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post #136 of 231

Hi everybody, proud new owner of a K702.


I'm amping it with a Icon HDP and it sounds decent, although compared to the other cans I have, a little "thin", and the upper mids are too strong for my taste, a little aggressive.


The bass is almost perfect, very tight and natural. It could use a little bit more punch, but it's already great.


The "reference" on the name is not by accident, really. They have the better neutral sound I've ever heard on headphones.


The soundstage makes me a little dizzy though, actually I'm not quite sure if its the soundstage or the way they press my head in certain points. biggrin.gif


Because my new amp is going to be a DNA Stratus and Donald made it with them in mind, I'm looking for a K1000 on the ads, I hope to get a < serial # 4000.

post #137 of 231

^ The word 'neutral' is a big one. The frequency response of the K 702 (according to HeadRoom; but you can run a sine sweep for yourself and most likely hear peaks and dips) isn't flat, so clearly they're colored headphones. It's the same deal with the K 240 DF I was talking about a few days ago; one can find many posts on head-fi alone where people speculate that the DF must have a flat frequency response because they sound 'so neutral'. But of course, the DF have a response far from neutral.


And yet, the DF (as I'm sure the K 702 as well) sound neutral. It's weird. Same thing with a bunch of other headphones people perceive as neutral.


Maybe it has something to do with getting the most important frequencies (the ones used for speech?) relatively flat, and the rest can be anything, and the phones would still be heard as neutral. Who knows.

Edited by vid - 7/21/12 at 5:32am
post #138 of 231
well of course. it's headphones. not speakers we're talking about. most IEM's are considered ''natural'' sounding for the very reason on how they are curved in the response to represent a flat speaker system in a diffused field. take in mind though akg compensations when they measure their headphones are completely different compared to tyll's,headroom,golden ears,ect. measuring method so there is no right and wrong to be exact. just what you hear and what you like. even though the DF's have their flaws i still find myself everytime i put them on is they sound more right than most other things i heard,especially their midrange.

the k702 measuring wise is much better over the df's but i still find the k701/702's not sounding as nice as my df's. just for some reason my df's and sextetts just has that ''magic'' where it's unexplained especially when it comes to vocals. even most stax i been experiencing lately hasn't given me that ''magic'' or emotional connection when it comes to the midrange. only other thing i love is my speakers in my treated room when it comes to midrange.
post #139 of 231

Finding a proper explanation of the diffuse field curve is a pain. All the free sources I've ever found seem either incomplete or ambiguous, and the research papers seem to never be free to view. Grr.


To the best of my knowledge anyway, the diffuse field curve represents the curve that a pair of headphones should measure out as (to supposedly produce a natural sound) when that measurement is taken at the eardrum of the listener (so including the effects of the ear's anatomy). Also to the best of my knowledge, a pair of headphones perfectly conforming to the diffuse field curve for a specific ear should sound totally flat to the listener possessing that ear.


Thus, if you do a sine sweep and hear any deviations in sound level, you should be getting a colored sound to your ear in regards to the original purpose of the diffuse field curve.


With my ear, I definitely get deviations with the DF, though mostly not below 2 kHz or so. Above that, quite a lot - and yet they sound neutral despite that. Most human speech sounds are below 3 kHz, which is why I mentioned those as possibly being the important frequencies to have flat to ensure a perception of neutrality (I'd imagine the brain is especially keen towards anything in those frequencies because of the importance of speech for humans, but that's a guess).

Edited by vid - 7/21/12 at 1:12pm
post #140 of 231
thing is it's hard trusting sine weeps cause lot of times they can cause harmonic distortion. that's why it's pointless to use sine waves to test you're hearing ability as well(you saw that crap in that one thread where people believed they had super man hearing,ect). i just listen to music mostly when i test speakers and headphones. only time i might use sine sweep is balance checking if i'm modding a pair of headphones.

for the diffused field. well, akg did it by having pair of flat frequency response mics 6'' away from the head dummy in a diffused field cause they believed that distancing the mic atleast 6'' away will offer a more realistic speaker like response and they played flat frequency speakers in an echo chamber using 2nd(or 3rd? i forgot) octave pink noise to measure and alter the frequency response of the driver. of course they probably had a well respected audio engineer to test it by ear maybe to give his/her final touches/inspect it and done. this is just guessing here about the last part but rest i'm pretty certain.

other headphones use their own way of measuring diffused-field so i have no idea on that part.
post #141 of 231

Wouldn't you be able to hear whether or not you're getting distortion? If you have enough harmonic distortion to affect the amplitude so much as to skew the response, surely you'd hear that it's not a pure wave? And so if you hear a pure wave, you know it's relatively free of distortions and thus reliable? Also, why would harmonic distortion affect sine sweeps specifically, when any sound (like music) is made up of pure sine waves as well? Just wondering, since I don't know this stuff at all.


But I'm not exactly sure how you'd get the HRTF when the microphone is six inches away from the ear either, though... But in any case, to my understanding, you can only define the diffuse field curve for one specific ear (whether that be an 'average' one or not). So having a diffuse field equalized response guarantees only that you get an approximation of that curve (which in itself is an approximation) with your particular ear (unless your ear is physically the same as the one the engineers used, which is unlikely), and so deviations are probable.

Edited by vid - 7/22/12 at 3:43am
post #142 of 231
good question. i do not know how to exactly explain it but most people can't tell if they're getting harmonic distortion or not unless it's very high and odd case lot of things cause harmonics in sound and it's certain harmonics people like and don't. for the sine wave genrator. it's most likely cause of software itself and of course your dac. lot of times is can be harmonics if using software like singen cause how the softwar processes and sends the signal maybe. can't say for certain,sorry.

the mics are positioned/toed in like pair of speakers from the head dummy. i had a demonstration document somewhere on my other computer but i don't know if i deleted it or something else. they did it the same way in a free-field with the sextetts but instead using different method of tuning. i doubt akg...i mean harman akg doesn't do it that way anymore though. they probably use computers to fine tune the driver nowadays. the head dummy if don't know is from doing measurement studies of thousands of individuals ears and molded for best compensation to sound ''alike'' to most people. that's the whole point of things like ''diffused-field'' and ''free-field''. was meant for monitoring purposes to sound like monitor ''speakers'' so of course there is gonna be dips and peaks at certain frequencies. common sense really. also certain dips make other frequencies sound louder than others and of course human hearing is not ''flat''.
post #143 of 231

The ear canal resonates a spike to all sounds at ~3 kHz, but we don't walk around constantly perceiving a huge peak at that range in every sound; our relative yardstick of a neutral sound includes that peak. To my understanding, a diffuse field equalized headphone should produce sound that, among other things, will measure at the eardrum as having that exact peak (given the supposed direction of the sound) and no more/less; anything extra would be perceived as a peak or dip rather than neutral. But the problem is, the location of that resonance peak depends on the size of the ear, and since your ear is most likely not identical to the 'average' one, the headphones won't get that peak quite right for you. (That they take the average of even billions of ears still means that the result is just one very specific ear that they equalize to in the end, i.e. one curve.)


I'm not trying to rag on diffuse field, though. The DF do sound natural and the soundstage is somewhat speaker-like, curiously. Yet, even though they sound natural, they also sound bright, which is why it's interesting. Like you can get away with a colored sound in other parts of the frequency range as long as some other more important parts are neutral. (The DF diffuse field curve seems a bit odd. It emphasizes a peak/hump around 5 kHz, which I've seen in some diffuse field curves but which apparently isn't the norm. Maybe it was the oldschool way to do it, I've no idea.)

post #144 of 231
post #145 of 231

cant wait to get my k550 my first pair of over $50 headphones

post #146 of 231

I took the K 240 DF drivers out of their DF cups and put them in K 241 cups. The K 241 uses the exact same cup and baffle design as the very first DFs and Monitors, whereas the later iterations of DF/Monitor use cheaper sound port designs - like my DF.


Below is the raw (uncompensated) graph of before/after. Blue line is the DF drivers in the DF cup; black line is DF drivers in the K 241 cup.



I'm not a fan of the extra brightness at ~3 kHz nor of the slight upper bass hump, but what I do like is the increased bass extension - the old graph starts dipping at 100 Hz (very early), while the new graph does so only at 60 Hz. This is evident in music listening as well; the bass goes deeper than it did before.


I have to say, the DF I've got (from the '90s maybe?) seems exceptionally cheap in its construction compared to the late-'70s K 241... The plastic inside the cups looks very cheap and, more surprisingly, just about all the solder joints were dull. Kinda strange.

post #147 of 231
Thread Starter 
Originally Posted by DGriff0400 View Post

Can't wait to get my k550 my first pair of over $50 headphones

Best price on the AKG K550 is from Thomann in Europe, even with the $36 shipping charge.

Not sure if Harmon/AKG USA honors warranties from AKGs purchased in Europe.

post #148 of 231

CSD plots for the mod from two posts up where I put the drivers from a K 240 DF (with small sound ports) into K 241 cups (big sound ports). Graphs are aligned at 984 Hz.


Regular DF:


DF in K 241 cups:


Two small ridges developed in the upper treble around 15 kHz and up, though they are low in level and quite high up in frequency. The positive effect is that the mids are noticeably smoother and the ridge at 4.7 kHz is gone.

Edited by vid - 9/29/12 at 5:11pm
post #149 of 231
I think my signature says it all for me...
post #150 of 231

Also, regardless of what the graphs say, the K 702s sound flatter to my ears than other "flat" headphones like hd 600 and dt 880


I think people are too used to speaker bass vs real life bass...

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