Headphone Reviews

I'm not much of a businessman. (If I were, would I be writing audio reviews for a living?) Still, after years of experience in marketing and advertising, I can't help but admire a good business strategy. That's partly why I like the Harman Kardon NC.

Lots of audio companies would like to take a piece of the business Bose does with its industry-leading QC-15 noise-cancelling headphone. Their strategy for competing with the QC-15? Copy, copy, copy. I like Harman Kardon's strategy better: Try to come up with something that looks cooler and works better.

There's just no arguing that the Harman Kardon NC, while larger than the QC-15, is much more distinctive-looking. The retro rectangular earpieces fit into a springy metal band, and a soft leather headband supports most of the weight of the headphone.

Weirdly, you can't adjust the length of the band as you can with almost all other headphones, but the NC does come with metal bands in two lengths. All of our West Coast headphone testers (including me) looked askance at this when we first saw it, but most of us were surprised to find that it worked quite well-although Lauren Dragan, our only female panelist on the West Coast, found that the NC drooped down on her relatively small head.

The detachable cable connects to a 2.5mm minijack on the left earpiece. There's a noise cancellation on/off switch with an illuminated "NC" that tells you when it's on. Unlike the Bose QC-15, the NC works even when the battery runs down (and as my measurements later showed, its sound quality doesn't change much when the NC is off). Incidentally, the noise cancelling is digital, something we've seen previously only in the Sony MDR-1RNC.

Most noise-cancelling headphones with a rechargeable internal battery charge through a standard micro USB connector. If you lose the cable you can get another at any WalMart or Best Buy or RadioShack. The NC charges through its 2.5mm input using a special 2.5mm phono-to-USB cable; lose it and you'll have to order a replacement. "For me, that's a deal-killer," Geoff Morrison said.

The earpieces fold flat for transportation, but they don't collapse into the band as many do. HK provides a leatherette carrying case that's fairly nice, but it measures about 8.25 by 8.25 by 2 inches; I found it somewhat large to pack into my computer case.

As luck would have it, I had the chance to take the NC not only on my usual trips on Los Angeles public transit, but also on a roundtrip flight from Los Angeles to Tokyo and some random wanderings on the Tokyo subway. I just know some of those Japanese kids wearing Beats (yep, they're big across the Pacific, too) were checking out my 'phones wondering if they were missing out on the next trend.

Halfway 'round the world with HK

After turning down the QC-15s the flight attendant offered me, I settled in for hours of movies and music-and even some sleep, using the NC to isolate me from the plane's cabin noise. Comfort-wise, I found the NC close to the QC-15, enough so that I needed to remote it for an "earlobe break" for only a few minutes every two or three hours.

I noticed right away that the NC has a mellow tonal balance. When I first use an unfamiliar set of headphones, I tend to turn the volume way down because so many of them have a big peak somewhere in the treble that I'll find fatiguing. Not so with the NC. It just sounds smooth, smooth, smooth, no matter what you play. Even Rush's "Red Barchetta"-which is, ya know, pretty trebly-didn't sound as thin as it usually does. It's not like Geddy Lee suddenly sounded like Michael Bublé, but that slight edge that's usually in his voice wasn't there. The bass-which is, ya know, pretty thin in most Rush tunes-was a little pumped-up, with Neil Peart's kick drum sounding more prominent in the mix. The upside was that even after hours of listening, I experienced no ear fatigue at all. I seriously doubt anyone would ever say the NC grates on them.

The cymbals on "Sweet Georgia Bright" from jazz saxophonist Charles Lloyd's Rabo de Nube sounded clear but didn't have a lot of ring to them, and I didn't hear a whole lot of breath and spit in Lloyd's sound. There does seem to be a narrow treble boost somewhere in there, though, because Frank Beard's high hat really stood out in "Chartreuse" from ZZ Top's La Futura.

That's all with the NC on, of course. With noise cancelling off, the sound thins out some; the bass moves to the background and you can hear the details in the mids and treble better. But on the balance, I liked it better with the noise cancelling on, just 'cause of that extra kick in the bass.

Will Huff, one of our other West Coast panelists, totally disagreed with me. With noise cancelling off, he gave the NC five stars. "When I switched the noise cancelling off, Santana's 'BMW' suddenly sounded like I was in a large club sitting second row center," he said. "The sound is accurate in all octaves. I also noticed when I played A Tribe Called Quest that the snare drum really snapped. For me, this is an ideal headphone design. It also feels like a high-quality product."

Although Lauren found the noise cancelling fairly effective, she couldn't come to terms with the NC's bass, which she found "flaccid" with noise cancelling off, and "muddy" with noise cancelling on. I can see her point, although I wonder how the poor fit she got affected the sound she heard.

For my return flight from Tokyo, I snagged a pair of the loaner QC-15s from the flight attendant and compared them with the NC. The noise cancellation wasn't even a close contest-but it never is against the QC-15. The NC nicely reduced the low-frequency drone of the jet engines, but the QC-15 reduced it even more, and also cut out most of the noise from the cabin ventilation system and the other passengers' chatter. I also found that I liked the QC-15's tonal balance a little better. It wasn't a radical difference-after all, no one would describe the QC-15 as bright-sounding-but I did appreciate that extra upper midrange and treble oomph and detail that the QC-15 offered.

Measurements

I measured the performance of the NC 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 correspond well with many of the characteristics our panelists reported. There's a bit of boost in the bass; in the left channel it was centered at 50 Hz in NC mode and 100 Hz with NC off. (Weirdly, I couldn't measure a bass boost in the right channel.) The 3 kHz peak that's present in so many headphones is very narrow here, as I suspected from my listening, and there's an additional treble boost from 5 to 8 kHz. Other than the difference in bass response noted above, there's little difference in measured frequency response whether NC is on or off. 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 has no effect with NC on and no significant effect with NC off.

The spectral decay plot (a new and somewhat experimental feature of our headphone measurements) shows a lot of resonance/ringing in the low frequencies, below 500 Hz, but a clean response above that, with only a few very narrow and probably inaudible resonances.

Isolation is just a little bit impressive even with NC off, at about -18 dB at 1 kHz, dropping as low as -35 dB at higher frequencies. The noise-cancelling function is, again, just a little bit above average, adding an extra -18 dB of isolation at 140 Hz, and delivering significant reduction from 50 to 600 Hz. (A typical noise-cancelling headphone might add -10 dB of isolation between about 100 and 400 Hz.)

The one measurement I found way out of whack with the NC was total harmonic distortion (THD) at 100 dBA. With NC off, THD was extremely low, rising to just 1% at 20 Hz. (Trust a guy who measures subwoofer distortion on a regular basis-you cannot hear that.) But with NC on, the distortion rises abruptly in the bass, typically between 16 and 34%. I redid the measurement a few times, tried both left and right channels, and confirmed with a completely separate measurement session-and as always, I measured the NC at the same time as several other headphones, and none of the others had this problem. It wasn't the measurement gear, either, because I could easily hear the distortion when I did the measurements. However, it's worth noting that I didn't notice this problem at the levels I like to listen at; you'll hear it only in the bass and only at high volume.

Impedance measures dead flat at 41 ohms with NC on, and averages about 36 ohms with NC off. Average sensitivity from 300 Hz to 6 kHz at the rated 32 ohms is 104.9 dB with NC off, 105.5 dB with NC on.

Bottom line

Whether or not the Harman Kardon NC is right for you is very much a matter of taste. Will loved the sound, while I liked it. I preferred the sound of the QC-15, but I've talked with a couple of people who've heard both and prefer the NC. I like the looks of the NC better, but I know some people (Lauren, notably) who find it too bulky. One thing's for sure: You won't see everyone else on the plane wearing the same headphones you are.