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History of the AKG K1000?

Discussion in 'High-end Audio Forum' started by mikeg, Jan 30, 2004.
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  1. hrklg01 Contributor
    To your questions:
    "1. Do you still work for AKG? If not, when did you stop working (approximately)?" 
    I stopped working for AKG End 1989 and started at Philips sound solutions - later NXP and nowadays Knowles, busy with micro speakers for mobile devices..
    "2. What do you think of the current AKG direction under HarmonKardon (for headphones)?"
    Sorry, no idea, I did not follow AKG because all my previous friends and colleagues left also and some went with me to Philips.
    "3. Are you still into headphones? What pairs do you own?"
    I'm owning the K1000 together with the BAP1000 as amp and the K240DF, and some inear headphone prototypes from Philips which we ccreated for Sony, Nokia, Apple, Rim and others. But Philips stopped that business after 5 years due to business reasons.
    "4. Were you involved at all with the K340. Those are certainly an interesting story in themselves as well."
    When the K340 was developed, it was approx. 1976, I was busy with dynamic microphones - the D 320 series - therefore I was involved in measurement issues with specific artificial ears only for the K340.
  2. Blackmore
     Thank you for sharing with us.
  3. Deep Funk
    I loved the K240 DFs. Even Blackmore is back for this thread [​IMG]...
  4. Mkubota1 Contributor
    I don't think I've ever come across anything so amazing on this forum-  a K1000 thread resurrected after EIGHT YEARS by one of its principal designers???
    This is one of the reasons why I love this headphone so much.  I get warm quickly and so I am limited to velour pads and super-expensive leather like the kind on STAX and Audeze headphones.  I can wear my K1000s all day long, although on occasion I do feel the pressure of the pads.
    We had a mini-meet the other weekend and although the company these headphones were in was pretty incredible (SR-007/9, HE-6, LCD-2, HD800, etc.), we all agreed that while the K1000s could not do rock or pop music very well, they were (still) unsurpassed in many vocal and acoustic genres.  To date, there is nothing like them.
    • There has been lots of talk on this forum (and others) about bass-light and bass-heavy versions of these headphones.  And I have seen photos of what appear to be slightly different drivers in regards to this.  Do you know anything about this?
    • You mentioned that you listen to K1000s with the BAP1000.  Do you have any other recommendations (general or specific) for amplification?  And any other advice on how to get the best listening experience out of these?  
    Thank you for your time!
  5. qazxsw80
    1.'d like to ask your about AKG K1000.When I read specifications i saw:
    Max. input power   1000 mW (measured with test noise to DIN 45582), equivalent to approx. 100 dB
    This means these headphones can't sound louder 100dB and for example if I want  105db they'll break down or probably just THD would be very high?  It's strange to see the limit like this, many headphones can sound much louder. Why do they have this border?
    2.And what about sensitivity? I was impossible to increase it because of weak magnets in the past?Actually, it's much more difficult to drive many old Akg's headphones than phones from other manufacturers...
    3.Also I have a question about Bap1000. How good is it?  Maybe cross feed algorithms have improved to the point where BAP1000 technology is now available for free via music player plugins? Is it realy works?
    4.Did you develop another Akg's phones besides K1000 and Df? Mabe famous Sextett?
  6. Amarphael
    Were there any cost limitations to the design or was it really a "Just show us waht you can do" project?
    Do you think it can be improved upon with today's materials? Such as different membrane material perhaps or greater magnetic flux.
  7. hrklg01 Contributor
    Comment to Deep Funk:
    The quite clean sound of DF adjusted headphones are not really great for all type of music styles. We at AKG recognized this of course also in the very past, this was the reason why we had headphones differently tuned. My personal taste is very clear for the diffuse field. May be this is because I love music from Pink Floud and similar sound....
    Comment to Amarphael:
    There was absolute no cost limits for the development of the K1000. This was the first time for AKG to go this approach. The reason was, that we thre developers (Helmut, Ewald, and me Heinz) started the project "under the floor" (meaning without order). Later the official development order came after first listening tests to first K1000 prototypes.
    Of course the product could be improved reasonable. This is because:
    a) The membrane material at this time was not brittle enough. We solved this problem by using "shellack" surrounding the coil at the membrane surface to stiffen this area.
    b) The damping within the membrane material (it's a 5 layer type) is not as high as it would be ideal. Today's very this materials can offer this very easily.
    c) The magnet force was at that time approx. 1/2 of today. This could be spent into higher efficiency and/or into damping.
    d) Mechanic precision was not on the level of today. This would add another efficiency and/or lower resonace frequency = more low freuency level.
    e) The mechanics to fix to the head was very "fast developed" at that time. In other words, we could do this much more comfortable today by Gel filled cushions.
    f) The amplifier to convert standard headphone output towards K1000 suitability could be integrated into the headphone - may be a small battery should be added to the cable.... But I'm not an electronic expert - sorry!
    g) When discussing the points with experts, I'm sure it could be added another major points.......
    Comment to Qazxsw80:
    To specifications I must say: "do not trust!"  :wink:
    It is very difficult even for experts to compare the performance of speakers of headphone with specifications. The reason is, that the signals are so different and the sensor type and position (microphone or various artificial ears) and of course: there is also some commercial idea behind...
    However: The K1000 is a very simple dynamic system with a very very low Q-factor. This implement, that the fundamental resonance frequency is offering the low frequency level only. I case of the K1000 it was originally designed to 25Hz and of course below would be a slope of 12 dB / octave. The problem was, that to manufacture those dynamic drivers, it would be needed much higher precision than at that time was available. Otherwise the fall off rate would be high. Therfore - after my leave from AKG - it was decided, to move the f0 to 35 and later to 40Hz. Ths means approx. 10 dB less fundamental bass level. Therefore it is very important when you compare comments from other users of the K1000 that you inform yourself from which production date it is...
    But your question concentrate very much more to high dynamic power for the headset... I guess. If so, the right answer would be:
    Any dynamic speaker slope down with 12dB / octave below the fundamental resonance. The K1000 is designed in a way that only the movement of the coil is the limitting factor. The thermical limits of the coil as well as the mechanic limits of the membrane far above. In other words: If you listen (and it's the best to listen to the K1000 outside - you could hear it much better when clipping) to the headphone with music which offer high bass level and you drive it by the amplifier sharp before clipping, it's ok! The THD is always very low and when driven extreme, it has "only" a second harmonic destortion which human cannot hear very much...
    When really measuring the K1000 on your ear entrance playing music, I'm sure your can measure approximate 115dB without any significant THD.
    The sensitivity of the K1000 is poor. True! This was the design drawback. Yes, it could be theoretically improved today by - may be 6dB - but still too less if you compare traditional headphones.
    To drive the K1000 no special amplifier is needed, because it's relative high impedance - high for speakers... :)
    Any reasonanble quality amplifier can drive it. The BAP 1000 is a sound processor for different ear adjustments. The amp inside is simple standard.
    Sorry, my major tast at AKG was to develop dynamic microphones for musicians. The K1000 was an experiment, because of my know how for very light mass membranes....
    Comment to Mkubota1:
    To my interpretation bass high or bass light is very much depending on:
    a) thightness to the ear channel and b) the acoustic adjustment itself.
    The K1000 was always developed towards reproducing the sound as ideal far field speakers - as it is a quite far field located speaker and very open designed and nothing more.
    As posted before, Du to the very uncritical impedance of the K1000, it does not matter much what amplifier is used as long as it offer enough voltage without distortion and a flat frequency response.
    More questions?
    BR heinz
    Baycode likes this.
  8. Mkubota1 Contributor
    Amazing.  I'm guessing there are not many headphones where you can say "there was no cost limit to develop them".  And the fact that there is so much more technology today that would lead to improvements is almost agonizing.
    Hmmm... so this definitely sounds like there was a bass-heavy and bass-light version.
    Mr. Heinz-
    -Your comment on the bass (f0) implies that they made three versions.  Did the first 25Hz version ever make it into production, or did they move to 35Hz before the initial release?  And does this driver change correlate with the exterior wooden box of the headphones?  Some speculate that the black box (earlier version) is the bass heavy (25/35Hz?) and the tan box is the 40Hz (later) version.  
    -Could these be the changes that you were referring to?  http://www.head-fi.org/t/500167/k1000-bass-heavy-light-fact-or-fiction/45#post_7237993  Also, do you know if the changes were just limited to the diaphragm, or were there also changes to other things (dampening material, electronics, etc.)?
    Thank you again for your time... I'm still amazed that we're chatting with one of the creators of this legendary headphone.
  9. Blackmore
    You should attend to one of the possible meets in the future, would be totally out of this world for headphones users, especially for those who adore AKG K1000 to meet one of its creators.
    Mr. Heinz, how are the things going with the rest of the developing group, I mean Helmut and Ewald?
    Do you think that to start a new production of K1000 is possible today, especially by keeping the costs at the healthy level? If the most costly developing part are already done, what kind of problems are there that will make this not possible, any idea?
  10. arnaud Contributor
    Dear Heinz,
    First, it's absolutely fantastic that you joined this board and made yourself available to discuss previous designs. A great many thanks for this and looking forward to your future posts.
    You mention about your strong preference toward DF equalized headphones. I was wondering how dependent this is from the recording head you used for the measurement? In particular, any two heads with different pinnea shape / acoustic impedance will yield different DF eq. curve. Is it because the recording head doesn't really matter as long as you are using the right calibration curve to assess the headphones performance (this is my intuitive feel and it is the only logical answer if I think about the huge variations in head shapes among the population). Or is it because you get much more variation between say FF (like +/-30 degrees in front plane) and DF than you get between any two measuring devices?
    Also, in your honest opinion, do you think the K1000 has its own set of compromises compared to a more traditional circumaural headphone? Among other things:
    - potential large amounts of distortion at low frequency because the driver has to be excessively pushed to compensate for the front/back cancellation.
    - inevitable presence of breakup modes in a large diaphragm at mid/high frequencies
    - diffraction from the edge of the baffle (which is less of a problem when the driver loads a cup which is then terminated by an absorptive foam) which probably can yield to some "speaker in front of the ears feeling" if the mind gets ticked by this
    Last, one would think that the easiest way to handle the poor efficiency of an unbaffled driver is to either add acoustic damping to the back side or possibly move to a 2 way design to tilt down the mid/highs response to balance out more the sound at the ear canal entrance. Was it something considered and dropped because it caused more harm than good?
  11. Amarphael
    X2 on both accounts. Nowdays AKG's 'flagship' is exactly the opposite direction, The 'best' sound for less buck as possible. Which was  great with the original K701 but with the FOURTH revision coming in it looks like a long worn-out filler for the real thing to come.
  12. Deep Funk
    I agree. The DF's found a new home. These days the K500 has taken its place alongside the HD250 II. I had to pass up on a K1000 but if ever I get lucky I'll consider the gamble...
  13. hrklg01 Contributor
    hello to all members,
    sorry for the late response due to busy time...
    Try to answer as good as possible:
    I like personally the HD250 II mainly because it sounds very good to my ears and it's good to wear... For me better than the K1000...
    But I do not know the background of the acoustic adjustment of it. And the acoustics cannot compete with the K1000 in respect to averaging human ears.
    The DF design of the K1000 is not depending on the users ear. This is exacly the great thing what I like so much!
    Imagnie, the K1000 is almost acoustically "invisible" ... this is the reason why it works so well. It's just "open" like ideal speakers in far field inside a standard listening room.
    This means in the same time, that the design is not dependent on the ear or on the artificial ear. ... This conv. remind me to a long time discussion with my previous boss Mr. W. Fidi...  :) he did not undestand what I am talking about :frowning2:
    In other words: Arnaud, you are right, you get with different ears always different result. But the correct measurement compares always the far field result with the haedset result and ... no difference is allowed....
    To the compromises of the K1000 setup:
    .... more than +- 3.5mm membrane displacement will occur recognisable distortion to human ear. First K2 and K3 later when driving much more...
    In other words, if you drive the bass too much, you should not wonder about some distortion. But to be honest, most human ear distort much earlier already in itself! Due to the very natural sound of the K1000, most human underestimate the real sound level on the ear..! Be careful, when you hear some clipping wile using a proper working K1000, you will have more than 115dB SPL on the ear already!
    By the way, ... break up mode are no problem with the K1000 membrane design... It took us more than 3 years to realize that!
    A two way driver system only can help, if the compared "one driver" system has problems with the transient oscillation. This behavoir is very depending on the real moving mass. This is NOT the mechanical moving mass only, but the acoustic and the mechanic one together. The acoustic mass is from most human very much underestimated. F.I. Just imagine how much acoustic mass is insie the front and rear holes of a capacitive driver... Believe me, it is much more than the total moving mass value of the K1000 system...
    Mechanic suspension of the K1000 system is almost linear till the maximum movement. The reason for that is, that we did not made any compromise on the 4 edges of the square, we just cutted the edges out and left the dges filled close enough to reach 25 Hz on the bathtub level...
    I do not know much about the K1000 resonace frequency variants... Sorry! But it's very clear: the older the better! Like an old good wine! :wink:
    To the old posts of Fizz:
    Really great pics! Thank you!
    The pics shows relative new versions however!
    The small bubbles in the membrane design shows this very easely. It was made because the factory at AKG could not get rid of the small uncontrolled gas bubbles within the membrane compound foil. I know this problem, it can be controlled by aging the foil before manufiacturing.
    But generically it does not matter to the fundamental resonance.. But due to factory insight I know, that those drivers are at the upper f0 ... sorry! :frowning2:
    The very large eary close to the coil with lacuer shows that the problem with the membrane bubbles was not well understood at that time.
    But: Please do not overestimate my comments, this drivers are still better than much others! They are just not on the theoratical optimum...
    By the way, my old colleagues and friends Ewald and Helmut are working still, while I'm in a kind of pension. Ewald is working on specific membrane designs for Knowles and Helmut is owning a company for acoustic measurement systems in Austria.
    Yes, it would be really great to start product development of a new kind of "K2000"  :wink:
    But I guess, the todays development cost would be approx. 300.000,-€ and manufacturing equipment cost would be 500.000,-€ for approx. 5000 pcs / year...
    :frowning2: I do not have this ammount of money I regred :frowning2:
    Did I answer enough? Please do not hesitate to ask further....
  14. Blackmore
    To be honest, but the costs are not that high, imo.
  15. Lou Erickson Contributor
    Like others have said, thank you for coming by and answering all our questions.  We appreciate hearing how development went!
    I spent several happy hours last night listening to my K1000's.  They're still appreciated and still something very special.  You and your team did amazing work, and it is still appreciated.
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