Burn-in Review: K701s #2896 vs #10073
Jan 8, 2007 at 5:56 AM Thread Starter Post #1 of 51


Headphoneus Supremus
Apr 12, 2004
[ Intro ]

For a long time, I'd been wanting to see if burn-in really exists for headphones, and not too long ago I jumped at the chance by ordering up another K701 on top of the one I already owned. Does burn-in really exist? While this probably won't turn skeptics into believers or believers into skeptics, I hope this is just as interesting for you guys as it was for me!

The K701 that I already owned was bought in April 2006 from HeadRoom and is #2896. The newer one was bought in November 2006 from BlueCraze and is #10073.

#2896 has now cleared 1,500 hours of usage. I've lost exact count of the number of hours on it so I'm estimating, but this number is a logical conclusion from inference. At this point, I think it's safe to say that burn-in has completed on #2896.

Prior to starting listening for this review, #10073 had absolutely zero hours on it. In order to reduce the effect of burn-in on #10073, I did not play my test tracks more than once - hence, reactions are based on immediate impressions rather than long drawn-out swapping. As a side-effect, this negated "placebo" to some extent.

[ Associated Components ]

To minimize the effect of alternating components (CDPs, amps, cables), only one setup was used:

Source: Arcam DiVA CD73 with Black Sand Violet Z1
Interconnect: Signal Cable Silver Resolution Analog w/ Eichmann bullets
Headphone amplifier: HeadAmp GS-1

For those unfamiliar with the GS-1, it's an amp that provides two headphone jacks, making it an ideal amp to use the two headphones with.

[ Test CD Tracks & Listening Impressions ]

Test tracks were played on #10073 first, and then on #2896, so as to maximize the potential for hearing differences/improvements.

- Soundstage:
Alison Krauss - "Sleep On" from Now That I've Found You
Jewel - "Standing Still," "Cleveland," & "The New Wild West" from This Way
Howard Shore - "Into The West" from Lord of the Rings: Return of the King

Compared to #2896, the soundstage on #10073 wasn't as deep, defined, and exact. In fact, there was a forwardness to it (not to be confused with forwardness in the frequency response) that made music seem like it was half the distance away compared to #2896.

Positioning of instruments was difficult to determine with #10073, and it seemed to blur the line between left and right. There was much more a sense of vertical soundstage rather than horizontal, and it also seemed blobby - a pocket of instruments off to the right, another pocket off to the left.

There was no sense of staring into blackness with #10073, which is a trait of #2896. A very fuzzy sense of space, and instruments sounded much closer. The distinctive airiness of #2896 completely did not exist on #10073 - #10073 sounded like it had been compacted and closed-in, as if from oppressive walls.

- Attack:
Jewel - "Serve The Ego" from This Way
Radiohead - "No Surprises" from OK Computer
Thievery Corporation - "The Karminsky Dance Experience" from The Outernational Sound

There wasn't really a sense of "lag" behind the fast, percussive notes on these tracks on #10073, but it was noticeably slower than #2896 - slow enough that the layer of clinks and tinks on "No Surprises" seemed like the notes were being cut in half. The tinks especially had a nasty tendency to sound incomplete on #10073, compared to #2896. #2896 was also able to easily render the licks and slaps of the drums on "Serve the Ego" and better convey the rhythm on the Thievery Corporation track. #10073 also lacked the "whink" of the high-pitched tinks on both "Serve The Ego" and "No Surprises."

In short, the attack wasn't fast enough on #10073 and it was pretty noticeable too.

- Decay:
Radiohead - "No Surprises" from OK Computer
Renee Fleming - "Meditation" from Thais

Decay was a bit longer on #10073 compared to #2896 - it held the trailing edge of sounds a bit longer. Only very marginally more though, as it still sounded like the K701's general decay behavior - it was still a bit unnaturally fast compared to other decays I've heard (like the ATH-AD2000's decay).

- Extreme Upper Treble (extension):
Orbital - "Way Out" & "Spare Parts Express" from Middle of Nowhere
Natalie Imbruglia - "Do You Love?" from White Lilies Island (the high harp run at 2:52)

Holy treble recession Batman. #10073 started petering out before 10 kHz. The highest-pitched effects & echo on the Orbital tracks were barely audible. It was much more noticeable on "Spare Parts Express" than "Way Out" due to that track's overload of high-pitched noise.

#10073 got barely any of the harp run on the Natalie Imbruglia track.

- Extreme Lower Bass (extension):
Massive Attack - "Angel" from Mezzanine
The Crystal Method - "Keep Hope Alive" from Vegas and "Murder" from Tweekend

No question about it, #2896 sounded like it reached lower than #10073. Neither has an amazing extension (they get soundly beaten by the ATH-AD2000), but #2896 managed to partially serve up the low bass drops, while #10073 sounded like it could barely crank it out - in comparison, that is. However, lest I take anything away from #10073, it was surprising that it was actually able to start digging down for the bass drop - I was expecting it wouldn't be able to. It seemed as if it was getting maybe the top-half of the bass drop.

Also there was a peculiarity here, as #10073 had a tad more signal strength on the opening bass line on "Angel." Fairly noticeable too.

- Mid-Bass Definition & Impact:
Future Sound of London - "Kai" from ISDN
The Crystal Method - "Vapor Trail" from Vegas

The mid-bass rhythm on FSOL's "Kai" was very blurred on #10073 - it was there, but not very strong, and hard to discern against the wash of other lower-bass sounds. #2896 had a much easier time - the throbbing/pulsating feel was much more apparent on it, and also a bit stronger. Definition here isn't one of the K701's strengths but #2896 managed to provide some tactility of the mid-bass rhythmic line, making it feel synth-y, whereas #10073 did not.

Amazingly, #10073 gave more relative strength on the "Vapor Trail" bass rhythms - both the backbone bopping (that starts at 0:11) AND the relentless crowd-rave-inducing thumper layer (that starts at 1:30).

However, neither K701 provided a satisfying thump or kick. Those who know the K701 know it's not for this kind of music, not even close.

- Mid-Range Warmth:
Jewel - "Break Me" from This Way
Massive Attack - "Teardrop" from Mezzanine
Portishead - "Western Eyes" from Portishead
Zero 7 - "Home" from When It Falls

All four tracks here sounded a clear cut warmer on #10073 than #2896, which I found very surprising. More of an "analog" kind of feel, with more lushness and fullness. Vocals sounded closer and more powerful, while instruments like guitar and kick drums had obviously more strength and provided a more tactile rhythm. Music overall was simply more energetic and lively on #10073.

I think I started preferring #10073 on this test, as it simply sounded more like the warm K601 in my collection. #2896 sounded thin and even somewhat hollow by comparison.

- Layer Separation:
Massive Attack - "Angel" from Mezzanine
Porcupine Tree - "Lazarus" from Deadwing
Radiohead - "Let Down" from OK Computer

It was clear #10073 had more difficulty with layer separation - mixes that grew increasingly complex also sounded more and more mushy and mashed-in. Turning down the volume seemed to help a little bit. Ultimately there was no contest here - #10073 simply wasn't doing what #2896 was effortlessly accomplishing. It was much harder to pick out a single instrument from the mix, and harder to focus the ears on any single layer in the music - they just tended to get "lost" in the mix on very complex passages.


I know this burn-in report isn't a completely fair assessment, as I was doing all the listening myself (having another person would have been ideal), but I was trying to be as psychologically fair to both headphones as possible. As far as I could tell, burn-in absolutely exists on the K701. #10073 sounded different enough from #2896 that it almost sounded like a different headphone in fact! Amazing what time can do to a headphone's sound signature. Knowing that the two were the same headphone, I'd peg an estimate that #10073 had approximately 80%-85% the sound of #2896, which isn't too bad all things considered.
Jan 8, 2007 at 7:14 AM Post #5 of 51
I wonder if the two headphones would measure the same if tested...
Jan 8, 2007 at 7:32 AM Post #6 of 51
I wonder if this is a case of different samples of the same model sounding different or if it genuinely needs burn-in. We'll see when the "burn-in" is completed on the new set.
Jan 8, 2007 at 12:54 PM Post #7 of 51
Thanks for a great review, something I've been thinking about doing myself!
Jan 8, 2007 at 4:02 PM Post #8 of 51
Great thing that you took the plunge!
That would be awesome if you could find a friend who is willing to help you do blind test to be realy sure of the results, now that, might shut the anti break in crew
Jan 8, 2007 at 4:16 PM Post #9 of 51
I've always beleived in burn in, but thanks for testing these out. I knew that mine sounded different in the ways you mentioned from how they sound now.

Lots of excuses will surface:
Can you scientifically measure it?
Different production run?
Did we really go to the moon?

Or could it be that burn in is simply real?
Jan 8, 2007 at 4:29 PM Post #10 of 51
This was well appreciated test. I believe in some degree of burn but I guess we can never know for sure if what you heard was a sample-to-sample difference due to production changes. To help alleviate that, now you have to run your new K701's for 1500 hours and then compare again

edit:I missed an opportunity to do the same test (I have two K701's bought new also)
Jan 8, 2007 at 4:29 PM Post #11 of 51
i'm not sure if it's burn-in or a different run of production that's giving the audible differences. could be one or the other, could be both. either way, hats off to you for buying a second set. i'll probably buy a 2nd of a headphone i love. knowing i have a replacement would put my mind at ease.
Jan 8, 2007 at 4:31 PM Post #12 of 51
Well-done, nicely written, very interesting study - I believe you did everything right to parse the differences between the phones. You did especially well to compare the two headphones using gear sensitive enough to render any possible differences. A good contribution to the debate, which seems to be resolving slowly but surely. Almost as good as a pre-/-post experimental design, which frankly I don't think is needed for this kind of issue. But perhaps you can have a few friends over to your place to bolster your results?

Of course, we're referring to headphone "break-in" (effecting headphone diaphragms), not "burn-in" (the subtler and much more controversial effect that's said to occur with some cables). It's an important distincton: some naysayers might try to negate your results for the wrong reasons.
Jan 8, 2007 at 5:04 PM Post #13 of 51
Where's the doc? We need some input from that Mr. Art Wells in here!
Did he not recently post about his impressions between a burned in K701 and brand new pair, saying there was absolutely and definitively no difference?

Anyway, great job Asr. Not only did you go out and buy the K601 as well as K501 for reviewing purposes, but you then purchased a second K701 for comparison! Takin' a few for the team, no doubt about that.
Jan 8, 2007 at 5:20 PM Post #14 of 51
Did you know which headphone was which while you reviews them? Did you simply write the impressions for headphone A and headphone B, or were you aware which ones were burned in?

I know the whole anti-burn in 'its all a placebo' thing seems ridiculous to some people, but in a world where a certain person can recieve the majority of the vote in a major election, I will never ever underestimate the power of self-delusion.
Jan 8, 2007 at 5:35 PM Post #15 of 51
wtg man, you must have some extra cash lying around to have $250 expriment, but I truly believed in burn-in all along, it is nice to get some more evidence to back it up, even if people can say it is subjective. Good Job

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