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AKG K550 Review - An attractive and well built closed headphone that has many strengths, but ultimately falls short on sound quality.

A Review On: AKG K 550

AKG K 550

Rated # 37 in Over-Ear
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Price paid: $300.00
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Pros: Looks, Build Quality, Decent tonality and fairly flat FR from midrange down to bass, no treble emphasis, decent soundstage for a closed headphone

Cons: Serious peak and resonance in one spot in the upper mids ruins an otherwise decent headphone


First Impression


When I first listened to these headphones, my initial two thoughts in this order were:

1. Wow these sound pretty fast and also fairly even

- 15 seconds later -

2. Wow something is wrong with the upper mids



who cares


Build Quality/Aesthetics

These headphones feel very well built.  I can't speak to their longevity or durability, but they are nice to hold, feel sturdy, the movements are tensioned well and feel solid, there's no creaking of cheap plastic.  The finish feels durable and well made.  One of the better headphones out there IMO for it's apparent build quality and finish. 


They look very nice when sitting on your desk, and in pictures.  A good design, but they are one of those headphones whose looks don't entirely translate to looking good when worn.  They have all the right shapes and dimensions relative to each of the parts, but the whole thing is just too big to look very good.  For their size, I'd say they don't look too bad as they are slim, so they don't stick out horizontally very much and give you the alien mind probe look that grados and many closed headphones do.  The headband is slim too since it comes together at the top of the cups, so it doesn't have that gigantic and unnatractive arc that the older AKG's have like the K240.  The headband hugs the sides of your head well.  Still, the cups are huge even on my big noggin.



Very good except that the earpads just aren't thick/deep enough.  Huge design flaw IMO because everything else was done very well for an extremely comfortable headphone.  The cups swivel in a really nice way since they have a good amount of friction in the movement, so you can place them at the right angle for your head, and they stay there.  Headband is comfy and is the right shape.  But the earpads aren't thick enough to keep the grill over the drivers from hitting your ears.  With such huge, soft earpads this is a pretty big fail IMO.  I tried putting the foam donut shaped inserts that Hifiman has in their earpads into the K550 earpads, increasing the thickness, and it had no effect on the sound and made them supremely comfortable by simply increasing pad thickness.  So as long as you don't have huge ears they should be fine.  Or if you don't mind a little pressure from the grills.  it doesn't hurt too bad on my big ears, but it just would have been so easy to avoid this situation.  I get the feeling they didn't do much real world testing on these and got carried away with computer modeling. 





They overall have a flat, balanced sound from bass to midrange with good tonality, and with a treble presence that is in balance with that part of the spectrum, which is very rare for headphones.  But there is a serious problem spot in the upper mids that ruins this headphone.  A resonant peak in a small part of the upper mids.  I would describe their overall sound as a slight rainbow shape FR, though leaning upwards towards the upper mids for enhanced sense of clarity.  They also can sound kind of fast for a closed dynamic.  Not ortho or stat fast by any means, and not Grado fast, but maybe 6/10 for speed.  Not bad. 



Good not great.  It extends down plenty low, it seems flat, there's no apparent midbass hump, bass does not bleed into the midrange or vocals in the slightest but is also well integrated with the midrange.  There's no "bass + mids"  or subwoofer effect where the midrange and bass feel separated by gaps in the spectrum.  They have a cohesive transition from bass to mids, likely from a fairly flat FR.  But bass is a bit low in quantity despite what the FR measurements suggest.  The bass is in the background on these phones, with emphasis on the midrange.  Not for bassheads at all.  Bass is not bad quality, but it sounds kind of dry and a bit soft, whereas better headphones have more definition and dynamics and detail in the bass.  Not bothersome, especially since it's in the background.  I'd describe the bass as being just enough to provide a foundation and not sound too lite, but too low to sound totally neutral- it keeps your attention on the midrange.  It gets out of the way so to speak, for better or worse.



I'd say the treble on these is very similar to the bass.  Good not great.  There's no emphasis in the cymbal range as far as I can tell.  If anything it sounds a bit recessed in the upper treble.  Nothing sticks out at you here or is glaringly bad.  But the treble is not that clean or precise sounding.  It is a bit rough/textured or papery sounding.  Like the bass, I'd say it's a backdrop for the mids.  Not a treblehead headphone either.  Yet despite this lack of apparent brightness, these phones have a strong sense of clarity about them.  I think this is what people like in this phone.  They don't sound dull or rolled off or warm at all.  Likely because of the slight lowering of bass volume, along with the emphasis in the upper midrange, the "clarity" range in the FR.



Here's the problem.  Both the bass and treble on these are both presented as a backdrop for the midrange but there's a serious problem in this area, so these phones wind up failling short for bassheads, and treble heads, and then have issues in the midrange.  First the good part.


The heart of the midrange and the lower midrange is done pretty well.  Vocals have both the proper richness for a male voice like Tom Waits or Chis Isaak, which is surprisingly rare- they don't make vocals sound thin despite the lack of bass emphasis.  They also don't sound overly rich at all.  Chris Isaak's voice sounds very good.  Vocals also give the proper air and breadth to female vocals like Emmylou Harris or the Audiophile favorite Allision Krauss.  But sometimes vocals reach up into the problem spot and sound off. 


Upper Midrange Issues
There is a spot in the upper midrange that has a pretty bothersome resonant peak.  I kept wanting to call it "glare".  The upper midrange glare isn't the most peircing or painful I've heard in a headphone but it is very bothersome and might be described as severely "jarring".  It doesn't seem to cause me to reach for the volume knob as feverishly as some phones have, but it does keep me from turning them up and leaves me in a state of fear wondering when something is going to hit this problematic range and if it is going to hurt, since it seems to be right on the threshold.  Any instrument in that range sticks out way too loud, and looses proper tonality as the sound in that range gets mangled by resonance and takes on a plastic tonality. You can clearly hear the coloration being added to what should be the original signal.  This is partly because it's such a specific problem spot.  You can sometimes hear an instrument or voice go up in the range and suddenly jab at you by suddenly increasing in volume while taking on this plasticky resonant glare.  The decency of the lower part of the spectrum gives it a "surprise attack" quality which is what generates the fear and hesitancy when listening.  If there was an instrument that existed only in this range, I am doubtful you would be able to hear what instrument it was.  Some recordings play well with this problem spot and it's not grossly apparent because of the frequencies being excited by that recording and the particular balance of the recording (if the recording has a peak in that spot too, it's clearly going to be worse).  But even on these recordings, this spot gives the whole spectrum a cheap plastic headphone feel kind of layed over the sound, as if you are listening to some very good throw away headphones.  I kept thinking of them as the best airline headphones ever.  Much better extension, tonality, more flat, but still plastick-y. 



Overall good size for a closed headpone, has a spaciousness about it, but there's something strange about it as well.  It's almost like there are 2 soundstages happening at once, the lower part of the spectrum sounds more spacious to me than the upper mids/treble, which sounds more constricted.  This gives them a lack of coherency, or a kind of bad crossover effect, where the sound is a bit disjointed.  I think this is because the resonance artifact in the upper mids destroys soundstage by getting in the way of the "trick" the headphones are playing on your perception.  Soundstage is also destroyed by a "driver dildo" that was installed on the back of the driver creating a tiny chamber behind the driver rather than the comparatively larger size of the earcup.  I'm guessing it was placed there in an ill conceived attempt to control the bass, but I have modded a pair of these by removing this dongle, and correctly damping the cups, and the soundstage becomes more coherent. 



Good looking, sturdy closed headphone that is fairly comfortable and has a mostly well balanced, even sound except for a very problematic part of the upper mids that sticks out sorely and ruins them. However, this part may not bother everyone.  If it doesn't bother you ie if you're not sensitive to resonance or FR irregularities, and you are looking for a well balanced headphone erring on the side of being a bit basslite for the sake of clarity, and you want good soundstage these may be a good choice for you.  If you are not bothered by Grados you may not be bothered by this resonant peak.  however, Grados have much more natural tonality, for example vocals sound more life like.  I recently had an MS1 here and despite their colored signature they sound better than the K550 in every way except may soundstage width.  There's no plastic tonality in the MS1's signature. 


Here is a picture of the inside of the K550's cups.  The lack of damping here contributes to the resonant peak, but after spending time with my modded pair which has damped cups, I have found that it is also being caused by the driver itself.  Damping the cups helps, but doesn't fix the problem.  The small rubber thing in the middle of the light gray circle around the driver, is the "driver condom".  This seals around the driver and makes a small enclosure size behind it.  The light gray area are vents, though they seem to be closed off with solid plastic.


AKG K550 inside the earcups- stock. The small rubber thing in the middle of the light gray area around the driver, is the "driver dildo". The light gray area are vents, though they seem to be closed off with solid plastic.


I listened to these at least 6 different times at Best Buy. Used their equipment, use some of my portable gear. I had the same first-impression as you. Glad I'm not crazy. These aren't for me.
I'll skip these for sure now, thanks...
I'm surprised at your impression of the treble, I found it to be a piercing. Anyway, too bad you didn't like the K550's, seem to be vehemently recommended all over the hi-fi world.
Ps. Best buy sells K550's? Wow...
Did you read what I said about the upper mids? We probably just have different ideas about where the problem spot lies. To me, it sounds like the upper midrange. It effects many instruments that are not in the treble area. Cymbals on the other hand are not exaggerated or pronounced. The problem spot actually probably lies between the upper mids and lower treble.
I also listened to these at Best Buy (Magnolia carries them) and thought they sounded a bit odd. I don't think I have well trained ears, but what I experienced was very well put in your description of the upper mid-range: "plasticky resonant glare." Thanks RD!
I dunno, how long did you burn them in? and what amp did you use, IME AKGs need about 200 hours of burn in, and can sound any manner of strange before then. Also if they are anything like the K242HD, then they are transparent and tend to show the characteristics of whatever they are plugged into way above their own.
Burn in does not change the basic frequency response and has no effect on resonance. And amps/dacs don't have any effect on resonance either. But maybe if I burn them in for 30000 hours they will turn into Omega2's. That would be great. I'll report back in 2 years.
FWIW, these were measured after I wrote this review (I wrote this review, then sent my headphones to Purrin for measurement) and the measurements back up everything I have explained here.
Regardless, from my experience, with prolonged use the sound does change, and things do tighten up. As for the amps, it does matter, it matters a great deal, Most of the AKGs I have tried are transparent in their sonic characteristics, and tend to sound like whatever you plug them into, and this includes adding unwanted resonances which a headphone like Denons will just ignore, to be fair they pretty much dominate most sonic characteristics except for those induced by impedance mismatches.
I am sorry, but I do disagree with you on burn in, it may not change the frequency response, but it does change the sound, something I have noted multiple times with AKGs, but never with Denons. And pads wearing/ sculping to your head during the process also matters.
No, it does not fix resonance that is BS. It is impossible. It's coming from the driver and the enclosure and is unaffected by amp and source. Yes, amps do change the sound, but they can only improve on what is already there, they can't change the driver or enclosure properties, no amp will get rid of this resonant peak in the upper mids/lower treble. The best an amp can do is mask it to some degree, by rolling off upper frequencies, but then you'll really roll off the treble with these phones. And there's no amp that would do enough for me. Yes, burn in does something sometimes but it will never change something like this. It's absurd how everytime someone points out a problem with a headphone, everyone shouts "burn in! better amp and source!" Would be like blaming the tires for the handling of a Prius. Yes, I'm sure fancy tires would have some effect but it's hardly addressing the real problems.
"Most AKG's are transparent"? AKG's are headphones like everything else, and have their pros and cons. These K550's are certainly not transparent. Look at the graph if you don't believe my impressions. They add that coloration to every single album. Which means they are not transparent. And before you call me an AKG hater, I have owned more AKG's than all but a few HF'ers, and speak very highly of many of their vintage models.
My point was actually arguing the merits of burn-in or even mentioning the amps you used. You may have a fair point with the resonances, I don't doubt your critical listening ability. I will get the k550 and spend some serious time with it and then I will be able to confirm or deny your findings.
Transparent is a bad word, uncoloured doesn't exactly work either, not even Stax are truly transparent, but what I meant by it, is that unlike Denons which only minorly change depending on amp, the AKGs change a great deal, and display the sonic characteristics of the amp, thats what I meant by transparent, if you have a word that makes more sense, please tell me, because I haven't found a suitable descriptor for months now.
I'm not calling you a hater, although to be honest I do think you are taking my comments too personally, this is supposed to be a constructive debate, not an argument. And if anything I dislike Harmon Kordon more then you, I personally think its run by execs, which is why every headphone feels incomplete or has some issue, K701, most of the adaptations of the K240 (except the direct renames like the k242.)
I also disagree with the "better amp and source" zealots, synergy is more important, talking of which maybe we should take this convo to PM? and then respond when we have agreed.
I'm not taking it personally, I just strongly disagree with many of these assertions and think they cause problems in discussion of audio gear.
The K550 has a sound to it that it will impart on all amps used with it. So it's not transparent in that way either. It's got some good things going for it, so whether you like it or not will come down to how much it's one serious flaw bothers you. It bothered me quite a bit.
Mediocre when at their best. Painful at their worse (with the low treble ringing). Same experience as you.
Hey RD... Nice review - I like the contrarian views.
That said, could you tell me to what are you comparing these to? That is to say, there is no doubt that compared to an Audeze LCD2/3, these will be crappy. But how does this compare to something like a DT1350? Or a Senn HD25-1 II? Do the K550 bests them or fares worse when compared to headphones at a similar price point?
I'm back, spent a few days with it, burn't in IMO.
And you are correct, for such amazing strengths in a closed headphone (soundstage, imaging, isolation, leakage) it has a serious flaw, it is not really an issue in movies, but in music, it makes artists like Lana Del Rey unlistenable. The resonance drowns out wording, its a real shame, and since IMO you rate a headphone according to its biggest flaw that is not a subjective sound signature preference, this headphone is worth half its retail price. The flaw is that bad. I am disappointed, especially since it does most things so well and so clearly, it should not have shipped like this. 2 stars for music, 5 stars for movies
The DT1350 is better, even the bad sounding ones in just about every way but soundstage and comfort. I can't say about the HD25 since I don't have a lot of headtime with them, but would guess the same is true.
The M50 is also better in every way except soundstage. The only reason you'd prefer the K550 is if soundstage is a huge deal to you, or if you want a bass-lite sound signature AND you're not sensitive to resonant peaks in response. Technically speaking, the M50 is the better headphone in every way. Faster, cleaner decay, flatter FR, cheaper, less distortion, better isolation, better vocals, better bass response, etc.
Indeed, I had put the M50 on (because it was right next to the K550 at the Headroom table at T.H.E. SHOW) to heal myself from the stabbing pain of the K550. Evidently the K550 renders RadioHead and Nirvana recordings into utmost pain.
treble knob, I used it, a lot, like -40% but I thought that was just me, I tend to be treble sensitive - my only gripe with my D7000 atm
rhythmdevils, probably we have exact same pair of ears.
I bought k550 out of curiosity and everything you said about it is true. Returned it today.
Thank you.
Anyone who can get any pleasure from hearing high brass fanfares through these headphones is also likely to enjoy the sound of a dentist's drill gouging his teeth.
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