Those FR graphs that ADUHF posted from rtings are interesting. I have always found the HD650 to be more bassy and dark compared to the HD600 and yet both raw and compensated curves are very similar.
They are similar. The HD 650 has a slightly darker overall tilt though than the HD 600. The easiest way to see the difference on the RTINGS graphs is probably using the compensated plots. And flipping back and forth between the two headphones, using the headphone selector on the left side above the graph. These are the two plots I'm referring to...
Senn HD 600 Compensated Frequency Response
Senn HD 650 Compensated Frequency Response
As I mentioned earlier, I don't have total confidence in RTINGS target frequency response curve, which is represented by the dashed line on both their raw and compensated plots. Imo their target curve still probably overestimates the average response in the treble. And doesn't do a perfect job of modeling the resonances on their head & torso simulator in the treble. So when I look at their compensated frequency plots, I will tend to look more at the position of the
peaks in the treble relative to the target curve, rather than the valleys or average response, to gauge the accuracy of the response in that region of the graph.
Imo, both the HD 600 and HD650 are pretty close to neutral in the treble and midrange. It's a little difficult to gauge which of the two is the
more neutral though based solely on the compensated plots, because of the issues with the RTINGS target response curve that I outlined above. The HD 650 looks maybe a little better balanced overall, due to it's slighty higher response in the bass. Audiophiles who prefer a somewhat brighter and more detailed sound might find the HD 650 a bit dark or lacking in air and sibilance though, because of it's darker overall tilt.
The left and right drivers also look a little better balanced on the HD 600 plot. The left driver on the HD 650, which is represented by the solid blue curve on the above graph, appears to have a slightly darker overall tilt than the right driver, which is represented by the solid gray curve. Imo, the left and right curves appear to line up somewhat better though on the compensated HD 600 graph. Whether that's consistent across
multiple units/headphones though, I have no idea. It could just be in the two particular units RTINGS measured.
FYI, I have never listened to either model to the best of my recollection. So most of the above info is just conjecture on my part, based on the two plots. Based on the graphs, both headphones also appear to be somewhat lacking in bass though, due to their open-back designs.
The HD 58x Jubilee is also open-back btw, and has a little better extension in the bass than the above HPs.
Senn HD 58x Jubilee Compensated Frequency Response
The Jubilee also appears to have a little more unevenness in the treble though than the HD 600 and HD 650.
