End Game Headphones

[bigcrunch]

There's a long and somewhat painful thread about group delay you can search for. Group delay is how quickly the phase angle changes with frequency (i.e. the derivative of phase wrt frequency). So a positive group delay means the phase is increasing wrt to frequency. A negative value means the phase is decreasing wrt to frequency.

If the plot of group delay is centered around some value (e.g. 0), it means the phase angle is oscillating around some constant.

Thanks for explaining that. The plot makes much more sense now that I know that it's the derivative with respect to frequency. I will see if I can track down that thread you mentioned to learn more about this...

 

[Ata]

IIRC the headphone driver itself is a minimum phase device, thus with a very good group delay. The group delays we measure are basically sound interactions between the driver and the cup, little frequency dependent sound wave reflections and resonances that result in these deviations. For the lack of a better description, I think of it as a different acoustic signature inherent in the overall design, which subtly changes the sound and our perception of it.

 

[bigcrunch]

IIRC the headphone driver itself is a minimum phase device, thus with a very good group delay. The group delays we measure are basically sound interactions between the driver and the cup, little frequency dependent sound wave reflections and resonances that result in these deviations. For the lack of a better description, I think of it as a different acoustic signature inherent in the overall design, which subtly changes the sound and our perception of it.

Interesting. It's a bit of a crapshoot, but in that case, do you think it might be possible to alter/improve the group delay with mods (e.g. additional dampening inside the cup)? I guess even if it was possible, it would require a lot of trial and error, and you would need a way to measure the effect that your mods have on the sound signature to know if they are improving it or not, but it might be interesting to try if there is a theoretical basis for it.

 

[radix]

Interesting. It's a bit of a crapshoot, but in that case, do you think it might be possible to alter/improve the group delay with mods (e.g. additional dampening inside the cup)? I guess even if it was possible, it would require a lot of trial and error, and you would need a way to measure the effect that your mods have on the sound signature to know if they are improving it or not, but it might be interesting to try if there is a theoretical basis for it.

I think one of the main things Amir looks for in the group delay is swings that might indicate the designer purposefully cut a frequency, such as to avoid a resonance. That's what's going on in post #12 where he says "don't EQ." He thinks that GD swing around 10 kHz corresponding to a FR dip is on purpose.

Personally, I think the designers for mid- to high-end headphones know about all this stuff and if there was a simple way to fix it without making bad tradeoffs, they would have done it. There's usually some Pareto front where you cannot improve one thing without worsening something else.

You could look at these posts

Does Phase Distortion/Shift Matter in Audio? (no*)

A viewer of my videos and member he suggested that I do a video commenting on a video that Paul McGown did on audibility of phase shifts. Here is Paul's video which was really about a different question (why we need wideband amplifiers) but turned it into phase being an audible problem: Here...

www.audiosciencereview.com

AES E-Library » Audibility of Loudspeaker Group-Delay Characteristics

Loudspeaker impulse responses were studied using a paired-comparison listening test to learn about the audibility of the loudspeaker group-delay characteristics. Several modeled and six measured loudspeakers were included in this study. The impulse responses and their time-reversed versions were...

www.aes.org

I'm not sure how the picture is different (if it is) for headphones vs speakers.

 

[etc6849]

Benchmark DAC3 B -> HPA4 -> AHB2 x2 in mono -> iFi iESL electrostatic energizer -> Stax SR-X9000 (new flagship).
By far the best headphones I've ever heard or owned. I am totally blown away; I've owned many flagship headphones before tri-amping my home theater and giving up on headphones altogether. Finally I can saw I have headphones to match my main system