Pros – Stunning sound. Super wide soundstage. A great fit – quite a unique headband design, yet simple. Linearity from a good quality speaker with the most open design of them all. Adjustable sound signature – just move the earspeakers towards or away from your ears as your mood dictates. A simple hinge but what a difference it makes to the sound.

Cons – Very expensive secondhand and becoming very old. Old means fragile. Old means inheriting problems. As I did. Needs lots of power. A speaker amp is needed. No spares are available in the World. Anywhere. If it goes wrong, you are in trouble! There may be something better out there now(MySphere), but I haven’t heard them. Yet.

The AKG K1000 Bass Heavy now fully restored to it’s glorious best
…..and maybe even better

This is a brief story. I shall attempt to explain to you how the impossible was not only dreamt of, but subsequently asked and then, to my amazement, was achieved. Perhaps the quirkiest headphone of them all; the AKG’s earspeaker design, their flagship model for many years, of which much hype has been written. Having these now, back with me, believe me folks; these headphones are a sight for sore eyes indeed.


There is much love for the AKG K1000. Much information can be found about this headphone on headfi  specifically the design parameters, the evolution and production and the differences between the earlier models, dubbed “bass heavy” and it’s later variant, the “bass light”. The forum thread is a journey in itself. The History of the AKG K1000 starts with just 2 sentences from @mikeg and for some 8 years the interest in the thread runs out of steam. A post made in Feb 2004 suddenly becomes answered in Sep 2012. Our mysterious poster is known as @hrklg01. I will quote this post because it marked the start of an even more incredible journey than my bass heavy headphones.

The post simply read : “Yes, we was influences by the STAX design too. However, it was the idea just to get nothing disturbing in front of the ear. So we created a huge membrane very light weight only…


This post, if genuine, could only have come from one of the original team behind the K1000, of which so little information was available at the time. Imagine if that was true! What a find this person would be…. After some more questions were put to this poster a picture began to develop. This was a man called Heinz Renner. He was responsible for developing the AKG K1000! Heinz had left AKG in 1989. He had since gone and made his fortune in the cell phone market, developing micro speakers by which we listen to our loved ones whispering sweet nothings in our ears or singing their version of “99 Problems” to us on facebook… No more work done on headphones. A lost genius. Yet somehow, the lure of headfi had brought this audio engineer back into the fold. Having joined headfi way back in 2012, my research eventually got me to that very same AKG K1000 thread and I was enthralled at what I was reading. The next step, listening to a pair, would take many more years to come to pass.

Before I finally had the chance to put a pair on my ears, I went through many other headphones and even a few earspeakers. The Audeze LCD2v2 being my first, Sennheiser HD800, Beyer Dynamic’s T1 Tesla’s and then inevitably into the earspeaker world. At one point I had 3 separate Stax models: the SRX Mk3 Pro, the Sigma Pro and the 4170 system. A brief spell of making sensible financial decisions had momentarily confused me into selling much of my collection a few years ago. The Stax were sold, as were the LCD2 and the T1 as well as many other amps dacs psu’s cables, you know the thing. I kid you not; I turned up to the 2014 Headfi London meet with an Ibasso DX100 and a pair of in ear monitors and bought nothing while I was there…


A hobby such as this does not rest for long. On the 25th April 2015 2 dedicated UK headfiers, @smial1966 and @pedalhead organised a meet up in Cambridge. On the night of the 26th, a frenetic micro meet took place in the hotel room of the Travelodge I was staying in. There, finally, I got the chance to listen to a pair of AKG K1000’s. I now know these to have been the bass light version of the K1000. The gent who was kind enough to bring them alas I do not remember your name and I have not seen you since! Let’s hope this review will prompt someone to recall the gent’s name and we can get back in touch. Even though the cable on one of the driver’s was damaged and had to be held into place, my few minutes with the earspeakers were magical. The listening experience was done with the earspeakers pulled out to their furthest position. That enables everyone in the room to enjoy what you are listening to, so make sure it’s not The Wurzels…… I didn’t realise at the time but I was listening to the later version of the K1000, the bass light version. The listening fraternity on the night were divided between those in love (myself and @Ithilstone and of course the proud owner) and the non believers. A switch was pressed in me. I had to find a pair.


Fast forward a few months and myself and a team of willing helpers had tracked a few pairs down across the World. I say a few because these earspeakers are becoming very rare and highly sought after. The manufacture of the K1000 was irretrievably stopped back in the late 1990’s. In short, the lathes that had created so many wonderful models had grown old and tired and were humanely destroyed. The earliest models(bass heavy, please keep up),were introduced in 1990. If you have 1 of those it could be 28 years old! I, of course, had a look on headfi’s classifieds for a model. No chance! They were snapped up within a day of advert and the last one added was a year hence. I found one on sale in Finland. It was a reasonable enough price and the seller was a German chap who I talked with at length on the phone. We trusted each other, a deal was set, and a few days later a wooden box arrived at my doorstep. The day had finally come! I had my earspeakers! The day was full of promise as I unpacked and made myself comfortable for a marathon listening session. I listened with breath held waiting for the magic to unfold. As it did. However…. not all was rosy in the garden. I had found a thorn! The right driver had a buzzing effect on subbass tracks that was subtle but noticeable. I had built myself up over the course of 3 months waiting for this moment and certainly that exaggerated the disappointment I felt. I wallowed in self pity beneath my red headband contemplating my next move.

My next move was…I did nothing. I listened and listened. The buzzing was something I was prepared to put up with. If in the future it couldn’t be fixed there was too much wonder between these drivers to even think of returning them and asking for a refund. What if I never found another pair? What if the price doubled yet again, as it seemed to do every few years as these got more and more precious. My decision had been made; this was a marriage of the audio kind, in sickness and in health…


That was back in 2015. I referred back to the headfi thread to ascertain that my model was one of the earlier models.

To quote Heinz once again:

“I do not know much about the K1000 resonance frequency variants… Sorry! But it’s very clear: the older the better! Like an old good wine!”

About there being 2 versions of the K1000 Heinz has this to say:

“About “bass heavy” and “bass light” versions: I remember back that the original ~ 5000 pcs was shipped with a black bright box. This version – I’m sure – was produced with the target 25Hz f0. There was no additional changes at least during the first 5kpcs..”

I have now seen the difference between my version and the later version that was produced. Heinz has since added the first production batch was up to the number 10,000. An easy way to see the difference: bass light models have a lighter wooden box and a different colour speaker connection cable. I am fortunate enough to have listened to a bass light and a bass heavy version of this amazing earspeaker. If you are up to date on what I have written so far you will recall that I fell in love with the sound of the bass light version. I purchased the bass heavy version without consideration of which variant I was ending up with. Suffice it to say I would have been delighted with whatever came through my door as long as it looked something like a deerstalker hat.


While we are on the subject of Heinz Renner and his friendship with headfi. Did you know that this very forum ignited in Heinz the idea to produce a successor to the AKG K1000? He must have seen so much love for the old model and so many ideas were being put forward regarding how the K1000 could be taken to another level on the thread that he decided to come out of the shadows and step back into the limelight once again. Heinz Renner was going to go back to the drawing board and come up with something even better than the AKG K1000. In October 10th 2015 you can read a fateful post from a headfier called @Nomax:
 and many a follower of that thread drew their breath in. Could it be possible that the original team could reform and do it even better?

The team are here from left to right: Ewald, Helmut Ryback – and to quote Heinz once again: “one of the 3 K1000 “Musketiers” as he was the main head for headphone design in the previous AKG years”, Heinz Renner himself and-the man who created the dream of a K1000 supercharged as far back as Oct 2015, the face of Nomax:) With a huge thanks to all of you reading this here that made this idea germinate and hatch and mature and flourish, the dream of a K1000 for the modern age has come true. Incredible!

Screen Shot 2018-08-13 at 20.44.28.png

There is a big thread now on the MySphere on our very headfi and at the time of writing it had got to 54 pages. Well worth a read it can be found here with a click of your mouse. The latest entry, as of August 6th 2018 states simply:

miketlse said
Is there a waiting list for the week long borrow? Or is one readily available and able to ship to the US?

“No waiting list anymore! :)
This is also true for the regular product to buy.

BR heinz”

We have come a long long way from Feb 2004 I think you’ll agree….


I digressed a few lines ago. I was meaning to tell you about my little adventure. Then I realised that there was an even bigger tale to tell. That told(sort of), let’s get back my Bass Heavy Buzzer dressed in red in a black box. The head turner of yesteryear; the K1000. I decided about 6 months ago that the time was right to get the earspeakers buzzing problem fixed once and for all. I did my research, which was primarily the posts on this forum made by Heinz Renner regarding the problem of the buzzing and the solution to fix it. It appears that the glue around the membrane that surrounds the drivers is prone to coming loose in humid conditions. Often all that is needed to eliminate the rub and buzz so called is to use a particularly high quality brand of waterproof white glue. Allow that to dry over a day or so and all should be well. In the course of inspecting my K1000’s, my friend found not only a glue problem. The foam inserts, being very fragile anyway, had all but disintegrated. I made enquiry after enquiry for 80 PPI reticulated foam. In the end, we decided on a compromise which was to experiment with other grades of foam inserts and see whether we could get a decent sound. I got a phone call from my friend; he felt he was onto a winner. He observed the bass response seemed deeper without noticeably damping the higher frequency response. I told him to proceed and to get the glueing done. I got the K1000’s back. I still had the buzz. It was less. But it was still there. So back to my fixer of all things. In the process of taking apart the earspeaker, disaster occurred. There is a wire that connects driver to the voice coil and it happens to be the thickness of a human hair. The wire snapped. My buddy was straight on the phone to me and we discussed our options. Given the scarcity of the K1000 and it’s pricelessness(to me at least) he was reluctant to go any further without the backup of spares. I hold no grievance with him for attempting the fix and breaking the wire. It could have happened to anyone and he was kind enough to get some really good foam in there. I haven’t mentioned the amazing recabling he did on them either….. I made various enquiries via email and telephone call. I found no one selling spares or offering a repair service. I couldn’t understand why. The headphones were only 28 years old for goodness sake! :grinning::stuck_out_tongue_winking_eye::wink:

In desperation I plucked up the courage and sent Heinz Renner an email and asked him where I could try and get them repaired. I knew Heinz would be working flat out trying to get his MySphere 3.1 and 3.2 to market so I didn’t hold out much hope. To his credit and my undying gratitude, Heinz offered to assist in the matter. He asked for pictures of the problem so as he could see whether it was possible to fix the damage. It seems that if the wire is snapped near the centre it might be possible for a very delicate resolder. If the snap was at the start or had pulled out from the voice coil or driver a fix would be impossible; that would spell the end for the AKG’s and they would have to be thrown in the bin! My friend sent some pictures. It looked like the split was in the centre to my eyes. Heinz agreed. He asked me to send them to his house and he would try and fix them but with no guarantee of success. I completely understood that as anyone should; if someone is doing this as a favour there can be no cause for complaint if all goes wrong.

Off went the package to Italy. It arrived in 3 days. Heinz immediately confirmed delivery and asked us to wish him luck. This is the transcript of the email that I shall never forget:

Hello Trevor and Dillan,
I worked almost 3 hours – but finally it was successful.
I had to change the coil and membrane. Luckily, I had these parts from the very first 0-series = still bass heavy
Today I stop to mount everything together, because my old eyes became tired.
My questions:

  1. Did you repair the rub and buzz on the left side already, or have I to open this as well.
  2. Can you please send me the full data (name, address) where to send it finally back please.

Not only had Heinz repaired the K1000’s and used up 3 hours of his own time in the process but he was now asking me whether he could do any more work on them! The man must be a Saint. :innocent: A subsequent email was sent the following day; Heinz had done so more work on the rub and buzz and eliminated it. He also did one final thing:
“I do of course a certain “burn in” with a unique test signal, as I changed important parts of the damaged driver. This signal simulates about 2 days continuous normal playing the headphone.”
I assume the same method is used for the MySphere Headphones.

I received the K1000’s a few days later. I unpacked them and had a listen. A miracle had happened! The earspeakers sounded perfect; let’s say that straight away. But more than that; the rub and buzz had of course disappeared; but the bass was deeper and richer and more visceral. I must add that the bass on the K1000s can be increased by putting the speakers closer to one’s ear, by sitting with your head against the cushions of a fine chair, or by eqing more bass through software or hardware adjustments. Indeed, Heinz uses a subwoofer in conjunction with his K1000s. I always listen to my K1000s with the speakers as far away from my ears as I can adjust them. That way I get the spatial cues similar to the reflections of a loudspeaker. What I also get is the intimacy and micro detail that only a headphone will give me. Thus, I get the best of both Worlds. You get the picture anyway.
Many of you will want to know how these earspeakers compete against their more modern counterparts. I can compare these to 2 other flagship headphones I happen to own.

The HD800 by Sennheiser. Modified by @dill3000 and myself.
The HD800 has a wide sound stage. Most of you are aware of this. The original model has a trace of steeliness in some of the higher frequency range. It was also slightly less visceral in the bass department for many people’s taste. I did a felt mod having researched other’s ventures into this. I went my own way and found the felt I liked the sound of. @dill3000 improved it further. Thus I have an HD800 with bass, smooth highs and the original sound stage. The K1000s are my favourite over the HD800. I prefer the linearity of the K1000 and the sound stage is wider than the HD800. The bass of the HD800 is harder hitting and slightly richer sounding. But it still comes behind the AKG in overall terms.

The HiFiMan HE-6 with comfy headband and open grill mod
The HiFiMan HE-6, when partnered with a beefy enough amp, is a world class headphone. I have a First Watt F6 power amp which I use these with. It is a 25 WPC speaker amp, and it (again) has been created using the DIY talents of @dill3000. It hits hard at the bass and has linearity right through the frequency spectrum. It makes music come alive. The tone is just right. The sound stage is more intimate than either the K1000 or HD800. Whether the HE-6 beats the AKG K1000 to my ears will take more time for me to be sure about. Some tracks come alive with the spatial attributes of the AKGs; I’m thinking about perhaps large orchestral pieces, Jean Michel Jarre, Vangelis, Enya, Enigma, Mike Oldfield, Pink Floyd and the like. Rock music, Pop music and acoustic music are such a delight to listen to on the HE-6.

I am a happy man. I have my beloved AKG K1000 Bass Heavy Earspeakers restored to their original greatness and arguably even beyond that. Ok; I’ve not got the latest and greatest MySphere 3.1 or 3.2 earspeakers. I haven’t even heard a pair yet. Heinz was not able to make CanJam London 2018 as he was so busy getting things together. When he gets to the UK you can be sure I shall be there in person to lend my ears to the debate. The debate being; have they pulled off the ultimate and beaten the K1000? With Heinz and the original team at the helm I’d put money on it that they have. In the meantime I shall have to content myself with owning the antique version. I’m sure there is room in my life as a headfier for all 3 headphones. And maybe, one day, we shall see a 4th addition to the happy family? I wonder, dear reader, what that headphone might be?

Heinz Renner
Thank you for everything you have done for me. Thank you for your loyalty and affinity with the headfi community. And thank you for stepping out from the past and taking a leap into the future.
Much respect