My new room is 8 x 16 x 32, what to do?

FWIW most empty rooms with out domestic furnishings such as rugs, drapes, pictures, furniture, etc will have echo slap. Don't let that overly concern you.

Apart from room induced nodes in the bass created by room dimensions, most of your room problems can be controlled by two things; 1)deadening the first reflection points on floor, side walls, and ceilings (don't overlook the latter if you don't have WAF's), and 2) put acoustic materiels on the wall behind the listening position which diffuse/dispurse the mid/high frequencies I'd be concerned that if you have treated the first reflection points well that using deadening materiels might overdamp your room. You might also put similar materiels behind the speakers but I wouldn't do both and, unless I had panels or electrostats, I probably wouldn't do much to the wall behind the speaker if I did all the other stuff.

Bass nodes and nulls will be determined to a great extent by where you place your speakers and listening position. Trying to anticipate these issues in advance by determining exact room dimensions by a formula is an invitation to disaster, especially if you do it with out an expert on-site to help, and even then I've seen a few 'expert' disasters in special built and treated rooms.

IMHO, in a rectangular room there will always be some bass nulls and nodes and all you will accomplish by changing dimensions is to move them around frequency wise. If you have a gross node you can always use a parametric type equalizer of the digital or analog type or if the problem is in the upper bass you can probably get some good results from using bass traps etc.

Hope that helps a bit and gets you pointed in a good direction. I'm sure some of the experts will opine as well.

you are lucky to have such a large room.

you may be able to avoid some of the effects of room boundaries by placing your speakers away from the rear and side walls.

for example, you could move the speakers, say, 10 feet from the rear and at least two feet from the side walls.

i assume you will place a hardwood floor over the concrete and maybe a carpet over that.

i suppose you will also select appropriate materials to place on the brick.

what about windows ? how many and where are they. glass is a reflective surface.

i have 6 windows in my listening room. it is a challenging to mitigate the effects of all that glass.

It is a basement so no hardwood floor. Only 2 small windows 2x3 feet at one end at the ceiling

I agree w/ 61: "BTW, great sounding rooms don't have to conform to golden ratios." You can certainly find hundreds of articles/advice on GS rooms and acoustics (type: "golden section" and acoustics into Google) but resonance and harmonic frequencies depend on multiples of a room's dimension(s) whatever they are. The whole "Cardas thing' just cracks me up! (BTW, I have a degree in architecture and acoustics, AND my last name is Golden, so I've certainly delved into the subject ;-)

I have two recommendations however:

1. I strongly urge you to set your speakers up on one of the long walls. At 16 feet, the room width is just a bit more than the minimum (15 feet) required to do this. And save that 32 foot length because with the L/R speakers far from their respective sidewalls, secondary reflections will arrive at the listening position too late to mess up the sound stage, so the usual sidewall absorbtive treatment will not be required. Large wool area rugs, without padding, are the best acoustically for the floor. Furniture can do the rest if it's upholtered with fabric, nice and plump, and enough of it ;-) A bookcase with a couple feet of walk space between it and the back of the listening sofa/chair will provide a perfect abffusor for the rear wall.

2. The other thing that could be a problem (or not at all) has to do with the low ceiling. Whether it's a problem requiring treatment, or not, depends on your loudspeakers. Line arrays (Pipedreams), d'Appolito arrays (Dunlavy, Dynaudio), ribbons (Dali), and panel dipoles (like Maggie, MartinLogan, SoundLabs, etc) tend to radiate mostly horizontally and very little vertically. So ceiling reflections (that bounce back down to the listening position) aren't significant. Otherwise, you need an absorbtive panel about 12 feet wide (L to R) and 6 feet across on the ceiling halfway between the speakers and listening position.

Just set up the speakers and listening position first as Onhwy61 says. Most speakers (not just dipoles) need to be at least 3 - 4 feet out from the wall behind them. That's pretty much it ;-) I sure wish my room was 15 feet wide so I could use the long wall - it makes acoustical life so much easier!
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The dimensions are definitely not good, there will be some serious room nodes, but the up side to this is the room is big enough to reduce at least one dimension to make a big difference. Your idea of reducing the overall length to 26' is a good one. The 6' space might make a very good equipment and/or music (LP, CD, etc.) storage area. With some homework you might also use the area as a giant bass trap. The best course of action would be some professional help, like Rives. This will be costly, but will be the best bang for the buck. Of course you can take the advice of the other folks above and just try it to see if you like it as is.