Hopefully we get tomorrow measured Stax phones 007/9 and 009/7 .
These are approximative non-scientific REW measurements with miniDSP rig, e.g. my HD650 measurements look exactly like Tyll Hertsen's - but that's just anecdotal precision
.
Note that he measurements for
@thinker 's Stax 007 mk2 drivers in the 009 housing are not here since I had a coupling issue with my rig, and the measurements didn't quite validate well. But take a look at the Libratum 3 measurements below, they were near identical. Also sound-wise they were very similar, large sound stage, relaxed sound, very musical, one can listen the whole day to them. Even the slight 7K notch was the same - which might be due to coupling resonances with my rig, so these plots are not to be confused with the truth
, but I could hear the slight reservedness or politeness of the sound in that area. However, that also means the sound has no hint of being honky or hard or harsh, ever.
FR of the Stax 009 drivers in 007 Mk2 housing and pads, no front grills, no dust screen. Soundstage is like nearfield, a bit closer to the ear, lively, expressive, not bright, a near-perfect monitor experience. You can see the FR is not much different from the stock 009 from below, but boy it sounds different indeed. I can hear it's the same driver, but in a much better presentation, no treble hash/fatigue, perhaps a bit forward in the mids but in a nice BBC monitor way. However, I don't know if the 007 housing is the best for the 009 drivers - I would think a bigger wooden enclosure might be even better.
FR
CSD.
Below you can see some slight hash in the upper frequencies, contributes to the perceived forwardness of the sound, but blends well.
Spectrogram (forgive the hash in the left, my measurement error).
This is best when uniform - you can see very few and only slight disruptions. A nice, coherent sound. A bit of forwardness around 500 Hz which might disappear with different pads.
Distortion. No problems here.
Comparison below between my modded 007 Mk1 (yellow), 009 (red) and the "009 drivers in 007 housing" (turquoise). Despite the nearly identical measurements, they sound pretty different.
Comparison below of my stock Stax 009 (red), Phenomenon Libratum 3 with my pads (green) and Focal Utopia (blue), levels set apart for less overlapping.
Despite the similar FR, they sounded quite different again. IMHO the spectrogram gives most intuitive picture about their sound.
You might think the Libratum might sound bright, but not the slightest way - actually the Utopia somehow sounds brighter or harder than both the 009 and Libratum, but that might depend on the amplification as well. Anyway, the Utopia is among the best measuring headphones ever, and that's a good starting point.
My personal favorite remains the Libratum 3 with my pads, but the 007 mk2 drivers in the 009 housing are nearly the same experience, some might like them even more. They both love tube amps, but sounded excellent from the Sirius amp, too.
What I would be really interested in are the 007
Mk1 drivers in the 009 or SR-Omega housing.
.
Thanks
@thinker for these experiments.
A repeated conclusion of mine is that don't overestimate the importance of measurements. One can hear far more differences with a trained ear than with measurements. However, the latter should be good enough - good measurements are a necessary, but not sufficient condition. Sounding good is also a necessary, but not sufficient condition
, but better compromise than the former (looking at you, Stax 009
).
