Foldable, closed-back professional headphones featuring natural surround sound and aluminum nameplates.

The Ultrasone package is pleasing. You get a little multilingual paper manual that covers various Ultrasone models (the English portions of the manual suffer quite badly from the English As She Is Spoke Effect), an audio CD full of demo tracks, and a neat-o drawstring bag to tote your ´phones around in. The bag´s thin and unpadded, but it´ll stop the headphones from catching on things, which should be all you need.

To fit into that bag, the HFI-550s fold up, like so. This kind of fold also lets you flip one of the earpieces around so the pad sits on your head above your ear, for one-sided I´m A DJ moments. The earpieces can also fold 90 degrees forward, so you can lay the ´phones down flat, or hang them on a small wall hook.

You also, as is normal for quality headphones these days, get a cable that terminates in a 1/8th inch plug, and a 1/4 inch adapter that screws onto the end of that cable. If you manage to lose the adapter anyway, you can use an ordinary un-threaded one. You just won´t feel as special.

The nominal impedance of the 550s is 64 ohms, with a 100dB efficiency rating, so they should play at decent volume from pretty much anything, including little portable players.

Fancy features

Ultrasone´s headphones have two Unique Selling Points - S-Logic and low electromagnetic emissions.

S-Logic is supposed to give you a wide, spacious, un-headphone-like sound field, by using "decentralised" transducers. In English, that means the little drivers that turn electricity into sound aren´t mounted in the middle of the earpiece.

Ultrasone also claim that the offset driver helps to protect your hearing, by generating "the same perceived volume at a reduction of 3dB over comparable headphones from other manufacturers". Less sound pressure level (SPL) at the eardrum, less damage to your hearing from a given volume level.

But, uh, loudness of sound is, um, defined by the SPL at the eardrum. A better-aimed transducer might give higher eardrum volume from a given amount of energy radiated from the transducer in the headphone ear-cup, but that´s not going to protect your hearing.

Ultrasone´s in-house scientician does have some downloadable reports here; only two are in English. One of those (PDF here) has a lot to say about how the author established in-head magnetic flux from headphones to be higher than that recommended in the TCO ´99spec for monitors, but since the TCO limits were basically just picked out of the air in the first place, I find myself strangely unmoved. Ultrasone say that an audio frequency magnetic field of 1000 nanotesla (nT) is cause for alarm; for some reason, though, the static 30,000 to 60,000 nT magnetic field of the planet is not.

The titles of Ultrasone´s German-language papers don´t appear to have anything to do with their S-Logic ear protecting SPL claim, either; the only remaining paper (PDF) talks about measuring outer-ear-mediated frequency response from different headphone configurations, but if there was a hearing-protection-related conclusion in there, I missed it.

Inside

The HFI-550 earpads use the common edge-slot mounting method, which makes them easier to remove than to replace. They´re loose enough that you can get ´em back on without too much use of your profanity allowance, though.

Looking at the earpiece plate, above, you can see the off-centre grille of the S-Logic system. The driver itself, however, is not obviously offset...

...and unscrewing the plate confirms it. This driver is, actually, exactly in the middle of the earpiece, just like the drivers in every other ordinary headphone, as far as I can see. The middle of the driver´s about 30mm from each of the three screw holes, and it´s mounted dead flat, too. It´s only the grille that´s offset.

The ear-cups have an interesting pseudo-bass-reflex sort of arrangement, with one little port in the back of the driver assembly, that leads around through the ear cup into the cushion area. I presume this has something to do with the headphones´ bass tuning.

The cable for the HFI-550s, by the way, is soldered to a little distribution circuit board in the left earpiece. Anybody with slight soldering iron chops will be able to replace it, if necessary, but it´s not a neat-o plug-in job like some headphones offer these days.

Listening

Surround sound and radiation balderdash aside, the HFI-550s sound good. Very good. Not incredible and amazing and life-changing, but certainly better than most sealed headphones I´ve auditioned.

And yes, they have what you might call, um, prominent bass, but not of the buzzy muddy one-note cheap-midi-system variety. In most of my test tracks, I didn´t object to the 550s´ bass emphasis at all; in a couple of chamber music pieces they pushed the double bass further forward in the mix than it should have been, but it wasn´t obnoxious, and their performance for various other stuff, including classical music, was perfectly fine.

And, um, solid. If you want your trance, organ music or death metal to sound as if a tiny PA system complete with Wall-O-Subs has been set up in your head, but without some kid on the mixing desk pushing the bottom ten EQ sliders to max, then these headphones will do the job for you.

They keep it together at high volume, too. Like all proper monitor/DJ headphones, the 550s can play loud without the bass breaking up the treble.

This doesn´t mean it´s a good idea to wind everything up to eleven, of course; listening at headache level and beyond for any length of time is definitely bad for your ears, and sealed ´phones like the 550s make it easier to listen at lower levels, by blocking outside noise.

As for the whole S-Logic thing - yes, these headphones do sound a bit "wider" than various others I´ve tried. The sound´s less surround than just slightly behind you, though, to my ears.

The crossfeed switch on my Total BitHead moves the soundstage in and forward a bit, as usual, and that´s a blessing when you´re listening to very stereo stuff. I´ve auditioned the HFI-550s for a while now and haven´t gotten sick of the S-Logic effect, though; for most program material, including spacy stuff, I think these headphones will be fine from an ordinary un-crossfed headphone output.

HeadRoom´s opinion of the HFI-550s´ frequency response is that there isn´t actually much bass boost at all. A little civilised hump around 60Hz (the location of most popular music bass drums), and useful response below 40Hz, though not down to the 10Hz that Ultrasone claim. Audacious extension of the quoted frequency response down to the -50dB point is, unfortunately, common even among reputable headphone manufacturers; all such specs should be taken with a large grain of salt.

HeadRoom also, like me, think that the 550s´ isolation (outside noise blocking) is pretty much on par for decently comfortable sealed headphones of this sort - the graph more or less lines up with that of Sennheiser´s HD 280s, for instance. The 550s are also very quiet when the ear-cups are pressed together; this matters for people who want to use them in a studio. The abovementioned AKGs are even quieter, but they cheat with a little switch that turns them off altogether when you remove them.

Oh - Ultrasone´s 20-track demo CD is worth a listen, too. It contains a bunch of well recorded music tracks of various types, plus some FX like applause, waves lapping a beach, fireworks, birdsong and so on. Some, if not all, of the tracks seem to have been recorded with a binaural microphone and minimally produced, which makes them ideal headphone-test material; there´s a bit of clipping in a couple of them, but overall the sound quality´s excellent.

Almost all of the musical pieces are just excerpts - the first couple of minutes of a jazz track, the end bit of the Pathétique, and so on. There´s a quite meaty pipe organ rendition of the famous opening passage of Thus Spake Zarathustra with bass-pipe rumble at beginning and end, though.

There´s a track listing for the demo disc on the back of the instruction manual, by the way. There´s also some minimally comprehensible Germanic CD-Text for each track.

Overall

The HFI-550s are, I´m happy to say, excellent headphones for the money. I´m not as impressed with Ultrasone´s weird marketing strategies for them, but since the S-Logic and magnetic shielding doesn´t jack the price up much, I say live and let live.

Ultrasone make "Proline" versions of many of their headphones, including the 550s, which include heavier magnetic shielding. I wouldn´t pay extra for that, personally. Fortunately, the pro versions also include plug-in cables (they come with a straight cord and a curly one - nice!), larger ear-pads (in the case of the 550s, anyway), and a couple of spare ear-pads too, which goes some way to justifying their higher price tag

I´d really like a plug-in cable on the HFI-550s, but you can´t have everything; the cable they come with looks tough enough to last for years of rough treatment, everything else about them looks pretty robust too, and they really do sound very good for the price.

Relatively civilised bass enthusiasts should definitely put the 550s on their shortlist, but you don´t need to be a boom-hound to like them.

Highly recommended.