How does the Momentum sound? Right off the bat, I can say that it sounds great for a closed, sealed design - remember that I have the open HD 600 and HD 595 in my arsenal. It doesn't have the soaring highs that an open design will have. However, it does have a very warm, very natural sound. No frequencies felt exaggerated. The bass had a depth and impact that stayed controlled and was never pumped up and in your face. The midrange is where the headphone shines with detail and clarity, although the upper treble is a bit pulled-back.

I listened to the Momentum with the new releases from The Civil Wars self-titled second album. "Dust to Dust" is a simple, beautiful ballad from the duo, and the Momentum lets every detail shine through. It's not just the clear treble in Joy Williams' voice, but the clarity of the reverb used on her vocals. Fans of the duo have complained that John Paul White's voice is too subdued compared to Williams', and I have to agree. Even with the slightly veiled high-end of the Momentum, I wanted to hear more of his midrange vocals.The subtle kick-drum sound and the lower register of the acoustic piano showcase the natural and accurate sound of the Momentum. The simple bass line was just wonderful - full and rich, but never overpowering.

The other recent release from The Civil Wars  is "The One That Got Away." Williams' voice soars above White's, but again, the detailed accuracy of the Momentum brings out things like the subtle twang of the mandolin, nicely differentiated from the dobro. The spaces between the words in the chorus, when the instrumentation stops to let the notes ring out really showcases the quality of the Momentum.  

S+V contributor Ken Pohlmann also listened to the Momentum and had similar comments. He typically prefers a warm, dark sound, so the Momentums were just up his alley, although he felt the treble was a little too pulled back and subtle. He noted, "Their dark sound was immediately comfortable, but unfortunately it was just too dark. If they pushed the upper mid, high end forward a bit, this could be my new fav headphone."

The quoted numbers: The Momentum has a frequency response listed at 16 Hz - 22,000 Hz and the impedance is 18 ohms. Total harmonic distortion (1kHz, 100 dB SPL) is less than 0.5% and the SPL is 110 dB. Brent Butterworth's measurements are below.

Measurements

I measured the performance of the Momentum using a G.R.A.S. 43AG ear/cheek simulator, a Clio 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 ear reference point (ERP), roughly the point in space where your palm intersects with the axis of your ear canal when you press your hand against your ear. I experimented with the position of the earpads by moving them around slightly on the ear/cheek simulator, and settled on the positions that gave the best bass response and the most characteristic result overall.

The frequency response measurements are pretty much textbook, with a broad bass boost, another boost centered at 3 kHz, and a somewhat stronger than usual boost between 7 and 9 kHz. Adding 70 ohms output impedance to the V-Can's 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp boosts bass by about +0.5 dB.

Total harmonic distortion (THD) at 100 dBA is very low at frequencies higher than 200 Hz, but it rises to 3% at 100 Hz and 12% at 20 Hz. The latter sounds like a big number, but it's at a very high listening level and a very low frequency, so if you do hear it, you won't hear if often.

Isolation is typical, maybe just a hair better than average, for an over-ear passive headphone. Impedance averages about 22 ohms. Average sensitivity from 300 Hz to 6 kHz, calculated for 18 ohms rated impedance is 100.7 dB.  -Brent Butterworth

Bottom Line

In conclusion, the Momentum are a great-sounding over-ear, closed back headphone. While they lack the "airiness" of an open design, the closed system will prevent listeners from annoying everyone around them. The over-ear design also helps block out ambient noise without adding any of the artifacts sometimes introduced by active noise-cancelling headphones. The Momentum looks terrific, and feel fabulous after many hours of listening. For serious listeners with an adult sense of style, these can't be beat. Pun intended.