Until a couple of years ago, I did nearly all my mixing using headphones. My reason for this approach was almost entirely economics-driven; usually one to maximize the bang/buck equation, I, like many budget home-recordists, determined that it made more sense to use a really good pair of 'phones than to compromise with a merely decent pair of monitors. Also, I have always used headphones for tracking and a good deal for pleasure listening too, so getting something durable, comfortable, and great-sounding seemed to suit my multitude of needs. When I discovered the Sony MDR-7506, I found what I'd been looking for: a rugged, comfy set of cans with plenty of punch, detail, and realism. And terrific bass definition-head and shoulders above the bloated boom of most consumer noggin- blasters. $99 bucks from a certain megachain music-gear retailer, and I had what would be my most trusted listening reference for years.
As I say, my approach has changed in more recent times. I use monitors frequently these days, and I now have access to a good deal of fantastic gear including a variety of high-quality, less budget-oriented headphones. Nonetheless, the Sonys have remained a go-to pair.
After first having acclimated to the terrific performance of the Sonys, I must say hearing Sennheiser's HD-600 'phones became another revelatory peak along my sonic journey. Their sound is sublime with an awe-inspiring, almost ethereal quality. The frequency-separation is fantastic with huge sense of "space" in the sound field. There is a palpable sense of "air" in the imaging that's unlike the "hermetically-sealed" feeling that most headphones deliver. A more speaker-like sound, you might say. And though they are extremely dimensional and detailed, they're way smooth. "If the Sonys are Jack Daniel's," I recall thinking, "these are Maker's Mark." Yum.
I figured that this would be cinch as my new reference can. But in using the HD-600 for recording projects, I realized that for all their delicious wow factor, they have use-specific weaknesses. First, because they are just so damn pleasant to listen to, certain frequencies that might ordinarily sound harsh or hard (particularly upper- mids and highs) are often smoothed out. That's great on a nearly or completely-finished mix, as it makes repeated listens possible without the fatigue that will eventually push you away from even the best music. But if you're not hearing that stuff from the beginning, you could be making it harder on yourself-and the ultimate listener-in the end.
Also, because there is a slightly laid-back quality to the 600's, one may be tempted to dial in a more aggressive sound (or play more aggressively, if using them for tracking) to achieve a more lively sense of dynamic energy. As a result, what may have sounded perfectly nuanced in the studio, might seem a bit ham- fisted in the real world.
And while I like the bass response of the 600's (round, well-situated in the overall balance) I realized that, with them, I don't tend to get the attack of the note the way I like to hear it. As a result, I've often over- used compression and EQ to compensate for the perceived deficiency, and I'm left with a low-end snarl I didn't quite intend.
So what about the new Sennheiser HD-650? When the hi-fi shop I manage ordered the new model, I decided it was time to revisit this series of headphone for Pro Audio applications. After requisite break-in, I put the spurs to the HD-650. My first impression was that this is definitely a more aggressive sound. The bass that sometimes feels a bit polite in the 600's, is definitely more forward and alive here. In addition, there seems to be a boost in the upper region of the lows-about 40 Hz, I would guess. The specs on these say that bass extension now descends to a staggering 10 Hz-as opposed to the 600's alleged 12 Hz. To be frank, I am always a little leery of such extraordinary claims, and the truth is few but a handful of genetic freaks will ever really be able to confirm the veracity of such a statement, as human hearing simply doesn't travel that far south. But there is something to be said for the girth and low-end authority that some subharmonics convey, and my sense is that the HD-650 reproduces these as well as any headphone I've heard.
Apparently, the upper-mids also have gotten a bit of a shove and the result is a sensation that things like horns, voices (particularly female), and electric guitar are "closer" and more immediate-sounding. I perceived the treble region to be a bit less refined and sparkling than the 600, but perhaps this is the result of the change in overall frequency balance.
In somewhat limited use, I have found that some of the mixing problems I've encountered with the 600 have been ameliorated with the new HD-650. For the reasons I've suggested, I find the HD-650 to be more useful as a recordist, and I suspect that others will also. And for tracking, I suspect that players, drummers in particular, will love the HD-650's ability to cut through and give a vivid picture of the other instrumentation despite the sound of their own performance. That is, as long as they're well isolated. Because the design of the HD-650 (like its predecessor) is of the over-the-ear "open-aire" variety-which allows for much of the spacious character of its sound-there is a far greater tendency for outside sound to bleed into the user's ear.
Ironically, perhaps the greatest strength of the 600-its supremely luxuriant listenability-has been diminished somewhat with the HD-650. The new 'phone, with its more muscular sound, may be more compelling and involving for limited blasts, but is ultimately more fatiguing than the old version. (Though the pillow-soft velour earcup retains its perfect firm/soft balance.) This said, the HD-650 is still far easier and more enjoyable to pull long hours with than the vast majority of headphones.
And the HD-650 don't come cheap. With a street price of $400-$450-approx. $100 more than the previous version-this is a luxury item for many. A huge upgrade over the HD-600? Perhaps not, but this is surely a world-class set of cans-one that maintains the essential character of a legendary staple while pushing new boundaries on fronts specifically relevant to recordists. So, if you've got the Benjamins, the Sennheiser HD-650 might be precisely the headphone you've been looking for.