookcases add diffusion, stuffed furniture adds absorption, all in moderation.  Avoid coffee table in front of the listening chair.  Try to locate absorption/diffusion on opposite walls, but don't fixate on any of this.  Decent speakers shouldn't require a special room to sound good.

[redjr]

Thanks for all the comments and ideas.  As I stated in one of my earlier posts I'm not trying to go nuts or over-board with the sound isolation, or room self-noise.  I simply don't need the massive amount of isolation due to the arrangement of the house and the location of the media room to it.  Secondly, while I like my movies and music somewhat loud, I never listen at reference levels, nor do I listen at unreasonable levels at 3:00am while others are trying to sleep.     When everyone is gone I can blast away without annoying the neighbors - since there are none for several hundred yards in any given direction.  I just want to ensure the walls won't rattle too much when I do.   

I have to make the proper decisions for me and the intended use of the room and then blend the best solutions and methods of isolation and self-noise control.  It won't ever be a recording studio.  I believe I can take a compromised approach and reach the level necessary to satisfy me for the type of environment I'm trying to create - whether perfect or not. 

Rick

[redjr]

...Note that addressing these two issues can benefit one while making the other worse.  For example the mass/stiffness of the interior wall is reduced when you go to double/staggered stud walls because there is drywall on only one side of the studs, thereby reducing mass by nearly half and stiffness even more...

Actually, the walls that really count will have rock on both sides with insulation.  I will likely double up on the rock in the room and only a single sheet of 5/8" rock on the outside.  Still undecided about the green glue (GG) though.

[JLM]

redjr,

You're right where I am.  My room is the cheapest in the house (cheaper carpet/door and hasn't allowed wifey to fill it with junk) yet I'm very happy with it.  Smart design and attention to detail will make more difference than throwing brute force and piles of money at the problem.  And as I've tried to say over and over in this circle, 90% of the advantages can be had with little effort/cost.  The room is the 2nd most important factor to overall good sound reproduction (speakers being #1), but at the same time we're used to listening in 'typical' rooms, so we only need to tweak it to our needs. 

Again size (bigger the better) and shape (not cubic) are primary.  I say isolation is 2nd because lower background noise allows you to hear more dynamic range and save your hearing.  And the furnace can run or strong winds blow anytime, you may want to listen at 3AM, wifey may be running the washer/dryer/dishwasher before going to bed, and the teens sleep schedule is 6 hours behind everyone else's.  Even though my ceiling isn't properly isolated, the room felt spooky quiet the first few weeks after moving in and I don't bug the rest of the family when my listening gets energetic.  After that just decorate to taste (avoiding the coffee table) and you'll be fine.

Going over the top with the room is akin to what most audiophiles do IMO and that's to fill all sorts of horrible rooms with 'mega' gear and then struggle to achieve audio nirvana.  Or try finding an audio show that vendors don't complain about the rooms.  i say gear of proper design should perform well in the real world like products in other industries do (cars, TV, computers for instance). 

[bpape]

We're mixing isolation discussion with self-noise. 

Isolation of the structure (double/staggered stud walls, furring strips, isolation pads, etc.) lowers the sound transmission in and out of the room.  Attention to detail (doors, electrical boxes, ductwork, etc.) is critical.  This does not affect how things inside the room sound.

Sorry but this is absolutely not true.  Do you close the door to your listening room to keep out outside sound? Do you shut off items that have fans to stop wind noise and lower frequency vibrations? Those things have technically no impact on how the room sounds but does impact what you hear, what gets masked etc.  The items you mentioned above do the same thing to isolate the room better from outside noise, hence lowering the ambient noise floor in the room allowing easier perception of low level information.

Bryan

[redjr]

redjr,

... Smart design and attention to detail will make more difference than throwing brute force and piles of money at the problem...

That's what I'm trying to achieve without going overboard.  Simple yet effective design and implementation.  I'm sure I'll over-engineer my wiring needs, but I will have more than 1 system in the same room.  I like to be able to jack right into the wall.     Hence the needs to hide all wiring and cables.

Rick

[JLM]

Sorry but this is absolutely not true.  Do you close the door to your listening room to keep out outside sound? Do you shut off items that have fans to stop wind noise and lower frequency vibrations? Those things have technically no impact on how the room sounds but does impact what you hear, what gets masked etc.  The items you mentioned above do the same thing to isolate the room better from outside noise, hence lowering the ambient noise floor in the room allowing easier perception of low level information.

Bryan

Seems like you and I somehow continue to struggle to communicate effectively.  So I'll give a last try to clarify for your sake.

Of course the more outside noises are reduced/eliminated, the better you'll be able to hear the sounds generated inside the room.  Is that not one of the reasons to isolate? 

But if there is no noise being generated outside the room having isolation or not wouldn't make perception of the sound in generated in the room change (except for secondary affects as a result of some isolation methods).

[rajacat]

Actually, the walls that really count will have rock on both sides with insulation.  I will likely double up on the rock in the room and only a single sheet of 5/8" rock on the outside.  Still undecided about the green glue (GG) though.

Green glue is expensive. Hmm... I wonder if GG is just butyl rubber caulk that has been repackaged and dyed green? Butyl doesn't ever lose its flexibility and has some adhesive properties. I'm skeptical that GG has any unique properties. It seem that any caulk that retains it resiliency  over time would perform that same function as GG.

[ctviggen]

redjr,

You're right where I am.  My room is the cheapest in the house (cheaper carpet/door and hasn't allowed wifey to fill it with junk) yet I'm very happy with it.  Smart design and attention to detail will make more difference than throwing brute force and piles of money at the problem.  And as I've tried to say over and over in this circle, 90% of the advantages can be had with little effort/cost.  The room is the 2nd most important factor to overall good sound reproduction (speakers being #1), but at the same time we're used to listening in 'typical' rooms, so we only need to tweak it to our needs. 

Again size (bigger the better) and shape (not cubic) are primary.  I say isolation is 2nd because lower background noise allows you to hear more dynamic range and save your hearing.  And the furnace can run or strong winds blow anytime, you may want to listen at 3AM, wifey may be running the washer/dryer/dishwasher before going to bed, and the teens sleep schedule is 6 hours behind everyone else's.  Even though my ceiling isn't properly isolated, the room felt spooky quiet the first few weeks after moving in and I don't bug the rest of the family when my listening gets energetic.  After that just decorate to taste (avoiding the coffee table) and you'll be fine.

Going over the top with the room is akin to what most audiophiles do IMO and that's to fill all sorts of horrible rooms with 'mega' gear and then struggle to achieve audio nirvana.  Or try finding an audio show that vendors don't complain about the rooms.  i say gear of proper design should perform well in the real world like products in other industries do (cars, TV, computers for instance).

Personally, I don't feel double drywall and other techniques are going over the top.  I added insulation and thick doors with rubber seals but no isolation and regular drywall to a "home theater"/music/playroom I did.  At a nice sound level in the room, somewhat loud but nowhere near reference level , my wife would get mad at me because you could hear the music/movie upstairs.  And, if the kids were playing upstairs, you could easily hear them in the room.  My next room will have double drywall, isolation, etc.

[redjr]

Green glue is expensive. Hmm... I wonder if GG is just butyl rubber caulk that has been repackaged and dyed green? Butyl doesn't ever lose its flexibility and has some adhesive properties. I'm skeptical that GG has any unique properties. It seem that any caulk that retains it resiliency  over time would perform that same function as GG.

I wonder if Liquid Nail would perform with similar effectiveness?  It's way cheaper at $1.66/tube of LN, as opposed to 15.00/tube for GG.

[bpape]

Seems like you and I somehow continue to struggle to communicate effectively.  So I'll give a last try to clarify for your sake.

Of course the more outside noises are reduced/eliminated, the better you'll be able to hear the sounds generated inside the room.  Is that not one of the reasons to isolate? 

But if there is no noise being generated outside the room having isolation or not wouldn't make perception of the sound in generated in the room change (except for secondary affects as a result of some isolation methods).

Sorry - was just responding to your statement that isolation provided no benefit to the sound inside the room.  IF (big if) there is NO sound outside the room adding to the ambient noise floor then sure, there's no reason for it. Not been in many places where that's the case though to be honest. 

Bryan

[rajacat]

redjr,

The problem with liquid nails is that when it dries, it's as hard as a rock. The main point in using GG is that it retains its resiliency after it has cured.

Here's some for $3.35 10oz. tube
 
http://www.amazon.com/dp/B000DZBFRE/ref=asc_df_B000DZBFRE2757947?smid=AXL381AZQM9Q1&tag=dealtmp1027435-20&linkCode=asn&creative=395105&creativeASIN=B000DZBFRE#productDetails

more @$2.00/tube
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=260907541525&item=260907541525&lgeo=1&vectorid=229466

[Big Red Machine]

This would be petroleum based and smell like oil if I remember correctly from having used it for repairs.  Not something I'd want to have seep through smell-wise.  Best to check it out.  GG is odorless for the most part.  I have leftover tubes and it still is gooey after 5 years.

[mcgsxr]

Agree that it is important to consider off gassing and fumes for something that will be in an enclosed room with you!

GG is expensive, and I decided against it for my own build, and am not unhappy with the results.  I extensively used Roxul Safe n Sound in the ceiling and interior wall cavities, and thanks to bpape for the tip to use standard pink to stuff my bulkhead saved a bit there.  No staggered studs, no double drywall, no GG in my basement.  I did use 5/8 drywall for the ceiling, and boxed the pot lights.  The main floor is tile and hardwood, so that might be helping contain the sound too.  In my case, I can listen at pleasurable volumes, and when I keep the basement door (also a Roxul safe n sound piece) closed, no one is disturbed at the bedroom level.  I have an extensive thread about the build in the HT circle here, where lots of excellent ideas were shared - I was crowdsourcing for sure!

I trust that GG does a great job, and I know that many are supremely happy with what they have achieved.

Given the OP's intent to do the best he can on a budget, he will have to consider the added $ for this step, and make a call.

[TRADERXFAN]

Description here of what is basis for these CLD type non-hardening glues.
http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach-70.html#post1736880

They are polyurethane based with additives

[rajacat]

This would be petroleum based and smell like oil if I remember correctly from having used it for repairs.  Not something I'd want to have seep through smell-wise.  Best to check it out.  GG is odorless for the most part.  I have leftover tubes and it still is gooey after 5 years.

Yeah... you may be right. I remember using some years ago but can't recall if it had a strong smell.
I might try a tube of the DAP product just as an experiment. Its supposed to have less smell.

[avahifi]

Actually some the information regarding the thought that a really dead really acoustically damped room is bad for audio playback is wrong.

Of course if you are in an anechoic chamber and talk to someone else in there your voice will sound strange - - no normal reflections at all.

But - - - if you record yourself talking in a normal live room and then play the recording back in that anechoic chamber, it will sound just fine.  The recording includes the acoustics of the original live room along with your voice.

I would suggest that a great audio system located in an anechoic chamber would be the ideal location, just as long as your speakers are not designed for nearby boundary augmentation.  They are not going to get this in the anechoic chamber.

Any sound reflections created by your listening room is wrong.  What is right is the reproduction of the sound reflections in the original performance environment, nothing more, nothing less.  The "deader" your sound room the higher fidelity you will have.  After the fact playback room reflections are not part of the original source material, they are just distortion.

My suggestion for a great listening room would be one as stiff as possible at low frequencies to eliminate bass boom (along with appropriate dimensions) and as dead as possible to eliminate as much mid and high frequency reflections at possible.

Frank Van Alstine

[Nyal Mellor]

Any sound reflections created by your listening room is wrong.  What is right is the reproduction of the sound reflections in the original performance environment, nothing more, nothing less.  The "deader" your sound room the higher fidelity you will have.  After the fact playback room reflections are not part of the original source material, they are just distortion.

My suggestion for a great listening room would be one as stiff as possible at low frequencies to eliminate bass boom (along with appropriate dimensions) and as dead as possible to eliminate as much mid and high frequency reflections at possible.

Frank Van Alstine

If the room is very stiff at low frequencies then that will cause "bass boom" because nothing is damping the natural room mode resonances. All rooms have resonances, that is inescapable. Better instead to have well damped walls. A single layer of drywall actually resonates at some frequencies and not at others so it selectively absorbing some of the bass in your room. A double layer of drywall with a damping compound does not have these dominant resonances and therefore in my opinion is a better way to build your walls if you have choice. Double drywall tends to need more in room absorption but you can get to a higher end point in terms of sound quality than using single drywall.

As to your assertion on reflections. Well that is certainly one opinion, though quite dated relative in context of the psychoacoustic research conducted in the last 30 years by Toole et al.

[Bob in St. Louis]

Frank, you made several good points that are presented in a way I've never thought about them.
Well done, I learned something. Thank you.

Bob