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AKG history - the introduction of the "parabolic" headphones (K 270, K 280). - Page 2

post #16 of 25

Thank you very much! Hmm, that's kinda lame. I thought they'd be a lot better considering Fitz said he'd keep a pair if he could. One less headphone to search for I guess.

post #17 of 25

Guys, how much would a pair of K270/80/90 cost?. I saw a K270 gone for 43$ in ebay last week (and i regret not biding for it)

post #18 of 25

I currently own the K340 and K240 Sextett, and I have owned the K141 silver (sextett drivers), original K140 silver, K280/90, K400, K500, K271 silver, K501, K701 and maybe some others I'm forgetting.  All of the vintage AKG's I have heard have had some of the best midrange of any dynamic in existence, IMO.  The Grado HP2 is also very good, but I honestly think the K240 Sextett might have the best midrange of any dynamic.  It's so rich and lifelike.  It has other faults though outside the midrange. 


So this is what is so surprising to me about the K280 and K290.  They seemed to improve on other designs in many ways, like soundstage, and I thought the treble was better then the Sextett and probably the bass as well, but then they messed up the thing they were always the best at.  It's hard to describe the sound because it was a while ago, but I think hollow or thin is the best I can do.  Vocals didn't have enough presence.  Which was weird because the rest of the response was quite rich and warm.  Maybe I didn't amp them well enough, but it didn't sound like something that would improve with better amping, it sounded like a FR issue or an artifact of the 2 drivers. 


But I shouldn't get you to be too critical of them, because if you're not hearing this, then that's a good thing!  Fitz liked them too, so you're not the only one.


I like the K340, but I think it has some similar issues in it's FR but in the upper midrange.  I suspect it's something between where the dynamic rolls off and the stat picks up, but I'm not sure about that since the stat is only producing very high frequencies AFAIK.  But there's just something uneven there, a dip in the response or something funky in that range.  IME.  Otherwise they are phenomenal.  A bit bright for my taste, but the combination of detail, speed and treble extension and the warmth of the dynamic driver is amazing.

Edited by rhythmdevils - 4/19/11 at 11:53am
post #19 of 25

I have a used pair of K270 headphones on order. In advance to actually listening to them tongue_smile.gif I thought I'd offer some information about multi-driver interference and comb-filtering in this context...


It is true that two separated sound sources *can* produce a comb-filter effect. This occurs when the distance from each driver to your ear is different, so sound from one driver reaches your ear in advance of the other driver. This can be a serious problem in high-performance loudspeaker design.


However in the case of the K270, the drivers are very small and closely-spaced. Therefore the difference in path length from the drivers to your ear is probably at most 1/2". This represents the wavelength of a 26kHz audio signal at sea level. Actually you get interference problems where the path length represents 1/2 the wavelength, so potentially there will be problems around 13kHz. Arranging the earcups so that the path lengths from the drivers to your ear are nearly identical will push interference problems into inaudible (and non-reproducible) frequencies. As long as the path lengths are similar, they will act as a single driver with double the surface area.


Regarding the "diffusor" plates over the drivers, these are commonly used to help achieve a uniform air load against the driver to give it a more uniform frequency response. The spacing of the holes in this case is quite small relative to the wavelengths of audio frequencies (rule of thumb: wavelength of 1 kHz tone is a little over a foot at sea level). Thus they are unlikely to produce interference problems except at very high frequencies, and even then only when you are listening well off the main listening axis of the driver.


Bottom line: comb filter problems from such closely-spaced drivers (or "diffusor" holes) can never descend into the midrange, let alone the bass regions. If the K270 has midrange problems then there must be a different cause...


Hope this helps clarify!





post #20 of 25

As a followup, I received my used K270's today and did a quick comparison against the Sennheiser HD280 Pro. This is in the context of making recordings.


Bass: the K270 carries a lot more weight, so you feel more bass, even though the Sennheisers have equal extension.

Midrange: related to the overly-tight bass, the Sennheiser upper-midrange is more prominent. The K270's are laid-back.

Treble: the Sennheisers are relatively bright, with what sounds like a broad peak in the 4khz - 8khz range. This emphasizes sibillance and makes them more "analytical", though they remain musical sounding.

Comfort/Fit: Even though the AKG's look larger and have heavier earcups, the Sennheiser ear openings are a better fit -- unless you happen to have perfectly round ears! Also while the AKG self-adjusting headband is clever, I much prefer being able to set the fit "manually". I think the rubberbands in my older AKGs are a bit loose so the earcups sit lower than I'd like.

Isolation: The AKG's seem to have an edge here, I think they produce more "quiet" and allow you to hear more detail in noisy environments.

Sensitivity: Though the impedance is similar (AKG: 75 ohm, HD280: 60 ohm), the AKG's require significantly higher driving voltage so may be less suited to portable devices.


In summary I like the K270 sound. It is a good counter-point to the HD280. I'd prefer the HD280 for monitoring, to help focus on vocal flaws etc. I'd prefer the K270 for preliminary mixing and for everyday listening. I found them musical and natural-sounding and didn't notice any significant midrange flaws. They are probably lacking in ultimate soundstaging and tonal neutrality, but they are among the better closed-back phones.


Bear in mind that this is a first impression, and that I lived with the HD280's happily for everyday listening before switching to HD580's many years ago.




Edited by rgonzale - 6/9/11 at 7:37pm
post #21 of 25

I agree about the AKG headband.  My K240DF has like new elastics and it's a bit uncomfortable because the headband is constantly pulling up on the ear cups.  My ear lobes are the only thing keeping them in place.  All my other K2xx have worn out elastics and they're comfortable.

post #22 of 25
Originally Posted by Ishcabible View Post

Thank you very much! Hmm, that's kinda lame. I thought they'd be a lot better considering Fitz said he'd keep a pair if he could. One less headphone to search for I guess.

I somehow missed this post.  I believe the one Fitz liked was the multichannel K290.

post #23 of 25
Thread Starter 

@rgonzale: Great Posts!


Good point about the wavelengths.


The distance between the outer edges of the transducers seems to be around 5 cm / 1.9 inches, but due to the very close proximity to the ear, the results of the interference pattern will probably be quite different from a loudspeakers using a similar configuration.



Your comparison to the HD 280 is quite interesting as well... It also shows how the perceived sound of headphones can depend on the person using them.


Some people seem to think the HD 280 is bass heavy while others call it neutral (I have no experience with them).


This article from a German studio magazine seems to consider the HD 280 significantly more "bassy" than the K 270 (and even the K 240 S, for that matter):





(if you're really interested, I can translate some parts of it).





I always found the headphones more comfortable with new elastics because they didn't rest on the top of my ears as much :-)


On the AKG forums, one guy even complained that his K271s with their auto-mute feature didn't play when he put them on. His head was too small to put enough tension on the inner headband in order to activate the "on" switch. He ended up padding them with foam, I think.

post #24 of 25

don't know how I missed this thread. I have long owned an AKG 280 parabolic (75 ohm) and currently use it for gaming because its spatial characteristics help with in-game orientation. I don't think it's competitive with newer audiophile headphones, but when I got it back in the late 80s it made me proud...

post #25 of 25
This morning I bought a pair of k-270s from eBay. Would a fiio e11 work well with these? iPhone direct drive seems like a f no being 75 ohms and 4 speakers.

Update got the k270s in, direct driving off iPhone, taking everything iPhone can give but is pretty loud, damn good sound, flat, I mean flllaaaaaatt. Bass can actually slam damn good if the song has it. Perfect, but man a weird cup interior design, I've never seen anything like this before
Edited by droido256 - 3/13/13 at 3:23pm
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