A visit to hrklg01 - the creator of AKG K-1000 and its successor, the MySphere 3.1
Part 1 - Mysphere 3.1 close up and personal
I remember seeing the review for the AKG K-1000 back in the day - in Swiss magazine called HiFi Vision. Considering just how patriotic Swiss are about everything Swiss, it was near miracle for the reviewer - although not without grudging - placed K-1000 on the throne for the best headphone - displacing none other than Jecklin Float ( Electrostatic ), which at the time was as thoroughbred Schweizer as it could possibly be. That is akin to French drinking Australian Chardonnay - only carried to yet another, higher level.
K-1000 was a very expensive product at the time - and, as advanced in thinking and concept/design ( technically speaking, not how it looks ) as it was/is, was anything but flawless. Used for the right purpose within the envelope of its limitations, it is still one of the best if not THE best "headphone" - ever. The proper term would be - earspeakers. The main feature of this concept/design is that it allows for natural use of our ears - without modifying outer or inner ear by earpads, eartips, etc. This makes for a far broader range of real people HRTFs to be covered than any other existing design. ( and even that can be helped further by processing the signal for each person's individual HRTF, as it has been done with the original companion for the K-1000, the BAP-1000, which was a processor and amplifier in one package ).
The moment you step outside the K-1000's "comfort zone" - it falls to pieces. If you try to play with it anything with heavy bass - you will not be satisfied, and should you use too big an amp, you may permanently damage the drivers.
K-1000 occupies another pinnacle - that of the most inefficient dynamic headphone in existence. I will spare you the numbers - suffice to say is that most headphone amps can not power it to anything like satisfactory levels.
K-1000 shines above anything else with binaural recordings. It does not modify our hearing in any way - no outer ear deformation due to pads/tips ( and resulting peaks and dips ), no natural crosstalk between the ears blocked by the same earpads/tips - as any other headphone in existence ( with the exceptions like Jecklin Float and Sony PVF-1 confirming the rule ) - ever made commercially available.
K-1000 has one unprecedented advantage over anything else - its acoustical openess. In K-1000, this is well above 70% - which means, it is almost inaudible when worn on your head and no signal is being played trough it. You can hear the environment you are in almost exactly the same as if you were not wearing anything at all; the only difference is slight shadowing above approx 15 kHz, which is, if not inaudible, certainly not objectionable. Try that with any "normal" headphone; you will most definitely be able to hear the difference between the sound of environment with and without headphones on your head. And exactly this difference is an inherent obstacle in practically any other normal headphone against achieving the result we all strive for - reproduced sound most realistically approaching that of the live sound.
K-1000 was a pioneering product - not a headphone, but the earspeaker. Trouble - it is , to a large extent - still built like a headphone. And here its troubles begin ...
Fast forward to present day; when it has been announced by the designer of the K-1000, Mr Heinz Renner - or hrklg01 on head-fi - that a successor to the venerable K-1000 is in the works, I contacted him via PM. Many PMs later, we finally agreed on the date of my visit to his brand new home in Italy ( not far from Venice ) - where he decided to move from a place close to Vienna to spend his freshly baked retirement in somewhat better weather and milder temperatures.
As I knew in advance this will be no ordinary visit - or private can-jam, if you prefer; FAR too many issues to be dealt with - I carefully approached him regarding the length of time for our meet. It ended with him expecting me at the train station at 06:12 AM and delivering me back to the same train station some 12 hours later... ! Very few people would be willing to do that - very grateful for the possibility !
Upon arriving to his brand new house at the outskirts of a not-so-small village, placed centrally in the living room stood a big table - half of which occupied by Mr. Heinz Renner's "toys" - and half of which was free, to be occupied by my "toys". One VERY strong coffee later ( I did not get any sleep that night, trip started at 02:30 AM, on top of the mishap with the 4pin XLR Y cable for two headphones at the same time which took much longer to fabricate than anticipated - but as it was absolutely required... no other way but no sleep !), I started setting up my gear.
https://imgur.com/a/FhE7m
( Please note this is my very first upload to any of the image sharing sites - the photos should be viewed in numerical order, from 01 to 16; I have yet to figure out how to make them to be displayed within a post in proper order )
On the left ide of the table ( hkrlg01 ) : AKG BAP1000, Lake People DAC. Lake People Amp, laptop
On the right side of the table( analogusurviver ) : Stax Lambda Pro, Stax SRM1MK2 amplifier, Stax ED-1 Monitor Diffuse Field Equalizer, iFi Micro iDSD Black Label DAC/amp, laptop, external HDD, Korg MR1 DSD recorder.
In the middle: among various prototypes for the Mysphere 3.1 and original pre-serial-number K-1000 ( as marketed initially as combo with BAP-1000 ) from Heinz; there is a "black" K-1000 modified by me. More about it later.
We started to listen first with both K-1000s and Stax system - so that we get familiar with the recordings, sound in general, etc. We mainly listened to my binaural DSD masters - which I know by heart, but were, of course, completely unfamiliar to Heinz. We also listened to the sounds coming from his left side, with necessary cabling changes, etc - so that Heinz could listen to familiar recordings. There were 3 pairs of headphones available at any given moment - K-1000s and Stax, roughly adjusted for level. More about levels later on.
One important notice: the 4pin XLR Y cable for two headphones was intentionally wired with one XLR female plug in correct absolute phase, another in opposite (180 degrees ) phase. This allows for phase reversal with unbalanced sources ( 6.35 mm TRS jack ) that do not allow for phase inversion within DAC/amp ( iFi Micro BL does have this provision ) - for those recordings that require such attention. We DID pay attention to this, so that when we were later switching various prototypes of Mysphere from head to head, we also physically swapped the connectors - at least maintaining the absolute phase the same for each listener with each headphone.
Originally, such 4pin XLR Y cable wiring was devised for unbalanced sources with two K-1000's - one being wired as usual, another being wired both channels out of phase; this allows for either positive or negative absolute phase with both headphones at the same time, without the requirement for the source to have absolute phase inversion possibility.
Very early on, Mr. Heinz started to listen to the "black" K-1000 - with great concentration. In head-fi parlance - it took the most headtime.
He was also surprised by the Stax SYSTEM - since he was not familiar with the ED-1 Monitor Diffuse Field Equalizer ( which IS tailor made for Lambda Pro - no other Stax model received such a thorough treatment - before or since ! ) before. As a system, this set up is in comparable league with K-1000; headphone and amp ( ANY amp...) only is far lower in overall quality. Another important notice: ED-1 Monitor has been modified by me, original does not allow for the bass to go basically unchanged compared to amp only setup. Original ED-1 has bass rather softened/subdued, robbing the Lambda Pro of one of its greatest assets - bass.
I guess readers by now expect to hear how did the prototypes fare compared to K-1000s and Stax. I will have to dissapoint you; it was agreed, long before my visit, I will not post about the sound of the new Mysphere. But based on what has been heard, it would really be inappropriate to talk about the sound at this stage; prototypes, although rather similar, are different more than enough and only Heinz knows how will he tune the headphone that will become - eventually - commercially available.
We did talk - a lot. We have many things in common - as the "interview - confessions" in Part 2 will testify. He understood I came to help - with recordings he quickly realized are non plus ultra, with superior sounding version of K-1000, with Stax system that is hard to beat even today - and sharing many experiences with building various audio devices, material suggestions, etc, etc. One day was enough only to scratch the surface ...
What I can and am willing to say about the new Mysphere is this : it is almost Lego alike, in stark contrast to the K-1000 where mere cable change involves a major disassembly. Each earpiece comes off, detachable cable can be attached either to the left or right side, cable length remains constant regardless from which side main cable is attached, it is MUCH more comfortable than K-1000 and no, power station to supply it with enough juice is no longer required. Treble is more extended than its predecessor, but this results in more details, does not sound particularly bright - or, God forbid - sharp. Prototypes had enough differences to preclude any meaningful conclusion regarding sound signature, imaging, etc - it would simply be describing something the end consumer would almost never get a chance to hear, thus making any such comment irrelevant.
There is one aspect of performance that will, to a large extent, remain pretty constant to what I have been able to hear. Mr. Heinz told me he had a lot of requests for "new K-1000 - but smaller". Lo and behold, the driver of the Mysphere is considerably smaller than that of the K-1000 - with a smaller effective piston area. He has compensated for this by increasing the piston excursion - from 3 mm in K-1000 to 4 mm in Mysphere - but since the SPL of a piston is governed by
(constant) x (( eff.area x excursion )squared)
that means that the ultimately achievable SPL output in the bass will be approximately similar to that of the K-1000. When using uncompressed recording of a symphonic orchestra, the tympani in the finale bottomed out the Mysphere prototypes - all of them that were available. However, the power required to reach this level(s) is far less than that required for the K-1000.
Mysphere 3.1 embodies yet another refinement over the K-1000 - which also concerns the bass. The new driver is designed ( with patent pending, one among IIRC 5 different patents filed for the Mysphere in total ) with proximity effect helping to boost the bass by quite a significant amount - on the order of 10 dB at 20 Hz - which means the drivers have to lie VERY close to the ear and can not be swiveled away from the ear as in K-1000 if this bass "trick" is to work. I have to admit to not paying enough attention to this during my visit to Mr. Heinz - and since we have been swapping the headphones at say maximum 1 minute listen ( on average, certainly music he really liked was allowed to be played in full ), really fine positioning/tuning the Mysphere, for which this design caters to the fullest by precise and repeatable adjustments, has not been performed. But, based on my experience ( my definition of experience ? Something you get instead of what was initially anticipated ), IT IS ESSENTIAL. For that purpose and , in particular, the first showing of the Mysphere 3.1 to the public at large at the forthcoming RMAF , I have also devised something I should have devised prior visiting Mr. Heinz in the first place - a short set of technical signals with which the listener can quickly verify that the Mysphere is adjusted correctly and performs as it should - on his/hers own head - prior listening to music.
Mr. Renner has shown me the open driver of one of the prototypes. It is really ingeniously designed and precisely made - particularly interesting is solution for the damping, which was handled in the K-1000 by foam ( foam rot of loudspeakers - sounds familiar ? ) that deteriorated over time and requires replacement from time to time. The new driver should have no such issues. I suggested him to consider also some different material(s) - all aimed towards achieving best SQ possible. I did not want to take any photos of the driver itself, as copycats and copycrows ( stealing the idea ) are all too quick nowadays ! The driver is far better protected from the elements than it was the case with K-1000; it even has reasonable water protection ( so called (German ) Spritzwasser
http://dictionary.reverso.net/german-english/spritzwassergeschützt) - i.e, rain, drops of water, but not running water or soapy water with low surface tension. IIRC - grills are held in place by magnets ...
Now, I know I could/should have come a bit better prepared ( too much music, DAMN hard to decide exactly what to use for "demo sampler" - took me a couple of days to even reach this state of (un)readiness ... ), which lead me to assemble the required Y cable in the very last possible moment, etc. However, Mr. Heinz "countered" by having no two samples of reasonably paired Mysphere 3.1s as promised; there were considerable differences in sensitivity ( order of 2-3 dB ), bass extension, etc, etc - meaning under given circumstances, matching as fundamental parameters as volume levels was not possible, since we did not have two identical amplifiers to drive two pairs of headphones with different sensitivity that would allow for exactly matched SPL output from both pairs of headphones. One of the prototypes had upon my arrival 0.0 hours of play - and no audio device as complex as Mysphere does not sound correctly right off the production line ( more production table in this case...), without being measured at all, let alone having been burnt-in. I "think" ( to think is to know nothing ... at least around here in Slovenia ) a re-visit under more controlled conditions once Mysphere reaches more mature status is in order - before anything approaching any credible evaluation of its performance is truly possible.
I have to stress the burn-in issue; since everything you read has been authorized by Mr. Heinz Renner, he has informed me that since my visit 11 days ago, he did subject the prototype with 0.0 hour play at the time of my arrival to a three day ( 72 hour period ) of playback of "normal music" at approx 100 dB SPL. He reports a major change for the better, particularly in the treble. Now, I can not but take his word for it - however, the occurrence has convinced him regarding the importance of proper burn-in; just as described in discussion in the part two of this report, where I stated any burning in that does result in change of sound should be done by the manufacturer - so that the end user never gets to experience it. Of course, only products above certain price level can be expected to be subject to a couple of hundreds of hours burn in and final (re) measurement with measurement certificate of each individual sample.
I did what I could given the circumstances; record a piece of music played trough all the headphones seen in the pictures using head worn binaural microphone that fed the Korg MR1 DSD recorder. I could have also recorded some technical signals - but , for that, the time to go trough all six pairs of headphones simply was not available. To top it off, the DC plug from AA NiMH holder seen in picture , essential to power the Korg ( by now, probably each and every of its internal LiPo batteries is gone - even NOS, if you can still locate one - and we all now resort to some kind of external power supply...5 pcs of NiMH AAs in this case) decided to disintegrate - an ohmmeter and some litz wire from Heinz's Werkraum allowed to make the remainder of the recordings. Another 15 minutes down the drain...
Again, these recordings are not intended for public use, but will help Mr. Heinz towards the final tuning.
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In the following Part 2, there will be "Interview/confessions/musings" - about our hearing, our ability to subjectively evaluate audio, burn-in, Mr. Heinz's career with Philips for 20 years after leaving AKG ... - and generally things about audio. As I have the presentation of my recordings ( on brand new loudspeaker prototype - no less ... ) at our own HiFi Multimedia Show in Ljubljana, Slovenia that runs October 6th and 7th, the same dates as the RMAF, I will write the Part 2 sometime in the week after this weekend.
. Where is the philosophy now all these years later on this. Thank you very much. Also, will you be in Toronto Taeves show? Thx
Kidding aside, it is a good list and I am familiar with about at least half of it.