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Originally Posted by PaulP  ... You say that your first reflections off the rear diffusors to reach the listening spot occur at 19ms, or 6m (19.6 ft). Is there really 2.7m (8.9 ft) between the listening spot and the monitors? It doesn't look like that from the photos. ... |
Let's see, the listening position is about 1,8m [~6'] away from the monitors. I estimated the additional reflection path (geometrically its not 100% correct) by doubling the distance of 3,3m [~11'] from listening position to the diffusors = 19ms delay.
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Originally Posted by PaulP ... First strong reflection at 3 ms (1m / 3ft), this must be from the black and white side panels (Edit: or is it from the floor?). Is the white part absorptive? I'm a bit surprised (not that I have anything to base it on) by the initial drop in level you have between the impulse and the first reflection. 10 db seems like quite a bit for a reflection off a panel so close by. ... |
The black (in fact dark green) and white side panels are fabric covered broadband-aborbers! The wooden panels reflect away from the listening position. So the
situation should already be pretty much reflection free (1st reflections of the speakers) right away. The 3,6ms reflection is most probably from the floor.
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Originally Posted by PaulP ... And why would this reflection drop by 8db when you add the diffusors at the back of the room? ... |
I don't see that the level drops when I added diffusers between {A} and {B}. Maybe you compared it with {D} which is the empty room?
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Originally Posted by PaulP ... The next strong reflection is at about 10 ms (3.1m / 10 ft). Where is that coming from? ... If this is indeed something between floor and ceiling why would it take 10 ms to begin? And why is it so cleanly defined, especially in "C" ? ... |
This where it really gets interesting: I simply don't know yet where it is comming from. My best guess would be that its
twofold reflection runing via ceiling/sidewalls but I have yet to prove that (I thought the cloud would prevent this path...).
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Originally Posted by PaulP ... Have you made several mesurements in the same spot? Are they all the same ... |
Yes, basically all the same -- I've posted just a few of a whole series of measurements.
See image below for better delay labeling (measurement {A}).