AKG K7XX (Massdrop) Measurement and Succinct Review

Discussion in 'Headphone Measurements' started by purr1n, Dec 28, 2015.

  1. purr1n

    purr1n Finding his inner redneck

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    AKG K7XX (Massdrop) Measurement and Succinct Review
    photoakg2.jpg

    OK, it's really the AKG 7XX, but I thought seven triple-X sounded more interesting. A huge huge thanks to Massdrop Will+Danny for supporting our community. Yes, the box actually says 7XX. I cannot confirm or deny if it is the 702 or 712 or 701. I really don't know. I'm not sure how much this unit is going to drop for, but I'm getting some indications this might be quite the deal considering what I am about to say.

    I'm going to be very straightforward with this one. Taking into account what I think the drop price may be, I really love this headphone. It is not perfect, there are some minor issues, but overall it is well balanced and works for a variety of music. It even passed the MFSL Nirvana Lithium test. Those of you may recall years ago when I listened to this same track with K550s (the early ones with the spiked treble) and had to jump out of my seat and rip them off my head. Well I assure you this is not the case here.

    The 7XX do not sound lean or cold like the early K701s. The 7XX has a warm full bodied sound with a slight hint of glare on metal percussion. There's definitely a broad elevation in the bass the balances out and helps mask a lower-mid treble bump. Even then, the nature of the bump seems mild. It's evident, but isn't difficult. And the rest of the treble is on the rough side, it could be smoother, just not as smooth as a high quality silk dome tweeter. I'm just nitpicking here. That's what I do.

    Overall, I really do like the K701's tonal balance. However, what impresses me even more is it's resolving capability. It's pretty darn good. Good articulation. Good attack. Good clarity except in the deepest bass. These are the traits that I know drew lots of people to the K701. The last headphone I had my hands on was the Z7, and the Z7, even with mods, sounded soft in comparison.
    7xxx box.JPG
    7xxx hp.JPG

    1/27/2015 update:

    Q: Now that the hyper is over, how to the K7XX compare against the venerable HD600?
    A: K7XX are complementary / different from HD600. Better quality bass, but poorer treble, no upper vocal peakage, but lower treble peakage. It's really going to depend upon your sensibilities. Personally, I've opted for the K7XX (I had to chance to get the HD600). There are good arguments either way.

    MEASUREMENTS

    K7XX L.gif
    right.gif
    K7XX CSD L.gif
    rightcsd.gif

    DRIVER MATCHING
    K7XXLandR.png

    ADDITIONAL MEASUREMENTS / VISUALIZATIONS - R CHANNEL ONLY
    K7XX R HD.jpg
    K7XX.jpg

     
    Last edited: Apr 26, 2016
    zobel likes this.
  2. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Here be my measurements of the K7XX. I'm guessing unit-to-unit variation is pretty low, but I did want to point out this is not the exact same unit that has been measured here already. I am also using a smaller tri-flange tip for my in-ear mic, so I am able to shove it in my gross ear hole further than before. This primarily boosts the treble measurements relative to my prior setup, but in a way that should be more accurate.

    Frequency response is not too surprising. Overall fairly balanced with a bit of a broad, low-end emphasis and some uneven, sometimes peaky treble. In my listening tests, I thought the lower-end warmth did help balance out the treble, but it wasn't quite enough to my ears. Channel matching is excellent.

    Distortion results are pretty good and low when 1KHz is calibrated to 90dB. Push it much further than that, though, and distortion rises rapidly.

    CSDs are pretty clean with the left driver exhibiting slight ringing around 1kHz and the right driver around 2KHz. The slight ringing in the upper-most regions is probably an artifact of some sort. Overall pretty decent and nothing worth being concerned about.

    Raw measurements were a bit finicky and were primarily determined by subtle mic placement and depth differences. Regardless, the end results averaged out well. This headphone is actually quite a consistent performer.

    Last measurement shows what happens when you put some 1/4" open-cell foam, the grey, medium density type that I've linked in other threads before, in front of the driver as I mentioned above. It's not perfect, but it does sound noticeably smoother and more relaxed to my ears than stock.
     

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  3. ultrabike

    ultrabike Measurbator - Admin

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    Alright, so here are some data points. First I almost never listen at loudness levels equivalent to 90 dB using a tone, much less 100 dB. Some weird high dynamic range song might come along, but even then most stuff is pretty compressed anyway.

    With a 90 dB tone sweep these are the distortion plots:

    k7xx_distortion_right_90db.png
    k7xx_distortion_right_100db.png

    Now, using a 30 Hz tone at 100 dB I checked the driver: It vibrated very little and that was it. No deformation or crap like that.

    100 dB is pretty loud. My 2i2 volume knob was almost all the way up, and I don't go far off half of what the 2i2 can give with these cans. Maybe 3 o'clock at most on some tracks (6 o'clock is mute, 12 o'clock is half...).

    At 90 dB, the 2i2 was pushing about 0.263 Vrms or about 1.1 mW (also rms - cans are about 60 ohm). That jives well with Tyll's numbers of 0.84 mW to get 90 dB for the similar K712.

    At 100 dB, the 2i2 was pushing about 0.8 Vrms or about 11 mW, which serves as a sanity check for the above.

    This means that 22 mW one should expect about 103 dB and for 220 mW about 113 dB. Those numbers are kind of crazy loud for a 30 Hz sine wave. Given the distortion results at 100 dB, going that far may indeed result in driver damage on the long run. Don't do it. My 2i2 can't do it actually, but some other amps have plenty of power reserves and have no problem blowing up these and most other cans to pieces. If listening to music at these levels, hearing can give the ghost as well.

    All this is not unique to the 7xx. 100 dB on HD600s, Grados, or whatever other open dynamic headphone should yield significant and apparent distortion in low frequencies. Dialing the amp to deliver > 110 dB at low frequencies may damage some of these cans as well, and IMO don't say much about the practical capabilities of the cans.
     
  4. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Not to be pedantic, but these are the K7XX, right?

    I ordered these earlier this year, but found the lower treble to be to harsh. I tried a variety of mods, but couldn't get them to where I liked them. Good bass, clear open sound otherwise.

    I have the HD650s now and am much happier.
     
  5. purr1n

    purr1n Finding his inner redneck

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  6. gixxerwimp

    gixxerwimp Professional tricycle rider

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    At the risk of being pedantic again, Massdrop claims that the K7XX is their version of the K702 65th Annie.
    https://www.massdrop.com/buy/akg-k7xx-massdrop-first-edition-headphones

    I heard the K712 briefly it sounded much more "together" than the K7XX, but it was just a quick impression from memory. I think I also compared with K/Q701/2 while at the store and thought they sounded similar to the K7XX.
     
  7. MoZo1971

    MoZo1971 Rando

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    Purin, Gixxerwimp, based on your experience and measurements would you say the HD650 are a singnificant upgrade VS the K7XX? I will soon have Bifrost Multibit and I have a Asgard 2. I like the K7XX but I too find a certain harshness in treble rich music. The HD650 seem like a valid next step. Your feedback will be greatly appreciated!
     
  8. gixxerwimp

    gixxerwimp Professional tricycle rider

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    For my personal tastes, if the K7XX and HD650 had babies, an "HK750" withs be just about perfect. From memory, the HD650 is a big step up from the K7XX in mids/treble clarity, resolution and engagement. It really does draw you into the music. And that's out of my humble iFi micro iDSD. Should sound even better out of your Schiit stack.

    But if you want the bass response of the K7XX, you'll have to EQ the HD650 (ramping up from 60-20Hz for me). It has pretty good mid-bass, so depending what you listen to it might be OK.

    Best to have a listen for yourself.
     
  9. MoZo1971

    MoZo1971 Rando

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    Thank you gixxerwimp for taking the time to answer ... I will be giving them a listen!
     
  10. ginsbu

    ginsbu Rando

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    I have the K7XX and HD600 on my desk right now and agree with your assessment in this case too. The HD650 obviously won't be quite as bright as the HD600, but your description is apt nonetheless. FWIW, I was never bothered by the K7XX treble, but the HD600's treble is decidedly smoother and clearer. My complaints against the K7XX were with some muddiness in the overemphasized upper bass / lower mids, and some coloration through the mids / upper mids. I don't dislike the K7XX, but the HD600 is clearly better to my ears in almost all respects. Both driven by an M2/M2 stack here.
     
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  11. zobel

    zobel Rando

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    Thanks for this review Purr1n. I have had the HD600 since it came on the market in the 90s. I have enjoyed it for what, 18 years? I also have the AKG K7XX, since it first dropped. I agree with you here, it is a matter of preferred presentation, but I too find myself not picking up the 600's anymore, even with upscale amplification (the Cavalli MCTH, Schiit Jotunheim, and lossless sources through good dacs ( the bifrost multibit now my fav.) I need the bass of the AKG, and don't miss the veiled quality of the Senn. , but prefer the overall presentation of the AKG with these same set-ups. The AkG are livelier with lesser amps, and down-scale (did I coin a new phrase?)..much better than the 600's IMO. The Focal Clear wipes them both out, without any question for my ears.
     
  12. zobel

    zobel Rando

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    But...for value...It goes without, or with, saying, AKG RULES here. The Massdrop K7XX, red or silver, are screaming values IMO.
     
  13. IAmTheLampizator

    IAmTheLampizator Rando

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    Thanks for the measurements! More than two years later, I'm looking at these again.

    I think one of the main selling points of the K7XX is its wide soundstage - of the whole series, even. That's not something you will ever get with Senn's, amped well or not.

    For me, I feel like the HD6XX's (and 650's) are known for their vocal prowess. For instrumental, the K7XX sound less colored to me.

    It's all down to what you listen to! And what makes you happy :)
     
  14. Shazb0t

    Shazb0t Rando

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    I have a Q701 with bass port mod that I go back to every once in awhile. It always surprises me with how good it sounds! This series headphone is definitely a great choice on a tight budget with it's own unique strengths.
     
  15. Scubadude

    Scubadude Almost "Made"

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    Last heard the K7XX several years ago and I was a little underwhelmed. I picked up a nice lightly used one last week as a modern reference as I plan to explore vintage AKG's. Playing through the relatively unknown KingRex Headquarters amp it sounds better than I remember ... Not overly hot and dry; instead it is nicely detailed and has good clarity, with a firm bottom end and reasonable timing. I think this one is going to stick around for a while.
     
  16. IAmTheLampizator

    IAmTheLampizator Rando

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    The amp selections are so difficult. Everything I pair it with doesn't drive it well.

    I mean, I guess some of the Schiit stuff would probably do the trick (except the Magni, didn't like that one) but I guess I don't own those either :D
     

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