The image of coloration that you shared is fabulous. I have never seen it before. I can't say I totally agree with it due to my lack of knowledge but I certainly agree with the parts I've personally experienced. I've downloaded it and will study it very carefully.
Ian has told me Axiom has both curves for all v4. He was going to ask Andrew to publish them but likely other matters took priority. I know from listening experience the M2 and M3 image and stage like the M5 and the M2, within its specified band, is more linear than the M3 and M5.
With regard to the curves Axiom publishes, the sound power is a composite of all curves using weight coefficients that Axiom has selected. You could call the sound power curve the weighted average of all curves. How Axiom selects the weights is largely what makes the "Axiom sound". We don't know how Axiom selects those weights - and they won't divulge the methodology - but it stems from experience, science and listening. I believe they've nailed the formula. Once the formula is nailed, it makes speaker engineering easier because the formula constrains or maybe informs the design. For example, if the sound power curve comes out "too lumpy" at say 200 to 300Hz, the curve weighting factors for that band won't be questioned. Rather, it will point to a deficiency in the design. The designer can then examine the mess of curves in that band to determine how the lump should be mitigated. The challenge is that to mitigate the lump, one or more lumps or dips may be introduced elsewhere. Would that be better or worse? The sound power curve for a modified design helps to answer that. If the new lumps and dips are within a specified tolerance, then the modified design is good to go. This is why for a speaker like the LFR1100, there may be thousands of curves to inform the final design. Those thousands of curves also include the curves for each driver.
The listening window and sound power are the only curves lay people need to judge how the speaker will sound in a room. The science says when these curves ride on top of each other, audio Nirvana is reached. Why? Because the direct and reflected sound fields become fused and the speakers acoustically disappear.
With regard to the slope of the curves, the science says a slope of 3dB/decade out to 15Khz or beyond will make the speakers sound natural in a room.
These two curves inform how wide and spacious the speaker will sound in room. In fact, what you listen to provided you're not sitting in the near field of a speaker is sound power.
The last factor is SPL. Ideally, we should have a family of listening window and sound power curves for various SPLs. If these two curves "deform" at higher SPLs, that spells trouble. I personally have not detected this trouble in v4. I can turn them up ridiculously loud, and they will distort, but the stage and imaging remain intact.
Last edited by Mojo; 05/20/22 06:31 PM.
