Originally Posted by Eyleron
I have a diffusion question.
I've read many times where diffusing, as opposed go absorbing, helps to preserve "precious" energy.
I understand that the overall level / power response will be lower through absorption. But what I'm wondering is why it's precious?
Is it in terms of how a loss of energy means one will have to turn up amps more (which may require other amps/speakers) to attain the desired level?
I have certainly experienced that, after adding FRP absorption panels. But in my case, I have no headroom (need better speakers). For others with headroom to spare, I imagine they can afford the energy loss.
Hmmm. I have never used the term "precious". "Finite". "limited", certainly, but never "precious".
But the energy is finite. It means that for a given response, the amount of non-direct specular energy available to bounce about the room and to later return to the listening position is finite.
What is absorbed is effectively lost to the system, (and assuming a perfectly resistive surface and ignoring air resistance), that which is redirected is preserved, and that which is diffused is reduced due to the large degree of loss imposed by diffractive losses and superposition.
Thus if a later well behaved laterally arriving exponentially decaying semi-diffuse soundfield is a goal, then ALL (as in as much as possible) of the available energy must be preserved so that it may be returned to the listening position.
And this has nothing to do with amplifiers. This is the case for ANY given gain level of the direct energy. If you want to turn the gain up so that the direct signal is 130 dB continuous so that the gain of the gain of the indirect returned energy is proportionally a bit greater, that is your choice (and not one I recommend), but it makes little difference to the relative levels between the direct and indirect energy.
The fact is a room is filled with a MYRIAD sources featuring an acoustical impedance that are not completely resistive and which therefore add to energy loss, and diffusion is simply one rather inefficient (lossy) method to provide this energy return in the more diffuse manner desired.