[bassboy]

I have some basic questions I need to address so I can begin to calculate cost.  I've been planning this for some time now and it's time to get into the details of the matter.  I have 2 options - build an entirely separate structure for this purpose, or use some existing space in an existing outbuilding.  My budget will go a lot further if I don't have to build a whole new structure, obviously.  I have more than enough extra lumber lying around in every size from 2x10 to 2x2 and all kinds of other building materials (but no insulation).  I can budget about $20000 (on top of my collection of building materials )for this but I'd rather keep it closer to $5000 if possible.  If I need a completely new structure it will certainly cost more than I can budget right now, so it won't happen this year.

The existing outbuilding is a pole barn, nice and close to the house.  Just built last year mainly for winter storage.  It's 40 x 80 feet and I am fully authorized to use up to 20 x 20.  If necessary, I may be able to haggle a bit more length if I give up some width.  I can easily make the ceilings 12 feet high, and if push comes to shove I may be able to get them as high as 15 feet.  Just in case you don't know what a pole barn is here are pics.  This is not my barn but it shows how these are framed.  Then a sheet metal skin is applied.  That's all there is to them, a very simple structure.  There is currently no insulation in the building (which makes it LOUD when it rains, and inflicted with a serious echo problem).  They may look flimsy in the pictures, but these things last decades and don't leak.





First question - is there any problem with this structure that would make it unsuitable for this purpose?  I'm thinking it's going to be fine.
Second question - should my room ideally have a concrete floor or a floating wood floor?
Third question - since I don't need any isolation for the benefit of others, and any isolation would only benefit me by keeping outside noise out, is it advisable to completely isolate my room from the walls of the structure?  Using the barn's existing framework to expand upon would save a LOT of time and money but it's possible to obtain perfect isolation if it's worth the cost.

With the answers to those 3 questions I should be able to estimate the cost of the new room pretty accurately.

[JLM]

Cool!!

I'd start here with the size/layout:

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Setup

and for the ultimate I'd go a bit farther:

http://www.cardas.com/content.php?area=insights&content_id=36&pagestring=Room+Setup+10

So, I'd go with the largest Cardas "Golden Trapagon" possible.  Size (bigger the better to take away as many of the room effects as possible) and layout are fundamental.  Most of what you seen done, treatments, DEQ, odd setups, etc. are bandaids to less than ideal size/shape/layout.  I built to the Cardas "Golden Cuboid" (limited to 8 foot ceilings) and use his nearfield setup and love it.

My only concern for using the pole barn would be for heating/cooling.  A dedicated furnace and air conditioner/heat pump placed on their own pads (not on the ceiling of this room) would be needed to keep fan noises out.  Use lined, flexible fiberglass insulated ductwork to keep it quiet.

I'd absolutely go with a concrete slab on grade.  All vibrations can then go straight to earth.  (A suspended wood floor could easily create a resonance chamber underneath.)  You can insulate underneath the slab with 2 inch styrofoam sheets or try looking for what we used, a product called "Insultarp" (double layer plastic sheeting with air space between).

I'd recommend building this as an independent structure within the pole barn if it is sided/roofed with metal, as the metal will expand/contract with the weather and sun thereby creating leaks/additional noises. 

While you're doing electrical work, make sure you have a whole house surge protector installed, and try to tap off the top of your panel to get the purist power for the audio system.  Use surface mounted light fixtures so as not to penetrate the insulated walls.

The door can be insulated fiberglass exterior (will have wood grain suitable for painting/staining).

You could also build an equipment closet into the front wall with doors and conduits for the speaker cables.

You should easily stay within a $20k budget, but do try for a much square footage as possible.  And do keep us posted.

[bassboy]

Thanks very much JLM.  I was looking for the cardas trapagon dims all over, since I thought I remembered seeing them on the rives site.  The trapagon was going to be my #1 choice for dimensions (if I can reconcile the space "wasted" by the flaring sides).  The other thing I did yesterday was an detailed inspection of the barn framing, and it seems that it would not save either time or money to use the existing walls as common walls with my room.  In other words, it would probably be harder if I didn't make this room completely independant of the existing walls.  Flared independant walls spaced in from the barn walls will appear to be a lot of wasted space so I'm not sure exactly how far I can push my luck.

The barn is already wired and power comes straight from the power lines, with it's own meter and box.  There's nothing ever on in the barn, so power should be fairly clean (compared to in the house).

I'm going to try to throw together an estimate.  It shouldn't be too bad.  Framing will be free, heating and cooling is free, a good deal of the hardware is free, labor of course is free, no building permits needed.  By far the largest cost is going to be insulation and the floor (at least until the final cosmetic steps).

[Ethan Winer]

is there any problem with this structure that would make it unsuitable for this purpose?

Yes, this is fine.

should my room ideally have a concrete floor or a floating wood floor?

I'd go with whatever floor you already have. A wood floor can flex, which means it can give some bass trapping. So don't pour concrete just for this.

since I don't need any isolation for the benefit of others, and any isolation would only benefit me by keeping outside noise out, is it advisable to completely isolate my room from the walls of the structure?

No. Construction that improves isolation usually harms the bass response inside the room. Again, the more things flex, the more bass is either absorbed or passed through to the outside. This is a Good Thing.

Also, I'd avoid 20 by 20 feet. If you can exchange more length for less width, and have a ceiling 12 feet high, make the room 21 by 17 by 12 feet. More on that here:

RealTraps Mode Calculator

--Ethan

[bpape]

I don't know that I'd go so far as to say isolation hurts bass response - it's just not as 'leaky' so it doesn't absorb as much.  It can, however, absorb LOWER - just not as much per unit area.  Yes, a truly isolated space will generally require a bit more bass control inside the space but the tradeoffs in potential dynamic range IMO can be worth the trade. 

I'll agree that setup is critical - probably the most critical.  However, you can set things up as perfectly as possible and deal with frequency related issues but that will do nothing to deal with time domain related issues and ringing.  Properly treating a room is hardly a bandaid.  It's a piece of the puzzle - proper room, proper setup, proper time control - they're all pieces of the puzzle.

Bryan

[bassboy]

Thanks very much Ethan.

I'd go with whatever floor you already have.

Currently the floor is dirt, so that isn't going to work.  It's got to be either concrete or suspended wood.  I'll probably choose one or the other based on cost (although I do a bit of floor vibration - wood seems lively to me and concrete seems a bit dead).

I know 20 x 20 would be a mistake, I just quoted those numbers to specify that I am fully authorized to use up that much space.  I'm going to try to push for about 27 feet of length, but again, based on cost it might have to be a bit smaller.  In any case, whatever dims I choose will be based on some type of golden ratio formula or recommendation, possibly trapagon.

[bassboy]

Thanks Bryan.  It looks like it's going to be much easier to build the framework inside the existing building than to tie it together and share common walls, so it looks like it's going to be pretty isolated physically.  In terms of a "truly isolated space" (which I think usually incorporates a decoupled wall with mass, then an airspace then another decoupled another wall with decoupled floor and ceiling), I wasn't planning on going that far.

Properly treating a room is hardly a bandaid.  It's a piece of the puzzle - proper room, proper setup, proper time control - they're all pieces of the puzzle.

This brings me to my next question.  I was assuming that even using effective exotic shapes, the room will still require some form of treatment, possibly lots of treatment depending on how big it is.  Every time I see pictures of an audio room in construction, they always frame, insulate, drywall (sometimes very very thick and/or constrained layer) and then treat the inside of this space extensively.

How important is the drywall layer?

How isolated do we hope to be?  It would seem to me that a room that was framed and insulated with the vapor barrier installed but no drywall would sound somewhat similar to being outside in terms of bass frequencies (not mid or treble so much).  If you set up the system at this point and simutaneously started adding drywall to spots other than the ceiling, main relection points and corners until it sounded "live" enough and covering the rest of the undrywalled area with felt or similar, would the lack of drywall not be an extremely effective bass (and mid and hf) trap covering 100% of the ceiling, all of the corner area and first reflection points?  Or is this not acceptable due to too much loss of isolation?

This seems to be exactly what is called for in the cardas plans for the very back ceiling area, and I suppose it's actively in use everywhere you see a suspended ceiling with acoustic tile and insulation.

[bpape]

The drywall is pretty much a must IMO. If you had the whole room as insulation with vapor barrier, you'd be way way overabsorbing pretty much all frequencies.  Drywall is also giving you a lot of the isolation you need.  If you have separate walls inside the basic structure, you only need to drywall the interior surfaces of the room.  The outside can stay just insulation and a light barrier as you were suggesting. 

A concrete slab is going to do much the same thing Ethan was describing with multi-layers of drywall - no give, no absorbtion, no feel.  IF DONE PROPERLY, a floor system can add some feel and a bit of absorbtion without causing issues.  Also, in your case, since you have ground below and nothing in terms of massive surfaces as in normal home construction, the cavity between them is pretty much effectively infinite in terms of bass buildup for the walls and ceiling - not so much with the ground but you have the height to make that floor system deep enough that the resonant frequency will be very very low and much more difficult to excite.

Since you have the height, you could certainly build a slanted ceiling being lower in the front and higher in the rear.  That minimizes 1 of the 3 dimensions from having parallel surfaces, slap echo, consistent axial modal buildup, etc.  As for the length and width, not sure I'd give up that much space.  To be effective, you're looking at 1" per foot of length per side.  So, if the room was 20' long, it would be approx 40" narrower in the front than in the rear.  Just something to consider.

Bryan

[bassboy]

OK drywall shell it is then.  I was hoping to get away with at least no drywall on the ceiling since it's dual layer insulation and would make a great cloud, but I guess it's perhaps too effective for that purpose.

...since you have ground below and nothing in terms of massive surfaces as in normal home construction, the cavity between them is pretty much effectively infinite in terms of bass buildup for the walls and ceiling

Still need bass traps though, right?  If the no drywall deal is a no go, what about "backless" panel traps (plywood instead of drywall attached directly to the studs, with a small air gap between the plywood and insulation and no backing behind the insulation?  I read that increasing the enclosed space behind a panel trap does not help, but does effectively increasing it to infinity by not affixing it to a plywood backing hurt?

Or should I not view this project as slightly unique and just stick with the methods everyone else uses in their regularly constructed buildings?

IF DONE PROPERLY, a floor system can add some feel and a bit of absorbtion without causing issues.

Are you referring to a completely decoupled floor, or just proper construction methods?

[bpape]

There's nothing that says you can't build some absorbtion into the cavity above - you just want a solid back/sides on it to maintain some isolation.

On the floor, you don't have to float it - you just need to make sure the floor is solid and the cavity below is fully filled with insulation so it doesn't act like a drum.

The whole point of a hard faced panel absorber is that you trap a cavity of air to act like a spring - ie, it must be sealed air tight.  In that case, the depth of the cavity and mass of the front panel are what determines the center frequency.  Also, remember that with this type of absorber, it's good for maybe 2 octaves.  Again, if you want to use some space behind the wall, you can certainly box in with MDF and leave the front either cloth covered (full broadband), or put a membrane on it like FSK (broadband bass, 50% or less absorbtion from say 700Hz up.)

Bryan

[bassboy]

I think I've got a pretty good idea of what's required so far.  Based on Ethan's dimension guideline of 21 x 17 x 12 I can count on about 40 sheets of 5/8 drywall, single layer only ($550), 40 bags of insulation, single layer for all walls, double layer for floor and ceiling ($1500) and $300 for OSB single layer flooring.  Not too bad so far unless I have to start doubling up the drywall and flooring.  (My estimates may be a bit low since they assume no waste)

Lumber is free, so $2500 or $3000 should get me into a workable (insulated, wired, etc) shell of a room, ready for treatments and further fine finishing.  Looks like it's quite possible that this could get started this year, although I can't guarantee it would be done enough to be usable before winter unless I pay for labor (unlikely).

[bpape]

That would be an excellent start and a very nice room for 2 channel listening.  Lots of placement freedom for speakers that require it, lots of room for seating to be in a good spot and not have a wall right behind you.  Try to plan the door to be maybe just behind halfway back on the side wall for the least interference with any treatments you plan to put up. 

If you have extra lumber and want something nice looking and something that will also help add some 'space' to the room - consider a coffered ceiling - maybe 4'x4' ish?

Good luck.  We expect pics as the project progresses 

Bryan

[PDR]

Have you thought about a suspended T-bar acoustical ceiling, with a layer of insulation on top? if you isolate your hangers with a piece of rubber at about the half way point you could eliminate a lot of sound transfer. I also live in the country and know that most pole sheds have metal roofs that sing like crazy with wind and rain. I have been a professional wall and ceiling mechanic for 29yrs, another suggestion I have would be  that before you drywall on top of your wood studs a layer of Tentest sometimes called buffalo board could be applied. If you find this too costly get a sheet or two(4x8) cut into 2" strips and tack on to studs before drywall application. You may also consider leaving your drywall up 1/4" off the floor and caulking the gap with acoustical sealant, this will keep some of the sound transferring from the floor to the wall. Another way to eliminate sound travelling through the wall is resilient channel, you fasten these horizontally to your wood walls at16" centers and then screw the drywall to it, by the wa I recommend screwing all your boards, dont nail as these will pop. One question, I don't know your climate, do you have heat or air cond in your space? if so you may want to consider some sort of air exchange. I'm from Canada where this is always a concern.

Cheers

[bassboy]

PDR I have not yet considered any type of suspended ceiling, constrained layer (I assume that's what the tentest is for), or resiliant channels, simply because I don't know anything about them yet.  This is still a very early stage in which I'm trying to determine if this is something that I can actually accomplish at all.  Seems promising so far.

You can bet I will be researching all of your suggestions and I appreciate the tip on screwing the framework, I was actually wondering if that would help.  My brother has many years in the construction industry (laboring, then schooling, then supervising, etc) so I will be counting on him to draw up the plans and make sure everything is up to code, properly framed, vapor barriers go on the correct side, correct R value of insulation (although I think I'll be covered there), air exchange is sufficient for the room volume, etc, etc, etc.  I don't know much about that stuff yet but I will soon.

I'm going to check out some of the examples of high end ($$$) audio rooms and try to come up with a preliminary plan that incorporates all the treatments into the finished decor.

[Ethan Winer]

I'm going to try to push for about 27 feet of length

Now you're talking!

[Rob Babcock]

Yep- there's no replacement for displacement.

[JLM]

Everybody uses retangles because they fit "best" into existing construction and so they are well known.  The Cardas "Golden Trapagon" would look weird/awkward from inside, but I'm sure would sound great.  I'm sure that right interior design can alleviate that though.  Note that relatively small rooms (even at the scale we're talking about here) have different acoustical properties than larger spaces (like concert halls).  I'd contact Cardas to ask what is meant by "leaving the back of the ceiling open to an insulated attic."  My guess is that some bass traps (like GIK 244 panels) would work just fine (and if not could be used elsewhere in the room).

Yes, trying to use the pole barn framing would be a PITA.  And building it independently inside the pole barn gives you a huge decoupled structure/airspace.  You'll probably need a concrete foundation of some sort for frost heaving and to keep burrowing vermin out anyway, so the concrete slab (with inexpensive commerical carpet) is the obvious choice IME.  For the outside I'd side with T-111 (4x8 sheets of textured wood siding) and roof with 29 gauge metal pole barn material (on a slope just in case of leaks in your pole barn roof).  So here's another reason to try the "Golden Trapagon".

Smaller rooms actually require more treatment than larger rooms, as the walls are closer and contribute more to the sound.  When I said treatments are the bandaids, I meant that the properly shaped, decently sized room, with good setup won't need as much treatment.  OTOH most folks don't have a properly shaped, decently sized room, so they spend thousands to fight a room that is flawed to start with.  I've been inside a couple anechoic chambers and the effect is really weird, not what anyone would want to live with.  Lining the entire room with treatments to get that sort of effect could blow your budget by itself anyway.  BTW, you really don't want exposed low density fiberglass.  Just remember that protective masks are recommended for installers.

In a dedicated/independent structure I see no reason/advantage to float the ceiling (suspended ceilings, resilent channels, etc.) or the walls.  In fact, I'd figure on 5/8 inch drywall and varying the stud spacings between 8 and 16 inches.  And I'd use at least 2x6 studs (2x8 on walls taller than 10 feet).  As a speaker cabinet can emit more acoustical energy than the drivers, so can flexible walls/ceiling/floor.  What flexible walls sound like or how to control it are unknowns.  So I agree with Bryan and disagree with Ethan and would go for structural rigidity and use treatments to tame whatever problems come along. 

I'd be extremely hesitant to try building any resonanting or absorbing chambers into the design without use of paid professional design help.

How is it that heating/cooling is "free"?  You'll need some sort of venting, even with a well insulated/sealed space.  Mold can overtake an unventilated space is just a couple of weeks, leading to a total loss.  And make sure you tell your homeowners insurance company about the room.

[bassboy]

Thanks Ethan and Rob, I agree bigger is better.  BUT if I can haggle those few extra feet it might come down to a hard decision of what to do with it.  The barn and house are only about 100 feet apart, but that's a long 100 feet to run in the middle of winter to get to a bathroom.   I'd like to have a small, simple bathroom out there too if possible, which would eat up that extra area.

JLM, thanks for your detailed reply.

 

I'd contact Cardas to ask what is meant by "leaving the back of the ceiling open to an insulated attic." 

That's a great idea and I will, once I get further into the project and assuming I choose to go with the trapagon shape as recommended.  Until then, here's a quote I found (from here http://www.positive-feedback.com/Issue16/lavigneroom.htm - and this room is also a great source of inspiration by the way) which I think explains why Cardas recommend leaving the back of the ceiling open to an insulated attic.

I wanted the ceiling to be special. My concept had been to have a ceiling that started low behind the speakers and increased in height as it went back... Richard explained that there were a few problems with that approach, due to pressure zones.

If this is indeed true for a tapering ceiling, I imagine a tapering ceiling and tapering walls would be even worse.  And also, if true, I don't think bass traps or any other conventional room treatment technique (except the one recommended by Cardas) is going to fix that.  Keep in mind that I have no real concept of these pressure zones, where they might be, and how they might be dealt with since I'm new to this.  Much more research is required on my part and hopefully I will make the right decisions so I don't end up painting myself into a corner.  At the very least I am planning a sloping ceiling (not sure of how much it will differ from front to back yet though) and I was thinking about using the room treatments to "round out the corners" of the room, similar to what you see in the link above.  Trapping the corners in such a way seems like a reasonable and fairly attractive compromise between rectangular and trapagon.  But like I said, I'm not ready to make any hard decisions yet.

Yes, trying to use the pole barn framing would be a PITA.  And building it independently inside the pole barn gives you a huge decoupled structure/airspace.  You'll probably need a concrete foundation of some sort for frost heaving and to keep burrowing vermin out anyway, so the concrete slab (with inexpensive commerical carpet) is the obvious choice IME.  For the outside I'd side with T-111 (4x8 sheets of textured wood siding) and roof with 29 gauge metal pole barn material (on a slope just in case of leaks in your pole barn roof).  So here's another reason to try the "Golden Trapagon".

There's a couple of things to comment on here.
First - the floor isn't really dirt, it's mostly gravel and small stone, not sure exactly what it's called but I seriously doubt anything can burrow through it.  OTOH, I could be wrong, so thanks for the heads up, I'll look into that.  WRT the frost heaving, I'm going to have to research this as well, but for now I assume it's not an issue, otherwise the whole barn would have the same issue.  I watched when the poles were put up.  They dig a 2 foot diameter hole about 5 or 6 feet deep, center the pole in the middle of the hole and fill it with cement.  I don't think it's moving anywhere, but I am still going to look into the price/performance difference of concrete and wood flooring.
Second - if I go to the trouble of pouring a concrete base, lining the outside of the walls with the wood siding siding and topping it all off with a metal roof, I see no advantage to building this inside an existing structure, might as well just build what you described as a free standing building since there's really no cost savings.  At that point it has to be looked at from another perspective - which of these will add more to the property value - a finished room inside the barn or a whole other finished free standing building.  (One more thing I need to research.)

How is it that heating/cooling is "free"?  You'll need some sort of venting, even with a well insulated/sealed space.  Mold can overtake an unventilated space is just a couple of weeks, leading to a total loss.  And make sure you tell your homeowners insurance company about the room.

Free because I'm pretty sure I have everything that will be needed around here...somewhere.  I understand that ventilation is necessary, but as with all the construction details that will be up to my brother to design since I have no idea about such things.  I know the acoustical considerations of system, he knows the code requirements.

Much to ponder...

[gedlee]

Thi8s is such a huge topic that its hard to know where to start.  I have a book on building good quality sound rooms and I am in the process of posting the chapters for free.  You can see it at www.gedlee.com.  Its the Home Theater book, but 1/2 of it is on sound and room design.  Don't pay too much attention to room dimensions, its not that important.  Avoid integer ratios of lengths, but other than that it doesn't really matter.  And definately use two layers of drywall held together with mastic and put on RC-1 resiliant channel.  This will give you the LF absorption that is so critiacl with the HF reflections that you will want.  There is a very tough problem and I encourage you to read some authoritive sources about how to do this as once its done correcting it is a big problem.

[TerryO]

Bassboy states:

Until then, here's a quote I found (from here http://www.positive-feedback.com/Issue16/lavigneroom.htm - and this room is also a great source of inspiration by the way) which I think explains why Cardas recommend leaving the back of the ceiling open to an insulated attic.

"I wanted the ceiling to be special. My concept had been to have a ceiling that started low behind the speakers and increased in height as it went back... Richard explained that there were a few problems with that approach, due to pressure zones".

If this is indeed true for a tapering ceiling, I imagine a tapering ceiling and tapering walls would be even worse.
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Bassboy,

Mike Livigne is a member of our Audio Club and his room is very nice and I have enjoyed listening to music in it. As for tapered ceilings and walls, I wouldn't necessarily rule it out as there's more than one way to skin a cat!
Here's some detail on another club member's room. It belongs to Winton Ma, the owner of the FIM label and is also very highly rated. They utilize different approaches and both rooms are amazing.

http://www.positive-feedback.com/Issue3/maroom.htm

http://www.positive-feedback.com/Issue3/maroom2.htm

http://www.positive-feedback.com/Issue7/maroom.htm

Best Regards,
TerryO
BTW: Both Mike and Winston have served as judges in every one of "The Puget Sound! DIY Speaker Contest"