[Mmaxed]

We are in the early planning stages of a new home.  I will have a man cave in the basement that will also be a listening room.  I had planned on a size of 20'x30' with 9-10' ceiling.  This way I could use on end of the room for listening and the other for exercise equipment, pool table, whatever.

Is this a good idea, or would it be too hard to get the room to sound good?

[FullRangeMan]

Just a idea, I like the room post #13:

http://www.youtube.com/watch?v=n1ZFCvSaGqI

[Ethan Winer]

I had planned on a size of 20'x30' with 9-10' ceiling.

A large room like that has the potential for excellent sound, with two caveats:

1) You should choose favorable dimensions that are not the same or even multiples, as explained here:

Graphical Mode Calculator

2) A large room is better than a small room, but it require more acoustic treatment simply because there's more surface area. You'll probably also need a larger sub to fill the larger space with sound. So that's a factor for effort / expense.

--Ethan

[bpape]

That's a nice sized space.  Remember a couple of rules.

1.  No dimensions equal or multiples of each other.

2.  W and L should be < 3x Height.

Bryan

[Rob Babcock]

Nice!  I wish I had a room that large to work with.

[ctviggen]

That's a nice sized space.  Remember a couple of rules.

1.  No dimensions equal or multiples of each other.

2.  W and L should be < 3x Height.

Bryan

W+L<3H?
W or L < 3H?

[JLM]

I went through the same thing about 8 years ago.  Lessons learned:

1. Yes room dimensions are critical and bigger is better.  I happily followed the Cardas ratio for what he calls a "golden cubiod": 1 x 1.61 x 2.62 (so my room is 8 ft x 13 ft x 22 ft).  I was limited by 8 foot ceilings.  Tons of other ratios out there but based on limited ceiling height this is the best for maximizing the other dimensions while avoided whole number multiples of each dimension.  As a result room treatments do almost no good (just aren't needed), but keep in mind I have nearly ideally "non-room-reactive" speakers too.  I keep moving (6) GIK 244 high density fiberglass panels around to no affect.  I also follow the Cardas nearfield setup recipe which helps.  The room has (3) tall bookcases on the side walls and an office setup in the back.  No TV.

2. Isolate the room from the rest of the house (so they don't hear you, but more importantly so you don't hear them).  By "them" I mean furnaces, softners, washing machines, dishwashers, foot steps, etc.  Insulation is your friend.  I used staggered stud wall constuction on interior partitions (even though the room adjoins storage spaces).  I used lined/fiberglass insulated ductwork (can barely hear the furnace).  I used insulated/weather stripped fiberglass exterior door (can't hear the furnace that's 12 feet away).  My biggest mistake was using recessed ceiling mounted can light fixtures (they are rated air tight and to be in contact with insulation - there's a foot of fiberglass above them) but I hear everything upstairs (probably worse than it seems due to everything else being so well insulated).  Use surface mounted fixtures (wall sounces or track lighting for instance).  My 2nd biggest mistake goes on the contractor, I'd specified a floating drywall ceiling (z channels connecting structure to drywall).  He refused, so sound does transmit.  The fix would be to add another drywall layer using Green Glue (and adding track lighting while at it).

3. Electrical power abberations is in my experience a highly localized effect, I've heard it but never had a problem with it at home.  Fortunately we have a new underground service with our own transformer, all fixtures were new, and contractor used as 12 gauge/20 amp design.  I had him wire (3) circuits that each serves a single cryo'd hospital grade duplex receptacle (my only real splurge - $100 total on the room) for the audio.  Contriversally I had him ground them together to a dedicated ground (some don't believe it meets code).  BTW all boxes are the recommended plastic.

4. Not audio related, but if you live in a colder climate have insulation added under the floor slab.  We live in Michigan and the basement floor is not cold (and it's the only way our house met the EPA 5 star energy rating).

Overall the biggest advantage I've found (after getting used to how spooky quiet it is in here) is that I can listen to what I want when I want as loud as I want.  Because of the ceiling light fixtures family can hear the music and I can hear machine/foot noises, but it's so much better than sharing the living room.  Frankly the biggest disadvantage is how little time I spend with family now.

Note that none of this is very costly.  The double stud wall was probably the most expensive.  Electrical was a flat price.  Builder insulated all interior cavities anyway.  The door was cheaper than the interior doors used elsewhere.  The carpet I selected is the cheapest in the house.  And not having extra storage space meant wifey didn't spend money filling with her junk.

[mikeeastman]

JLM could you please explain how your  the isolated ground was done.

  Thanks, Mike

[bpape]

W+L<3H?
W or L < 3H?

Sorry - maybe english....  Neither length nor width should be equal to or more than 3x the height.

Bryan

[bpape]

I went through the same thing about 8 years ago.  Lessons learned:

1. Yes room dimensions are critical and bigger is better.  I happily followed the Cardas ratio for what he calls a "golden cubiod": 1 x 1.61 x 2.62 (so my room is 8 ft x 13 ft x 22 ft).  I was limited by 8 foot ceilings.  Tons of other ratios out there but based on limited ceiling height this is the best for maximizing the other dimensions while avoided whole number multiples of each dimension.  As a result room treatments do almost no good (just aren't needed), but keep in mind I have nearly ideally "non-room-reactive" speakers too.  I keep moving (6) GIK 244 high density fiberglass panels around to no affect.

I've seen you write this several times now and I can't resist commenting. Don't want to take the thread off track though.

While you many not see/hear any difference in the frequency domain, I will guarantee you that 6x 244 panels in an 8x13x22 ft room will show a measurable difference in the broadband decay time - not to mention a measurable change in the impulse response if used at the reflection points.

Carry on....

Brya

[Mmaxed]

That's a nice sized space.  Remember a couple of rules.

1.  No dimensions equal or multiples of each other.

2.  W and L should be < 3x Height.

Bryan

OK, time to admit how much high school math I can't remember after 35 years.  Can some one please explain "multiples of each other"?

Thanks for all the responses.  lots of good ideas.

I am planning the room this large so that it can be more of a multi use space.  The size of the room was the only thing in all our wants that the architect commented on.  Might be tough to get, we'll see.   

[FullRangeMan]

OK, time to admit how much high school math I can't remember after 35 years.  Can some one please explain "multiples of each other"?

Thanks for all the responses.  lots of good ideas.

I am planning the room this large so that it can be more of a multi use space.  The size of the room was the only thing in all our wants that the architect commented on.  Might be tough to get, we'll see.   

Multiples: If your room is 4 metres wide, a multiple is 8 or 12, so avoid a 8 metres long room, 7 metres would be nice.

For a less ressonant room you may want use the golden ratio: 1 x 1,618 x 2,618 or 3x5x8, in a room is  Hi=3m, Wide=5m and Depth=8m.

[JLM]

JLM could you please explain how your  the isolated ground was done.

  Thanks, Mike

As I recall he simply grounded the three circuits/duplex convenience receptacles to a separate grounding rod that went into the concrete slab.  Many here say it's a code violation, but we had a tough electrical inspector.  I dunno, I'm hardly an electrical expert.

[JLM]

Check out Chapter 13 of the "Master Handbook of Acoustics" for a good explanation.  What you're trying to avoid is axial resonance modes (those that would bounce straight back and forth off parallel/opposite walls) for the same frequency to correspond for length, width, and/or height.  So a cube (or sphere) would be the worst as peaks/nulls from all three axis would be additive.  Wavelength equals 1130 ft per second (speed of sound in air near sea level) divided by given frequency per second (Hz).  So a 56 Hz sound wave is 20 ft long (peak to peak).  So a 20 ft by 40 ft room would have double the amount of echo at 56 Hz and three times if it were 60 ft tall. 

The ancient Greeks, in building their highly reflective stone temples wanted to avoid echo.  So the western asthetic that we now think looks best is in the 5:8 ratio (front/back wall and ceiling/floor) which also minimizes these multiples and provides better acoustics.  All hard surfaces and the enclosed spaces they use echo (reflect sound) and it's something the human ear has acclamated to, but only to a point. 

[Scottdazzle]

Multiples: If your room is 4 metres wide, a multiple is 8 or 12, so avoid a 8 metres long room, 7 metres would be nice.

For a less ressonant room you may want use the golden ratio: 1 x 1,618 x 2,618 or 3x5x8, in a room is  Hi=3m, Wide=5m and Depth=8m.

The 3 x 5 x 8 ratio is a very simple and helpful bit of advice. thank you.  I'm planning a room that happens to be just about exactly that... what luck!

[FullRangeMan]

The 3 x 5 x 8 ratio is a very simple and helpful bit of advice. thank you.  I'm planning a room that happens to be just about exactly that... what luck!

The 3m x 5m x 8m is the dimensions from a B&W room in Steyning UK, it is a standard room(I mean say a reference room project), and a easy room to be made.
For a out side picture see second photo in the post #1:
http://theartofsound.net/forum/showthread.php?t=4711
Of course the Golden Trapagon project from Cardas is better, how much better I would like to know.

The ressonance mode calculator linked by Ethan Winer on post #2 in this topic is very useful to see a ressonance graphic before spend money to built a room:
http://www.realtraps.com/modecalc.htm
Thanks Ethan.

[JLM]

The listening room used by the Canadian National Research Council (well known for audio research) follows IEC 268-13-1985 and is 6.7m x 4.1m x 2.8m.

Search for the Bolt "blob" (ideal range of length/width ratios).  Note some say that there cannot be an ideal, but why not try to get close?

[mcallister]

Not trying to thread jack but maybe someone can help me out without starting a new thread.

I'm also in the midst of building a new house with a dedicated listening room/home theater. For my front three speakers I use 3 GR Research LS9s. Yes huge speakers therefore I need a large room. I'm looking at a minimum of 20x30 feet. With the 3x5x8 ratio mentioned that would make for a very high ceiling which I'm not sure is feasible. Any suggestions for dimensions for a room with these speakers would be greatly appreciated!!

[rockadanny]

5:8 ratio (front/back wall and ceiling/floor)

 

please explain this more

[FullRangeMan]

The listening room used by the Canadian National Research Council (well known for audio research) follows IEC 268-13-1985 and is 6.7m x 4.1m x 2.8m.

Search for the Bolt "blob" (ideal range of length/width ratios).  Note some say that there cannot be an ideal, but why not try to get close?

This room are 1 x 1,464 x 2,4 proportions, not the Golden Rule as 3x5x8 but a more practical room to built, a very interesting room too.
This room dimensions may be a good starting point to the Golden Trapagon room.