The basics: these are $349, over-ear, open-back, high-impedance headphones; designed for a flat frequency response and natural soundstage. In case you have never heard the term “soundstage”- it is a way to describe how wide and/or “deep” the presentation of sound is. Professional and Hi-Fi audio systems can produce extremely real “soundstaging”, and having access to that is essential for mastering, mixing and tracking. AKG says these are “pure perfection for precision, listening, mixing and mastering”. I would argue with the word “perfection”, but more on that below. (Here’s a link for actual specs http://www.akg.com/pro/p/k702).
I picked these up as an upgrade from my tried-and-true Audio Technica ATH-M50, which I had used for over 7 years, but were starting to show their weaknesses (more on that below). I still use multiple sets of the ATH-M50 for tracking and some mixing duties, as they are my favorite recording session headphones (here’s a link to my blog/review on them- http://fuzzywallz.com/ath-m50-headphones-review ). As I state in the ATH-M50 blog, I started finding that the low end response (about 90 to 160Hz) was rather hyped, and the “sub” response (about 5 to 60Hz) was rather lean. This was causing issues where playback on other systems ended up too sub-heavy, with a weak lower midrange. The midrange and treble were pretty decent, but had a bit of a boost/harshness at about 1.5kHz and again at 10kHz or so. There was/is also a certain “boxiness” to the ATH-M50’s that was skewing midrange performance. At the time, my room wasn’t properly tuned for mastering speakers of any sort, so I decided I needed more accurate headphones. After doing quite a bit of research, i kept seeing glowing reviews for the AKG 702- saying they are the flattest headphones out there, and are THE BEST currently available for mastering duties (i still see this on the internet often). I really wish i could have tried them out before buying, but auditioning high-end headphones isn’t easy or cheap.
After they arrived (along with my Fiio X3 Hi-res DAP/DAC), I immediately started to burn them in and check their sound out, by listening to tons of music of all styles and eras. After a few songs, I started writing little notes on their sound. Here’s some of what i wrote down that first day:
-“the perception of depth between ears, AND on each side is startling”
-“tons of midrange detail! I am hearing effects, panning and tonal characteristics in my music collection, that i had never noticed before”
-“these ear pads are soft, but the headphones are BIG and fragile-feeling, in general”
-“un-hyped bass…low end content seems fairly selective, based on song”
-“Wide-ass stereo image…..w-i-i-i-i-i-d-e!”
-“I am NOT missing the boxiness or midrange harshness that existed on the ATH-M50’s.”
-“turning them down, because i can really hear (even subtle) program distortion on loud, probably clipped masters”
-“These headphones are most assuredly on the bright side….”
Now that I have used them for a year, I look at those comments and kind of chuckle to myself. I can tell that i really WANTED to like them, but obviously I was hearing the issues right off the bat. Even after using them for weeks, I couldn’t get used to them. These new headphones were unforgivably bright (from 2khz all the way up) and surprisingly skimpy on the low-end (from 10Hz to at least 100Hz). The frequency response wasn’t nearly as flat as I had hoped for. However, the soundstage on them was (and still is) very useful for hearing depth, high-end detail and ambience, but EQ would be needed for them to be useful.
So…I tried using the Sonarworks headphone calibration system to flatten the response of the AKG K702, but it just never sounded right to me. In both linear phase and minimal phase mode, the EQ correction was just too much and sounded super-blurry, unnatural, and definitely worse than before. Pictured below is what the Sonarworks AKG 702 preset curve looks like; Sonarworks then applies an equal and opposite curve, from what you see here-
My solution- using the basic EQ shape that Sonarworks suggested, mixed with what my ears were telling me, I managed to come up with a simple EQ curve that works pretty well. I chose to stick with using the smallest amount of adjustment needed, and chose frequencies that could be replicated on the built-in equalizer in iTunes, J-River and my Fiio X3 Hi-Res player. I figured that doing too much EQ-ing is waaaaay more destructive than having natural, slight deficiencies; but that’s a whole other can of worms! Anyways, below is a pic of the EQ curve i ended up with-
Once I had the EQ curve/correction sorted out, my AKG K702 got some “new life”! At this point I had owned these for maybe 3 or 4 months. The new (EQ-ed) frequency response made them quite a bit more useable and trustworthy (especially in the midrange and treble), but having to remember to turn the EQ on and off became quite an annoyance. I probably had to re-export more than I’d like to admit! Even more importantly, the low-end just never got to sounding, or responding as I desired. I started reading, over and over, that many other people felt the same way about these headphones, even after EQ correction. I also (every so often) felt like the K702’s would make make my eardrums pucker and close-off temporarily. I know this sounds odd, but it happened numerous times (ONLY on these headphones) and literally brought mastering sessions to a halt. Perhaps the open-back design, coupled with the complete ear cup seal throws off my inner ear? Either way, it was back to the drawing board…. This time I REALLY got into researching, and in the process, learned a ton about headphone technologies and physics (thanks especially to Bob Katz and http://www.innerfidelity.com for some crucial input). I feel like I could write a novel about it at this point!
By the way, I was “feeding” my K702’s from the built-in headphone amp on my UA Apollo interface (for mastering) or from my Fiio X3 (mobile listening). I could tell some differences between the amps/DACs, but nothing that changed the overall characteristics of the headphones enough to mention. I should add that these are rather power-hungry when compared to all my other headphones, so I’d recommend using them with a decent amp with good amounts of clean gain.
After much debating, cost-checking and saving, I ordered a pair of Oppo PM-3 ($399), along with a Little Labs “Monotor” headphone amplifier ($550; reviews coming eventually). Almost immediately the Oppo PM-3 became my workhorse headphones, and they even beat-out my updated speaker system when it comes to “flatness”. The only thing that the Oppo PM-3 don’t do as well as the 702’s is the soundstage (probably because of the closed-back design), so I still rely on my AKG 702 to asses spatial information, panning, depth and to triple-check things before i finalize them. They also work amazingly for hearing sibilance issues, checking fade-outs and revealing low-level information (like crackles, phase issues, and hiss)….For these reasons, I am keeping them forever, even if they eventually get relegated to the house Hi-Fi system! I should also mention that using the K702’s with my new “Monotor” headphone amp has made them sound incrementally better, but not much. Below is the “Cliff-notes” version, with basic ratings.
PROS: Amazing soundstage, extremely detailed midrange and treble, cool mini-XLR cabling.
CONS: Expensive, too bright, lean on the lows, and some comfort issues. Power-hungry.
the “COMPETITION”- Sennheiser HD series, other open-backed AKG models
UPDATE (5/1/17)- I am selling the AKG k702 because I rarely use them, now that the Oppo PM-3 are my main set of “cans”…The k702’s were just too bright, finicky, and needed too much power. Sorry AKGs!