I measured the Level Ins using a G.R.A.S. Model RA0045 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-Can headphone amplifier. Measurements were calibrated for drum reference point (DRP), roughly the point at the center of the listener’s eardrum (or, in this case, the center of the measurement microphone). I used the Samsungs’ medium-size memory-foam eartip because that’s what fit the RA0045 best. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
The Level Ins’ response clearly shows the cause of the bright tonal balance I heard. The rise in the bass centered at 130Hz is normal, as is the peak centered at 3kHz (if perhaps a tad high), but the relative amount of energy between 5 and 9kHz is extremely high. My guess is that the balanced armature Samsung uses as a tweeter is set for a level about 5dB too high.
Adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amp, usually has a large effect on earphones with balanced armatures. With the Level Ins, the effect is not large in magnitude, but it kicks the treble of an already bright-sounding headphone up another 1.5dB.
The Level Ins’ response is quite similar to that of Sony’s XBA-H1s, which I love so much, except that the Samsungs’ output between 6 and 9kHz is 5 to 10dB higher than the Sonys’. The Audiofly AF140s show more of a “boom’n’sizzle” response than either the Samsung or Sony earphones.
The Level Ins have one of the cleanest spectral-decay plots I’ve seen in any type of headphone or earphone, with near-zero resonance. I redid this measurement three times and got the same result every time; other headphones measured in the same session gave me more typical results.
The Samsungs’ total harmonic distortion (THD) is fairly average at 90dBA: typically, around 1%. But at 100dBA -- a very loud listening level -- the distortion is pretty high, and consistently so through much of the audioband, running 3 to 5% below 2kHz, then rising to 9% in a narrow peak centered on 4kHz.
In this chart, the external noise level is 75dB SPL; the numbers below that indicate the attenuation of outside sounds. The Level Ins’ isolation is very good for universal-fit earphones, reducing noise at 1kHz by about 15dB, and reducing noise by 35dB or more between 2.2 and 11kHz at higher frequencies. Between 5 and 12kHz, the isolation is 5 to 10dB better with the memory-foam tip than with the silicone tip.
The Level Ins’ impedance is low overall, remaining below 10 ohms up to 1.5kHz, but is flatter than usual for earphones with balanced-armature drivers. The impedance phase response is also close to flat.
The sensitivity of the Level Ins, measured with a 1mW signal calculated for the specified 16 ohms impedance, is 98.2dB. That’s enough to get you a reasonable level from a portable audio player, but most of the earphones I measure deliver 6 to 10dB more output from the same signal.
. . . Brent Butterworth