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Quote:
arnaud - thanks for the observations, much appreciated.
However, the potential measurement artifact to which I'm referring is the dip at 8.8KHz (not the bump at ~11KHz) because 8.8KHz appears to be the only freq at which the new LCD-3 displays less freq response than the original LCD-3.
Just asking - 'cause it would be great to have a better understanding of what's going on from an empirical perspective.
On the subjective side; the music I'm listening to with the new LCD-3 sounds sublime, and I'm a totally happy camper with the outcome.
Yes, this one is likely extremely sensitive to the measurement. It's a zone of zero pressure AT the microphone location, it would probably dip down by more than 10dB if this graph wasn't frequency averaged. Resit the headhone very slightly and it will be gone. The other thing is that you should be more concerned about the broad peaks than narrow dips, c.f. Purrin's numerous posts, so I actually don't even "see" these dips when I look at a curve.
Quote:
The reduction is damping is likely resulting in an increase in the efficiency of the headphone. We should be normalizing the curves by loudness (e.g. perceived volume) when comparing headphone responses, rather than normalizing by the response at 1kHz or 250Hz or some other arbitrary value.
I am not sure where the damping came from but it seems like orthos response drastically to resistive screens placed in front of or behind the driver. What there is little to debate about is that, regardless of the severe frequency smoothing, the "new" LCD3 is much less damped than the previous one, e.g. the resonances are much more visible while the green curve is quite smooth. In this frequency range (above 5kHz), a felt material could both affect the effective mechanical damping of the driver as well as acoustic damping in the chamber.
As to how felt affects the response of orthos in general, I don't have your first hand experience and can't comment. But, unless you always use the same felt material, I would be hard pressed to make generic comments about how the results will turn out given there is such a range of variation for felt / resistive screens properties (e.g. huge changes in flow resistivity, porosity etc. based on the density of the material, size the of the fibers and how packed they are, presence of glue to make the screen almost impervious...).
