It's been a while since my last post on here, but here are some measurements. These are not really accurate sub 300Hz as the seating of the coupler determines the bass response greatly.
I'm using the Dayton IMM-6 mic with a DIY coupler and AudioTool Android, similar to this set-up: http://www.head-fi.org/t/830062/crinacles-fr-measurement-database-150-iems-measured
Another thing. Don't take these measurements literally. These measurements are nowhere near IEC711 stuff. This is for comparision only.
For reference here's my test measurement of the Trinity Phantom Master 4 compared to
earfonia:
Anyway towards the A4. The scaling (dB) is very wierd, due to AudioTool being finicky. I will adjust the graphs later down the strech, after my measurements are more refined.
Black(b)-Blue(f)
Black(b)-Black(f)
Black(b)-Green(f)
First you might notice the bass response, and how it is greatly different even though Black(B) was the only filter used. Generally speaking, insertion depth and (in this case) covering the front port has great effects on everything sub 350Hz. This is why some of you have different opinions on low-end quantity. I found Black to be very sufficient in quantity, although YMMV.
The midrange (in particular around 2-4kHz) is quite interesting to look at. Black(f) is the most recessed, where as Green and Blue both are more elevated around 2kHz. In case you are interested, the amount of "pores" covered on Green and Blue are identical. I presume the thickness of the filter itself is different, hence the extra little boost in the treble with the Blue(F)'s.
I prefer the FLC8s overall compared to the A4 due to the slightly more linear treble response. There is a rather large dip after 4kHz, which goes up again around 6.5kHz, down and up again at 9k. Blue(F) and Black(F) are rather similar in that regard, although the former is more extended. Green(f) has a bigger dip after 4kHz.
Have fun with it. Ask right away, in case you guys have questions.