[jimtranr]

More than five months ago I indicated to robd that once I finished tweaking the bedroom audio system I'd give diffusion another shot at the first-reflection and then at the second reflection points, and further back, by placing scatter-plated 244s there.

Although the tweaking is not yet complete--I'm awaiting an Uptone LPS-1.2 power supply upgrade for my ISO REGEN--I've done the diffusion listening tests in the following order:

1. I borrowed a pair of scatter-plated 244s from my living-dining-room system (so I wouldn't have to remove similar panels from the bedroom's rear walls) to test their effect at the first reflection point;

2. I moved the borrowed S-P panels to the second-reflection point (and some points further back) and reinstalled standard 244s at the first-reflection point;

3. I returned the borrowed S-P panels to the living-dining-room system and placed 2'x2' SRL Acoustics polystyrene QRD diffusers atop the second-reflection-point four-foot-tall 244s;

4. I put the 244s down on their sides so the bottom of each SRL diffuser was parked two feet above the floor.

In each instance, my ears were at least five feet from the respective-side scatter plate or diffuser. I tried different listening positions (a tricky proposition atop a bed) from extreme nearfield to the apex of a roughly equilateral triangle based on the toed-in positions of my Paradigm Studio 20s. What I settled on as the "ideal" position put my ears just slightly forward of the side-to-side plane formed between the scattering/diffusion devices. I diagrammed the room layout three posts earlier in this thread.

For source material, I listened to rips and downloaded 16/44 tracks of digital remasters of analog-sourced Lyrita classical recordings engineered and pressed by Decca during the 1960's and 1970's. I selected those because I'm familiar with the performances (compositions by British composers William Alwyn, Arnold Bax, Gustav Holst, and E.J. Moeran) and the naturalness of the mostly-Kenneth Wilkinson-engineered recordings. My reasoning: If anomalies showed up in these recordings, the rest was inescapably forgetaboutit.

Conclusion: I've reverted to the original trap configuration diagrammed three posts below. In each instance where scatter or diffusion was employed at either the first- or second-reflection points, or points further back along the side walls, I heard peaky mids not unlike the squawks emanating from a horn-loaded midrange driver or two I played with way back (I mean way back) in the Dark Ages. I could discern no benefit (e.g., a sense or perception of increased spaciousness or "airiness") that would even begin to offset the audible downside.

So in this room, at least, the rear-wall scatter plates suffice.