quoting from self
Caesar,
The difference between an existing ~ 14x20 or a new 15x22 would lead me toward the renovation of the existing 14x20. Of course, that is if your isolation needs can be met in the existing. I do prefer a bit more width but 14' W should easily be fine (ceiling height depending). That just seems practical.
Below is the text from the Room Size and Construction Section of my co-published white paper (with Nyal). You are going to have room modes (in fact we want them). What you are hoping to achieve by optimizing room dimensions and construction is that the modes are evenly spaced and have similar modal strength. Then treat to taste (simplifying on purpose) and locate spkrs/ears carefully and enjoy.
G: Room Size and Construction
• Square footage should be in the range of 224 to 475 sq. ft.
• Room volume 1,750 to 4,750 sq. ft.
• The room dimensions should mathematically have no common divisors and no pair of dimensions should share more than one common divisor
• The use of (2x) layers of 5/8” gypsum board is advised for walls and ceiling
• Irregular shape rooms, rooms with varied construction methods on different surfaces and rooms with adjoining secondary spaces should all be carefully considered for the task of high performance listening.
Both the Square footage and Room Volume are excellent qualifiers of a performance driven dedicated listening environment. The desired range of square footage should be between 225 and 475 sq ft. The room volume should follow suit with a desired cubic volume of 2,250 to 4,750 cu ft. So then, what should the exact room dimensions be?...well, it depends (sorry, no easy answers exist). However, having at least one dimension between 20’ and 25’ allows the room’s lowest mode to be lower than 30Hz. The ceiling height should be 9.5’ to 11’ as this places the listener’s ears comfortably below the floor to ceiling modal null. Regarding internal room volume, the targeted range yields greater modal density extending down toward 50Hz. Following these guides will offer tangibly smoother and more even bass response and a more pure connection to the speaker’s true overall sound.
The ratio of room dimensions (width, height and length) is a foundational aspect of your listening experience. In this regard, your room should be thought of as an instrument. Proper relationships between the room dimensions will yield the smoothest, most consistent bass response, period. Sorry to report though, there are no “factory set” ideal room ratios. There are good starting points such as the Louden Ratio of 1, 1:4, 1:9. If given a blank page, the room dimensions should mathematically have no common divisors and no pair of dimensions should share more than one common divisor. The goal is to yield an even density and distribution of room modes.
How the walls, floor and ceiling are constructed is a significant part of the sonic signature of a listening room. Massive concrete surfaces retain nearly all “bass” energy while lightweight residential partitions allow nearly similar amounts to pass through to adjoining spaces. Optimal sound quality in this realm is a lot like Goldilocks…not too hot or too cold but just right. Sonically (not factoring isolation needs), “just right” is a double course (2x) of 5/8” gypsum board. This yields enough mass for the low frequency energy to be punchy and focused when desired but not so much that the resonances are overwhelming. Further benefits can be had from use of certain isolation hangers and dampeners as they diminish “after-ring” elements that building materials can exhibit when fully excited by sound vibrations.
