[SMA]

We have a 14.5' by 26' open area with a 7.75' high ceiling (except for one soffit at 7' because of HVAC) in our basement. I use most of it for a listening area, two channel only, and my wife has an art work bench in the back third or so. The walls are drywall but the ceiling is currently suspended tile.

We are planning on remodeling this winter. We do not plan on moving walls but do plan on drywalling the ceiling and getting rid of a large corner brick raised area that currently holds a propane stove. My question is to the benefit of double drywall and resilient channel. I intend to use resilient channel for the ceiling and to insulate the ceiling. However, we can keep most of the existing drywall on the walls and it would be very expensive to tear out the existing drywall and then add resilient channel and a second layer. The room is currently, to me, pretty quiet. We live on 12 acres well into the country, so any noise in the listening room is HVAC or other related. Also, we are empty nesters so I don't bother others when listening. Typical sound levels are between 35-40 db's in the room when quiet. I have Salk Song 3 speakers driven by an Anthem STR Integrated amplifier (I use ARC DSP for bass only). I am happy with the sound and rarely listen much above 75-80 db's but if the remodeling can make any improvements I am interested.

My questions is whether, other than sound proofing, does resilient channel, insulation and double drywall make any perceivable improvement to the sound of music that cannot be accomplished with absorption and/or diffusion added after the remodeling (I plan on working with GIK once we are done with the project)? I have searched the internet and read Floyd Toole's book, but have not seen anything definitive on actual improvement to sound other than a lower noise floor.

[paul79]

In my experience, eliminating the ambient noise in the room from your appliances, A/C/heater, outside noise, etc. is important for lower volume listening and low level detail retrieval. Less so if you listen loudly. If you like to listen loudly, the steps to improve the structure will be more beneficial then. I tend to follow a rule for myself, in that when the images are the right size, I have the correct volume setting. It may be much lower in volume than one thinks. In my very quiet listening space, very low volume levels are very satisfying and are a very good interpretation of the real event.

[richidoo]

My questions is whether, other than sound proofing, does resilient channel, insulation and double drywall make any perceivable improvement to the sound of music that cannot be accomplished with absorption and/or diffusion added after the remodeling (I plan on working with GIK once we are done with the project)?

No.

The only purpose for resilient channel and double drywall is soundproofing. It does not improve sound quality inside the room. Actually it will sound worse than the unfinished wood joist/plywood ceiling you have now, but I understand the need for soundproofing the upstairs. You will also lose that extra foot of height with drywall installed.

[Mag]

At your listening spl level IMO you don't need to soundproof. I however soundproofed part of my living room and instead went with basement because I still could not contain the music at my spl listening level. The soundproofing however helps in keeping out outside noises such as dog barking etc.. I can have the neighbors dog bark next door and I can barely hear it in that room.

Acoustic absorption and dispersal panels is what you want. But you don't want to take all the liveliness out of a room.

[poseidonsvoice]

No.

The only purpose for resilient channel and double drywall is soundproofing. It does not improve sound quality inside the room. Actually it will sound worse than the unfinished wood joist/plywood ceiling you have now, but I understand the need for soundproofing the upstairs. You will also lose that extra foot of height with drywall installed.

Ummm. Not exactly. Every little bit counts, especially if you are/were like me and threw the budget out of the window (for the OP, see my systems page under the room description). The benefits primarily lie in the bass, ie below 100Hz and more specifically in the time domain around 60 Hz.

Nyal Mellor summarizes it well here (both improvements in the bass due to soundproofing as well as the in room acoustical methods to improve bass performance):
http://www.acousticfrontiers.com/room-acoustic-design-insights-five-steps-to-amazing-bass/

Best,
Anand.

[JLM]

Keep isolation and treatment separate in your mind. 


Isolation factors that are often ignored:

1.) Door (I use an insulated exterior fiberglass door that can be stained/painted and has a weather seal - a cheap solution);

2.) Ductwork (I use insulated/lined flexible ductwork and can barely hear the furnace fan - warning, it cuts down on air flow);

3.) Wall/ceiling penetrations (recessed light fixtures and a single layer of drywall attached to the joists above was my downfall as builder refused to use resilient channels to suspend the drywall ceiling).  My only do over would be to use wall sconces and suspend the ceiling.  As it is I can hear footfalls, washing machine, dryer, dishwasher, and dog barks.  Fortunately most of my listening is early morning so those sounds aren't present.
 
Went the extra mile and used insulated staggered stud interior walls (that adjoin storage spaces) and initially the room seemed spooky quiet and isolated from the rest of the house.  Another consideration is electrical.  I have (3) 20 amp cryo'd hospital grade duplex receptacles serving the audio system, each on a separate 20 amp circuit, and grounded together (apart from the rest of the house).  Have never had power aberrations, so these last steps were done on a "while you're at it" basis.

Doubling up drywall and varying stud spacing affects the room's bass response at high spls. 

[SMA]

Thank you all for your responses. I do plan on adding two subwoofers to the system. I liked the Acoustic Frontiers article and it has me thinking I will price out re doing all of the walls along with potential bass traps and subwoofers. I don't consider myself a bass head but I have found as my bass has improved with speaker placement and the Anthem DSP that better bass seems to make the midrange and treble sound better.

[richidoo]

OP didn't specify that there was no budget, so I assume there is, which implies that efficiency of the bass treatment is desired.

The internal friction of calcium sulfate (chalk) in a flexing drywall layer does very little to absorb bass. Nothing "floppy" will affect low bass by itself except by it's own internal friction while bending, which is always very low. So whatever damps the diaphragm motion must be very efficient and loose fiberglass batt is not, nor is green glue. Green glue is good at damping higher frequency vibrations in contrained damping layer. It damps drywall's own trashy resonant sound, and is useful in damping speaker cabinet vibrations. It is not effective as primary damping element in LF diaphragmatic absorber. It only adds friction through resisting sheering motion. When the whole wall/ceiling is suspended as a unit on springs then the bending of drywall is reduced along with the sheering movement in the greenglue.

Will drywall system affect bass? Of course - every golden ear knows that "everything affects everything," but the effect of a drywall system on damping bass reverb is not strong enough to warrant the price, unless soundproofing is also needed.

Why is drywall system so inefficient as a bass trap? The air velocity inside any diaphragmatic absorber must be directed into the friction material for there to be a damping effect on the diaphragm motion, but the resilient channel lifts drywall diaphragm away from the studs allowing air to escape pressurization into the absorbant material. Technically, it is not a diaphragmatic absorber at all, so we shouldn't expect it to perform like one engineered specifically for bass reverb control. The only damping affect on room bass reverb is drywall internal friction and sheer friction damped by greenglue, neither of which are strong enough to significantly damp LF reverb inside the room.

But, if the drywall barrier is well sealed to prevent air leakage, and the resilient channels allow diaphragm movement, then it acts as a vibration isolator, to prevent LF sound from being transferred mechanically to upstairs, but there is minimal "shock absorber" on those springs so the bass damping inside the room is very limited.

Efficient reduction of low frequency reverberation is found in electrically active bass traps like PSI AVAA and by engineered diaphragmatic absorbers using activated carbon as the damping agent, a far more powerful absorber than FG.

My friend's room is 15 x 23 x 8 with 5 walls of resilient channel, double 5/8" drywall with green glue and FG insulation behind. He got his money's worth with the incredible soundproofing effect. But it didn't improve the bass reverb inside the room. There remained very strong modes in the listening position. They were treated with passive FG absorbent panels on walls and corners in the traditional method but it's still not cured.

[SMA]

Thank you. Your response makes a lot of sense to me and I definitely do have a budget. Also, I am by no means a golden ear (perhaps a 59 year old slightly tarnished copper ear?). I think I am going to get bids for every step of the project but will probably leave the existing walls alone, insulate and use resilient channel on the ceiling which has to be drywalled anyway and then slowly work into additional subwoofers and treatments to taste.

[SMA]

JLM. That is interesting that the builder would not use resilient channel on the ceiling. I used it in a previous house where we had a 5 channel system just below our master bedroom and the builder had no problem using resilient channel. Also, when I mentioned it to our current builder a few weeks ago he didn't have any objection. To me, for sound proofing, that is the area of the room that makes the most sense for separation of the sound from the joists. I appreciate your comment on the door. After reading it I put on some music and then went upstairs. I heard very little that sounded like it was coming through the floor (music was at about 75 db), but I could clearly hear music that was escaping from an opening to a stairway about 35 feet from the speakers. We have a door opening cut in already so I will look into an insulated door when the time comes.

[Rob Babcock]

If you can do the resilient channel that's the way to go.

[poseidonsvoice]

OP didn't specify that there was no budget, so I assume there is, which implies that efficiency of the bass treatment is desired...

My friend's room is 15 x 23 x 8 with 5 walls of resilient channel, double 5/8" drywall with green glue and FG insulation behind. He got his money's worth with the incredible soundproofing effect. But it didn't improve the bass reverb inside the room. There remained very strong modes in the listening position. They were treated with passive FG absorbent panels on walls and corners in the traditional method but it's still not cured.

Thanks Rich, very good and salient points! In my own room, although there seems to be some hand waving theory that resilient hat channel with CLD using green glue can help dampen the 60Hz resonance, I do not have a method of proving it (and I do doubt the effectiveness of doing JUST that as you suggest). I had to to use room treatments AND a multisub setup to be satisfied. In fact, I would argue that just using room treatments can lead to an overdamped room (especially if broad band treatments are used) and the use of multisubs is a necessity (especially if your main speakers use a monopole design).

The soundproofing however is a nice touch, given that the kitchen is immediately next door and the son’s bedroom is immediately above. I also have 2 external solid core doors that must be opened prior to entering my room. One opens towards the outside and the other towards the inside of the room. 

Best,

Anand.