- Joined
- Jun 20, 2001
- Posts
- 11,025
- Likes
- 6,633
Thanks again for all the careful work being done to measure these headphones. I feel very flattered that my favorite open-back headphone is getting this much love Personally, I think this is all fascinating, but I need some clever people to help me understand something here, because there are two points I'm awfully confused on now.
1) Only a few posts back, several headfi members were ready to skewer Tyll's head on spike. But if there's a consistently measurable 2-4 dB bump in H2, are we really still ruling second-harmonic distortion out as a possibility? Maybe it's just a happy accident, but that should be totally audible, no?
2) It should be possible to engineer a structure to a damp certain mode shapes. This could give preference to H2. I still don't know why one would intentionally engineer that, because higher harmonics of a pure sine tone are always an aberration. (In any case, Jude's communications with Sennheiser would indicate it wasn't intentional.) I would have thought it preferable to have a resonant mode at some low frequency to boost the bass, but I would have expected you'd want the emphasis of that resonance on the fundamental. Or am I overlooking something here?
A 2-4 dB difference at the fundamental frequency should be audible, imo. But a 2-4 dB difference in 2nd harmonic, with H2 being down by -30dB vs. the fundamental? I have my doubts about that...
Having said that, I'd agree that a consistent 2-4 dB bump in H2 for the HD800S vs. the HD800 shouldn't be offhandedly dismissed.
If you look at the measurements we made in better conditions, what we're actually talking about is centers of the ~3 dB H2 differences we're measuring at approximately 45 dBSPL lower than the fundamental (at 90 dBSPL). Remember, we're also talking about the second harmonic, exactly an octave up. This does bring up an interesting discussion about masking thresholds, which perhaps we can examine more thoroughly when I'm back from CES.
Again, the reason we're doing the FFT is because that was the test done that led to the suggestion that Sennheiser deliberately engineered higher 2nd order harmonic distortion into the HD800S, which has become what is essentially a longstanding universal truth where these headphones are concerned, the accuracy of which we're examining in this discussion. Remember, there are a couple of key things to point out about that original FFT. First, that FFT shows the HD800's 3rd harmonic as marginally higher than the 2nd, which might reasonably be said shows significantly different harmonic distortion characteristics than the HD800S. Secondly, as a result, the H2 difference was shown as 20 dB. That constitutes a substantial difference, and led to the theory in question.
Again, once we get a new HD800 (and even more used ones), we'll measure them and post them here.