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Positive Feedback ISSUE 34


akg acoustics

K-701 headphones

as reviewed by Max Dudious





The relatively new AKG K-701 headphones have been around more than a year now, and they have developed a kind of reputation that is good to know as the Xmas season draws near. They have the right price (often lower than published on-line or in the mail-order catalogues, and negotiable over the phone), the kind of looks, and the kind of high performance that makes them a perfect Xmas gift. At the actual price offered by HeadRoom (, and others like Audio Advisor, they sort of sneak up on the 'phones that are twice their price, and more. They are very smart and clean looking, with their excellent fit and white trim finish, compared to many of the grody looking cans of years gone by, and many still on the market. But it is to their performance that I will address myself in this little essay. I think these cans can "can the crap" and cut the mustard. Let the competition begin.

In general, a product with a good mid-range can often stand comparison to the heavyweights. It is in the ability to reproduce the outer two octaves, or so; the ability to capture extreme shifts in dynamics (very soft to very loud); and the ability to discriminate chords down to their component tones, that the "very good" is surpassed by the "excellent." The analogy some folks make is to sports cars. An excellent sports car can brake down from high speed to low, take a hair-pin corner, and accelerate away in shorter time (with more braking horsepower/weight) without, as lesser cars might, swerving off the road, rolling over, or fishtailing. It that lower center of gravity, and better suspension, you see. Heaven help the wanna-be's!

In terms of audio, an excellent product will be able to handle a full orchestra's going from triple pianissimo to triple fortissimo, and still discriminate small differences in tone clusters as the inner voices move from major to minor while the orchestra screams its grief, say, as in the "death of Tybalt" section of Prokofiev's Romeo and Juliet ballet (Telarc SACD-60597); or able to capture the full range of subtle violin tones and techniques as on the fabulous recording of Joshua Bell playing Corigliano's Red Violin Concerto, with The Baltimore Symphony Orchestra (Sony 82876 -88062-2); or able to hit all the right notes of a very good jazz group at work as captured in the wonderfully engineered recording Cobb's Corner, Jimmy Cobb, (Chesky SACD/CD #327). In other words, the average "good" audio product handles about 90% of the recordings in good shape, but doesn't do as well with the most difficult sonic hair-pin turns in the software.

I can tell this is what is happening when I, as proud owner rationalizing to myself, have to turn down the gain on the grounds that "the recording engineers weren't careful" in this particular passage. With visitors, I've often used that ploy, and unfairly fobbed off the responsibility for faulty audio products onto absentee recording engineers, while I turn the gain down. The acid test seems to be the very loud passages, but during a soft passage a very minor change (micro-dynamic), like capturing the little detail that is "down in the mix," is another challenge.

A lot of the stuff that some loudspeaker critics dwell on, like getting spatial relationships right, or hearing a lot of "air" between the instruments, delicacy and balance, or image height, I believe to be due to room interactions, which contribute largely to the characteristic sound of many free-standing systems. Thankfully, listening through headphones eliminates room interactions. The AKGs seem to get the rest all pretty right on. They are a high performer of the highest grade.

How I listen is as follows: I use an older Sony top of the mid-fi line CD player of ten years past ($350, then), the XA3ES "Current Pulse D/A Convert System," because it does an excellent job on standard CDs. This is especially through the Australian Burson Buffer Amplifier ($300), which takes the Sony's edge off, smoothes things out, makes the sound rounder and fuller, and approaches more closely SACD and LP sound. The analog red-book feed goes from Sony to Burson and to my HeadRoom Desktop Millet Hybrid (tubed output) 'phones amp, (about $1K) with an optional stepped-attenuator Volume control, and an optional Class "A" motherboard (both now standard). The Millett is powered by a HeadRoom Desktop Power Supply ($350, an older model, since superseded). I like this set up (about 2 kilobucks) a great deal.

I've had some more expensive units in my headphone system: a $4400 Marantz SA-CD/CD 11S1 CD-player that enjoys a great reputation for being silky smooth, a $3500 Single Power "Supra" all tube 'phones amp (with a power supply that could drive a truck). The pluses and minuses gap opens a little wider with these, while the price goes way up (the law of diminishing returns). I have as my reference guides the Sennheiser 600 'phones that I like a lot with their stock cord, and like way more with a "Cardas Headphone" model 600 cable; my Grado GS 1000 'phones; and an old pair of Grado SR 1's, both with Grado's best cord. I've had these three around a long time, and I know what they sound like. The AKG's can execute the hair-pin turns with the big boys.

Interconnects I use at various times include a pair of Home Grown braided, eight filament, solid core silver, Teflon and air insulated, cables; a pair of Grado twisted, four- conductor, stranded copper, polyethylene insulated, rope laid cables; and a pair of Monster, Sigma Retro cables, with annealed stranded copper conductors, PEX-2 cross-linked polymer dielectric, and with a twist geometry, that I switch back and forth to tame the high end. Paradoxically, I can't quite explain how or why this happens, but each of these different cables (of widely varying design philosophy) seems to have similar bandwidth, dynamic range, and they each widen and deepen the sound stage. Yet the Home Grown works best with some gear, and the Grado or Monster with other gear. Maybe it's capacitance and resistance matching. It's a mystery.

To do a fair test, HeadRoom sent me two sets of AKG 710's; the least pricy ($450 MSRP or, manufacturer's suggested retail price, $309 from Headroom) with their stock grey cord in an unbalanced wiring configuration, terminated by a-quarter inch unbalanced plug; and a pair with their black "Fat Pipe" cord that bears a Cardas patent number, that is wired in balanced configuration, and is terminated by two Neutrik XLR type plugs, and has a Neutrik to 1/4" plug adaptor for unbalanced use (for a total cost of $609 with HeadRoom rewiring). I use the adaptor with the AKG's and my Sennheiser 600's because the Millett amp doesn't have balanced drive wiring or outlets. Unlike the Sennheisers, the AKG's do not have a plug socket on each of the ear cups, so you can't easily compare from among the many headphone cords the one that best satisfies your needs, or taste. You have to choose upon purchase, and if you want the upgrade, HeadRoom will solder in any cable they carry that you specify. So in a way this review will be a bit of an evaluation of the two cords (AKG 'phones with the stock cord, or AKG's with Cardas/HeadRoom black "Fat Pipe" cord) the last of which, again, would have to be wired in place by HeadRoom.

The AKG stock gray cord is sorta-kinda OK if you don't have the loose cash to spring for the upgrade. It definitely doesn't show the AKG's to full advantage, though. The Cardas cables are so much of an improvement that you might say the stock cable holds the headphones back. At about half the price, the AKG's with stock cable are not as clean, overall, especially in the highs (where much spatial information originates); and, as a result, it doesn't separate the various instruments with anything near the clarity of the Cardas/ Headroom Fat Pipe cable. Neither does it do as good a job on full orchestra at full cry, nor does it pick up as well small details "down in the mix."

The Fat Pipe cables are available to view at the HeadRoom website listed above. They were developed specifically for the Sennheiser HD-580, HD-600, and HD-650 series, but they can be used with the AKG if they are hard-wired in at assembly. They are a double shielded, four conductor design, configured in the Golden Ratio, with Constant Q, and Crossfield; and they use Pure Copper Litz wires. They feel somewhat stiff in the hand because they use Teflon insulation. They are a seriously designed cord, for serious headphone listeners. You can check out the prices for various termination hardware and lengths at the HeadRoom website. These cables lower the impedance and are clean as a whistle, and they are pricey owing to the labor intensiveness of the modification, and the two sets of Neutrik connectors required to fabricate the adaptor.

Sonically, the AKG 'phones, with the stock cable sound a bit dry, with an emphasis on presence over soundstaging. With the black Fat Pipe cable AKG's sound a bit more romantic, and the emphasis moves more toward the Sennheiser sound, with improved sound staging. With the Fat Pipes the AKG's begin to resemble the Sennheiser 650 while playing some recordings, and the Grado RS-1 on others. The bass becomes a tad or two bigger, they display a very lifelike midrange, and the highs clean up another tad or two over the stock cable to offer more detail. I believe the stock cable does keep the AKG's from fully reaching their potential and displaying the excellence of their design. With the cable upgrade, they seem to have the see-through quality of the Grado RS-1's and the romantic string tone of the Senn 600's. At the very least, I can say the AKG's (with the Fat Pipes) can play in the same league as the others.

There is a law of diminishing returns in effect here. The last few increments of performance become smaller, following the asymptotic curve usually used to describe diminishing returns that never reach perfection; while the cost goes up exponentially. The black Fat Pipe cable is $300 more expensive than the stock, effectively doubling the cost. It is a most worthwhile improvement, in either balanced or unbalanced mode. So which to choose?

I guess that's a personality call, as well as a priority call. If you are the type of person who likes to know he has the best available wire feeding his headphones, go for the Fat Pipes. If you are a budget-conscious personality, keep the stock cable until you have enough cash for the upgrade. (Remember, you'll have to ship the 'phones back to HeadRoom, and also absorb the shipping expense if you deal with them, and you can eliminate some of the cost if you either can live without the adaptor that comes with the modification, or you can live with only a regular 1/4" plug.) If you are among the more fortunate, go with the black Fat Pipes. You will have a pair of very fine headphones that have many of the qualities that define truly great sound.

I'd be remiss if I didn't have a few cautionary words here. The AKG's don't seem to like to be driven very, VERY LOUDLY. In my experience, the bass gets wooly, and breaks up when the 'phones are driven out of their comfort zone. That might not be the case with a totally solid-state design 'phones amp that has greater damping. But you'd have to listen at dangerously loud levels to hear that. With the stock cables the AKG's can get a tad harsh. Not so much so that it would automatically disqualify them from consideration, but a definite tad played very loudly. That harshness goes away with the Fat Pipes cable, demonstrating that with the Cardas/HeadRoom cable, the AKG's become a serious audiophile's headphone. With the stock cables, they fall a bit short, but they are still pretty damn good because their strength lies in their mid-range.

So, what have we here? We have a well-designed, excellent set of headphones in the AKG-K-701 that can be improved upon by a cable upgrade. I think the deal offered by HeadRoom make this a very attractive pairing for the audiophile who doesn't want to break the bank, or his domestic tranquility. At $609 with the cable upgrade, they are a bargain, able to compete with the Grado's at $750 (MSRP) and $1000 (MSRP), and the Sennheiser 650's at about the same price with their Cardas cable upgrade. I think the wise, maybe sly, audiophile might take this opportunity to buy a pair for his wife, as a Christmas present—so she can listen to her favorite tunes while he plays his favorites on his big rig—if you get my meaning.

And when you do, slurry on down to the stone soul telephone to place your order, and tell 'em Maxie Waxie sent ya.

Ciao Bambini.

Max Dudious