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AKG K702 (The Classic) vs. K612 Pro (The Upstart) – Review and Comparison

post #1 of 198
Thread Starter 

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My full sized headphone journey has been a long one (mostly mid-fi), but a distinctly enjoyable one.  It has allowed me to learn a lot about my own preferences, and also allowed me to spend considerable time with some good, some great, and some not-so-good cans.


This thread is an introduction to the K612 (virtual unknown), and a comparison with the more popular K702.


Before I start – I’ll preamble with a bit about myself (to give you all a baseline of my preferences) – then I’ll give you my personal thoughts on the K612.


Pre-amble (about me)
I'm a 46 year old music lover.  I don't say audiophile – I just love my music.  Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current entry/mid-fi set-up.  I vary my listening from portable (i-devices) to my desk-top's set-up (PC > coax > NFB-12 > LD MKIV > HP).


My Head-Fi journey has taken me in order (full-sized only):
eH250, SRH840, MS1i, AD700, DT880 Pro, SRH940, HD600, HM5, K701, DT880 600 ohm, SR325i (woody) SRH840 (again), Q701, SRH1840, Mad Dogs 3.2, K702, HD600 (again), K612 – and the very soon to arrive RS1. 


I’m fairly certain now that I’m going to end up with either 2 or 3 cans – RS1 + either HD600 and/or HD800 and/or Alpha Dogs (trialling soon).


I have very eclectic music tastes listening to a variety from classical and opera to grunge and hard-rock.   I listen to a lot of blues, jazz, folk music, classic rock, and alternative rock.  I am particularly fond of female vocals.  I tend toward cans that are relatively neutral and balanced - with a slight emphasis on the mid-range.  I am neither a bass or treble head.


This is a purely subjective review/opinion - my gear, my ears, my experience.  Please take it all with a grain of salt - especially if it does not match your own experience.




Packaging / Accessories

I purchased both headphones from the forums – and both arrived in excellent condition.  Both have very similar full sized boxes (K612 in white, K702 in black).




K702 Front K702 Rear


Apart from the sales blurbs – the main descriptive differences seem to be in the main description.  The K702 description is “Premium Class Reference Headphones”, whilst the K612 is described simply as “Reference Class Headphones”.  The uses listed also differ – for the K702 it’s “Professional Use – Mixing, Mastering, Home Recording”.  For the K612 it’s listed simply as “Natural Sound Imaging For Professional Monitoring”.




K612 Pro Front K612 Pro Rear


It does surprise me that neither state ‘for musical enjoyment’ ;)


Anyway – I digress – both boxes are similar build – with the usual printed sleeve over a 3-way flap opening inner box.  I’ve always loved AKG’s way of doing this.  Each flap opens individually and is part of a 3 way message – “Expect” …… “And Discover” …… “Perfection”.



The K612 Inner Box - 3 Way Flap K612 Inside The Box


Inside both boxes are the headphones, documentation (warranty / manual), and each cord has a 3.5-6.3mm screw on adaptor (fitted).


Nothing fancy – no spares – and both very similar.


Technical Specifications



K612 Pro

Headphone type



Audio frequency bandwidth

10 to 39800 Hz

12 to 39500 Hz

Sensitivity headphones

105 dB SPL/V

101 dB SPL/V

Max. Input Power

200 mW

200 mW

Rated Impedance

62 Ohms

120 Ohms

Ear pads              

velour – angled - circumaural

Velour flat circumaural


3m replaceable

3m fixed


3.5mm with 6.3mm adaptor

3.5mm with 6.3mm adaptor

Net Weight




Frequency Response Graph

Unfortunately I can’t find a frequency graph for the K612 (at the time of writing) – so I’ve used the K702 and K601 graphs – mainly because it fairly closely matches what I think I’m hearing.  When they eventually do graph the 612 I’ll update the chart.


Sonically - the two are very similar (to my ears) - with the K612 being slightly warmer - and actually sounds a little more 'natural'.


Build / Comfort

I've always found the AKG build (and style) to be very satisfactory.  Both the K702 and K612 Pro fit pretty snug on my head and although a lot of it is plastic - they always feel relatively solid to me. 



AKG K702 AKG K612 Pro


The headband assembly seems almost indestructible - although (apparently) the elastic tension bands do become looser over time.


The K702 (my version) has 8 bumps – many people find these uncomfortable.  Surprisingly these aren’t as bad as my old K701s.  I’m wondering if this is because my 701s were 7 bumps (meaning one was always central).  The K702 with 8 bumps at least isn’t pushing right at the apex of my skull on a single bump – now it’s shared by 2 (take that as you will).  If I was keeping these, I’d still probably remove the bumps – and replace the underside with soft leather (I did it with my old K701s – just soft Lamb leather and a glue gun – easy).



K702 Headband "Bumps" K702 Headband


The K612 Pro has a flat pad – no bumps.  No real padding – but I still find it pretty comfortable.  I’ve noticed mine is slightly wrinkled already on the underside – really AKG – a slightly better class of material would eliminate this!



K612 Pro Headband - Flat & Comfortable! K612 Pro Headband


Of the two – I prefer the K612 headband style.  Both are self-adjusting, and this works well.


Both sets of pads appear to be made of the same material, and very close dimensionally – except the K702 pads are angled at the back, and the K612Pro are flat.  They are replaceable and have a very easy way of detaching and reattaching – just rotate and pull gently to remove, or sit them almost over the latches, push and rotate to reattach.  Both pads also fit the other headphone – so it is easy to pad swap (more about that in the SQ section).



K702 Left - K612 Pro Right K702 Left - K612 Pro Right
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K702 Left - K612 Pro Right K702 Bottom - K612 Pro Top


Overall on comfort – I’d give the nod to the K612 Pro – simply because of the headband.  It’s nice to see AKG bringing out their new models without the ‘torture bumps’ – but may I say ….. it’s about bloody time ….. your critics (and fans) have been asking for this for years.


Build on the other hand – while very similar – is better on the K702.  First there is the detachable cable – and I’ve always liked the mini XLR set-up on the K702/Q701 etc.  It’s pretty easy to make your own cable (I made a cheap Mogami mini star quad one when I had both my Beyers and Q701).  Not altogether a fan of the coiled cable on the K702 – but easy enough to change out to whatever your preference is.  The connector seems solid and fits nicely.  The actual diameter and the strength of the cable seems very slightly thicker on the K702 as well – maybe by 0.5mm – but it is noticeable in the feel of the cable (the K612’s is more flexible – and feels somewhat ‘cheaper’).



K702 Left - K612 Pro Right K702 Mini XLR Connector
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K612 Pro - Fixed Cable K702 Detached Coiled Cable

Next difference is that the plastic on the inner capsule of the K702 extends out approx. 5mm further than the K612.  They both appear to be the same diameter though.  Finally – the lip on the outer cup of the K702 is thicker (almost as though it has an extra ‘cap’ over it.  This not only feels sturdier – but does look better.  Overall though – the build differences are minimal.



K702 Inner Capsule K702 Thicker Bevel / Lip
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K612 Pro Inner Capsule K612 Pro Thinner Bevel / Lip


Both are very similar weight - and feel very light when worn.


Finally - "style" - I love these.  The AKG style to me is timeless.  They really are an attractive headphone in my opinion (especially in black).  Both really do look like a reference studio phone.  I'm glad AKG hasn't changed the overall aesthetics.


Both are labelled as “Made in Austria”.   The K702 are serial 29074 & the K612 are 00126.



AKG K702 AKG K612 Pro


So how do these two sound, and where do they differ?


Sound Quality

Let me start by saying that I really like the sound of both.  I’ve always been a fan of AKG’s presentation.  If I was to sum them up in a short sentence (both headphones) – then it would be:
Quite flat response with slight roll-off in lower bass, slightly forward mid-range, and generally detailed and airy treble.  I always felt that the AKG K701/Q701/K702 and now K612 sit nicely in the gap between a DT880 and HD600.


I’ve personally never found the AKG x701/2 series to sound ‘plasticy’ in the mids (as others have found them) – of course this may well be my amp (NFB-12 is quite full bodied – powerful, but maybe slightly coloured).


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K702 Driver K612 Driver


So let’s concentrate on the differences.


Both are reasonably detailed headphones – that sound wonderfully clear and articulate.  The main difference is that the K702 have slightly more air and upper detail.  I am guessing (if the K601 graph is indeed similar to the K612) that this is the larger peaks between 5-8 kHz on the K702, and also seems to be attributable to the pads.  I tried the angled 702 pads on the K612 – and the impression I got was a slight increase in both air and treble.  I did this several times and each time (though subtle to me), the difference was the same.


Soundstage & Imaging
Size (of stage) goes to the K702 – but this is largely because of the angled pads.  However I’ve always found the overall size of the X701/2 soundstage to be slightly too large, and more elliptical than round.  Left and right seem further away than central – and because of this it sometimes feels there are gaps in the image to the left and right of center.  The K612 (with the flatter pads) has a smaller but more circular stage.  Because of this I find the imaging actually superior.  I tried this with some live recordings (in particular Loreena McKennit’s “Live in Paris and Toronto” and also Joe Bonamassa’s “An Acoustic Evening At the Vienna Opera House”) – and each time I felt the K612’s presentation as more realistic.  During L McK’s set – you can clearly hear the applause between tracks, and I’ve always found this very interesting to use as a baseline for sound staging and imaging.  The HD600s are the most natural headphones I’ve heard – and every time I hear this – I get goose bumps, because if you close your eyes you ARE sitting among the crowd.  On the K701 – the same sections sounds distant.  On the K612 Pro – I’m back in the crowd again – not quite the same detail/realism as the HD600 – but close to being believable (and isn’t that what we are striving for)?


So although the stage size is bigger on the K702 and their sense of detail is slightly better – I prefer the K612 – they’re simply more natural sounding.


Overall Sonic Impression (or bass/mid/treble)

K702 are flat with slightly more bass roll-off (low bass), and a bigger peak in the upper mids/treble.  K612 have slightly more bass (marginal), remain quite flat, and don’t have quite the same peak in the highs (a little ‘more polite’).


In layman’s terms – I’d say the K612 sound extremely close sonically to the K702, but just a little warmer (not dark though), and without the glare in the upper end.  To me the K612 are actually more balanced overall – and would be my preference.


Power Requirements
Both the K702 and K612 are not very efficient headphones, and although they are only 62 ohm and 120 ohm impedance respectively, they do require some reasonable amping to get the best out of them.


I found this explanation (worth reading) [http://lsirui.wordpress.com/2009/04/15/k701-vs-hd650-electrical-measurement/] when I was originally researching my K701.  It also applies to the K702 and K612 IMO.  The better the amp's ability to deliver - the better the overall bass response and frequency overall should be.  Anyway - don't skimp on amping.


On the plus side - depending on the dynamic range of the recording (classical suffers a little) - a K702 can get to reasonably loud levels straight out of an iPhone4 at around 70% - and still sounds pretty good.  BUT - it definitely lacks bass impact from the iPhone and can deliver glare in the treble on some tracks.  The K612 is very slightly harder to drive – requiring slightly more volume to get to the same SPL – but on the iPhone actually sounds a little better (still missing bass and lower mids though).  Bottom line though - not recommended straight out of a DAP.


Both my NFB-12 and the LD MKIV (to my ears) are very good with the K702 and K612.  I definitely don’t feel I’m missing anything.  My actual preference with both is the NFB-12 over the LD.



I’ve gamed with both – and no real preference at the moment.  I certainly don’t feel the K612 are diminished in any way for directional queues in FPS gaming, and the slightly warmer tone actually adds to the enjoyment.





K702 Left and K612 Pro Right K702 Right and K612 Pro Left


Thanks for bearing with me for this longish post.  Bottom line – both headphones are very good – and preference will depend on individual tastes.  If you like a slightly more expansive stage – with a crisper detail oriented signature – the K702 will be better for you.  If you like a more natural overall presentation, with a touch more warmth – then the K612 is really very good.


If I could get the K612 sound, in the K702 body (complete with removable cable), staying with the K612 pads and headband though, I would be completely happy.  As it is – I am likely to sell both I think.  The exercise has been fun – but ultimately neither gives me what my HD600 does.  And I’m narrowing down my stable.



My personal preference - the K612 Pro - suits me sonically, better comfort, and better value


Hope this review/comparison helps someone for the future.


Edit - corrected driver photos (had them wrong way around - thanks Viralcow

post #2 of 198

Thanks for the comparison. I agree with everything mostly.

I've had both headphones for a very long time.


K601 (and maybe K612?) does seem to have more bass and warmth than the K702 but not the Q701. Just in case anyone cares about that.


BTW are the K612 pads softer than the K702 pads?


When you press down on the K601 they go flat super fast and the K702 pads are much harder.


Maybe AKG made some flat Q701 pads that use harder foam for improved bass.

post #3 of 198

Great review Brooko, thanks.  I've been considering the K612 as a complement to my RS1i (if it is indeed a "new" K601... it has more or less the same specs) as I am looking for something with a relatively flat FR.  Plus Computerlounge is carrying them now for a nice price. :)

post #4 of 198
Thread Starter 
Originally Posted by Edgard Varese View Post

Great review Brooko, thanks.  I've been considering the K612 as a complement to my RS1i (if it is indeed a "new" K601... it has more or less the same specs) as I am looking for something with a relatively flat FR.  Plus Computerlounge is carrying them now for a nice price. :)

@ Edgard


If you don't mind used - then I'm probably going to move mine on.  I was never going to keep the K702 or K612 anyway.  The purchases were more to satisfy my own curiosity.  Now that I have my HD600 back, and RS1 on the way - both are no longer required.  PM me if interested.  They're basically in like new condition.  I have the retail box etc.  It just saves me using TradeMe.  I'm in Invercargill.

post #5 of 198
Thread Starter 
Originally Posted by tdockweiler View Post

BTW are the K612 pads softer than the K702 pads?


When you press down on the K601 they go flat super fast and the K702 pads are much harder.


Maybe AKG made some flat Q701 pads that use harder foam for improved bass.


Tdock - the K702 pads are slightly firmer - K612 are slightly softer.  I wouldn't say it's a huge difference though.

post #6 of 198

The K 712 review out at Headfonics and received lots of praise. Looks like the new K series is not just (as some claim) some sort of re-branding of previous versions. A comparion of the K612 and K712 would be interesting indeed.



post #7 of 198

Thanks for posting a comparo of a brand-new AKG® model and a known champion from the same manufacturer.  The K612, being a 120Ω model, will be part of the showdown I am currently readying, along with four beyerdynamic® and six Sennheiser® models, for my Asus® CM1630's next headset (see also "Recommendable headphones and/or headsets for Asus XONAR Essence Series?").

post #8 of 198
I'm really liking that K601 graph. If the K612 is anything like that, I'm surprised it's not more popular, for those looking at a balanced sound signature. Makes me wanna try the K612 for myself.
post #9 of 198
Thread Starter 

At the price point it sells for, it's an easy recommendation.  I'd love to see an actual K612 graph to see if it actually mirrors what I heard.

post #10 of 198

Great comparison, glad someone finally reviewed the K612. Thanks for all the pics too.


I do agree and wish they'd use a different headband material. Mine was crinkled straight out of the box.

post #11 of 198

Sweet review, great photos and presentation I like it! the graph indeed looks better on the 612, maybe the angle pads on the 612 can be the answer for some. About the Soundstage & Imaging, Over the years I had the chance to hear my K702 from many sources, amps & DAC's and I can insure you the soundstage and imaging is different from each source.

post #12 of 198
Hm, so the HD600 ends up being the darling in the comparison. I wonder if I would agree with that, since I'm thinking of going over to AKG (or whatever I may find instead) from the HD600. I don't think there's much to like, it's just not very unlikeable, but it's constantly flirting with it nonetheless. It sounds very particular, and though it presents everything flat and in good detail, nothing I hear sounds very good or appealing to me. In a few, special instances, it does, but that probably goes without saying and is not an accomplishment. One would probably describe it as polite, but there's still a sharpness around the corners of the presentation.

Maybe it doesn't go so well with the O2ODAC. I bet the so-called or real objectivity is very picky. No matter, it will probably be a while until I find out if there's really anything better out there (since they always come up, and complaints only start to dwindle either in the lower budget and expectations or the top budget area).
post #13 of 198

Awesome comparison, one I've been curious about for a while. :D


One mistake I caught - the driver pics have their labels swapped.

post #14 of 198

Just for fun, here's a non-smoothed graph of the K702 vs K601...


post #15 of 198
Originally Posted by Mad Lust Envy View Post

I'm really liking that K601 graph. If the K612 is anything like that, I'm surprised it's not more popular, for those looking at a balanced sound signature. Makes me wanna try the K612 for myself.


The K601 sounds nothing like the graph really. I was always suggesting you try them since they're much better for gaming IMO than the K702 but not Q701. I think the upper mids peak is more present on the K601 compared to the Q701.

I actually find the K601 more fatiguing than the Q701 with very bright/harsh recordings.


FYI they do have less bass/warmth than the Q701/annie though


Most likely the K612 sounds a lot better than the K601.


Like the K601 it may turn into a complete fail for AKG. I sure hope not! K601 deserved to be more popular than the K701.

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