Look at the reviews from Brooko and HiFiChris for more graphs with different filter configurations:
https://www.head-fi.org/showcase/flc-technology-flc-8s.21068/reviews
What's confusing me tho is that in csglinux' graph, the curve goes up after 2kHz, while the curve only goes down after 2kHz in both Brooko's and HiFiChris' graphs:
Colored = Brooko
Grey = HiFiChris
White = csglinux
Why is csglinux' graph that much different while the other two are at least somewhat similar? (sorry if it's a stupid question, I'm new to this)
Not a stupid question at all. There can be a lot of subtleties to this. Generally, you don't ever want to compare results from two different rigs, because there are a whole host of things that could legitimately be different, including:
1) Different types of eartips
2) Insertion depth
3) Unit variation between headphones
4) Coupler transfer impedance
5) Coupler microphone
We know 1) and 2) play a large role in the treble.
@Brooko and
@HiFiChris are probably not using the Cp100 eartips I'm using. I think Cp100 are more comfortable and sound better (to me) than the stock FLC tips, but I'm not judging. Others have to decide for themselves, because different eartips and insertion depths will give different results for different people. 3), 4) and 5) could cause discrepancies anywhere over the frequency spectrum. To give an indication of 3), look at the variation in the left and right channels of my FLC8s and FLC8d using gunmetal filters:
(Note that the previous results I showed were averaged over the L and R channels.)
BTW, somebody else had asked to see results with the gold HF filters. Here they are:
And an L/R averaged comparison of the two headphones, both using gold HF filters:
You can see that the channel balance on my FLC8s and FLC8d is fair but not perfect. We have to expect some variation from unit to unit.
As for item 4), I believe both
@Brooko and
@HiFiChris are using what's called a Vibro Veritas coupler. I have one of those too, and they're perfectly fine - but they will give a different response to that of a 711 coupler. (My measurements were using a GRAS RA0045 coupler). Compensation files can help, but you can't expect a perfect match between Vibro Veritas and 711 measurements when hopping back and forth between sealed and ported IEMs.
In my experience, the biggest discrepancies usually come from 5), i.e., the coupler mic, and in my experience, the Vibro Veritas mic is its Achilles heel. It's not particularly flat, even just from 20 Hz -> 10 kHz. Having said that, if you're wanting to know which of these measurements is correct, there's an easy answer to that: none of them. None of them will exactly match the response from your own ear canal. But that doesn't mean these measurements aren't useful. What we're looking for is the trend and any rig (711 or Vibro Veritas) will be able to show you the effect of switching from gunmetal to gold HF filters, or from switching from FLC8s to FLC8d, etc.
As for trying to get individual rigs situated on the other side of the world to compare with one another... actually, we're working on that too
We have a little touring IEM project which anybody (
@Brooko?
@HiFiChris?) is welcome to join:
https://www.head-fi.org/threads/ety...phone-for-your-ears-and-your-couplers.908512/