ToTo Man
the band not the dog
How far is the back wall from the listening seat? If it's anything less than 1 metre I'd be inclined to use absorption there instead of diffusion, especially if you're considering building a 1D diffusor with deep wells, because if you sit too close to it the sound waves won't have enough time to disperse properly and you'll hear the wells beaming/ringing. The effect can be quite pleasant but it's definitely a form of colouration! The deeper the diffusor, the further away you must sit from it to hear it diffuse properly.Thanks for coming back TTM, yes I’ve wanted to measure the room for some time now as it is bright. When I’ve posted pics you’ll see it has the challenge of the alcove(s) either side of the fireplace and hard surfaces. Alas for family life and getting the most out the room the hifi set-up is dictated. I will add a rug and possibly some grip-mat on the table and will be building a 2m x 0.5m ish diffuser behind the head ie. just above the listening sofa, described to me as sorting the W effect of the Pac-Man bouncing of sound from speaker to wall to fireplace to listener.
But I have wanted to understand the room at different frequencies and then negotiate on the cosmetics, I doubt ceiling diffusers will get approval for example. The acoustics are possibly the reason I prefer the 66 to the RS10 in this room, they’re not challenging the room as much.
If you don't want to completely absorb the back wall reflection, an alternative would be to use absorption panel with a thin scatter plate on it, like the GIK Alpha, GIK Impression or GIK Scatter Plate panels (other manufacturers are available!). It's still fairly reflective at high frequencies but not as much as a bare wall and you can sit closer to these without hearing beaming/ringing artifacts.