What is ideal dimension size for a home listening room?

@audioquest4life , thanks for your kind words. Music is music indeed, and I enjoy music through my car stereo enough to know that sometimes you just need to turn off the audiophilia nervosa.  We all live in a real world and deal with compromises.  But a post like this invites dreaming, so dream I did.  It is akin to someone asking "What is the ideal 2 channel system?"  

I agree that near field listening can be wonderful.  In fact, I'd love to be able to build a system around that paradigm.  But if I were designing a new room, I would not want to get locked into a particular paradigm.  I'd want a room that would likely be as friendly to a near field paradigm using a monitor/dba approach as a more traditional full range system with the listening position further back.  I'd want a room that could work with panels, line arrays, point source, and horns.  

For the last 6 years, I've been "enjoying" my first dedicated listening room in which I'm using my first set of full range speakers.  It has been a challenge making it work, and I'm not completely there yet.  I've got the main issues addressed, so I'm getting close.  What remains is fine tuning, and it is not easy.  It takes a lot of critical listening to a lot of different recordings and an equal measure of critical thinking about what I am hearing. 

Most of the issues I've had to deal with were baked into the cake with room dimensions and construction choices that I had no control over since we bought an existing house.  Next time will be different.  I will either be going new construction or buying with the intent of building a music room as an add on.  

Right on Brownsfan, I think Rettinger sure appreciated Bolt and summaries as most of the Magic ratios as falling outside his unity adjusted ideal area. Hence my paraphrase to work reverberation time.. too bad about that cancellation node you have. I can move my chair just enough to get out of it. You might actually be a great candidate for swarm or some analog EQ down low, although based on the deep knowledge you show in your post I suspect you already know this

best

jim

Like all things, labor and importantly expertise needed to install these products in a systematic way to achieve best results per $. What a lovely thread :-)

Considering  people doing "near field Listening " , having speakers a few feet from you , I doubt size matters .
Just make sure  you've taken care of  bouncing sound

brownsfan made many good points. I suggest that you find a good on-line Room Mode Calculator which speaks of Schroeder Frequency,  Bolt Area, Bonello, etc. to help you better understand the consequences of room dimensions. You might consider consulting with a professional because once the walls are up you are stuck with the design.

You might also consider non-parallel walls. Our purpose built room was designed with non-parallel walls and the results are well worth the effort. The calculations are more complicated but worth it. They help minimize the need for absorption and diffusion. The end result is a lively (not bright) well balanced room. The next time you are at an indoor live venue check out the enclosure you are sitting in.

If possible, consider which family of speaker design (mono-pole, dipole, point source, line source, omni-directional) you will likely end up with. This consideration doesn't necessarily influence the optimal room dimensions which is more about distributed room modes and a smooth bass response but it will influence the interior room design and treatment needed.

Consider built in or free standing corner bass traps. There are real reasons why qualified professionals recommend corner and soffit bass traps. Don't believe the general statement that too many bass traps will absorb all the mids and highs and make a room sound over damped. Not all bass traps are created equal. For example, DIY "bass traps" that are basically a 4" thick block of Corning fiberglass wrapped in fabric are marginally effective as bass traps and are really broad band absorbers that can, if overly used, over dampen a room. A REAL bass trap (bass attenuation only) typically has a membrane covering the fiberglass which reflects the mids and highs back into the room and does not over dampen the room.