Phiaton PS 200 in-ear headphones Measurements
Deciding what is the optimal frequency response for a pair of headphones is neither obvious nor trivial (see www.stereophile.com/features/808head), compounded by the fact that I don't have a microphone small enough to be inserted in my ears. The only measurement I perform on headphones, therefore, is of their electrical impedance, to determine how difficult they are to drive. To take these readings, I inserted each set of 'phones in my ears.
The Phiaton PS 200's impedance and electrical phase are shown in fig.1. The impedance meets the 39-ohm specification at 700Hz, but drops to 28 ohms in the lower midrange and bass, with another minimum of 20 ohms between 7 and 8kHz. The rise to 88 ohms just below 2kHz will make the Phiatons sound a little forward in the upper midrange with headphone amplifiers having a high output impedance.John Atkinson
Fig.1 Phiaton PS 200, electrical impedance (solid) and phase (dashed). (10 ohms/vertical div.)