Hi folks, as some of you might know from reading this thread, Oratory has measured my unit of HD560s that I sent him....he's done many different measurements on them and also provided commentary and explanations on each of the graphs he sent me, I asked him if I could cut & paste his words as well as show the graphs he sent me, and he's totally fine with that, some of this is quite educational generally as well, following is Oratory's measurements & words (cut & pasted):
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Pretty good (low) unit variation on this one.
I have measured the HD560S before, but that one had one of the earcups perform significantly different than the other (much more energy at 1-3 kHz).
Your unit (#0141) performs basically identical to the well-performing earcup of the first unit I measured.
I couldn't get the same performance in the bass in all measurements, which is likely caused by seal. I did verify that by doing one measurement on the 43AG (which has a flat cheek), where it performed just as expected. The other measurements are done on the 45BC, where not all headphones get a good seal.
For the EQ settings I used the low-frequency performance as measured on the 43AC, which is closer to what we hear when wearing them on a human head (where the headphones seal more easily due to the flexible skin).
Channel Matching on your Headphone:
Sensitivity Measurement:
This shows how the SPL increases at increasing signal voltage. From this we can very accurately calculate the sensitivity. You'll notice that for very low frequencies, the measured frequency response starts to become slightly different at very high signal levels, that's because the driver can't reach the full excursion anymore and starts saturating/distorting. Remember though that this only happens at very high signal levels. Not a big problem.
All Measured Frequency Response as an Overlay:
this shows how much power compression is happening: at 20 Hz the SPL is about 2 dB lower than expected when the headphone is playing at full power (>113 dB).
I did measure the headphone up to 1.75 Vrms / 2.5 Vp (25 mW).
For a more detailed view:
Here's the measured SPL at 100 Hz over different input levels . When we scale the voltage-axis logarithmically, we get a linear curve. That's the "characteristic curve" ("how much output at a given input").
At 20 Hz, the characteristic curve starts to become nonlinear:
The power compression itself ("SPL being lower than expected") isn't audible, but what could be audible is the effects of that: The power compression necessarily causes harmonic distortion (because the characteristic curve is nonlinear).
So if we look at THD at different voltage levels, we see that for very high levels (equivalent to 113 dB at 1 kHz) we see 5% THD at 20 Hz:
A more intuitive view is to plot the THD-axis logarithmically:
There we see that the THD rises by a fixed amount depending on the input voltage, as we would expect from a system like that.
All of that is interesting to look at of course, but it is of no big concern when actually listening.
The biggest issues of the HD560S are the treble peaks at 4-6 kHz. The rest is fine actually.
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This is me talking now, Rob....so that's some pretty comprehensive testing there by Oratory & some good explanations/commentary. It looks like good channel matching for this unit and also very low distortion, I'll have a look now at some comparisons re distortion against other headphones to put it into some context & edit this post in a short while....
EDIT:
re putting distortion measurements into context, better distortion measurements than the planar headphone DCA Aeon RT closed back:
better than another planar headphone the Hifiman Sundara:
better than another planar headphone, the Hifiman Ananda:
better in the mids & treble than the much lauded (deservedly) & expensive planar headphone Hifiman HE6se, not better in the bass though:
better than the HD600:
better than the planar Hifiman Arya:
better than the deservedly well-lauded Sennheiser HD800s dynamic driver headphone:
Ok, ok, I'm not gonna keep posting graphs, because that's enough comparisons. I will say that distortion is one of the lesser important headphone variables in my experience, which is how my K702 can be my joint favourite headphones whilst still having relatively high measured distortion, so I'm not a "low distortion headphone nut" because distortion level doesn't equal my preference for my headphones, but I think it's interesting to compare headphone distortion measurements, and if all else is equal it's better to choose a lower distortion headphone.
EDIT#2: it's possible the smoothing levels are different between Amir & Oratory for their distortion graphs, which might iron down some sharp peaks in Oratory's, but I don't know....general trends will still be the same though.
EDIT#3: Oratory let me know he uses 1/24th smoothing which wouldn't remove any important peaks in the measurements, so they are comparable with Amir's results re distortion measurements, the following is what Oratory said cut & pasted:
"....for the record, I used 1/24 smoothing, which is very little smoothing.
The only thing it does is smooth out the noise artifacts that arise from the measurement method.
Less smoothing (or no smoothing) would not reveal anything about the device under test (=the headphone), only about the measurement method / the calculations done after the measurement (mostly the windowing and sweep length)"
