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History of the AKG K1000? - Page 12

post #166 of 193
High. A perforated foam reduce the damping factor of the driver and can cause rubber&buzz due loose particles too.
replace it by a 80ppm foam with complete open bubbles. It's a so called "recticulated" foam original from company Recticell.
post #167 of 193
The material described sounds like what you can find in a fish filter foam at a pet store - they come in several densities. The original foam is kind of dense so I never thought to try such an open type of foam. When the foam crumbled on my pair I put a thin aluminum craft screen in first then a piece of transpore porous medical tape (paper type) and finally some standard sparkly packing foam from a Grado box cut to size. That seemed to work very well and gave me the best sound. Now I want to try some 'fish' reticulated foam.

post #168 of 193

Hi,

difficult to judge if your approach is ok without measuring. However, I made a failure: the foam is 80ppi not ppm.

ppi stands for porous per inch.

It's quite easy to count the poures under a strong magnifying glass

But important is that the poures (cells) are totally open (no membranes between the cells)!

BR heinz

post #169 of 193

Thanks for the info MR Heinz, It's good to see that you're still around. I did a fair share of searching but couldn't find the type of reticulated foam that's above 45PPI, Unfortunately it's also gets quite expensive as the density increases.

 

I guess I'll try my luck in the pet store, as per realstar's tip, before contacting AKG. It's just that i have to make an order for parts thru my local distributor which is a pianfully slow process.

post #170 of 193

Try here http://steplaw.com/reticulatedfoam.html

 They send out samples which might be enought for the K1000's

 

 

Quote:
Originally Posted by Amarphael View Post

Thanks for the info MR Heinz, It's good to see that you're still around. I did a fair share of searching but couldn't find the type of reticulated foam that's above 45PPI, Unfortunately it's also gets quite expensive as the density increases.

 

I guess I'll try my luck in the pet store, as per realstar's tip, before contacting AKG. It's just that i have to make an order for parts thru my local distributor which is a pianfully slow process.

post #171 of 193

Try here http://steplaw.com/reticulatedfoam.html

 They send out samples which might be enought for the K1000's

 

 

Quote:
Originally Posted by Amarphael View Post

Thanks for the info MR Heinz, It's good to see that you're still around. I did a fair share of searching but couldn't find the type of reticulated foam that's above 45PPI, Unfortunately it's also gets quite expensive as the density increases.

 

I guess I'll try my luck in the pet store, as per realstar's tip, before contacting AKG. It's just that i have to make an order for parts thru my local distributor which is a pianfully slow process.

post #172 of 193
Unfortunately the fish filter foam I recommended is pretty hard to find in 80ppi configuration. Mostly seems to be from 45 to 60 ppi. However I wonder if an 80ppi foam buffing pad would work ok? Not sure if it's reticulated foam but it may well be.

http://www.bestsupreme.com/Black-Foam-Grip-Pad-80-PPI_p_202.html
post #173 of 193

Hi -that's the right one!

Make sure that:

1. no loose particles of the old foam get into the magnetic air gap - otherwise you got R&B

2. the new foam is about 5mm in thickness

post #174 of 193

Excuse my hesitation, What makes you certain it's reticulated type foam?

post #175 of 193

Hi,

The link " http://steplaw.com/reticulatedfoam.html " is the right one, because of the picture and the fact that the name is "reticultated".

I used as developer of the K1000 this foam so often. That's why I know it just from the picture.

BR heinz

post #176 of 193
I found a polishing/finishing pad at a local auto parts store to try. It's definately reticulated foam, if you look under magnifying
glass it looks more like a dense web with the central bubbles missing. These kind of foam pads are not that hard to find even
at local stores. Basically anywhere you find auto polish and wax there is a good chance they may have this kind of polishing pad.
Black colored ones seem to be 80ppi other colors may be different.

The actual pad I bought was 6" in diameter and 1.25" thick. I had a little trouble cutting out suitable round sections.
Best method I had was to use a hole saw with the drill bit taken out of the center and carefully run the drill in reverse.
This leaves a clean round hole instead of tearing/ripping the foam. Afterwards I did my best just cutting across with
the scissors to form some usuable round pieces. I wasted a lot of material but ended up with a few good pieces to use.

I tried the new foam and it does seem better than what I was using before. After testing I still prefer the sound with the thin
aluminum grill and micropore tape in the bottom before inserting the foam. Don't attempt this unless you are very comfortable
opening up your K1000. I previously put a thin rubber seal inside the frame of mine so it can be opened/closed anytime without
using glue. (Permatex motoseal - dries rubbery and easy to peel off later if needed)
Edited by realstar - 7/4/13 at 4:34am
post #177 of 193

Thank you realstar and Heinz for this information.  I hope that I'll never have to do this, but I am definitely keeping this in mind just in case.  realstar, could you possibly post photos of what you have done?  That would be great!

post #178 of 193
Quote:
Originally Posted by hrklg01 View Post
 

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

 

 

Hello Heinz,

 

Did you or any of your colleagues design the K500 too? I've been listening a lot to the K400, K500, K401 and K501 the last few years and through modification and experiments with modern amps have found that the K500 exhibits extraordinary qualities in the right environment. Would be very interesting to know a little bit more about this design and development.

 

About 20 years ago I visited the AKG plant in Vienna for a reportage and talked with several designers of the staff, and one thing that stuck in my mind from the female head engineer was that "new diaphragm materials were less important than design of the housing." Also saw a pair of loudspeakers using about 40-50 (estimated!) K1000 drivers that I was not allowed to photograph!

 

Best wishes

post #179 of 193
Quote:
Originally Posted by MDR30 View Post
 

 

 

Hello Heinz,

 

Did you or any of your colleagues design the K500 too? I've been listening a lot to the K400, K500, K401 and K501 the last few years and through modification and experiments with modern amps have found that the K500 exhibits extraordinary qualities in the right environment. Would be very interesting to know a little bit more about this design and development.

 

About 20 years ago I visited the AKG plant in Vienna for a reportage and talked with several designers of the staff, and one thing that stuck in my mind from the female head engineer was that "new diaphragm materials were less important than design of the housing." Also saw a pair of loudspeakers using about 40-50 (estimated!) K1000 drivers that I was not allowed to photograph!

 

Best wishes

 

Loudspeaker with K1000 drivers .... very interested :k701smile:

 

I own a K501 (get it from an ex AKG stuff member) , I had a K1000 for a while (loan from an AKG stuff, bust get them back) and now I have the new K812 Pro

 

All this offers another line of music presentation in contrast to the K/Q7xx line.

 

Have you some contact to ex AKG stuff members, please send me a PN/PM

post #180 of 193

Hi,

To your questions Fritz,

No, I was not involved in the development of the later headphones like K500 because I left at that time AKG after 17 years R&D there.

Yes, housing material and design is very important too. This is because of two effects: 1.) The body sound caused by the moving mass (mechanic and acoustic) which interact with the housing and causing resonances there. 2) The air pressure inside the phone which just do the same negative effect but not in the same phase.

I would not judge if material of membrane or headphone housing is more important, because it's not really comparable at least to my understanding.

To your experiments with amplifieres I can only agree to. The quality of Amps are very much inderestimated.

BR heinz

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