AKG K701 Headphones
A new reference!
Review By Phil Gold
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  I'm a sucker for a good pair of headphones. I've raved in these pages about the Ultimate Ears UE-10Pro Canal Earphones, and I've had great fun with the amazing AKG K1000 Ear Speakers. Can anything outshine these two wonders?

Well, if you can take the manufacturer's word for it, the AKG K701 may be just the thing. It replaces the K1000 at the top of the range, but comes in at a reduced price and is much friendlier to headphone outputs everywhere. You no longer need to attach them to the binding posts of your power amplifier! AKG designed the K701 jointly with the award winning Austrian firm Kiska, so they look the part too.

I'm going to compare the K701s directly with the K1000s, with a little bit of UE-10Pro thrown in for good measure. I will not be discussing the Grado RS1 or the Sennheiser HD650 because, despite their aural qualities, I am only interested in headphones I find comfortable for the long term. Both the Grado and the Sennheiser exert too much of a clamping action for my taste, making me not just uncomfortable but making my ears hot into the bargain, so I tire of them quickly. Today we consider only comfortable headphones, my personal candidates for reference status.

The K1000s have been around a long time, since 1989 in fact, and have excited both fierce enthusiasm and instant dismissal in the headphone community.

Here are some pros for the AKG K1000: 

And here are some cons for the AKG K1000: 

Let's face it, these are just about the most quirky headphones ever made. AKG insist on calling them ear-speakers, and they are absolutely right. These babies image like real speakers, and unlike almost every other headphone ever made. Those that love them will debate forever exactly which amplifier best matches them (usually favoring low powered tube amps although I use a high power transistor amp) and which cable upgrades to spring for.

The Ultimate Ears UE-10Pros on the other hand are also not strictly speaking headphones. They are canal earphones, custom molded to your ears and worn inside the ear rather than outside like conventional headphones. They can challenge the AKG K1000s for quirkiness.

Here are some pros for the Ultimate Ears UE-10Pro:

And here are some cons for the Ultimate Ears UE-10Pro:

So you can see why I'm still looking for a new reference. Now let's focus in on the new challenger. These large and relatively conventional dynamic headphones are reasonably efficient and they make a real effort to overcome the comfort problems of other phones. How so? Well, the soft glove-leather padded headband is self-adjusting. Meanwhile, the cups around the open backed diaphragm are so wide they fit around the ears, using 1" of soft foam inside breathable velour ear pads. AKG call this 3D Form. The headband is clearly derived from the original K1000 design, but this time instead of the red, black and silver color scheme we have an iPod compatible white finish with grey ear pads, brown leather and brushed aluminum accents. To my eyes they are a great example of modern functional design, up there with the recent and ultra expensive Sony Qualia 010 Headphones. The look but not the color scheme is shared with the much less expensive K601 phones.

AKG used the latest generation of time-energy distribution (Wigner distribution) measurement technology, along with FEM / BEM (Finite Element Measurement / Boundary Measurement Element) simulation and laser interferometry in the development of the K701.

What special technology goes into the K701? This is not a short list, but here goes. According to AKG:

They also claim the K 701's all-new diaphragm continues the evolution of the K1000's multi-layer design. Advanced production technology combines two different materials: the first optimizes diaphragm motion, while the second dampens undesirable breakup modes. Each individually tested and numbered K 701 comes in its own storage cradle, which in turn is enclosed in a presentation case. I love reading all the technical stuff, but what really matters is how they perform. And perform they do, but only if you give them a really long run-in period first – we're talking 300 hours or more. Here's what I found.

If the UE-10Pro is tilted down, and the K1000 tilted up, then the K701 is just right. This is a killer achievement in a headphone – flat as a pancake across a very wide frequency bandwidth. The K701 also maintains a lot of the ear speaker imaging ability of the K1000, so it sounds a lot more natural than most headphones, although its older brother does hold all the aces here. By moving the phones around, which you can do easily since the cup is so much bigger than the ear, you can modify the imaging characteristics, although to a much lesser extent than on the K1000.

As for resolution, my first thought is that the K701 doesn't reach the superb level of the K1000, but in fact it does. The difference is that the leading edge is not so sharp here, but there's detail galore, and in this area it is a close match for the UE-1Pro too. All three are detail champs.

The biggest difference between the two AKG models is in the level of warmth. The K701 is warm and full out of the box when paired with a fine transistor headamp like the reference Graham Slee Solo. The K1000 on the other hand is revealing to a fault. If your amplifier is lean, it will sound lean and lacking in presence, while if you want warm you'd better be thinking tubes to fatten up the midbass. No question which one I prefer here, the K701. It doesn't so much add warmth as reveal the warmth in the original signal, the warmth I can hear with my Wilson Benesch Act 1s on well recorded material, the warm acoustic of a good concert hall. The UE-10Pros have similar qualities on the temperature scale, and this important quality helps greatly when listening for longer periods.

The single measure that separates a truly satisfying piece of equipment from the run of the mill is the ability to do justice to the full dynamic range of the recording. This in my mind is where so many electrostatic headphones and even the much-praised Sennheiser HD650s fall down. Dynamic compression creeps in, especially at the all-important high end of the spectrum. This is the elusive quality the K1000s have had all along that has brought them such attention. These headphones convince because they can play loud or soft without a trace of distortion or compression. The K701s come within a whisker of the K1000s ability here, with the UE-10Pros just a fraction behind but still streets ahead of most rivals. You simply don't get that you are there feeling when the dynamic range has been squashed. That's also why the mega powerful amps so often sound better than the flea amps – for that tiny fraction of a second when you need a powerful transient, they will not let you down, you'll preserve the full force and power of the music.

I could easily tell you the K1000s have exceptional highs, clear, colorful and unstrained, or that the UE-10Pros have killer bass. The K701s evoke no such superlatives for any part of the spectrum since you don't really break down the performance octave by octave in that way. The sound here is simply continuous and balanced up and down, never calling attention to itself but always serving the music. On so many recordings I have found little to write about, because there's nothing to criticize here. Yes, it could be more visceral, as a quick comparison to the Grado RS1 will confirm, and the deep bass could be more solid, as the UE-10Pros confirm, but you don't notice this as you listen. Instead you relax into the music, enjoying the performance and not noticing the equipment.

There's going to be some recordings that sound better on one or other of the rivals, but in most cases I preferred the K701 on a wide range of musical selections. Let's take a closer look. We're listening to a Meridian G08 CD Player feeding the Graham Slee Solo Headphone amplifier, with Nordost Thor and Valhalla cabling. The K1000 is driven directly from a Perreaux Radiance R200i amp.

Starting with solo piano, Claudio Arrau playing Beethoven Sonata Opus 101 [Philips 462367-2], always a revealing test even for large speakers, the K701 is spacious, warm and resonant. Strong attack, fast speed, slightly clangy. The older K1000 has a stronger attack and greater dynamics but the bass is weaker, yielding less warmth and a lower level of realism, but majoring in purity. On balance, the K701 wins on this recording, so on to the Diabelli Variations [Philips 462369-2], same pianist, same composer. Again the K1000 comes across as analytical and a mite hard, but its reflexes are remarkable. The K701 reveals a much more beautiful piano tone with plenty of weight, quite similar to the UE-10Pro, while neither of these emphasizes the leading edges in the way the K1000s do.

Moving to a recent and fabulous recording of the Shostakovich Piano Concertos played by Marc-Andre Hamelin [Hyperion CDA67425], we can see these impressions confirmed, but now with the presence of a full orchestra, differences in imaging and tonality also emerge. The K701 posts a very seductive piano, realistic wind instruments and clean tight trumpet solos, excelling in conveying the most delicate passages. It also reveals a natural, life-sized image here, and this repeats on almost all recordings. The K1000 is clearer. Trumpets have greater attack and the piano less weight, as expected. But the image is stretched so that it is both wider and shallower than the K701. The UE-10Pros come close to the K701 except they lack the open top end and add a touch more presence in the bass and mid range. When there is a lot of high frequency energy in the recording, the UE-10Pros miss the sparkle of the two AKGs, but otherwise come close to the same sound through a very different path.

The last piano test is the powerful jazz playing from the Benny Green Trio on Greens [Blue Note CDP 7964852]. Here the UE-10Pros come out on top courtesy of a visceral rendition of the powerful bass notes from the bassist and the pianist. The power and control here are simply phenomenal and I have never heard another headphone capture this amount of drive and energy. The K1000 is from a different planet here. Percussion is tizzy, the bass, piano and percussion all seem disconnected, the bass player conveyed with accurate pitch but no power and the piano tone shallow. It's all crystal clear but no fun. The K701 integrates the trio wonderfully into a coherent whole and reveals real jazz swing. This is a very valid alternative to the UE-10Pro, more rounded and musical but without that deep bass drive. A close second.

Regular readers will remember my passion for chamber music, especially string quartets. If you want a great start in this repertoire, try the Kodaly Quartet's performance of Haydn Op 74 No 1, 2 and 3 on the budget Naxos label [NXS-8.550396]. Don't try them on the K1000, because you'll find them thin and forward, but you'll love them through the K701. The sound is spacious, present, well balanced, and rich, with bass strength when needed. Now the music is glorious. With even greater immediacy and bass weight the UE-10Pro excels here too, although at the expense of some top-end extension.

Joan Baez laid down a demonstration class track in "Diamonds and Rust" [Vanguard VCD3-125/27] and it reveals many of the strengths and weaknesses in these components. Through the K1000 the music is captivating and full of unexpected detail, often at low levels way down in the mix. Clarity is superb, the voice clear but without question, this is tilted up and there is no bass warmth to speak of. If it's bass warmth you want, the UE-10Pros have it in spades. Baez's voice is more resonant and full and there is less emphasis on treble detail – it's still there but not calling attention to itself. These phones come closest to my reference speakers, the Wilson Benesch Act 1s on this track. But if there's one thing missing here it's speed, which is more evident on both the AKGs. The K701 gives an outstanding presentation here. The voice and instrumental color are more beautiful, the bandwidth wide open, detail is outstanding and the image is wide, deep and stable. This makes it so easy to make sense of the complex mix. The bass foundation, so lacking in the K1000 is supportive here but not intrusive, and the string tone has really flesh to it. Outstanding!

Another chanteuse with a voice to die for is Chava Alberstein, and her disc of Yiddish Songs [NMC 20126-2] includes the memorable Margeritkalach. The K1000 disappoints with a disjointed image and a top heavy voice, but the K701 nails it, with a warm rich voice and colorful strings, much like I remember from the superb SoundFusion Hyperion active speakers at around 20 times the price.

I love it when everything points in the same direction. It makes my life as a reviewer so much easier. I also prefer components that excel on a wide variety of music rather than being biased to one type or another. Reading what I've written so far, you may conclude the K701 walks all over the UE-10Pro and the K1000, so why did I include them in the review. That's what's so special about the K701, it does shine out here, especially for its overall balance and musicality, but I want to remind you just how spectacular the K1000 and UE-10Pro are in their own rights, each easily ranking among the top headphones ever made. You've just got to be a lot more careful about system matching to get the best out of them.

You have to admire the dedication of the engineers at Grado, Sennheiser and Stax, who continually polish and improve their designs, adding refinement over succeeding generations of phones. But I take my hat off to the AKG developers for thinking outside the box and coming up with radical innovations which challenge existing thinking and push the state of the art on so many levels.

The AKG K701 is one beautifully rounded performer. Top shelf sound, superb ergonomics, a competitive price and no quirks. The new reference has arrived and I'm not letting it go. Anyone wanna buy my K1000s?

Specifications

Type: Circumaural, open back headphones

Drivers: 2 layer Varimotion design with flat wire voice coil

Frequency Response: 10Hz to 39.8k Hz

Efficiency: 105 dB SPL /V

Maximum input power: 200 mW

Impedance: 62 Ohms

Cable: 10 ft captive biwire featuring 99.99% OFC copper

Input connector: 0.25-inch stereo plug

Finishes: White and grey with brushed aluminum accents

Headband: Padded glove leather

Weight: 8.3 oz without cable

Warranty: 2 years parts and labor

Price: $450 ($479 Cdn)

Company Information

AKG Acoustics GmbH
Lembockgasse
A-1230 Vienna
Austria

Voice: +43 1 86654-0
Fax: +43 1 86654-8800
E-mail: sales@akg.com
Website: www.akg-acoustics.com

AKG Acoustics US:
8500 Balboa Boulevard
Northridge, CA 91329

Voice: (615) 620-3800
Fax: (615) 620-3875
E-mail: akgusasales@harmon.com
Website: www.akg.com/us

Canadian Distributor:
Soundcraft Canada
9629 Clement Street
LaSalle, Quebec H8R 4B4
Canada 

Voice: (514) 595-3966
Fax: (514) 595-3970
E-mail: information@soundcraft-canada.com
Website: www.soundcraft-canada.com