Well this certainly escalated overnight.
He has a knack for making just about anything seem insidious. My main point in showing the GRAS measurements was to show that a better seating on the same fixture he uses is possible with that headphone. Not including the THD measurements from the better of our two GRAS seatings (Fig.5 in my previous post)) was not a Machiavellian oversight. It was because my main point in bringing the GRAS 45CA in was to discuss the seating upon it. And, as I mentioned, the THD with was rather similar with it anyway (compared to the 5128). Here they are, at 90 dBSPL (1 kHz) compared to the 5128, and 94 dBSPL (425 Hz) also compared to the 5128:
Fig.12 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the GRAS 45 CA (one seat) and Brüel & Kjær 5128 (two seats).
Fig.12 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the GRAS 45 CA (one seat) and Brüel & Kjær 5128 (two seats).
Again, the main point in bringing the GRAS 45CA into my previous post was to discuss seating. Looking at his frequency response measurement in Fig.1 of my previous post, I think it's reasonable to question the seating. It seems Amir disagrees. and he even suggested that I must have resorted to using bungies to do it:
We did not use bungies, rubber bands, or any other artificial means to secure the headphone to either of the fixtures in any of these measurements. Again, that's one of my main points: He should consider revisiting his placement, especially considering the frequency response he measured, both in the bass and treble.
Rather than even consider the possibility that he could get better placement in light of what's been shown, he'd rather suggest that we had to artificially tension it. Again, we did not artificially tension the headphone in any way. If we did, I think you'd see a much flatter measurement in the low bass.
While Amir did include a THD level measurement, it was not really the featured THD measurement, nor was it the one at the crux of his key THD criticisms. Once again, while he's now suggesting my use of THD as a ratio (a percentage) is some kind of trickery, he's basing most of his THD-related conclusions (both in his annotations and in his post) on his THD
ratio measurements seen in Fig.6 and Fig.7 of my previous post.
Also, while there are valid arguments to be made for using THD level more on balance, Amir and I are not alone in currently using THD expressed as a ratio as our primary THD measurements -- most everyone else does, too.
Again, while choosing to show the Y-axis with a linear (versus logarithmic) scale is his judgment call (and I do not recall criticizing that), I tend to prefer (and so use) a logarithmic Y-axis, as I find it easier to read and interpret. Again, that's a judgment call, and perhaps some prefer the linear Y-axis. From what I can tell, most in our space use log scale when showing THD ratio.
Other than perhaps lowering bass distortion (THD%) by improving his placement, the other key point I made was regarding his use of THD at 114 dBSPL. Again, while I think that's a reasonable thing to look at as an academic exercise, it's a level I will not drive most of the headphones here to -- a level that can cause hearing loss in under two minutes. No doubt some headphones will do better than others driven to those levels. Again, from 90 dB to 104 dB, though, the treble distortion did expectedly increase but it did not shift with the DIANA V2.
Going back to the seating discussion: Amir stated that he verified his measurement with his own ears and equalization. While I respect that he trusts that method as validation of a measurement or seating well done (and suggests that we should trust it, too), I'm not as confident. I still think he should (and will) find ways to improve his seating -- yes, without the need for bungies or other mechanical assistance he'd have you believe we used. After six years, we're still finding ways to improve our methods. I think our method of doing real-time approximations of frequency response as we place the headphones an important step for us.
Last week, I did something similar when someone brought RTINGS' measurement of the AirPods Max to my attention and asked me to post about it. (At the time of my post, I did not know that the measurement I was looking at was by RTINGS.) Again, in that instance it was a discussion of placement, which I posted about with supporting measurements. (I was able to recreate on the 5128 most of what they were getting on their Head Acoustics manikin.) You can see that post by
clicking here. I haven't heard from RTINGS yet and don't expect to. If they do contact me, I hope it's more productive (and more civil) than this.
I'm unclear if we are to expect additional third party measurements (arranged by Abyss) [the DMS measurements?] or if Head-Fi was "the one".
