Advice on dedicated room

you need to ask a contracter........

if you get nice earbuds from JVC that is better

2x4’s are fine. 2x6’s were/are used in ext walls in order to get thicker insulation (more R value)You may want to consider the golden ratio (1.6) as a guideline for the short wall. Or set up the system in the corner facing diagonally into the room and leave the size as is. FWIW i am a retired builder contractor/carpenter/woodworker

I'm a General Contractor.  2x4 will be fine. I do strongly suggest you buy a product called "Rockwool" and use it in all your wall studs and add a layer to your ceiling if it is currently R19 Batt.  I do this on all my new home builds for home offices and master suites since current designs are open plans and are much noisier in gathering spaces.  

What do you want to accomplish? Sound proofing or Acoustic Treatment? If both or either one you will need a plan and importantly some knowledge of how to set / realize the goal.

I agree. Simply ‘throwing in’ insulation (blown-in cellulose may be better), or even ‘sound batt’, may not accomplish a goal for sound transmission or treatment. That is a science all to itself. Resilient channels, green glue, etc. are things often thrown out without any science backing up their use. And you may still need sound treatment on the drywall itself, regardless.

I'm not an expert in acoustical treatments, and a professional who is should be consulted if that is a goal in installing a suspended ceiling.

Sound isolation ("soundproofing") is an entirely different thing from the internal acoustics of the room. In my experience building a room in our basement, they can work in opposite directions. The less leaky the room (to sound), the stronger will be bass nodes and peaks, and the greater the need for acoustic treatment.

When using two layers of sheetrock, I suggest using different thicknesses. Or you can use a commercial product like QuietRock, which has two different thicknesses with a resilient layer (like Green Glue) bonding them.

I worked with an acoustician who pointed out that any holes allow for sound transfer. So if that’s important in your room (it was here, to keep out HVAC noise), all electrical boxes need acoustical putty pads, edges of sheetrock should be sealed with acoustical caulk, and so on. You can find more info about construction practices on the QuietRock Web site. I also got a few things (door seals, mostly) and advice from The Soundproofing Company.

I used QuietRock rather than resilient channel because I couldn’t afford to lose the few inches of height that the latter takes. The finished room is just 7 ft high.

The hardest thing to reduce proved to be structure-borne LF vibration, such as the sound of a refrigerator above. But at night, the SPL A weighted is about 28 dB . . . very quiet!

When construction is done, you treat the room as you would any other audio room, with products from GIK, ASC, RPG, Vicoustic, or other acoustics vendors.

I hope that’s helpful and that it’s not TL;DR material.

if you get nice earbuds from JVC that is better

What the hell does that even mean??

Thank you everyone for the great input. I will be looking to soundproof and treat when it’s all done. The ISO wall was touting the extra bass absorption their system has so I thought it might be worth trying. I know there will be in room treatments as well after the room is complete. 

I will probably just go the double drywall green glue route. I will add in wall sound proofing as well. My basement is unfinished so I have options on the direction I take. Thank you again everyone 

Have fun with the project, & let us know how it works out!

Hate to tell you this but at 15x16x8 your room dimensions are your biggest challenge. LxW is very nearly square and almost perfect 2x H. Do the math, work out the modes, you will see they cluster big time. I would do this first before anything and plan accordingly. Maybe you can use a false wall to make one dimension less a multiple and incorporate a bass trap behind it tuned to absorb in the range that is left. This will be far less intrusive and way more effective than adding traps later. 

Do not fall into the trap of thinking more and thicker is always the answer. As already alluded to this only traps and stores energy in the room. Sound energizes all room surfaces. What you want is not so much to try and kill this as shape it in a way that sounds good. Your room is small but if done right will be made to sound more spacious than it is.

This small a room will also make it more important than ever that you use a distributed bass array and Townshend Podiums and Pods for isolation. The DBA will make your small room sound huge, and isolation will greatly diminish the rooms impact on the sound by energizing it less. Money spent on these will far outweigh a lot of much more expensive acoustic treatment. 

If you don't know how to work out the modes then look on-line or get Robert Harley's The Complete Guide to High End Audio. My first edition has step by step instructions for mapping room modes. There's probably faster ways now than a pencil but however you do it just be sure and do it. Whole lot easier to fix it first on paper and build it right than to try and fix it later with a lot of expensive space wasting tube traps.

@mike_in_nc  
Thanks for the first hand experience advice it is very helpful. I will add a system to my page when it’s all done. Ordered my speakers today ! 
@millercarbon 

I will probably be adjusting for a better ratio and the DBA is on my list too. I have Robert Harleys book and am reading it now in my limited spare time. I will go to the modes section and learn about it. It’s a fantastic book! Thanks for the advice. 

Regarding bass: I agree with the suggestion to use a DBA. My main system has two JL Audio F112 subs, and I was delighted by the improvement when I added a third (a small B&W ASW 610) as proof of concept. That improvement went up another notch or two when the B&W went back to my desktop system & was replaced in the main system by an SVS SB-3000.

Just FYI, my room dimensions = 20.1 ft L × 12.5 ft W × 7.0 ft H. Calculated modes don’t agree terribly well with measurements. The effective dimension is not always at the interior wall surface, it seems.

You can take a look at my system in my house of stereo. It includes construction pics and details in the comments section that may be helpful to you. Have fun with the process. Be patient.

Home builder for 35 yrs.. 2x4 studs with closed cell foam on exterior walls. Open cell in ceiling. This is what I do in basements here in the Midwest to control temp and sound through the ceiling to first floor. Good luck. 

@baylinor and @mickeyb 

Thank you for the advice. I’ve received a lot of great input from everyone.  
@mickeyb 

Does the closed cell foam go between drywall and stud or in the space between the studs? 

Sound insulation behind a drywall will essentially do nothing for the room acoustics. It will make elsewhere in the house quieter. If that is your aim then good. Double thickness drywall will help a little inside the room, ensure the two surfaces are very well glued together and very well attached to studs. I have smaller room than this with 45 degree corners, that seems to help a little. Remember sound doesn't know what size the room is it is purely a mechanical acoustic response to the whole environment i.e. furniture, carpets, surfaces (hard / soft), angles etc. There are three aspects reflection, absorption and diffusion. You usually have a mix but rarely the right mix. Carpet the floor maybe plus rugs, the ceiling is a big flat space, and reflective but quite a way away. Some diffusion is good, two ceiling fans perhaps? I have a very large recliner in soft material and its effect is dramatic. Other softer material seats help and I have built some prototype bass traps that diffuse, absorb and use membranes, they do work but are difficult to get right. 

room modes online calculators abound…note that they don’t include a non parallel wall…hint, frame that in now. Also you want low noise in the room, so insulation will improve the sound. S/n is important. 

Jim Smiths book is great - Getting Better Sound.

Fix your room before adding subs. It’s not all about bass. 1st reflection points have nothing to do about bass. Talk to experts from GIK/ASC/Acoustic Fields to get your room right with diffusion and absorption, then start adding whatever you think you need to make your system sound the way you want

I spent a gob of money on a dedicated two-channel room 2 years ago, managing to avoid most of the usual pitfalls.

One of the most successful money pits was Quietrock 545. It REALLY works. 5 layers of drywall, one layer of sheet steel, 1 1/4" thick. Thing about walls is that they flex with the sonic compression wave, turning your drywall into a very low class speaker. Q 545 is a beast that does not flex. Good sound insulation to boot.

Glue and screw construction. None of this nail gun crap. I used two elastomeric products from Chemlink, M1 and BuildSecure. Many cases.

Dimensions also matter, as your intuition tells you. Don’t listen to the usual suspects and their snake oil here; actual scientific research has been done on this subject, and it’s absolutely free. Check out the School of Acoustics at the University of Salford (UK). They did a quarter million simulations to find that MOST rooms are poor, a third are OK, and 2% are good. Half inches matter - I’m serious.

Good luck!

Some diffusion is good, two ceiling fans perhaps?

The air transmits your high fidelity sound. Setting it in motion with fans cannot be a good idea.

Proper Planning Prevents, Piss Poor Performance and don't for get about KISS.
Questions:
1 Save me time or save me money?
2 What is your budget? If answer to 1 is "save me time" forget about cost.
3 What are your performance requirements? This needs to including, HVAC, Power including ground plane and noise (EMI/RFI), Lighting, Acoustically, Human factors, ....
4 Now you have the information to build a model to figure out acoustic, electrical, and thermal performance. Manufacturers post performance characteristics of products you can insert in to models and predict the result. At this point you will need to decide, DIY, Contractor, ... or Engineer.

I did this kind of work as an engineer for awhile where the answer to question 1 was "save me time" and I have seen the work of some others. There are some highly capable people out there in this field of work for every budget. I have also seen some disasters. 

Get some professional help, the result will better and take a pole. "Survey says."

Let's slow down a bit. A lot of conflicting advice. Yes, identify what you are trying to accomplish. No need to over insulate unless you want it quiet for people outside the room.
Once you add drywall, you are adding an element/surface you will need to treat.

Raw ceiling joists are inherently good acoustic surfaces. It may look ugly...but adding drywall...again, is adding a problem you will need to address.

The room is small, yes...but making it even smaller to get 'your golden ratio' may not be the best tactic if you can make it 'feel longer acoustically' through other means.

Your room is somewhat challenging. I would spend a year learning about acoustics and sketching various scenarios out before breaking ground.

Here is a link to a room-mode calculator:

Amroc room mode calculator

Thank you again for all the different views. This will help me tremendously moving forward 

except the ear buds thing. 😂😂

When the OP says 'I am going to start building...' I take it to mean he is at the stud stage with pretty much all options open.

Moving might be best but lets assume that is not an option. 


Is there are reason that both side walls can not be tapered in at the speaker end? Or will the speakers wall be on the shorter of the two walls?

The ceiling could also be tapered for additional asymmetry. 

Get your dedicated lines installed now too.

@ chorus 

I have concrete on three sides with the two opposite concrete walls probably extending out an undetermined amount. I haven’t started anything yet so all options are open. I have a dedicated sub panel that serves the main floor home theatre that I will also use for the 2 channel room.  
@sensesundertime 
I consulted with one company that I believe was going to design Helmholtz in the room. I didn’t go with them because they said it would cost 50k when done. Far too much for me but I will still look into it. Thanks 

Agree 100% with millercarbon:

This small a room will also make it more important than ever that you use a distributed bass array and Townshend Podiums and Pods for isolation. The DBA will make your small room sound huge, and isolation will greatly diminish the rooms impact on the sound by energizing it less. Money spent on these will far outweigh a lot of much more expensive acoustic treatment.

I have had nothing but excellent results with a DBA in 4 different rooms (two of them smaller than yours).
Though I have yet to try isolation podiums or pods, I also got great results isolating with springs under each of my mains and also under each of my 4 subwoofers.

@artemus_5 +1:

Or set up the system in the corner facing diagonally into the room and leave the size as is.

I have a 15’ x 15’ exact square room set up very similar to figure 2 at: DECWARE - Article about Setting up a Listening Room without Treatments
If not for experimenting with this diagonal placement, I probably would have given up on the room.
Very noticeable improvement over anything I tried regarding "traditional" speaker placement.

Lots of great advice in this thread.
Great thread too! I’m sure a lot will benefit from the many great contributions.

OP - Best of luck to you on this journey!

We are all agreed you need to make the room more oblong.

Why not build a separate storeroom on one side for records, books, equipment, whatever.
Build about 5-6 feet wide reducing the 16.5ft dimension.
Clear all the crap out of your room.
I did this when I built my room.  I have art on the walls in place of loads of LP racks and a great open feel.

More than anything else it helps just to keep in mind. No room is perfect, and one can easily spend more on the room than the system.   

Back when I was searching around going to all the audio stores within a couple hundred miles the best sounding system by far was in a room just like yours. Corner Audio, only the long axis was vertical. The room was roughly 15x15 with a ceiling twice as high! Yet he had easily the best imaging, most engaging sound of any store up and down I5 from Seattle to Portland.   

That is the main point I would like to make. Harley has an excellent book, and there is a tremendous amount of information. These things are all about compromise. The more you know the more likely you will be happy with your particular set of compromises. 

I’ll tell ya what works for me:

My room is 19 x 29. The ceiling has a gable on one side and dormers on the other. The gable roof is 12 ft at the apex, 3 ft at either wall.

The ceiling is covered with 17” of rock wool. The walls have 6”. NO SHEET ROCK: I covered the insulation with fire resistant burlap. 
My 3,000 book snd 6,000 LP library line some of the walls. 

The floors are plank hardwood. I cover the floors almost completely with throw rugs. Only four small windows: blankets cover the windows in the dormers during listening.

This has given me a fairly dead, semi-anechoic room. The acoustics are superb. Most people notice immediately upon entering the room the difference in how their voice sounds.

The room was added to my system three years ago. My system has otherwise been the same for 36 years. The room lifted the overall quality to a place where I don’t feel any need to be looking for a anything else to make it better. I sit back and enjoy the music.

My room was designed by a Cooper Union/Harvard trained architect (and friend) who came up with this concept with a classmate who is a “sound scientist/architect”.

The Square shape of your room is a problem. I would put a wall in to create a 4.5 ft wide room along the length, and put your equipment in there, and your record library in there (yes, I’ve made an assumption there, but whatever). 

@ronboco, the concrete walls are not bad as a surface inherently.
Concrete is damped / well damped ( below grade ) but very reflective.
The entire audible spectrum will be reflected making diffusion and absorption more important.
Addressing the low end with the ISO wall is a very good idea and find out how much benefit can be expected. If drywall is put up then damping the resonant areas behind the finished wall would be important.
The concrete walls help with sound isolation as well. 

2x6...definitely 

I would not add a wall reducing the limited space you have. It is entirely possible to treat the room and have superb acoustical performance, even if the room is a perfect cube. The idea of building a new wall to provide non parallel walls I would also dismiss. Having a changing dimension will not remove problematic nodes, just change them for different ones that still need taming.

You have what can be considered a small room and as such needs absorption more than dispersion. Absorption must take the form of broad-band construction to be effective. The often recommended: 'just add a rug/curtain/bookcase etc. are only narrow-band absorbers and although they are better than nothing they will not reduce the decay sufficiently across a broad range of frequencies. You mentioned putting a 45 degree angle on 2 corners: that is where you could/should fit bass traps which will greatly improve the room's performance below the Schroeder Frequency. Strongly recommended.


A suggestion is to buy a microphone and use the excellent free download REW and measure your room. This will take the guesswork out and provide solid evidence of what any added treatment is doing and also help find the optimum place for any sub/s.

@lemonhaze, I disagree. I think it is better to make the room as good as possible, and then treat it. But then, my crystal ball has been busted for some time now.

Hey Terry, I don't disagree with you disagreeing but in his smallish room it's the lesser of two evils. It was a popular consideration for awhile but lost momentum. I unfortunately lost a lot of links and papers when my computer died, I would like to have provided plots of a room where they were taken with zero treatment, then with increasing treatment and the same room with the roof sloping, done as part of a dissertation. Essentially the results were close just with some of the treatments in slightly different locations. So the way I see it, why go to the considerable expense and bother for very little if any gain.

Strength is not an issue using 2x4 framing. What is an issue is isolation and vibration control. Using a 2x6 framing allows you to stagger your vertical studs so the sheetrock on each side of the wall is independent from one another.  You are almost as good as 2 2x4 walls.  
Lay the first layer of 1/2" sheetrock vertically or horizontally.  Then use an adhesive to add 1/8" of polystyrene to the whole wall & ceiling.  Finish with a second layer of 1/2" sheetrock the opposite direction of the first layer.
The walls & ceiling will have zero vibration and great isolation. 
Fill the empty wall cavities with insulation ..of course. This really works.