If you get anomalous results, try moving out a little bit until things start to make sense.
I took some measurements of the R speaker & am not sure what to make of them. I dumped them in
my gdrive in case you were interested to look at the raw data.
I took 3" measurements for each individual driver, 12" for the woofers as a whole and tweeters as a whole and 1m for the speaker as a whole.
As far as I know, the crossover is at 1500Hz & the crossover is different for each tweeter so that the middle tweeter behaves differently to the top and bottom tweeters in order to control the dispersion pattern in some way (I've never seen explicit details of how this works so that's as much as I know.
All graphs are smoothed using acourate's psychoacoustic & FDW functions (basically what it provides as macro 1).
tweeters_3inch.jpg; red = top tweeter, green = middle, brown = bottom
woofers_3inch.jpg; red = top woofer, green = bottom
12_inch.jpg; red = woofer, green = tweeter
correction.jpg; turquoise = sub + r at listening position, blue = speaker at 1m, black = correction filter
FWIW I tried importing these as wav's into HolmImpulse but holm crashes every time I do that, not sure what format it is after (I tried the 3 different ways acourate can export it; 24bit pcm, 32bit, 64bit).
My thoughts;
Tweeters
- the individual tweeters do appear to behave quite differently, the 3inch measurements may well be useless as a result
- the 12in tweeter measurement shows rising frequency response above 10kHz which isn't in the 3in measurements
- the 12in measurement is about 3dB down from 2kHz to 10kHz, my target curve is the b&k curve (6dB down from 1kHz to 20kHz) which is also about 3dB down between 2-10kHz
- the 1m measurement does *not* show that same downward tilt >2kHz
My gut feel is that I should leave the tweeters alone as their natural response appears to be approximately the shape I'm after anyway. The mystery is the spike above 10kHz though this is not found in a measurement at the listening position.
Woofers
- the individual 3in measurements match quite closely; they both show elevated levels between ~130-300Hz, a dip centred on ~400Hz and then rolling off from 1kHz
- the 12in measurement accentuates the 400Hz dip but moderates the <300Hz levels though there is still a peak centred at ~150Hz
- the 1m measurement still shows that ~150Hz peak
The question here is whether I should do something about the 150Hz peak & also whether the 400Hz dip should be compensated for.
Looking at the correction filter I have I can see it is cutting <200Hz so this is being "fixed" without speaker correction.
The speaker is ~280mm wide which I think corresponds to baffle step issues hitting at ~410Hz. Is this coincidence? Again the room correction filter is seeing this as the 400Hz region is at 0dB in the filter so it is trimming around that region.
Overall it looks like acourate is handling this pretty well without needing me to correct the speaker. The 1m measurement (once smoothed) seems v similar to the listening position measurement >300Hz and you could argue that <300Hz, in an untreated room, is just going to result in correcting one way then the other for questionable benefit.
I would be really interested in other views though. All this is getting me more interested in building my own speakers