World's best dynamic headphones?
Live long enough in America. You'll risk terminal immunity to hyperbole. For example, cross the remote Sonoran desert and stop at any crummy no-man's diner for some greasy chow. You're liable to order the World's Best chili con carne with corn bread. Or, drive through Northern California and its Garlic Capital of the World. Going an illegal 70mph, you probably missed this wonder because it took all of 10 seconds to pass through. So much for absolutes.
But boy do the AKG K-1000s ever compel the question of World' Best. You wonder whether, for anything approaching sane dough versus fanatical excess, something better exists, somewhere, somehow. No credible reviewer should pretend to know for sure. Still, with the wooden Sony MDR-R10 discontinued and the Grado RS-1 and Sennheiser HD-600 in-house for direct comparison -- generally regarded as the two best currently available dynamic headphones in the money-matters arena -- I could make a reasonably educated guess.
How trustworthy are memories?
I first chanced upon the AKGs during the Tigris' ascendancy at Mesa Engineering. I needed to demonstrate the integrated's tubular headphone output with some world-class cans at CES. I wanted something to attract showgoers already on looks and rarity. The K-1000s fit the bill to a dime.
Darn, I shoulda read the specs before ordering up though. At 74dB/mW free field sensitivity, the K-1000s need far more juice than regular headphone sockets provide. They are fitted with a 4-pin XLR connected tail that terminates in four high-level amplifier leads. This scheme didn't gel with my -- carefully -- hatched plans.
And while I drooled over the sound via the amp's speaker terminals, disconnecting the speaker leads each time I wanted to demonstrate headphones was out. Hence CES came and went and the AKGs returned to their maker. I stuck with my wooden Grados and loved them faithfully ever since. Still, I never forgot the K-1000's phenomenal performance. Nor their $1,200 sticker shock.
Years passed. My hair turned gray. My hearing declined. I grabbed the only job left under these desperate circumstances - audio reviewing. More years passed. All my sane friends left. I turned lonely (loony?) and relocated to 6moons.
Then headphone maniac Tyll Hertsens of HeadRoom promised to enter my crater-ridden but rarefied low-G domicile. He suggested a Maxed-Out Home amp and Senn 600s for the occasion. A quick perusal of his site and -- Eureka! -- I ran into my old flame, the K-1000s. Priced at 529 smackers? A flummoxed call confirmed that this wasn't a typo or short-term inventory dump. It's a new, radical and standing arrangement with the supplier. Not what passage of time and inflation usually implies.
Aural fantasies of past lusty transgressions die hard. Could he include a pair with his shipment? Affirmative. Would the past-meets-now encounter equalize expectations? $529 puts the K-1000s center of the range between the Senn's $449 and Grado's $695. It would make for a reasonably balanced peaches vs. peaches comparison (hey, none of these are garden-variety apples or oranges - by a long shot).
To level the playing field, I asked HeadRoom to fabricate a replacement tail for the AKGs with a standard 1/4" plug. I had been promised a review Portal Audio Panache Integrated whose headphone socket -- with the Ks' 120 ohm impedance -- is said to output approximately 8 watts. I had already driven the Ks speaker-level on my 6wpc Art Audio PX-25. Its optional attenuator cranked open less than half gave me all the loudness I could stomach. This suggested that despite very low sensitivity -- and Tyll's skepticism that even 8 watts would be sufficient -- perhaps less power was required than seemed mandatory.
Being a good sport, Tyll sent out the adapter tail. The Panache hadn't arrived yet so I plugged the new tail's 1/4" jack into Tyll's Maxed-Out Home. I fully expected a load of hot air and not much else. Wrong! Granted, I had to open the attenuator to between 4 and 6 o'clock, i.e. run the amp nearly or all the way open. But even on classical CDs with extreme dynamic range -- i.e. mid-levels recorded abnormally low -- I never was deaf enough to require or want volume levels in excess of what the Maxed-Out's times six voltage gain could deliver.
To boot, I had the PX-25 and 120/360wpc Bel Canto eVo 200.4 to ascertain by comparison whether added power delivery impacted dynamics, resolution, frequency extremes and intelligibility. I was all set to use the AKGs in a variety of contexts. Afterwards, I could do an even-steven comparo between three headphones driven from the same set of electronics despite a potential handicap for the Ks.
Ear speakers, not headphones
Even beyond the famed Stax electrostats that pioneered the term, the K-1000s are earspeakers, not headphones. The wire-mesh protected transducer panels are 2.5" wide x 4.25" high x 1" thick. They're hinge-mounted to the front of the crossbraces that hold the contact pads and connect the two red metal frames on each side. The rear contact pad is mounted to a slider that allows width adjustment for the most comfortable head fitting.
Because the transducers are of the open-air design and not clamped to or sealed around the ear, the only points of physical contact are your temples right above the ears, and the self-adjusting head band across the skull. The pivot for each speaker is upfront. Once you release the lock, each panel can be rotated outwards to either parallel your ears -- which in front are closer to the skull but splay outwards toward the back -- or create additional airspace such that each ear perceives yet further cross-channel data. Think of speakers-en-miniature floating in front of your ears like the Jecklin Floats of yore - but now toe-in's adjustable just like with "real" speakers.
Why did AKG's engineers bother? Because they wanted to enhance binaural hearing qualities. Just as with conventional speakers, this natural process of human hearing (duplicated in our binocular vision) relies on each ear receiving the same two channel information.
This parallax delivery is time-delayed due to the closer ear receiving the information first. The time arrival differential is what the brain processes to allocate the diverse apparent sound sources their specific positions within a three-dimensional sound stage.
When listening to normally encoded material, conventional headphones impose an unnaturally hard left/right/center-of-the-head effect. Each ear only processes single-channel data. The right ear does not hear what the left one hears, nor vice versa.
HeadRoom's well-known but proprietary crossfeed algorithm addresses this dilemma in the electronic, AKG's engineers in the acoustical domain. The penalties for eschewing electronic compensation is sound leakage (since this couldn't be a sealed design - if total privacy is a must, forget it); and low sensitivity because the free-air driver deals with far greater air mass than is trapped within your ear canal by conventional ear-hugging approaches. We'll soon get to the very real advantages of AKG's crafty acoustical solution.
But first, a few final specs: Weight is <10 oz or 270 grams; total length of the very flexible wire lead (the captured plus the XLR-connected half with the binding posts pigtails) is a generous 13 feet; rated impedance is 120 ohms; frequency response (as per a graph in the five-lingual manual) is 50Hz to 20KHz essentially flat within an enviably tight -2dB overall window, and -4dB @ 40Hz, -8dB @ 30Hz, and -20dB @ 20Hz.
As common sense predicts and these measurement confirm, free-air dispersion causes more rapid rolloff in the bottom octave than equivalent sealed designs. Another unusual element is the "ventilated linear dynamic" radial NdFe magnet yoke engineered for "minimum aspect ration and maximum flux density". The size of the dome driver appears to be 1 inch, with a composite diaphragm of elastic intermediate layers finished with a 16th century violin varnish to suppress ultrasonic ringing.
Fit'n'finish and wear comfort are of the highest pedigree - think famed Teutonic luxury cars. No undue pressure exertion onto the head. Precision-engineered hardware tolerances. Zero chintz in sight. Shipped in a wooden box with serial number, comprehensive owner's manual and clear hookup instructions. In short, what you'd expect in a $1,200 headphone system.
At $529 however, it makes the now-closely priced HD-600 Sennheiser's marbled hard-plastic construction a bit less, ahem, classy. Admittedly, that's a "superficial" appearance comment, to be filed in the pride-of-ownership lower drawer. But for some, it might belong into one of the upper drawers when it comes to spending serious bread on headphones - more on that later.
Make no mistake then - even before being hooked up, the K-1000s already strike one as veritable class acts, samples of superior engineering with bespoke attention to every conceivable detail. All of which amounts to naught if the ears didn't pleasurably curl up. Not to worry ...
Setup
I connected the HeadRoom amp to the tape-outs of my Bel Canto PRe1. Then I wired the speaker lead tail of the AKGs to the Art Audio PX-25. By muting the PRe1, I could cut signal to the tube amp when unplugging the AKG's captive tail from its other half - most SET output transformers smoke under signal without driving a load. No need to risk frying my reference amp. However, the PRe1's tape-outs would still pass signal. By simply hitting mute and swapping leads, I could toggle to the Maxed-Out Home and sample the K-1000s to compare against the tube feed, then adjust volume and compare to the Sennheisers and Grados.
The Max really came to life when I bypassed the attenuator of the Birdland Audio Odeon-AG DAC for its undiluted full bore 2.7V RMS output (7.68V peak-to-peak). When not used amplifier-direct but into a preamp, the manufacturer recommends the Odeon's 3 o'clock attenuator setting. It gives a slightly lower-than CD standard 1.5V RMS output and optimizes impedance for preamp connection. Though the Max retained sufficient output in this mode, the sound became somewhat thin. Feeding it a stronger signal -- and reducing its attenuator setting instead -- significantly fleshed out the music.
The biggest difference between either hookup? Via the Max, things sounded zippier, brighter, with a mild prominence in the upper midrange and sharper, more highlighted outlines 'round performers. With edgier material, this could turn slightly aggressive. The PX-25 packed harmonic meat on those bleached bones. The presentation became far more relaxed and full-bodied. Any former tendencies for some potential stridency sneaking in were abolished.
Did the AKGs favor tubes as a matter of tonal synergy? Did the Max not possess enough raw drive and thus somehow skew tonal balance? Did it curtail extension at the extremes to emphasize the upper midrange for this whitish leanness?
Yes and no. Substituting the Bel Canto eVo opened up extension in either direction. More drive, more linearity. But by comparison to the PX-25, it still sounded a mite like hornspeakers driven by regular solid-state: Very dynamic, very fast, but somewhat upfront. Eventually, it could get just a bit relentless.
My Avantgarde DUOs absolutely thrive on tubes, and, truth be told, so do the AKGs - at least with the immediate solid-state on hand. With the PX-25, I cherished bona fide Avantgarde performance sans massive horns.
There was their raw sense of startling immediacy as though sounds coupled to the air more directly than via conventional schemes; the superior speed and startling dynamic swings; phenomenal openness; and palpable image density that filled out sonic outlines with bursting color and vibrancy.
I need six ears!  AKGs plugged into PX-25 speaker-level; separate feed into Maxed-Out Home;
second 1/4" input for either Sennheiser
SD-600 or Grado RS-1 |
发表于 2011-3-9 11:23:21
楼主
In this drawing from the owner's manual, you can appreciate the intricate super structure that positions the transducer center of the frame, and also make out the radial magnet sections that power it.
The 4-pin XLR juncture with speaker level leads
