Originally Posted by pocket5s
So that leads to the next question. What in the sims tells me to move on to another driver? ragged FR response? Impedance? A smooth response is obvious to see, so would over excursion. The rest, I'm not quite so sure what I"m looking at as it relates to good/bad for a particular combo.
Is there a general ratio of BL to cone that would be considered good? For example the three hybrid drivers all use the same basic motor which measures at ~13.6.
I'll be honest - I am still learning what works and what does not. I have seen that smaller drivers can get away with a higher Qes. I think this is partly because the Mms is lower. Also - look at more than just BL, BL^2/Re is a good start. I divide this ratio by cone area, BL^2/Re/Sd. Numbers depend on units, but if in typical metric or SI units, I look for this ratio to be greater than 0.12 and less than 0.25. Even this is not a guarantee of a good driver. The cone has to be strong, and the driver has to have sufficient displacement to make the SPL you're after.
Real specs matter here. I can't emphasize this enough. Specs that come from the marketing department are often useless. If I did not measure the driver, I had better know and trust the source. Complex cabinets are not as tolerant of deviations in driver specs.
All of the output graphs in Hornresp are valuable. I look at all of them when designing a sub. Sure, I start with as flat an SPL curve as I can make happen, but that is the first thing I compromise to get the rest right. The time domain side of things matters too, and you can't exactly "see" those issues in the SPL plot.
Then, there is also the simple fact that at some point (and it will be different for every driver and horn combination) the predictions will not match the reality due to losses that Hornresp can not account for. Certainly, there are commonalities as to when things come off the tracks, but I have not developed any hard and fast rules yet. I can only afford to waste so much time and plywood building things that don't work.... Compression ratio is part of it, expansion rate is another.
Acoustic impedance and reactance are most often overlooked. They do matter. Group delay is usually not too big of a deal for subs, provided nothing is outrageous, but needs to be looked at too.
There is a lot more to it than I can distill into a single post. Like I said - I am still learning, and though I have theories, I still can not fully explain some of the things I have measured.