Here's what I got
https://docs.google.com/spreadsheets/d/1HmiGrNsTEJFe4wqdJym5I48TcWTiFTWR2ZsPuPsxx0U/edit?usp=sharing
The frequencies per band were less, so that took a while to correct.
Again, please point out any errors.
SCORE: ~4.73
SCORE ignoring LFX: ~7.58
Great work, thanks again. I’ve spotted a couple of mistakes though. Looks like your LFX formula in the spreadsheet for the lower extension frequency at the -6 dB point, using the ‘closest Hz less than’ method, takes the value from the listening window, when it should take it from the sound power curve i.e. it should be 62.2559 Hz, not 58.5938 Hz (the formula is also incorrect for your NHT speaker spreadsheet, although the value happens to be the same as for the sound power curve in that case.)
As I said in the
Speaker Equivalent SINAD Discussion thread, using the ‘closest Hz less than’ value makes much more sense in terms of matching up with Sean Olive’s description and formula for the LFX variable in his paper. You said:
For -6db, what if it’s 39.5Hz, wouldn’t using 39.5508Hz be more accurate to use than 38.8184Hz?
Yes, it may be more ‘accurate’ mathematically, but that’s irrelevant if that’s not the method Olive used in his
AES paper. (He says ‘
first frequency x_SP’ for a reason, not ‘nearest’ or ‘closest’.) We have to match Olive’s calculation method as close as possible, as the formula correlating these variables to actual preference scores was based on this method – we have no idea how changing the method would change the correlation. And as I said, I think it’s pretty obvious from Olive’s description of LFX that he was using the ‘closest Hz less than’ method. As the formula stands currently in your spreadsheet, using ‘closest Hz greater than’ translates to a ‘-6 dB’ low extension frequency that has
not reached -6 dB, but is at a higher amplitude than this. Using ‘closest Hz less than’ gives you a frequency that
has crossed the threshold of -6 dB, and so satisfies the criteria of Olive’s formula and description of LFX.
With these corrections, I arrive at a score of 4.86 for the Revel C52 (used full-range on its own – I presume for the second score, ‘ignoring LFX’ means ‘score if used with an ideal subwoofer with -6 dB point at 14.5 Hz’, as we discussed previously). The NHT speaker’s score is then also adjusted to 2.39 (up from 2.31 in your original spreadsheet).
As for what exact frequency bands to use for the calculations, I think that is a bit more ambiguous, and needs to be checked with Sean Olive. I’m still leaning towards him meaning ‘bands with center frequencies strictly between 100 Hz-12 kHz’ in the NDB variable definition, due to his description of bands using center frequencies in Part 1 of his paper (
excerpts here), as well as the fact that ranges presented in scientific papers are most likely to be strict lower and upper bounds of variables within that range, and less likely rough bounds that can be crossed (if the latter is the case, ‘approximately’ is almost always used as a qualifier). So I think the correct approach would be either using center frequencies, or lower/upper bounds, but in both cases always
within the frequency range Olive prescribes. Oh, did you solve the SM (smoothness) variable discrepancy by the way?
