Here it is folks. The original PowerPoint presentation:
http://www.juloaudio.sk/Umiestnenie_reprosustav/History of Harman Target Curve.pdf
I believe the green, dotted line on Slide 10 is the ‘pre-preference’ curve.
Comments there reflect those linked to earlier, that Harman is basically:
1 - From 250hz down to 20hz Harman rises by around 6dB, and that should be flat, or at most a more modest +2dB.
2 - Harman's 'peak' at 3-4khz is around 2-2.5dB too low, and remains around 2-2.5dB low for the remainder.
What’s interesting is when we now compare something like that curve with the AKG K371 and something as diverse as the Sennheiser HD600/650 and the Beyerdynamic DT990s.
Leaving aside the heightened treble of the latter for a second. Compared to pre-preference Harman, the AKG is spot on, and the other two bass-lite.
Compared to this pre-preference curve, the AKGs roughly overshoot on bass by around the same amount as the other two come in under (more or less).
This is important for EQ, as the less you have to boost bass, the less distortion you’ll introduce.
Interesting that, even in the 'reference room', which we're sort of using as shorthand for for what it
should sound like, listeners preferred more bass.
Also interesting (though we knew this before), older, more experienced listeners didn't want as much extra bass, and older listeners wanted a little more treble.
On their own, those factors are all interesting. Added together, we suddenly get a much broader picture of what's going on.
What I take from all this is that (a) Harman has too much bass, though how much too much is open to debate, and (b) if you're older (I'm 56) you might need a little more treble than Harman; this isn't a 'preference', it's down to natural degradation of high end frequency hearing over time.