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History of the AKG K1000? - Page 11

post #151 of 202
Quote:
Originally Posted by analogsurviver View Post

Well, here is the catch -  acoustic openess.  If you LOOK at the driver(s), you will see that they are not visibly transparent - there will be some "shadow" due to diaphragm, mounting/supportring structure(s), frames, pads etc etc - which is normal. If nothing, with zero size, would be able to produce sound  as heard by ,istening to say live music, that would present an ideal transducer. Anything bigger than zero will have more or less of an acoustic shadow, in addition to reflection between itself and our earss/pinnae, if we talk about headphones/eraspeakers. That acoustic openess should be as high as possible , but certainly exceeding 50 % . 50% is theorethically possible with ESL - in an transducer where stators are composed of rods of the same diameter as it is free open space  - that gives 50 % acoustic openess. Real ESL driver would have to include some surface around the effective diaphragm area, in order to accomodate clamping for the diaphragm, electrical contacts as well some form of increasing the rigidity of the whole structure, bringing acoustic openess below 50 % in real world designs.

You have to realize that acoustic transparency of a perforated stator is actually very high so you can't just look at this from the perforation area ratio. a perforated plate like estat stator pretty much do not block any sound.

Furthermore, in case of a driver like the k1000, the large discontinuity at the edge of the driver frame generates its own set of issues, one of which is major: acoustic diffraction. If you take something like HD800, the micro-perforated baffle plate and high absorption from the earpad actually make it much less prone to these issues, which probably partly explains why it images so well.

Quote:
Originally Posted by analogsurviver View Post

Look at the K1000 driver - there is practically nothing to be seen - they ingeniously were able to increase the acoustic openess to just below 80 %, a figure unmatched to this day. Since you do have K1000, Jecklin Float and Stax (any, does not matter in this case which model )), you can do a very simple test.. Play some music over loudspeakers or simply listen to the conversation ia a room - first without anything, just your ears, then put on K 1000, then Foat, then Stax - WITHOUT phones being connected to appropriate source. . You will hear that putting K1000 on your head will have very little, if any, sonic effect. If you hear any significant diference, congratulate yourselves - your hearing above 15 kHz is still going VERY strong.. Putting on Jecklin Float should have a marked awareness of "something" being acoustically present close to your ears - you are hearing ESL drivers, which are in Jecklin Float case an equivalent of a 10 by 10 cm square plate. This condition is still far more acoustically transparent than any Stax that use earpads. 
Here, you are using the acoustic isolation, of rather lack thereof of the headphone in order to make a claim about the superiority of the design, but I fail to see how acoustic isolation relates to driver performance in the least. Acoustic isolation in a float comes from the sound absorbing material close to the ear, it means any relfected wave from the skull will be absorbed back by the frame, can't be a bad thing, and can't say as much about the k1000.
Quote:
Originally Posted by analogsurviver View Post

This was of coure oversimplification of the problem, but it goes to show just what is happening when we try to listen with heasdphones/earspeakers - which is not nature has equipped us for. The very perception of our hearing, with which we have learned to hear, is considerably distorted by any cans - it is just K1000 almost gets away with it  far better than ANYTHING else.

The main issue is not the oversimplified bit but rather misleading argumentation. I mean, in terms of physics (in the sense of vibro-acoustics and sound propagation/ diffraction), I don't see the points you're trying to make. If I then go by subjective impressions, it turns out I could feel like a speaker being driven next to my face when I sampled it, which would mean it can't be the perfectly acoustically transparent transducer you're claiming it to be.
Quote:
Originally Posted by analogsurviver View Post

Of course, electrostatic principle is superiour to dynamic one - in theory, at least. However, practical liumitations are rendering this gap esl has ever smaller - new materials for the diaphragm of dynamic drivers, such as carbon nano tubes, have raised the bar for the dynamic drivers to hitherto unheard of levels - the piston like behaviour of the membrane is now possible without any appreciable breakup far higher in frequency than ever before. This is due to order(s) of magnitude better mechanical characteristics for the carbon nano tubes compared to any material used before.

I was laughing when I read your comment about carbon nanotubes, and I am glad you clarified later in the thread about this referring to the future, possibly in your lifetime wink.gif. Now imagine what kind of thin estat diaphragm we may be able to come up with through similar advances in material science wink.gif.
Quote:
Originally Posted by analogsurviver View Post

In order for the esl to work, you need voltage - AND current. As an esl is practically pure capacitance in electrical terms, that means you need ever more current whenever you increase the frequency.  That means you would have to have infinite power available from the "amplifier" driving the esl if it is to reproduce highs perfectly. Even this condition, which can not be realized in practice, assumes there are no HF loss due to mass of the esl driver ( largely composed of the air trapped inside driver itself, can not be appreciably lowered with diaphragm material, moving mass of an esl is largely the layer of air that is governed by the design chosen as tradeoff among low and high frequency limits and efficiency ).

The amplifier gurus should answer this one, but this HF limitation is only effective if you're trying to make an estat transducer for bats. Within the realm of audible audio (say 20kHz to be very conservative), I believe amps like the BHSE and other T2 actually have no issue with any of the stat phones.

Also, the effective mass is indeed affected by the air trapped in front of the diaphragm at low frequency but that certainly isn't true at high frequencies. The high frequency response of the transducer is limited by the diaphragm mass, not that of the air layer around it. This is another huge advantage of estats (and clearly audible too, take the example of cymbal shimmer): the moving mass is orders of magnitude lower than any dynamic or ortho driver for that matter (that is until carbon nanotubes transducers eh smily_headphones1.gif).
Quote:
Originally Posted by analogsurviver View Post

I gave up at about 500-600 VA constant power consumption being needed to drive a single pair of Jecklin Floats. Direct drive high voltage output transformerless amp - FAR better any transformer can possibly hope to achieve. Dangerous, lethaly so - many times over. Even with this behemoth, esl highs are still a bit softer than the real thing - the inevitable consequence of the phase shift you get when not using ideal infinite power drive for the esl. The laws of physics and electricity are what they are and we can not do anything about it.

Is there some reference for this mysterious phase shift for stat amps at high frequency due to current limitation? You mean limited slew rate?

Talking about phase shift, what do you make of the low pass filter used to compensate for acoustic cancellation of the front/back waves in the k1000? If anything, this passive electrical network is at least introducing 90 degrees phase shift from the mids up, isn't it?
Quote:
Originally Posted by analogsurviver View Post

K 1000 driver is NOT perfect - some would go as far as to say it is outdated.  Even so, whenever used within design envelope, it will sound superiour to anything else given good recording.

Now imagine what K2K, retaining all the positive aspects of K1K, with all the latest tech tricks developed in 23 years since the introduction of K1000,  could bring to the table ...

I am all for the k20000, but your claim of the k1000 being unsurpassed is surreal. It is a special experience due to the natural xfeed but other than that I don't see it. As for good recording, it is a good point as the k1000 is for instance unusable with binaural recordings.
post #152 of 202
Quote:
Originally Posted by Donald North View Post

Dynamics are driven by the voice coil. Depending on its diameter, it could be towards the center, middle, or outer edge. Because the diaphragm has a suspension, it has the potential to move uniformly, depending on the diaphragm geometry and material. Tweeter domes can operate pistonic to above 20kHz before they start bending modes.

Electrostatics are driven essentially uniformly across the diaphragm, however the diaphragm doesn't move uniformly because the edges are clamped.

The first mode of an estat is same a drum skin: max displacement at the center, no displacement at the edge. But this in no way presents a limitation or generates distortion. It couples extremely efficiently to the surrounding acoustic space, and that's visible in the measurements (stats typically go down to 10-20Hz flat) as well as audible.

Most dynamic drivers seem to be made of this large surround / combined spider which moves nothing like a piston so, while I agree with the "potentially", I don't think we're ever there in practice.
post #153 of 202

You have obviously not heard about the new diaphragm under development based on the principles of quantum physics

Apparently its a spin off of the work being done with the HEDRON collider, based on harnessing dark matter and offers the most realistic lifelike sound in the universe!

 

 

Warning: Spoiler! (Click to show)

 

 

Quote:
Originally Posted by arnaud View Post


Also, the effective mass is indeed affected by the air trapped in front of the diaphragm at low frequency but that certainly isn't true at high frequencies. The high frequency response of the transducer is limited by the diaphragm mass, not that of the air layer around it. This is another huge advantage of estats (and clearly audible too, take the example of cymbal shimmer): the moving mass is orders of magnitude lower than any dynamic or ortho driver for that matter (that is until carbon nanotubes transducers eh smily_headphones1.gif).
 
post #154 of 202

Hello,

 

First of all I want to thank you very much for all your comments so far.

Especially I want to thank your the link about the 50 headphone benchmarks... At least for the K1000 I assume it's the best overview I read till now.

Also many thanks for the explanations about "openness" of a headphone.

 

To clear up about the previous design targets we gave ourself during the design phase:

It was the late 80th when the design was fixed and it was the time when computing power to simulate and acoustic know how of for simulation increased dramatic. Also measurement setup was developed to show decay time for all frequencies in one picture.

Also it became understood the difference much better between a far field and a near field sound source.

All this influences lead us to following priorities:

1. We wanted no audible difference from outside source and headphone source.. = "openness"

2. The impulse response should be at least the same as the Jecklin Float

3. The frequency response should be linear between 30 - 22kHz from the driver

I know that many of you would now think that target 2. and 3. goes hand in hand anyway. But this is not totally true when you measure the driver inside the typical headphone "box" ;-)

4. The mechanics should be simple and quite "automatically" adjustable as the most AKG headphones offer at that days.

Sorry, I know now that we did not focus anough on the last point and it's may be the weakest point of that design creating worst case a kind of rub&buzz sound and you have to wear the product in sitting or standing position too. :-(

 

If I would design a "K2K" today, I would focus to improve in following order (priority):

A. The mechanics and the total mass

B. The bass response

C. Easy "wearability"

D. Decrease of moving mass

E. Power consumption

D. Decreased market cost to approx. 800.- €

 

One point more about practical difference between a speaker source (or better the true source) and the headphone is that the left ear does not hear the sound from the right driver and vice verse.

This effect I cannot change, but AKG offered the "Audiopshere BAP 1000" to compensate at that time. I can really recommend this amp for the K1000 !

 

As I'm almost "away" from the headphone market since more than 20 years, it's really difficult for me to estimate if the above target list for improvements would be correct so, that a K2K would be a "runner"...

 

As before ... any further input would be very helpful for me to get an idea for the next steps.

 

BR heinz

post #155 of 202
Quote:
Originally Posted by arnaud View Post


You have to realize that acoustic transparency of a perforated stator is actually very high so you can't just look at this from the perforation area ratio. a perforated plate like estat stator pretty much do not block any sound.
Furthermore, in case of a driver like the k1000, the large discontinuity at the edge of the driver frame generates its own set of issues, one of which is major: acoustic diffraction. If you take something like HD800, the micro-perforated baffle plate and high absorption from the earpad actually make it much less prone to these issues, which probably partly explains why it images so well.
Here, you are using the acoustic isolation, of rather lack thereof of the headphone in order to make a claim about the superiority of the design, but I fail to see how acoustic isolation relates to driver performance in the least. Acoustic isolation in a float comes from the sound absorbing material close to the ear, it means any relfected wave from the skull will be absorbed back by the frame, can't be a bad thing, and can't say as much about the k1000.
The main issue is not the oversimplified bit but rather misleading argumentation. I mean, in terms of physics (in the sense of vibro-acoustics and sound propagation/ diffraction), I don't see the points you're trying to make. If I then go by subjective impressions, it turns out I could feel like a speaker being driven next to my face when I sampled it, which would mean it can't be the perfectly acoustically transparent transducer you're claiming it to be.
I was laughing when I read your comment about carbon nanotubes, and I am glad you clarified later in the thread about this referring to the future, possibly in your lifetime wink.gif. Now imagine what kind of thin estat diaphragm we may be able to come up with through similar advances in material science wink.gif.
The amplifier gurus should answer this one, but this HF limitation is only effective if you're trying to make an estat transducer for bats. Within the realm of audible audio (say 20kHz to be very conservative), I believe amps like the BHSE and other T2 actually have no issue with any of the stat phones.
Also, the effective mass is indeed affected by the air trapped in front of the diaphragm at low frequency but that certainly isn't true at high frequencies. The high frequency response of the transducer is limited by the diaphragm mass, not that of the air layer around it. This is another huge advantage of estats (and clearly audible too, take the example of cymbal shimmer): the moving mass is orders of magnitude lower than any dynamic or ortho driver for that matter (that is until carbon nanotubes transducers eh smily_headphones1.gif).
Is there some reference for this mysterious phase shift for stat amps at high frequency due to current limitation? You mean limited slew rate?
Talking about phase shift, what do you make of the low pass filter used to compensate for acoustic cancellation of the front/back waves in the k1000? If anything, this passive electrical network is at least introducing 90 degrees phase shift from the mids up, isn't it?
I am all for the k20000, but your claim of the k1000 being unsurpassed is surreal. It is a special experience due to the natural xfeed but other than that I don't see it. As for good recording, it is a good point as the k1000 is for instance unusable with binaural recordings.

Yes, perforated plates do not block the same as unperforated ones.

 

Yes, AKG K 1000 does have diffraction issue that needs fixing. I have not seen HD 800 up close or heard it, but a friend has it and we will arrange for listening session in near future. The microperforation you mention sounds like a good idea.

 

Well, I should have put it more clearly, acoustic isolation and driver performance are of course not the same. Still - even if you have perfect esl, driven by perfect non existant "amplifier", that requires pads ( that distort our natural hearing ) in order to function properly, short of very badly flawed driver , the game is over before it began. The gizmo without pads will be better overall, more true to the actual live sound. I am certainly not saying I do not love/adore/enjoy esl low and high frequency extension - else what is  Stax Lambda Pro doing on my head right now, when I am trying to discern the last n-th degree of "everything" an much improved tonearm has to offer ?

 

Careful with that axe, Eugene ( the title of an older Pink Floyd song, IIRC ) - regarding carbon nanotubes. Do try the  JVC HA-S500 - you are from the only country it is available in stores and do not have to import it, as the rest of us poor souls do. My interest in carbon nanotubes grew the moment someone in one of numerous threads on head-fi mentioned CNTs sound similar to Stax. HA-S500 has a massive thread here on head-fi, please check it. HA-S500 is something that might be called technology demonstrator - completely conventional dynamic supraural closed can with one twist - carbon nano tubes for diaphragm.  It is capable of cymbal shimmer few  esl will likely be able to duplicate, for example. It has extremely good dynamic range, about equaling Stax Lambda Pro / SRM1MK2 at lowest levels and running ring around it at loud levels - it can play back Telarc's recording of Tchaikovsky 1812 and most, if not all Asian ( HEAVY bass) drum music. These blockbusters would tear any Stax to pieces, let alone K 1000. HA-S500 is far from perfect, anything that is not made of nanotubes in it is below par, sonically the most objectionable is small congested soundstage and exagerrated bass with stock pads - but it is hardly believable how much has the the knowledge about and sound of HA.-S500 advanced as a result of this thread. 

 

http://www.head-fi.org/t/621063/the-new-jvc-ha-s500-40mm-carbon-nanotubes/3150

 

Yes, the high frequency phase shift in esl amps stems from the current/slew rate limitation - it is not misterious in any way -  can NEVER be perfect, unless you use infinite power and risk getting electrocuted, should isolation ever fail. I am always amused whenever frequency response above officially accepted limit for the humans of 20 kHz is mentioned - always BATS ! Does not have to be that way, as an anecdote that happened for real suggests.. About 20 years ago  I had a cat that would always try to remain in my vicinity unless certain music played from turntable with a MC cartridge and listened over Jecklin Floats driven by my big amp was played - zoooom, the instant that was on, cat retreated to another room. Tried classics, rock, jazz, pop, you name it - not musical genre related. It finally occured to me - DIGITAL recording. Whenever a digitally recorded LP was being put on the turntable, that cat interrupted its nap in an instant and fled to a quieter place. Cats do hear above 20 kHz - and this one clearly objected music being truncated the way CD standard creators would like you to believe is "perfect forever". I personally object any audio that does not support say at least 40 kHz from input to output. I am not superhuman and my hearing ability to hear pure sine wave is average for my age - yet the moment I hear a frequency response limited reproduction I am immediately alerted something is wrong - it just does not sound real to me.

 

A friend has TAKET Batpure supertweeters -  at first, I was pretty sceptic about it, but after some blind listening tests, and particularly after playing back music without Batpure that was previously played with Batpure, I could not but accept that i can SENSE it i(and its high frequency extending waaaay above 20 kHz ) in some way. Skin/bone conduction - no idea, but I  can sense it somehow - and it is not a placebo. I can only guess what would my late cat be doing now with DSD recordings ?!  Demand CatPureFriendly tweeters? 

 

You are right, K 1000 uses phase compensation for the reason you cited. No such thing as perfect banana, I am afraid.

 

Regarding unusability of K1000 for binaural recordings - your reasons ? I believe exactly opposite is true.

post #156 of 202

This thread is awesome!

post #157 of 202

What matters is the system acoustic phase response. Phonographs, for example, are pre-equalized when cut onto the master lacquer and then de-equalized during playback.

 

Dipole electrostatic speakers also require equalization to maintain a flat frequency response into the bass and in the case of the Quad ESL-63, can still reproduce a squarewave.

 

One attribute of the K1000 which I find special is the fact that it doesn't create a trapped air cavity as most headphones do between the diaphragm, ear cushions, and head.

Quote:
Originally Posted by arnaud View Post

Talking about phase shift, what do you make of the low pass filter used to compensate for acoustic cancellation of the front/back waves in the k1000? If anything, this passive electrical network is at least introducing 90 degrees phase shift from the mids up, isn't it?
 
post #158 of 202
Quote:
Originally Posted by Piotr Ryka View Post

 

 

This "cleeping" could be some explanation, but I don’t know why sometimes (rarely) this cleeping appears, sometimes not. For example last tree days were completely free of this phenomenon.

I use Xonar only as a source for amplifier. (Good amplifier.) The sound is slightly raw, but high notes are good illuminated.

HD 800 vs K1000? That is a long story (in Polish). Generally HD 800 are more mild and boring. But with really good source, like top Metronome for example, and with appropriate amplifier, they are very interesting, particularly for old recordings. K1000 are more aggressive, with better highs extension and more realistic sound. With proper system their presentation is simply more beautiful.     

To me, in audiophiles dialect, headphone top tier is: Orpheus, SR-Omega, SR-009, Omega II mk1, Sony MDR-R10, HiFiMAN HE-6 and AKG K1000. (I've never heard Audez'e LCD-3 and Sony Qualia).  


Totally agree!!

post #159 of 202
Quote:
Originally Posted by Donald North View Post

What matters is the system acoustic phase response. Phonographs, for example, are pre-equalized when cut onto the master lacquer and then de-equalized during playback.

 

Dipole electrostatic speakers also require equalization to maintain a flat frequency response into the bass and in the case of the Quad ESL-63, can still reproduce a squarewave.

 

One attribute of the K1000 which I find special is the fact that it doesn't create a trapped air cavity as most headphones do between the diaphragm, ear cushions, and head.

+1, on all three counts. I will re-measure my pair of K1000s for square wave reproduction - from previous attempts, I remember, although good, it was not exactly stellar performance. Quad 63 got FAR too little recognition for its achievement in reproduction of square wave - indicating nothing else but the fact vast majority of available recordings are so imperfect/compromised ( in case of multimiking, a lost case and mission impossible to begin with ) . To show you what I mean, you will have to get this CD : 

 

http://www.artsmusic.de/Percussion_XX/topic/blueline/shop_art_id/200/tpl/artsmusic_article_detail

 

It has been mastered with Quad 63 - and it shows, most clearly, how much better sound reproduction overall  would become if phase coherent speakers that can approach reproducing perfect square wave(s) were mandatory/compulsory during mastering.

 

I would like hrlkg01 to enligten all of us, who after seeing the price for BAP 1000 back then, simply decided to - pass. It allowed for the proper equalization for each individual listener.

 

I have a huntch that AKG K1000, once correctly equalized for each individual,  should generally produce similarly close to perfect square wave(s) for that individual. BAP 1000 did have an "average" setting, that was more or less in the middle within the envelope that was measured on large number of subjects - plus it did allow a couple of personalized settings to be entered in its memory. BAP 1000 is, by today's standards, an obsolete digital dinosaur, but its intention and purpose are as relevant, if not even more so today due to the better awareness of the issue(s) it tries to correct. Unfortunately, never did have the privilege to audition it properly.

 

So - BAP 2000 too ( but with DSD digititis this time ...), perhaps ? Or an app with K2K in mind for foobar2000, jRiver or similar player that does support DSD ?

post #160 of 202

Yep like the Jecklin float but the transducer is about 4 times the area

Quote:
Originally Posted by Donald North View Post

One attribute of the K1000 which I find special is the fact that it doesn't create a trapped air cavity as most headphones do between the diaphragm, ear cushions, and head.

post #161 of 202

I have had several opportunities to purchase one of these but in discussions with AKG is Austria they said most of the stuff required to do the individual tailoring was obsolete unless you spent several years trying to recombine all the components.  There was a card I believe that contained the profile that plugged into the front of the BAP, software various CD's etc.  I don't actually know anyone who has a full set of kit to make it work as originally intended.  Perhaps there is one in an audio museum or AKG have one in the basement! biggrin.gif

 

Quote:
Originally Posted by analogsurviver View Post

I would like hrlkg01 to enligten all of us, who after seeing the price for BAP 1000 back then, simply decided to - pass. It allowed for the proper equalization for each individual listener.

 

I have a huntch that AKG K1000, once correctly equalized for each individual,  should generally produce similarly close to perfect square wave(s) for that individual. BAP 1000 did have an "average" setting, that was more or less in the middle within the envelope that was measured on large number of subjects - plus it did allow a couple of personalized settings to be entered in its memory. BAP 1000 is, by today's standards, an obsolete digital dinosaur, but its intention and purpose are as relevant, if not even more so today due to the better awareness of the issue(s) it tries to correct. Unfortunately, never did have the privilege to audition it properly.

 

So - BAP 2000 too ( but with DSD digititis this time ...), perhaps ? Or an app with K2K in mind for foobar2000, jRiver or similar player that does support DSD ?

post #162 of 202
Quote:
Originally Posted by complin View Post

I have had several opportunities to purchase one of these but in discussions with AKG is Austria they said most of the stuff required to do the individual tailoring was obsolete unless you spent several years trying to recombine all the components.  There was a card I believe that contained the profile that plugged into the front of the BAP, software various CD's etc.  I don't actually know anyone who has a full set of kit to make it work as originally intended.  Perhaps there is one in an audio museum or AKG have one in the basement! biggrin.gif

 

I believe it was quite a hassle, software, CDs and all the stuff. Yet - if the basic recipe towards achieving "perfection" is known, for about 25 years now, probably some dusting off is in order - to see how it work(ed) and try to come up with up to date user friendly solution that would not cost an arm and a leg. Today's computers are powerful about where it should be doable; - that from an - analogsurviver !

post #163 of 202
Quote:
I used to be an archaeologist. Any span of time less than 100 years qualifies as "shortly" in my view.

D.

 

I used to be a geologist. Any span of time less than 1 million years qualifies as "shortly" in my view.

post #164 of 202
Quote:
Originally Posted by dmort View Post

 

I used to be a geologist. Any span of time less than 1 million years qualifies as "shortly" in my view.

 


According to God.  Any span of time qualifies as "shortly" in His view.  wink_face.gif

 

That aside, thank you all for your input.  I started this evening looking to upgrade my airline (Westjet) headphones and found myself enjoying this thread.  I hope what I've learned ... 'sticks'.

 

Cheers!

post #165 of 202

Doing a bit of a refurb work on my pair, I've noticed that the rear driver foam disc has started to disintegrate. Is anyone in the know of what might be suitable replacement material perhaps?

 

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