[analogsurviver]

Quote:

 
   Isn't it the same cause as that of the already discussed bass rattle? If you haven't read about it yet, it is caused by the disintegration of a foam disc that fulfills a damping duty. Just a thought...
   Also, make sure all the screws are tight. I have experienced a similar phenomenon a few years ago and it was caused by a loose screw, one of the four that help fix the leather headband against the plastic parts that the temple pads are attached to. You must "open the wings" of the k1000 to be able to see the screws.
 

Well, K1000 can be very temperamental in this department - and are temperature sensitive. In cold weather ( or churches I usualy record in and are unfortunately always cold ) they rattle and resonate more than in more pleasent conditions. Still - checking for any loose screws, particularly those two at the bottom of the earpiece holding together grids clamp and plastic piece covering the cable exit, is always a good idea.

 

[Piotr Ryka]

Quote:

 
   Isn't it the same cause as that of the already discussed bass rattle? If you haven't read about it yet, it is caused by the disintegration of a foam disc that fulfills a damping duty. Just a thought...
   Also, make sure all the screws are tight. I have experienced a similar phenomenon a few years ago and it was caused by a loose screw, one of the four that help fix the leather headband against the plastic parts that the temple pads are attached to. You must "open the wings" of the k1000 to be able to see the screws.
 

 
No, it isn't. As I wrote, it is some tremble distortion problem and it isn't applicable to bass rattle or wire vibrations. It is something what make impossible driver to appropriate perform highest grand piano sounds. Undoubtedly it is some driver problem. I changed driver, and after that for some time (about a few hundreds hours) there was no distortions, but that new driver wasn't able to perform such highest tones at that time. When you change stereo channels, distortions are in left.  

 

[Currawong]

hrklg01: Thanks for providing so much insight into the K1000. It's always great to have actual engineers here to discuss aspects of headphones and their design. I heard a pair for the first time on the weekend and was amazed. Now I think I will have to find a pair and a suitable amp for them I think. 

 

[analogsurviver]

Quote:

 
No, it isn't. As I wrote, it is some tremble distortion problem and it isn't applicable to bass rattle or wire vibrations. It is something what make impossible driver to appropriate perform highest grand piano sounds. Undoubtedly it is some driver problem. I changed driver, and after that for some time (about a few hundreds hours) there was no distortions, but that new driver wasn't able to perform such highest tones at that time. When you change stereo channels, distortions are in left.  

What happens if you play a mono recording or switch the system to mono - is the mentioned treble distortion always on the same, in your case, left side ? 
 
If yes, you can proceed as follows:
 
1.) Play your piano with high notes in mono on one channel only - K1000 should be on other person's head or on a appropriate stand, listen from at least a metre distance. 
2.)Reverse the channels - now listen to the other one.
3.) If there is a difference, it will be far easier to hear than listening to K1000 on your head
4.) If there indeed is a problem, try to listen to the defective driver from various angles, from closer distance. Try to touch grid(s) of this driver with a finger on various locations of the grid - if it changes/goes away, it is grid resonance, not the driver being actually defective. That is very rare with K 1000, did not hear about treble problems in drivers  before.
 
If that identified the problem, I can perhaps suggest how you can damp the grids - without to have to open/dismantle them. If you find it difficult to constantly search on  CD in order to get that high note causing trouble, I will post a link to a signal generator you can use for this purpose.
 
I know how much distraction a situation like yours can cause listening to the artistry of say, Gilels ...
 
Good luck !

 

[hrklg01]

Hi ... about some buzz out of the K1000:
 
Yes as I wrote before already such buzz problems might happen.
 
But I wrote now from Piotr Ryka, that he use the K1000 without front grid...
As long as I understand this way of use - it would result into buzz by human hairs touching the vibration membrane... it's causing non harmonic distortion ... very audible and disturbing...
Also this problem can happen sometime although the grids are protecting the membrane, because the grid opentings are just too large.
 
Therefore I like the description from analogsurviver very much... this is the right approach to detect the root cause.

 

[hrklg01]

Hi, two things more to the K1000 design:
 
1) The build in filter is a band pass and not a protection filter for the driver to get too much bass level! The band pass filter's function is to reduce the natural effect of increased level in the range of 3-7kHz resulting out of the large membrane area in front of the ear entrance.
 
2) The lack of very low frequencies, below 35Hz or so depending on the version, is a fact of the membrane resonance frequency only. It's not any effect from sound cancellation because of the open design. This is true because the membrane is in the very near to the human ear. The reason why we designed the f0 not lower is jsut the fact that the need of membrane displacement goes with the 4th order of the frequency.

 

[Piotr Ryka]

Quote:

Hi ... about some buzz out of the K1000:
 
Yes as I wrote before already such buzz problems might happen.
 
But I wrote now from Piotr Ryka, that he use the K1000 without front grid...
As long as I understand this way of use - it would result into buzz by human hairs touching the vibration membrane... it's causing non harmonic distortion ... very audible and disturbing...
Also this problem can happen sometime although the grids are protecting the membrane, because the grid opentings are just too large.
 
Therefore I like the description from analogsurviver very much... this is the right approach to detect the root cause.

Thank you for answer, but hair problem is too simple solution. I know hair influence and avoid it. And I have hairs on both sides 

 

[Blackmore]

Have you tried different amps, maybe its your amp that cause this. Also, some tubes can behave really bad.
 
Quote:

 
No, it isn't. As I wrote, it is some tremble distortion problem and it isn't applicable to bass rattle or wire vibrations. It is something what make impossible driver to appropriate perform highest grand piano sounds. Undoubtedly it is some driver problem. I changed driver, and after that for some time (about a few hundreds hours) there was no distortions, but that new driver wasn't able to perform such highest tones at that time. When you change stereo channels, distortions are in left.  

 

[analogsurviver]

Quote:

Thank you for answer, but hair problem is too simple solution. I know hair influence and avoid it. And I have hairs on both sides 

If none of the answers from hrlkg01, blackmore or me helped to find the cure, there are at least two more sources. If you do not have it already, please download the Service Manual : http://www.akg.com/mediendatenbank2/psfile/datei/34/k10004055d23c1050f.pdf
 
1.) K1000 has a very elaborate headband adjusting/tensioning arrangement. Using coils spring and a ball, parts #9 and #10 in the Service Manual. 
      Rarely but sometimes these can resonate like crazy, causing sounds similar to your descriptions. WARNING : if you choose to open/check for this,
      best way to proceed is to work over large plate/box ( I use "baths" for chemical reactions ) - after unscrewing the two screws holding everything in     question together, spring #9, ball #10 and pulleys #4 (2 pcs per one earpiece) WILL fall out - they are tiny and easy prey for the Carpet Monster. One way to adress this situation is to assemble everything back in reverse order of disasembling - with one exception; you can apply a little amount of grease on the spring 9 - that should prevent any rattling/resonances going on there. Or, if you are pragmatic as me ( read: lazy ), simply omit pulleys #4, spring #9 and ball #10. 
 
2.) What are you driving K 1000 with ? K1000 is about as hard to drive properly as it gets - small amplifiers are incapable of supplying enough voltage swing and clipping on piano can/does sound like you described; big amps ( 100 W+ into 4-8 ohm load ) can simply exceed K1000 excursion capabilities causing bottoming, but that is normally a low and not a high frequency problem. Try different amp(s) and if the problem persists, it really is the K1000.
 
3. If procedure 1.) and 2.) do not cure your problem, ask yourself fairly if you ever really grossly overloaded that left driver - like pulling the RCA cable out by mistake anywhere preceding the amplifier , or switching between two sources having considerably different levels without reducing the volume when going from low output to high output source ( in extreme cases, can amount to 20 dB or so , say  between  output of an extremely low output MC phono cartridge and a CD player ) - in that case, I am afraid you will have to brake one piggy bank with appropriate amount  in order to get new driver.

 

[Piotr Ryka]

As about my system, it's like on the picture. Croft Polestar1 is a 25 W/8Ω power amplifier, so I don’t think it is not enough strong. I've tried my K1000 with other systems, and never heard distortions, but on the other hand I've used by many weeks HiFiMAN's HE-6 and HE-5LE in quite the same as K1000 configuration, and also didn’t heard any suspicious tones.
So? So all this story is slightly strange.
I can only say, that this distortions are undoubtedly generated by drivers, and only with my system, where highs are great. (But maybe not enough appropriate?) And only time to time. And only with highest grand piano tones. And I don’t know why.   
Thank you everybody for yours attention and suggestions; maybe some day I solve this problem, maybe not. I've changed both drivers and cable. Without any result.    
 
 
 

 
 
As you see on the picture, I've modified shape of headband arches. If someone find AKG K1000 head pressure too strong, this is helpful. 

 

[Blackmore]

Piotr, Croft Polestar1 is hybrid, right? Which tube inside, Mullard? Try to roll, like I wrote, tubes can behave very badly. For piano work I would choose Brimar or some Tung Sol. Mullards are great, but only the one that been made before 1965, from 50's are the best, but from 70's are ****.
 
Other than that, you set up are fantastic, thanks for sharing.

 

[Piotr Ryka]

Quote:

Piotr, Croft Polestar1 is hybrid, right? Which tube inside, Mullard? Try to roll, like I wrote, tubes can behave very badly. For piano work I would choose Brimar or some Tung Sol. Mullards are great, but only the one that been made before 1965, from 50's are the best, but from 70's are ****.
 
Other than that, you set up are fantastic, thanks for sharing.

 
Yes, Polestar1 is a hybrid. As about the tube, I can submit original message from Mr. Croft to me:
 
"Hi Piotr,
the standard tube for the Polestar 1 was the 5965 but as you have discovered it will work with many other valves such as the ECC83, 5751, ECC81 and even the ECC82 though the gain will be a lot lower. (…)
 
Best regards,
Glenn Croft."
 
I have and I've tried many tubes with this machine, like Mullard E180CC, Mullard ECC83 "longplate", ECC83 Aperex, original General Electric 5965 and finally the best what could be – 5965 "longplate" by Telefunken. The best sound is with longplate Mullard and Telefunken.

 

[Blackmore]

Very, very nice, that you can roll such different tubes I mean, so, then I dont know, probably K1000 have, sometimes, the difficulty of reproducing the particular piano records, probably by reaching their limit somehow, because you wrote that its present, but not all the time.
Oh, do you have always this issue with the same piano record or its just one time it is and another not? If so, then its the driver, I guess...
 
THX
 
 
 
Quote:

 
Yes, Polestar1 is a hybrid. As about the tube, I can submit original message from Mr. Croft to me:
 
"Hi Piotr,
the standard tube for the Polestar 1 was the 5965 but as you have discovered it will work with many other valves such as the ECC83, 5751, ECC81 and even the ECC82 though the gain will be a lot lower. (…)
 
Best regards,
Glenn Croft."
 
I have and I've tried many tubes with this machine, like Mullard E180CC, Mullard ECC83 "longplate", ECC83 Aperex, original General Electric 5965 and finally the best what could be – 5965 "longplate" by Telefunken. The best sound is with longplate Mullard and Telefunken.

 

[analogsurviver]

Quote:

As about my system, it's like on the picture. Croft Polestar1 is a 25 W/8Ω power amplifier, so I don’t think it is not enough strong. I've tried my K1000 with other systems, and never heard distortions, but on the other hand I've used by many weeks HiFiMAN's HE-6 and HE-5LE in quite the same as K1000 configuration, and also didn’t heard any suspicious tones.
So? So all this story is slightly strange.
I can only say, that this distortions are undoubtedly generated by drivers, and only with my system, where highs are great. (But maybe not enough appropriate?) And only time to time. And only with highest grand piano tones. And I don’t know why.   
Thank you everybody for yours attention and suggestions; maybe some day I solve this problem, maybe not. I've changed both drivers and cable. Without any result.    
 
 
 

 
 
As you see on the picture, I've modified shape of headband arches. If someone find AKG K1000 head pressure too strong, this is helpful. 

Nice setup! With one, but in your case, fatal flaw. It is very likely underpowered for your needs - voltage swing may well be not enough to reproduce piano in full dynamic range.
 
If you have access to the oscilloscope - compare input to the Croft with output to K 1000; set the gain on oscilloscope so that both are exactly the same amplitude, invert phase on one and then sum both together - perfect result would be straight line, no signal at all. It is normal to see small deviations like some distortion/noise/phase shift - if "horns" are visible while you play your high piano notes on peaks - the amp is clipping and that is the cause of your trouble . New, more powerful ( voltage swing must be great enough ) amp is in order. The reason why it does not happen with your other headphones is the fact they are low impedance designs not requiring so large voltage swing as extremely inefficient 120 ohm impedance K 1000.
 
Wait - just had an idea. As you say it only happens on certain high pitch notes - have you tried various tube damping rings etc - it might be one/some of your tubes have mechanical high Q (undamped) resonance at that frequency - damping rings and similar might help to solve the problem - if it is not clipping related as described above. Please check for clipping in any case first.
 
K 1000 is ultimately still incapable of real piano dynamic range, no matter what you are driving it with. Particularly in the bass - I would never use it to monitor live uncompresed feed from the microphone when recording a piano. For most recordings, using large enough amp should be "enough" - if you want to stay with (hybrid) tubes, I would reccommend RKV . It was made for high impedance ( 600 ohms ) headphones and although 120 ohm of K 1000 is at the very lowest limit of its capability, reportedly this is one of the best, if not THE best match for K 1000 to date. It has one decisive advantage over Croft (and most other transformer coupled tube amps) - no output transformers. 
 
Piano recording/playback is one of the most demanding tasks in audio - unfortunately, price(s) of the associated equipment reflect(s) this.
 
BTW - LOVE your headband arches shape modification - for larger heads, original can be something Inquisition might have been using in order for you to "confess" !

 

[Blackmore]

I would also suggest pretty cheap solution, unless you dont have the right amp to drive them, buy K701 or K702, both can do the piano very good and cost nothing these days, cheaper than switching to another amp etc, imo.