Building a dedicated listening room

The best room shapes for acoustics are irregular shapes ones. Symmetrical rooms with parallel walls are sub-optimal due to standing waves. So a box shape room can be problematic even though dimensions fit the classic golden ratio of 1 x 1.6 x 2.56 (height, width,, length). Room treatment can overcome some of these issues.

Concert halls and commercial theaters use the trapezoidal shapes. Houses with cathedral ceilings can be relatively "better" listening environment. However, cuboids are preferable because you can calculate the locations of nulls and peaks whereas with trapezoids those locations will be unknowns. Main objective of room shapes is to break the standing waves. As long as one can work this out, pretty much any room can be designed for a good listening space.

my room is an oval, no 90 degree corners. lots of built in diffusion. the ceiling is also irregular so standing waves don't get supported.

however; it is very important to have an absolutely symmetrical room, if you want your soundstage to approach perfection. otherwise it’s by degrees a mess.

even side to side allows for the musical parts to be complete and located properly with full frequency and the bass connection to the proper part, everything seamless side to side, up and down. it’s how stereo recordings are mastered to sound.

of course very fine sound can be found in rooms that are not symmetrical, but there will be a limit to how fine it can be. when you push it hard it will break down. there is a good reason concerts halls are symmetrical. they can scale without limits. so does my room.

this acoustical headroom I speak of at high SPL’s does require much fine tuning to achieve. it’s not any sort of plug and play kind of thing. took me many years.

The biggest issue to tackle with any room that is dedicated to audio listening is controlling reverb and minimizing delayed reverb. And by that, I mean if you completely eliminate all reverb in a room it will sound dead and lifeless. As an architect I design all kinds of rooms and spaces that have specific STC requirements and none of them use carpets/area rugs as an element to control sound. Ceiling treatment is one of the most important surfaces to consider. Smaller performance spaces have very different requirements than larger concert halls. Even local music clubs that have great live performances, if you analyzed the space, would be non-starters for 90% of the crowd here I imagine because they weren't "designed" to be perfect.

There are ways to treat the ceiling (gypsum board) without resorting to acoustical panels (which are often applied after to correct acoustics). You could benefit from using an acoustical gypsum plaster finish system. Upfront it will cost more than traditional gypsum but it will dramatically help with acoustics. We use this for large areas/performance spaces and other spaces that require acoustical control without "deadening" the space.  Walls can also be built to have a good STC rating for sound transmission (out and in) but you will still want to acoustically treat with properly positioned panels vs an acoustical finish on the walls.

Soft furnishings (area rugs, comfortable seating, drapery) can all have nominal acoustical benefits but the most important aspect of them is making the space comfortable to be in. You want to be comfortable listening to the music vs adopting your body to a single spot in a room.  You should talk to an acoustician about your space and how you want to use it. They should be able to design and specify the material finishes and help with panel placement (where needed). No space can be perfect.

My forever listening room will also be my library/den which means it will be a rectangular room with/ plenty of natural light for daytime activities and a view towards the pond and forest beyond. My listening position will constantly change in that space but I will have a dedicated spot for optimum speaker performance but also won't sweat it too much as the room is for overall enjoyment of what I like to do while listening to music - read, draw, write and purposefully listening as well.

First, I want to thank you all of guys for chipping in with your own experiences and advice.  This is what I had hoped for when I began this thread.  I also hope that others building a dedicated room will find the information here helpful.  

In discussing (many times) this room with our builder he told me he wanted me to be directly involved in the entire process of building my audio room.  Amoung many aspects of the room we discussed, I told him about the dedicated lines using 10 gauge "cooper" wire and he said no problem, he only uses cooper wire throuhout the homes he builds, just not 10 gauge.  He then suggested using a sub panel for the audio room and maybe a whole house electrical filter.   

Though I have not settled on the type of wall and ceiling construction all of your input has given me food for thought.  If you are wondering the room will be on a concrete slab.  

Finally, for everyone beginning a project like this I cannot encourage you enough to do your research.  Over the last three months I have spent several hours pouring over every aspect of building an audio room and Mike, I read your article...twice.  Your pictures really helped me see what is possible not just for acoustics but ascetics too.  It is a beautiful room and I would love to visit you.

One final note.  My wife has always supported my hobby and she enjoys the music just not as much as I do.  She is not only a supporter but a meaningful contributor too.  You should know she is a quilter/sewer/stitcher and will have her own 500+ square foot room...on the other side of the house.  

Keep this ideas and suggestions coming.  

@bipod72 Good post. I much agree with your point about making a comfortable space. I will also be using my new dedcated listening room as my den/office.

I've had two dedicated listening rooms and I'm presently building the third. The first one I designed from scratch for a new house, and the second is in my current house which is a repurposed bonus room. I'm building a new house now so I have the opportunity to design and build my third dedicated room.

My current listening room is fairly large (35 x 17 x 8.5) but its dimensions are far from optimum. It's upstairs so it has a floating floor. It has wall to wall carpet and no specialized room treatment. The walls and ceilings are standard construction. I have my components on racks spread against the front wall and the speakers sit out in the room 6' from the front wall. One wall is Ikea bookshelves full of albums, books, and tchotchkeys. My CDs are in several dowel racks that tilt each row of CDs up (good diffusion). My desk and computer table are in the back of the room along with other furniture. I have a leather listening chair, a turtle shaped leather ottoman, and a leather couch. There is a coffee table, lamp table, egg chair, and other furniture. I haven't put up system photos on Agon because its so cluttered and messy that I'm embarrased when I look at other member's rooms that look like they came out of an audio magazine ad.

The reason I'm going into so much detail about my current room is that it sounds fantastic. I've had a few other audiophiles listen to my system and they all have been very impressed. The guy who sold me my Thiel CS6 speakers told me that if they had sounded that good in his system he wouldn't have sold them. The overall point I want to make is that this room defies most of the conventional wisdom about listening rooms but it sounds wonderful. In fact, it sounds better than my custom built listening room from my previous house that had all sorts of specialized construction details like stand-off brackets for the drywall and sat on a concrete floor. I had treated the room with absorbtive panels as well.

For my new project I decided to relax and not worry about audiophile listening room "wisdom." The floor is standard, the walls and ceiling are standard, and I'm going to cover the floor with typical carpet.. The one area where I will do some heroic things is the electricity where I will have a dedicated 100 amp service and several 20 amp circuits just for this room. The room is 19 x 29 x 9 so I've got quite a bit of room.

My plan is to decorate the room with stuff that will provide absorbtion and diffusion. I'll keep my CDs and albums in the room and I will put my desk, computer table, sideboard, and other furniture in the back of the room with my stereo equipment and a TV monitor in the front. Basically the room will have a lot of stuff all over the place which will provide natural absorbtion and diffusion and serve to break up standing waves. If I end up with sonic problems I will consider commercial sound treatment as a final step.

In preparing for this project I've read quite a bit of material and watched more YouTube videos than I care to admit. I've seen several audiophiles report the they built a new room using audio construction techniques and their rooms sounded horrible when they were done. Then they had to spend large amounts of money on commercial sound treatment to get things right.

I don't want to oversimplify things but the single best indicator of your listening room is the slap-echo test. Clap your hands sharply (once) and listen for the reflected sound and the decay. Do this in several places in the room. If you do this in a variety of rooms you will get a good feeling for how this defines the room's acoustics. If the echo goes dead immediately then the room is likely too dead. If the echo goes on too long the room is too live and will muddy the music. You cal also listen to how defined the echos are. A well defined machine gun echo will be a problem.

In summary, I have come to the conclusion that how you decorate and furnish your listening room will have a bigger effect than it's design and construction. Basically, fill it with furniture and tchotchkeys until it sounds good. Take the money you save from not using fancy drywall and exotic construction techniques and buy a nice big couch. If you make the place interesting and comfortable good sound wlll likely follow.