[rich121]

I don't care about stopping the sound from leaving the room I just want to make the room sound it's best.
The room is 24' long, 18' wide with 8' ceiling.
On the northeast corner of the room is a space taken by a small pantry and a stairway. Both of these will be shut in with doors.

The 2 short walls, and one long wall are "outside walls". They are a nominal 6" thick and will have a 1" layer of spray foam insulation on the inside of the siding, with a layer of 5 1/2" fiberglass insulation covering that...the outer walls will be air tight from the sprayed in foam.

I will have my system set up on the short wall (18')

I was thinking of using 2 layers of 5/8" sheetrock on the walls

I also was pondering a way to leave the ceiling acoustically open, which is also the floor of the second level and is 2"x6", so that I can get a more open and taller/larger soundstage... any thoughts?

I would be very happy for any and all suggestions...

Thanks...


Rick

[JLM]

First, bigger the better, so good you've got a decent sized space.

Second, proper proportions (length to width to height) is essential to minimize standing waves (echo) being reinforced when the ratios are in whole numbers.  As you might imagine a dome is the worst, followed by a cube.  Like most folks you are limited by the height of the room.  The correct proportions (to eliminate echo from one direction reinforce another) are in the following ratios: 1 x 1.61 x 2.61.  That means your room should be smaller (roughly 13 ft x 21 ft).*  As it is your space is exactly 3 times longer than it is high and the width to length are in an exact 3:4 ratio.  Exact ratios are bad.  Think about turning part of the space into built-ins for equipment or infinite baffle woofers.

Even if you don't have concerns regarding sound leaking out, you won't want it leaking in.  Noise from wind, traffic, furnace/air conditioner, washing machine, dishwasher, and foot steps can all leak in.  Using an insulated fiberglass exterior door with weather seals and lined/insulated flexible heating duct can help reduce noise greatly.*  Seems like you're on the right path with the foam/fiberglass on the exterior walls.

Another potential source for noise is possible electrical power aberrations (dirty power).  At a minimum run dedicated audio circuit(s) and if possible use a separate ground.*  And splurge for a hospital grade wall receptacle (they grip harder, especially the red ones).*  Ideally you'll live in a rural neighborhood with a new substation, have your own underground feed/transformer, and have all new appliances as these are all sources of electrical power aberations.

5/8 inch drywall is good, doubling it up is even better.  But reducing the stud spacing could be even better as halving the spacing will increase stiffness 16-fold.  Some recommend varying the spacing between 8 and 16 inches, again to randomize any reverberation from the walls.

Hopefully those pantry/stairwell doors will be solid core (seals can be added).  And be sure to fill in any windows.

Keeping the ceiling "acoustically open" would "allow" you to hear every foot fall.  The even spacing of the joists would create a huge comb effect (bad!).  And I can't understand how 2x6's can span floor loads 18 feet.     Do you have additional beams/columns in this room?

*Steps I took on my listening room.

[ctviggen]

Another potential source for noise is possible electrical power aberrations (dirty power).  At a minimum run dedicated audio circuit(s) and if possible use a separate ground.*  And splurge for a hospital grade wall receptacle (they grip harder, especially the red ones).*  Ideally you'll live in a rural neighborhood with a new substation, have your own underground feed/transformer, and have all new appliances as these are all sources of electrical power aberations.

5/8 inch drywall is good, doubling it up is even better.  But reducing the stud spacing could be even better as halving the spacing will increase stiffness 16-fold.  Some recommend varying the spacing between 8 and 16 inches, again to randomize any reverberation from the walls.

Hopefully those pantry/stairwell doors will be solid core (seals can be added).  And be sure to fill in any windows.

What do you mean by running a separate ground for audio?

You can add staggered stud construction and insulation in the walls.  See:

http://www.soundproofingcompany.com/library/articles/staggered_stud_wall_construction/

[bpape]

Actually, having larger spacing between studs will increase isolation.  While counter-intuitive, what it does is lower the resonant frequency of the structure so fewer and fewer notes excite the resonance.

Now, if you want a balance between somewhat better isolation and spreading things out, try 2 walls with 16" spacing and 2 with 24" spacing.  Preferably, have a 16" and a 24" facing each other - or - 24" at the ends of the longer dimension and 16" at the ends of the shorter dimension

Doubling the drywall and then leaving the ceiling acoustically open doesn't make sense - sorry.  If you're going to do DD, then do it on the ceiling too.  If you're going to leave the ceiling open, don't bother with double on the walls.  Just a waste of money.

While the spray insulation will do an air-tight seal that will help with mids and highs, the lows will flank right through it just like the other walls and up to the above (or down and in from above).  Just trying to convey not to think of this wall any differently than any of the others.

For the doors, use solid core wood doors.

Bryan

[JLM]

Bob,

At the recommendation of a audiophile/electrician the three circuits that serve my audio system have their own grounding rod.  I don't know nothing about electrical, but it passed the mustard of the nasty electrical inspector.

I did staggered stud construction on the inside walls (but both back up to storage spaces, so it was a waste really).  I'd used staggered stud walls on other projects with great success.

Bryan,

From my understanding of structural dynamics you're right, larger spacing would lower resonant frequency, but would also make it easier to vibrate.

[ctviggen]

Bob,

At the recommendation of a audiophile/electrician the three circuits that serve my audio system have their own grounding rod.  I don't know nothing about electrical, but it passed the mustard of the nasty electrical inspector.

Interesting.  As long as this ground rod ties into the home ground rod with the appropriate gauge of wire, this is up to code.  Whether it provides a benefit or not, I'm not sure.  I'm going to run an isolated ground to my system.  This in theory should provide reduced RF coupling into the AC line for the system, although it does nothing for junk that's already on the AC line. 

I was going to do double drywall + GG, RSIC (isolation clips) + hat channel on the ceiling and "interior wall" and staggered stud and DD, GG on three walls, etc., but I have a fireplace, two windows, and a sliding glass door.  I was counseled that all of the work I was going to do would be wasted, so I'm saving all my clips, hat channel, GG, sound isolation caulk, etc. for the next house.

[mshan]

http://www.rivesaudio.com/services/servframe.html

[rich121]

My walls are all built with 16" spaced studs, and like I said, I'm not worried about inner wall isolation, so the addition of the second wall is not needed.

So, I should install fiberglass insulation on the inner wall, and 2x 5/8" drywall on all walls and ceiling?

As for adding an extra or isolated ground rod.... that is a very bad suggestion and whoever your electrician and electrical Inspector is, they should be reprimanded...this is a very dangerous practice and against code.
How do I know? I have been a Journeyman electrician for over 20 years, IBEW local 112.

For electrical, I will be adding an isolation transformer to power all audio circuits.

I thank everyone for the suggestions so far, and if there are more, please add them, I'm all ears   

Rick

[ctviggen]

So, I should install fiberglass insulation on the inner wall, and 2x 5/8" drywall on all walls and ceiling?

As for adding an extra or isolated ground rod.... that is a very bad suggestion and whoever your electrician and electrical Inspector is, they should be reprimanded...this is a very dangerous practice and against code.
How do I know? I have been a Journeyman electrician for over 20 years, IBEW local 112.

Assuming the grounds are tied together per the NEC, could you point to a section in the NEC where this is a code violation?  I have both the 2002 and 2005 codes, and don't see how this is a code violation. 

As for really treating this room, you may want to hang out here:

http://www.avsforum.com/avs-vb/forumdisplay.php?f=19

Also be advised that all of this stuff is very expensive.  When you start getting into green glue, wood core doors, fire putty, etc., it adds up quickly. 

[rich121]

"Assuming the grounds are tied together per the NEC, could you point to a section in the NEC where this is a code violation?  I have both the 2002 and 2005 codes, and don't see how this is a code violation"

You could go back to much earlier NEC codebooks and it's still a violation...

It's really scary when people have a copy of an electrical manual, NEC Code book or whatever, and without any knowledge of electrical practice, and think they can comprehend it, give "advice" or actually install...very scary...

Read article 250 "Grounding and Bonding"

When a solution recommended by inexperienced individuals is to isolate the electronic equipment from all other power equipment by disconnecting it from the power equipment ground, safety is compromised when the equipment grounded to an earth ground isolated from the common power system ground.
Isolating equipment in this manner creates a potential difference that is a shock hazard.
The error is compounded because such isolation does not establish a low-impedence ground-fault return path to the power source, which is necessary to actuate the overcurrent protection device.

Rick



 

[rich121]

http://www.rivesaudio.com/services/servframe.html

I would like very much to be able to afford their services, but my budget won't allow for it, as I see their least expensive to be at $1,200.00 plus whatever extra.

I started with a contractor that my son was working for...ended up firing the contractor, kept my son on, and had to "re-do" 3 weeks work that was previously done... I'm putting along with barely enough to finish the remodel.
I'm looking for the best/affordable means to do the room.

Rick

[Bill A]

I'm in the process of remodeling our basement, too.

First Problem:  My basement ceiling is 8ft with 12x12 fiberglass tiles glued to the sheet rock.  The tiles are dirty and scarred and need to be replaced.  I want to be able to put fiberglass insulation between the upper level floor joist and be able to open up the ceiling for mechanincal repairs if needed.  Since a drop ceiling just won't work with the current built-ins I needed something that attached right to the ceiling/floor joist and ceiling link looks like just the ticket http://www.ceilinglink.com.

Second Problem:  Much of the basement wall area is either concrete or cinder block.  I need to cover these areas with a material that absorbs sound rather than reflect it.  The first material that came to mind was a carpet like material that is typically used on walls in a dentist's office to muffle the screams of the patients.  I found several sources, here's one http://www.acousticalsolutions.com/products/fabrics/crosspoint_fabrics.asp

Another soution is this, which really appeals to me http://www.fabricmate.com/store.php.  The system uses a sound absorbing substrate 1/2" to 1" thick attached to the wall.  A track goes around the perimeter and fabric is attached to the track.

I've not used any of these products yet, but if anyone has I would appreciate the feedback.

Bill

[TomW16]

Hi Rick,

Hang in there.  I am also finishing my basement for a dedicated 2-channel/home theater.  It's tough slogging but I hope the effort is worth it in the end.  I am just comming up on the drywall phase.

I followed the advice of 24" spacing on 2 walls and 16" spacing on the other two walls as Bryan has mentioned.  This will allow you to use standard insulation without cutting each peice to size.

Isolation and acoustically treating the room appear to be at odds with each other.  Isolation is used to contain sound within the room and keep outside sounds from breaching the room.  What works here is an air tight room with heavy walls (i.e. double drywall).  You must treat the whole room otherwise the sound will find a flanking path and the effort (and money) is for not.  Green Glue and other dampening products will help to reduce vibrations from transferring to the room structure. 

By containing the sound within the room, however, you will need to accoustically treat the room so that the sound is relatively even.  Without acoustically treating an isolated room the bass will combine and cancel in places throughout the room giving uneven sound.

If you don't need isolation, many people have found that letting the bass energy escape actually improves the sound.

Regarding my electrical, I didn't do anything to alter grounding but did put in separate and dedicated circuits for the audio equipment and the amplifiers.  I used 10 AWG wires to reduce resistance.  It probably doesn't matter much but for the price difference, it was peace of mind.

Good luck!

Tom

[JLM]

Note that hospital operating rooms for decades used isolated grounding systems (due to the risk of explosion from flammable anesthetics).  And (again I'm ignorant of electrical) we have a whole house surge protector.  So I'm not worried about running a separate ground. 

As a licensed engineer with the first 8 years spent doing structural, what I would be very worried about is your reference to 2x6 floor joists spanning 18 feet.  The only wooden things that should span 18 feet are huge timbers, large laminated beams, engineered I-joists, or trusses.

[rich121]

Note that hospital operating rooms for decades used isolated grounding systems (due to the risk of explosion from flammable anesthetics).  And (again I'm ignorant of electrical) we have a whole house surge protector.  So I'm not worried about running a separate ground. 

As a licensed engineer with the first 8 years spent doing structural, what I would be very worried about is your reference to 2x6 floor joists spanning 18 feet.  The only wooden things that should span 18 feet are huge timbers, large laminated beams, engineered I-joists, or trusses.

First, Isolated Hospital circuits were NOT isolated because of any "Flammable" risks, that is not true...
They are isolated because of the life saving SENSITIVE equipment that was plugged into them. Ever notice the "TURN OFF YOUR CELL PHONE" signs when you walk into the parts of the Hospital where they have sensitive equipment?
The isolated ground keeps the noise from other equipment grounds away and are the same as what should be run for Audio systems. All they are is a two wire bonding system.
One wire or the conduit the wire is in, bonds all the electrical parts of the electrical system.
Then there is a second ground, the "isolated" ground, that goes directly to the special "isolated" ground type receptacle, in this case, Hospital Grade, this will have a triangle on the front of the receptacle showing that is an isolated ground type receptacle. The other end of the wire that is terminated at the isolated ground plug, goes directly to the ground bus in the electrical panel.
This is nothing special. If you run a 12/2 w/ground romex directly to the box with your receptacle, then directly to the power panel, you have the same thing, as long as you use a plastic box.

Your whole house surge protect has nothing to do with the reasons why you would want to run an isolated ground. Your surge protector is to help drain away the large amounts of voltage from a lightning strike or voltage spikes from the power grid... this is for safety and equipment safety, not to help clean up the noise on the lines.

As for the 2"x6" ceiling joists, I never said they spanned 18', and I never said they were single run.
The room used to be divided into 2 rooms, with a 10' archway that connected them together. I removed the wall and archway, creating one room that is 18' wide, and 24' long, instead of 2 rooms that were 18'x12'.
I installed a 12"x7"x18.5' LVL that spans the area where the wall/archway once was. I cut the ceiling joists so that the LVL would fit into them and up against the floor above, making it even stronger.
I have a 6"x8" column at each end, with expensive, heavy duty Simpson commercial beam brackets at the top of each column, connecting it to the LVL.
I also cut into the cement in the basement directly below the columns on the first floor. I poured 24"x18" deep concrete footers for the 6"x8" columns I installed in the basement to support the 6"x8" columns directly above on the 1st floor.
Connected to either side of the LVL are the ceiling joists, which are in "pairs", and they only span about 11' of free air, 16" center, with 13" of space between joist pairs.

This is way "over built" and very very solid. All outside walls were 2"x4" construction. I "firred" them out by adding 2"x3" lumber, which adds much more strength and solidness to the walls.


Rick 

[bpape]

Bryan,

From my understanding of structural dynamics you're right, larger spacing would lower resonant frequency, but would also make it easier to vibrate.

Correct - which better allows the cavity to act as a damper and better absorb all sound except that at the resonant frequency.

A concrete slab is about as massive and stiff as you'll get - and it's still an excellent path to allow bass to flank under walls and into the rest of the structure.  That's why when really going all out, we float a floor on top of it.

Bryan

[mjosef]

I installed a 12"x7"x18.5' LVL that spans the area where the wall/archway once was. I cut the ceiling joists so that the LVL would fit into them and up against the floor above, making it even stronger.

I am trying to visualize the Italic sentence...so you notched out about 50% of the vertical dimension of the support beam at each ceiling joist? And how many floors are there above this?

[satfrat]

Be forewarned, I jest,,,,,,, but here's an acoustic idea straight from last weekend's NY RAVE gathering. 

 
 
 
 

 
We'll even throw in Emil!
 
Cheers,
Robin

[rich121]

I am trying to visualize the Italic sentence...so you notched out about 50% of the vertical dimension of the support beam at each ceiling joist? And how many floors are there above this?
[/quote]


I have no idea what your talking about. Your statement makes no sense at all. I suggest reading my whole post.

In the post you will find the following information:

 before: 2 rooms 12'x18' each, after: one room 24'x18' with 18' header replacing wall/archway

"Connected to either side of the LVL are the ceiling joists, which are in "pairs", and they only span about 11' of free air, 16" center, with 13" of space between joist pairs"

As from the measurements given, the ceiling joists are perpendicular to the header, as they only can be, they were cut to allow the header to be installed within, up to the bottom of the floor above, for added strength, and to hide half the thickness in the ceiling. The joists are attached to the header with joist hangers.

Rick

[JLM]

Rick,

OK, so now I understand the structural comments.  Having the 18.5 inch deep laminated beam (LVL for the straights here) hanging down 12.5 inches below the 2x6's across the middle of the ceiling is a bit of a drag, but unavoidable.


BTW hospital isolated grounds were only used in anesthetizing (and rarely intensive care) locations due to the prevalent use of oxygen.  The grave concerns for explosion also had other safeguards added in operating and delivery rooms including conductive flooring, shoe cover prohibitions, special venting of the rooms, those round/green grounding plugs, and warning signs before entering the suite.  Fortunately anesthetics have come a long way since 1976 when they quickly were replaced in hospitals. 

Some still use isolating grounding to drain current leakage from equipment in the operating rooms away from patient's heart muscles that could cause heart attack.  Better surgical equipment build standards have reduced this concern and nowadays the primarily leakage comes from all the documentation equipment and the cheap stereos brought into the rooms.  Dropping the requirement for isolated grounding allowed savings of $25,000 per panel and the option to have power from both the normal and critical branches fed to the rooms, so you don't have to fully rely on the emergency transfer switch to work.

And with the improved telemetry equipment, concerns related to cell phones use in hospitals have all but gone away in the past 5 years.  Cell phones were never a problem with surgical equipment (patient monitoring in recovery yes, but not in the operating or delivery rooms).

So have fun with the room, but do try to eliminate those even ratio room dimensions and take care of the doors/windows.  Look at the Cardas website.  You have the space, you might even want to consider installing extra/interior skewed walls as Cardas shows.  (This could also take care of the door/window issues.)