Formica's Audio / HT room... the construction

[formica]

This is just before demolition 2005 (as i was moving stuff out)

looking towards fire place again, and you can see the existing utility

room door to the left

The dark grey looks so much better than the beige...

[formica]

Another one from 2005 but looking toward the soon-to-be "demolished" wall

[formica]

The other side of the wall which will be demolished. Old room behind playroom area for storage

[formica]

Same area, but the other side... this is the actual storage...

[formica]

double post...

[formica]

Other side which will become the "office" area...

Here you can see the existing supporting beam, as well as my 1930's

tiger-oak bookcase i rebuilt/restored. It was originally a

built-in unit, it's almost done... but i temporarily put it back on

pause.[:$]

[formica]

Still office view and still 2005....

[formica]

Part 9: Acoustical isolation:

Acoustic isolation, as in the transfer of sound through the walls and

ceiling, is a subject often discussed when looking at room acoustics,

even though they aren't related. That is why I decided to clearly

separate the two.

Once again, I was faced with some compromises... Most of the

proven acoustical isolation techniques like building a room within a

room, double stud walls, adding mass, sealing all air infiltrations*,

etc... require reducing the finished space. So I had to put

this into perspective versus what I had to gain.

My home is generally quiet; no HVAC, no attached neighbours, no sump

pump, electrical heating, and electrical hot water. I do have the

usual appliances like a refrigerator, freezer, washer and drier, and

de-humidifier in other rooms but the only one that is audible is the

dishwasher due to structural vibrations. Ideally I should install

some isolators on it next time I have to service it

The most noticeable background noise I do get is some traffic noise

from the adjacent boulevard through the double windows. Replacing

those with modern units may help things a bit.. and I may leave my self

room for that this spring (changing windows in November su¢ks).

That leaves insulating the sounds from the actual HT so not to pollute

the rest of the house (rather than the inverse). Given I have

three bedrooms above overlapping the room... ummm... I may be

fighting a loosing battle.

Attack plan:

1) Existing walls: will remain as is...

2) New walls: given the IB, it'll be just as loud on either side so I'm

not worried about STC ratings. OTOH, given the IB and khorns,

these will be built as rigid as possible including multiple fire-stops,

wool, ½" plywood, and gypsum.

3) Floor: given this is built over a slab on grade... just a wood subfloor with thermal insulation.

4) Doors: all doors leading out of the space will get some seals

installed round them, including both the new storage and office

door. I will probably keep all the existing hollow core doors

with the exception of the door the top of the staircase which I'd

replace with a solid core one (the door which technically leads to the

space)

5) Ceiling: working with the existing joists, I would like to add

2-1/2" to 3" of acoustic wool (Roxul, SAFB, etc...) resilient cannels,

and 1/2" gypsum. I would only loose 1/2" in height and still get

a STC of 51 (according to CGC lab tests). Adding thicker gypsum

like 5/8" actually reduces the STC to 50 given the resilient channels

are stretched more. I won't be using a recycled fibre soundboard

(Sonopan here) as the NRC found little benefit when installing it under

the joists.

The biggest sound transmission problem I can see, apart from shaking the whole house, will

be through the light fixtures. I HAVE to use pot (recessed)

lights... if I don't want guests whacking their heads into surface

mount ones. This will put a ton of holes into that ceiling, as

well as pose a challenge in installing insulation around

them. They sell "insulation" boxes to install pots in

attics... but their metal sides seem to buzz just by breathing on

them. I'm actually worried that the fixture itself may vibrate.

I'm trying to decide whether I buy the attic boxes (about 350$ total)

in attempt to seal air infiltrations but risk them buzzing, or simply

install the lights without them. If I forgo the boxes, I would

need to build some mesh cages to keep the continuous insulation away

from the lights. Anyone have experience with vibrating attic

boxes?? I've thought about building my own boxes, but temps reach

90C inside the bought ones... so I'm not sure about experimenting with

that.

BTW, I'll be running an input and output tube to the other room for a

hush box I'm considering building a for the projector. I don't

know hot warm these get... so maybe installing a fan at the outlet in

the next room (and filter on the inlet) would be a good idea? My

subwoofer amplifier (a fan cooled pro amp) will also be placed in an

adjacent room.

ROb

[DrWho]

The "buzzing" of the attic boxes goes away when installed...just like

the ping on a metal midrange horn gets vastly reduced by simply

installing in the cabinet. If you're worried about problems and don't

want to have to go back to correct them, then I would suggest just

using a little bead of caulk in all the areas you're concerned about.

Btw, I would highly recommend using a fan at the outlet of your

exhaust. Those bulbs get very very hot and the air coming out gets very

hot too. So if you're running an exhaust that's more than a foot long,

that little fan on the back isn't going to be powerful enough to get

the heat moving through the long pipe.

Ya know, I'm actually surprised that projector manufactureres aren't

implementing a design prebuilt for attaching an exhaust...btw, keep in

mind that you're going to need an intake of some kind too. The more

resistance you have to airflow, the louder those motors are going to

get.

[Tom Adams]

WARNING! WARNING! HI-JACK IN PROGRESS!!!

Shawn - I've always had the notion of installing a small LCD so I can make setting changes via the OSD without having to fire up my projector. Talk to me about that 7" unit you mentioned. I've been looking for a small AC powered LCD but to no avail. HELP!!! []

HI-JACK OVER.

Tom

[sfogg]

Rob,

As far as sound transmission through your house that is going to depend upon how solid your room is. Even with it extremely solid you need to be a little realistic about what you can accomplish. In my room (kitchen/living room right upstairs (hardwood floors)) with music playing I can get very loud without it being intrusive at all. With movies it isn't a problem exept for the big blasts of LFE at THX Reference Level. I have so much bass capacity in the theater it just isn't able to contain it all and big booms are shaking things upstairs too. The bedrooms on the second floor however are still quiet though so I'm OK from that standpoint.

"5) Ceiling: working with the existing joists, I would like to add 2-1/2" to 3" of acoustic wool (Roxul, SAFB, etc...) resilient cannels, and 1/2" gypsum. I would only loose 1/2" in height and still get a STC of 51 (according to CGC lab tests). Adding thicker gypsum like 5/8" actually reduces the STC to 50 given the resilient channels are stretched more.

Another idea for the ceiling.... if you are going to have the existing ceiling removed and are back the joists one additional idea...

Skip the resilient channel.

Rebrace your existing joists with 90 degree braces and remove the existing 'X' braces between the joists. That opens up the space between your existing joists to fit new joists in place for your ceiling without hardling reducing headroom. The new joists anchor to the top plates of your walls and will further isolate the ceiling. If your current framed walls are tall enough you will loose only a very little bit of headroom this way. And because you are now on your own studs heavier drywall is fine compared to the resilient channel.

You can see the second set of joists in this picture somewhat:

"The biggest sound transmission problem I can see, apart from shaking the whole house, will be through the light fixtures. I HAVE to use pot (recessed) lights... if I don't want guests whacking their heads into surface mount ones."

Why not use a lot of wall mounted sconces instead of lights in the ceilings? If you are going to be cutting a bunch of unsealed holes in the ceiling the resilient channel and/or new joists is likely a large waste of money.

"BTW, I'll be running an input and output tube to the other room for a hush box I'm considering building a for the projector. I don't know hot warm these get... so maybe installing a fan at the outlet in the next room (and filter on the inlet) would be a good idea? "

Yes, you will need a fans on the exhaust to pull the hot air away from the projector.

The intake is on the far side, exhaust on the near side using two hoses. The third hole on the near side is for video/power cables. Be sure you plumb your setup for whatever method works for your projector when it is inverted upside down. You don't want the projectors exhaust blowing toward the 'intake' side of the hushbox. I used a pair of 100 CFM fans on the exhaust lines outside of the theater. If you can don't attach them to anything connected to the theater to cut down on theier vibrational noise. A $25 'Table Saw Switch' at Sears is used to automatically turn them on and off with the projector.

Shawn

[sfogg]

Some additional pictures of the hush box if it will help give any ideas....

Projector mounted, the mount is actually recessed between the studs to conserve height. The hushbox is all MDF and large (big projector) so it is heavy. Bringing the frame up with chains made it much easier to get up there. The front is sealed with optical glass.

Looking up into the box with the bottom access plate removed...

I ended up having to add T-Nuts to the bolt holes for what holds the access plate in place.

Shawn

[sfogg]

(Weird... pictures are displaying in the preview window but not when I actually post them... sorry about that)

Tom,

"Talk to me about that 7" unit you mentioned. I've been looking for a small AC powered LCD but to no avail. HELP!!!"

No need for an AC powered unit. Just get any 12v DC unit you like then pick up a 1 amp (1000ma) 12v power supply at Radio Shack to power it. Cost $15 or so.

In my case I actually just powered it from one of the programmable triggers on my Lexicon. They supply 1/2 amp each which was enough juice for the unit I'm running. Most triggers on pre-pros don't have nearly the current ability of the Lexicon's though so you will need an external power supply.

Its cool because I can turn the trigger on/off by remote control which means I can turn on/off the LCD by remote control too. For example when I bring up the menu system for my DVD changers I have the remote automatically also turn on the LCD for me too. A programmable trigger on any pre-pro could be used to turn on/off the LCD by inserting a normally opened 12v reed relay into the power line to the LCD itself and run the relays coil from the trigger in your pre-pro.

As far as what to feed the LCD I feed most of my sources directly to my video processor over component, SDI or DVI. I also take the composite feeds from each of them and feed it to the Lexicon which does composite video switch for me. From the composite output on the Lex (with OSD) I run that to the LCD itself.

That way I have the OSD available for any/all of my sources as well as the Lexicon's OSD too but the OSDs don't appear on the projected image so there is no distraction there.

I mounted the LCD on the side wall so it was easy to see any mostly out of the normal viewing way for the pictures. This picture is basically the view from my side entrance door.

Shawn

[formica]

Even with it extremely solid you need to be a little realistic about what you can accomplish.

Trust me, I am... esp given I have one floor (buffer) less than

you... so I expect to hear and feel most of it upstairs. [:$]

Another idea for the ceiling.... if you are going

to have the existing ceiling removed and are back the joists one

additional idea... ... fit new joists in place for your ceiling without

hardling reducing headroom.

I recommended something similar to a co-worker building a home studio

(with the second series of staggered joists sitting on a second set of

wall studs)... it's a good technique. Unfortunately in my case I

also have my main electrical panel in the same area, which translates

to a rat's nest of large wiring to deal with.

Why not use a lot of wall mounted sconces instead of lights in the ceilings?

Unfortunately, due to number of asymmetrical doors and windows, I don't

think I can get enough wall sconces to light the space for when I get

gatherings. Even though I don't have to worry about WAF,

I'm very an@l on my own when it comes to appearances...

The "buzzing" of the attic boxes goes away when

installed...just like the ping on a metal midrange horn gets vastly

reduced by simply installing in the cabinet. If you're worried about

problems and don't want to have to go back to correct them, then I

would suggest just using a little bead of caulk in all the areas you're

concerned about.

I may buy a couple of attic-boxes and look closer at their

joints. Perhaps a little caulk, aluminium foil tape, or

similar... may make me feel more at ease with using them.

Some additional pictures of the hush box if it will

help give any ideas.... Projector mounted, the mount is actually

recessed between the studs to conserve height.

I like

that... the dept leaves more options open. Dual fans

it is... and I will be pre-wiring several switched plugs for

fans, subwoofer amp, and EQ.

Actually I still have an "electrical" post coming...

ROb

[formica]

Ok... here are some more pictures.... demolition phase I...

I removed the closet, wall, and built in furniture at the far end of the room...

[formica]

Looking towards the future screen...

[formica]

One of my trips to the dump... Getting the junk out of the

basement is a pain in the a$$... but nothing like tearing the ceramic

out...

[formica]

Speaking of which... here is 1/3 of it done. There has been

several renovations in my basement... a the ceramic was layed out on a

"sandcoat". I decide to strip just the tile, and lay my new floor

over the existing base.

[formica]

Part 10: Audio wiring

1) Hollow conduit: I'm planning quite a bit of conduit; even for the

wires I need immediately... so that I can easily replace / add / remove

them at a later time. It'll avoid having a ton of unused wires in

my walls... and missing just what I do need.

- 2 conduits from my rack to

the storage room

the bathroom nook ceiling (with trap)

the projector

- 2 conduits from the storage room to my existing utility room, through the bathroom nook

- 1 conduits from the storage room to the projector

2) Access traps / pull boxes: I'm thinking of leaving the

conduits open into the storage and utility rooms... while I might build

a recessed box behind the equipment rack to access them in room.

I will put an access trap in the bathroom nook ceiling at the joint of

the 4

3) Line level wire: I will try to run all my line level wires

inside the previous conduits... basically from the rack to the storage

room for my subwoofer amplifier

4) Component / DVI: I will try to run all my video wires inside the

previous conduits... basically from the rack to the projector at the

moment. I can run a LCD panel wire at a later date. Obviously the

conduit will have to be big enough to pass a DVI connector through it.

5) Speaker wire: One of the few wires that I will probably run directly

in the walls. I'll wire up for 7.1 ... with wall plugs in the

nearest walls. I'll also take Shawn's advice in foreseeing for

some of bass shakers by running the conduit in the floor to my storage

room.

6) HTPC: I have no intention of building one now... but if I do, I'd

like it in the storage room due to the possibility of fan noise.

With conduits from the storage room to the Rack and Projector... will I

be ok?

Ok, that's about all the design work i have to post... Did i miss something??

ROb

[sfogg]

Rob,

Couple of comments on the wiring.

For the conduit for the projector... bigger is better like you said.

But if you have to there are specialized cables with interchangable

ends to make it easier to run them in tight spaces. It is fairly

expensive though.

When you run your cables, esp. your line level cables, keep them at

least a few feet away from any AC lines they are paralleling. Cross at

right angles. I think I ran all my AC at 2' height and the low voltage

cables at 5' in the walls.

For the speaker levels cables not in conduit and the AC wiring be sure

you fill in the holes through the studs that the wires pass through.You

don't want to have a wire rattling against the stud during loud bass

and being a distraction.

When you run power keep the outlets for your equipment (including the

project and any remote equipment) on their own dedicated circuit(s). If

you need more then one circuit for the whole system keep them on the

same phase of the incoming power into the house.

Put the lighting on the other phase and if you are going to use dimmers

use good ones like the PCS units which don't put as much noise back

onto the lines.

Have fun!

Shawn