Headphone Reviews

Sound Quality
I know Philips wants to call this an audiophile headphone, but it's not. At least not in that it's neutral. The X1 has a lovely warm tilt. It will however put a big smile on the face of an audiophile when in the mood for a fun listening session. Bassheads will melt in their own pool of love for the X1; it's a great basshead can.

Most big-bass headphones have problems with their coloration. Add a bunch of bass, and the stuff in the mid-range often suffers from lack of attention. Even the V-Moda M-100---a basshead can I really like---has dips and peaks in its frequency response that let some things get lost in translation. Most basshead cans are sealed, which allows designers to get good extension into the low frequencies, but sealed cans sound closed-in and usually lack the airy, spacious sound of open headphones. The Philips Fidelio X1 doesn't seem to suffer from these problems.

Listening to the X1 is almost overwhelmingly fun. The bass is big, and though a tad loose down real low, is marvelously musical...maybe because it so seamlessly transitions into a remarkably present and even mid-range...and then into a into a treble response that, while a tad artificial sounding, is neither to bright or too dark, and (wonder of wonders) delivers a surprisingly good image. I'm telling you, I don't think I've ever heard a headphone quite like this: A big-bass headphone with good dynamics, and even response across the board with airy spaciousness. Bloody amazing!

I think I should elaborate just a bit on the two flaws I heard, the slightly loose bass, and slightly artificial treble. Having an open design means you're sort of stuck with having the bass roll-off as it goes below the primary resonance of the driver; in this case that's at about 70Hz. Below that you not only loose level but also suffer some phase shifting. Add that to the high resistance of the stock cable and a few Ohms of output impedance from the amp and you end up with a slightly soft sub-bass attack. I'll mention however that the response at 70Hz is 10dB higher than at 1kHz, and the response at 25Hz is at the same level as 1kHz, so there's plenty of low frequency energy...plenty. (Remember to replace that cable and get a low output impedance amplifier for best results.)

The treble with these cans has me a bit baffled. In some ways it's just a bit gritty sounding, cymbals and brushes on drums are just a tad edgier than natural. On the other hand, the imaging is quite good, and an open sense of space is apparent; these things usually require pretty good treble response.

I'm gonna do something I don't normally do, and post the frequency response plot here because I think it tells the story quite well.

In the compensated plot above (blue and red), though having a warm tilt, the frequency response from 70Hz to about 6kHz is almost a straight line! Now there's reasons to think the frequency response compensation I use isn't quite correct, and a straight line might not be optimal, but that curve looks pretty darn good to me. Moreover, that's what these cans sound like: A hearty warm tilt, but otherwise very well behaved.

Summary
Hell yeah I'm gonna recommend the Philips Fidelio X1! While their big bass and warm sound will keep me from calling them an audiophile headphone, it won't keep me from calling them fun. I'd bet any headphone audiophile that's into a bit of Electronic Dance Music, DnB, Ambient, Hip-Hop, and the like will find themselves grabbing these cans when the thumping tunes are in the mix.

The Philips Fidelio X1 has the uncanny ability to be both a big bass headphone and deliver an airy spacious sound. I've simply never heard that before in a headphone, and now that I have, I'm hooked. Yup, these are going on the Wall of Fame as the best open basshead headphones I've heard to date.

Resources
Philips USA home page and Fidelio X1 product page.
Head-Fi Philips Fidelio X1 appreciation thread.