keeferdog,
The echo sound when you clap your hands is likely flutter echoes between two hard parallel and untreated surfaces while the weird resonance is likely a room mode. Treating a room your size is challenging due to its small size. For example, the theoretical decay time based on your room dimensions is just over 200ms which is the bottom limit of a generally accepted 200 - 500ms rule of thumb. You don't want to line your walls with absorption which would lower it further and make listening uncomfortable like a quasi-anechoic chamber. Instead, you could opt for bass traps of 6" thickness with a wooden facia to help preserve the mids/high frequency decay times to avoid an overly dampened room. For the sidewalls, use reflective boards on an angle to deal with 1st order reflections from the closest speaker (L speaker->L sidewall) and farthest speaker (R speaker->L sidewall, and vice-versa) to create a quasi-reflection free zone while maintaining mid/high frequency energy. Behind you in the corners and centre of the back wall place thick absorption panels, and place on either side of the centred panel 2D Skyline or 2D QRD diffusion panels of about 4" - 6" depth in order for you to sit 5-6 feet from them to help kill slap/flutter echoes. On the front wall place 1D QRD diffusion centred on the wall with bass traps in each front wall corner. With the bass traps having a wooden facia (See GIK Acoustics for example), sidewalls having angled wooden boards and the backwall a combo of diffusion+absorption that leaves the floor and ceiling to treat. Place a small wool rug and underpad just large enough to capture the floor 1st order reflection bounce and 2D Skylines for the ceiling. This combination of reflecton/diffusion/absorption of bass should go a long way towards improving your sound quality.
Room Treatment Help
I just moved to the DFW area and drew the short straw for the wife assigned small 10 x 12 x 9’ soon to become, dedicated listening room. It’s in dire need of treatment as there’s a weird resonance, echo sound when clapping your hands. I’ve tried LRS + and open baffle speakers (Spatial Audio Lab) with a nice tube pre and both tube and ss amps. I’m just not happy with the room acoustics. I know I need help and realize small rooms are inherently tough to get good sound. My question is, where in the world do I start? GIK, Primacoustic, Acoustic Fields (Dennis Foley- this guy makes sense) etc? There are tons of YouTube vids out there, I’ve probably watched most of them but the topic is as confusing as trying to come up with end game components for an audiophile. Thanks in advance for your thoughts and experiences as they are highly appreciated!