I have started to find the speaker setup DSP operation quite useful for temporary use when not sitting in the primary listening position due to its delay option that adjusts relative speaker delay according to distance.
However, it would be really useful if the gains had a auto option that filled in the gains automatically based on normal SPL loss over distance in air (ie -6dB per doubling of distance).
As the delays are entered by specifying a distance, then calculating a suitable gain adjustment is easy and could be automated.
For eg, I have just setup a 320cm / 260cm distance adjustment. A relative gain adjustment hear would be around 1.8dB for the relative distance between the speakers in order for the SPL reaching the listener to be compensated for distance which results in a correct sounding stereo image at the alternate location. Without the gain adjustment, then while the delays are correct, I can sense that the image center is very slightly off to one side as may be expected.
I think automating gain adjustments (via an ‘auto’ button/option perhaps) would simplify speaker setup to give a better listening experience especially for a probable majority of people who may not even be particularly aware of SPL loss over distance and certainly unlikely to know how to calculate it, nor find a suitable online calculator.
I should imagine this could be a very easy feature to implement.
Your calculations only work in free field without room boundaries and for ideal point source speakers only, so things are not as straight forward as you might think when applying common sense…
However as I lack 50+ years in audio academia and a the no doubt requisite 50000 word thesis to bring some credibility to a suggested alternative I can only suggest the only broadly accepted value I am aware of, even if it is free air.
Once you start looking at 3dB per boundary, interference zones etc then it all gets too messy anyway and really becomes the realms of room DSP to do properly. However I am trying to keep things simple and still useful.
Intuitively I may be more tempted to suggest a nominal value of 3dB per doubling of distance however that is just my own guess informed mostly from post recording tweaking after multi-micing instruments and especially drum kits in live rooms over the years. I have tried it in this scenario as well, and actually I think it works better than 6dB.
Either way, it is still not something the average person is going to calculate in their head or probably even know a formula for (which I do), so I suggest there is utility is having a useful calculation done for you.
If a user wants absolute perfection and cares nothing for simplicity, well there is always fire up REW and get the measuring mic out and setup a new convolution etc
