[o0CosmoMemory0o]

Yes, it's exactly as you have written it. But I didn't want any of the debris going into the driver nor did I want the headphones retaining any odour of past use. I have cleaned all parts both thoroughly and sensibly. That thin foam could be easily replaced with a similar alternative if the user felt absolutely necessary or another thin cloth disc can sit behind the foamless disc. I'm just glad they're clean; same with the earpads. When I washed all of my earpad skins in warm water and alcoholic gel, the water went black and yellow as I got all the impurities out. Brand new foam in, stitch up and whilst may not be as dark black as brand new, the result is still great.

 

[2leftears]

Yes, it's exactly as you have written it. But I didn't want any of the debris going into the driver nor did I want the headphones retaining any odour of past use. I have cleaned all parts both thoroughly and sensibly. That thin foam could be easily replaced with a similar alternative if the user felt absolutely necessary or another thin cloth disc can sit behind the foamless disc. I'm just glad they're clean; same with the earpads. When I washed all of my earpad skins in warm water and alcoholic gel, the water went black and yellow as I got all the impurities out. Brand new foam in, stitch up and whilst may not be as dark black as brand new, the result is still great.

I just had a quick look inside my own pair. The foam probably used to be white, but is now a pink hue. I probed a tiny bit of it with a small screwdriver, and it seems to behave exactly like old camera foam. The polymers have destabilised over time and it has become both sticky & crumbly. However, usually this stuff stays in place fine if you don't disturb it...

I have had this pair since new and always taken great care with them, plus I don't smoke. Hence no immediate need to clean the driver backs + cloth/foam, so I'll leave it well alone for now. Fortunately the earpads are easy to detach and I clean those regularly.

 

[o0CosmoMemory0o]

Yeah, I think the destabilized foam would have stayed in place but I decided to be overzealous and remove it all from the cloths that had large crumbled sections. I have about five or six pairs where the cloth/foam is like new so I had no need to clean/remove it. Comparing the sound between them, I can't hear any difference.

 

[2leftears]

Incidentally, how did you remove the foam from the cloth? That stuff is a sticky mess. In cameras I need alcohol or naphtha to remove it, which might not work well for these cloths I suspect...

 

[o0CosmoMemory0o]

When I submerged it in water and agitated it by rubbing, it rapidly came off.

 

[the Ortherion]

The HD600 cable and the HD540II headband with a couple of clips for holding the headband pad on would set you back £25 GBP including postage to Portugal, if you think that's fair.

You will have to provide the headpad though. I don't have one to go with this headband.

I know. I can arrange one. In fact I don't need the headband. Just gathering spare material. How do you like the hd600 cable vs the original one. I will be using it on the hd560

 

[o0CosmoMemory0o]

I personally prefer the HD250 cable, which has the correct plug sizes for the HD540 and HD560. I think it's a lower capacitance cable than the HD600 one as well.

 

[the Ortherion]

What do you mean low capacitance? I don't know what that means. The sound is affected? Btw guys anyone has ever tried the AKG K501 and compared it to the HD540/HD560?

 

[o0CosmoMemory0o]

In physics, electrical capacitance is the ability of a material to store charge when a voltage is applied across it. 1 Farad = 1 Coulomb per Volt
 
All materials have capacitance, no matter how large or small the charge capacity that they possess. There are no such things as perfect insulators either; only poor conductors, so even cable sheathing may affect the overall electrical capacitance. I don't know enough science to elaborate on this.
 
Whilst the capacitance of capacitors can be in the order of whole Farads, millifarads or microfarads, cables can have capacitance in the order of picofarads (10^-12 Farads), which is very small but is still measurable and can still have an effect on signal transmission. Think of it like this: If you are sending a rapidly changing signal down a conductor and the material electrical recovery time is not rapid enough to keep up with the changes, then there will be what is called intermodulation distortion. This term describes the time lag of the material behind the true signal. Seeing as I did some neuroscience at university, perhaps look up "relative refractory period" and "absolute refractory period" of nerve impluses; it is a similar kind of principle in that if wave intervals are too rapid for the material to keep up with, the output will be different than if the signal is sent down the material when in its "resting" state.
 
Long story short, if the material has a higher capacitance, it will store more charge when the signal propagates down the conductor, affecting subsequent signals adversely. So a lower capacitance means less charge stored per unit of potential difference, meaning less intermodulation distortion (material recovery won't lag behind the signal speed), meaning purer audio due to more faithful phase alignment. 
 
Sorry if this is confusing. It may not be completely accurate. I haven't checked it; this just came out of my head and is how I reason with the principle.

 

[2leftears]

In physics, electrical capacitance is the ability of a material to store charge when a voltage is applied across it. 1 Farad = 1 Coulomb per Volt

All materials have capacitance, no matter how large or small the charge capacity that they possess. There are no such things as perfect insulators either; only poor conductors, so even cable sheathing may affect the overall electrical capacitance. I don't know enough science to elaborate on this.

Whilst the capacitance of capacitors can be in the order of whole Farads, millifarads or microfarads, cables can have capacitance in the order of picofarads (10^-12 Farads), which is very small but is still measurable and can still have an effect on signal transmission. Think of it like this: If you are sending a rapidly changing signal down a conductor and the material electrical recovery time is not rapid enough to keep up with the changes, then there will be what is called intermodulation distortion. This term describes the time lag of the material behind the true signal. Seeing as I did some neuroscience at university, perhaps look up "relative refractory period" and "absolute refractory period" of nerve impluses; it is a similar kind of principle in that if wave intervals are too rapid for the material to keep up with, the output will be different than if the signal is sent down the material when in its "resting" state.

Long story short, if the material has a higher capacitance, it will store more charge when the signal propagates down the conductor, affecting subsequent signals adversely. So a lower capacitance means less charge stored per unit of potential difference, meaning less intermodulation distortion (material recovery won't lag behind the signal speed), meaning purer audio due to more faithful phase alignment. 

Sorry if this is confusing. It may not be completely accurate. I haven't checked it; this just came out of my head and is how I reason with the principle.

You are mostly correct, but not regarding the intermodulation distortion in my opinion. Theoretical pure capacitances do not generate intermodulation distortion. Practical ones may do a tiny bit, depending on the non-linear characteristics of the dielectric used. Electrolytic capacitors are notably bad and can introduce intermodulation distortion, depending on the configuration and quality of the electrolyte used. Cables will introduce negligible intermodulation distortion however. Together with both the resistance and inductance of the cable, the capacitance will create a low-pass filter, i.e. higher frequencies will be attenuated (we are talking MHz / GHz domain here though, unless the output impedance of the source is very high like several Mega Ohm). This will give you a first or second order low pass filter, which does introduce a frequency-dependent phase shift, but no noticeable intermodulation distortion.

I very much doubt whether any difference in capacitance between the HD250 / HD600 cable would be audible, even if it were 20 meters long.

In any case, what makes you think the capacitance of the HD250 cable is lower? has the capacitance been published somewhere?

 

[2leftears]

Whilst the capacitance of capacitors can be in the order of whole Farads, millifarads or microfarads...

Twenty year ago I would have said you were barking mad . Capacitors of one Farad or more (in reasonably useful voltage rating) would need to be electrolytic and be the size of several stacked beer cans. Nobody would make or want one like that.

Well, they are in the shops now, electrolytic and the size of several stacked beer cans. Mostly for in-car "hifi" use it seems...

 

[o0CosmoMemory0o]

An engineer I know of measured the electrical capacitance of both HD250 and HD600 copper cables. I'm sure he said that he measured (multimeter, I guess) them both to be in the order of hundreds of picofarads, where the HD250 cable was a couple of hundred less than the HD600 one. My memory may be incorrect here. You seem to have more understanding than I do with this topic. Wouldn't surprise me if "whole Farad" electrolytic capacitors are also used for industrial applications such as in power supplies for regulation/smoothing and resevoir energy for demanding loads. Just a suggestion;I haven't got my facts straight.
 
Even small differences in picofarad-order electrical capacitance may produce audible effects in audio playback, because the wave transitions are so rapid. Again, just a suggestion; I'm not an engineer. I might have the right kind of idea but simply use the incorrect terminology. Perhaps I have misunderstood intermodulation distortion to be what occurs when one or more parts of a transduction chain are not proficient enough in speed or rigidity to adequately represent the original signal. For example, a context where I have read about it is: cone driver vs electrostatic driver.
 
Thanks for your response. I encourage you to correct me when I get things wrong. I'd like to carry on learning. My life has stagnated recently and I'd like to get back my old fire.

 

[2leftears]

An engineer I know of measured the electrical capacitance of both HD250 and HD600 copper cables. I'm sure he said that he measured (multimeter, I guess) them both to be in the order of hundreds of picofarads, where the HD250 cable was a couple of hundred less than the HD600 one. My memory may be incorrect here.

You probably remember correctly.

Wouldn't surprise me if "whole Farad" electrolytic capacitors are also used for industrial applications such as in power supplies for regulation/smoothing and resevoir energy for demanding loads. Just a suggestion;I haven't got my facts straight.

They do, although often they use battery banks then. My father used to work for an aerospace/aviation research laboratory that has a full-scale wind-tunnel for aerodynamic testing nearby. The fan in that wind-tunnel has a momentary power draw of almost 13MWatt (not kidding!!) when switching on which needs to be buffered by a huge battery bank, otherwise the lights in the entire nearby town would dim (that's a person standing underneath):

Even small differences in picofarad-order electrical capacitance may produce audible effects in audio playback, because the wave transitions are so rapid. Again, just a suggestion; I'm not an engineer. I might have the right kind of idea but simply use the incorrect terminology.

Well, it wouldn't be the first time that theory dictates something should be inaudible, but head-fi ears disagree!

Perhaps I have misunderstood intermodulation distortion to be what occurs when one or more parts of a transduction chain are not proficient enough in speed or rigidity to adequately represent the original signal. For example, a context where I have read about it is: cone driver vs electrostatic driver.

Indeed, there it does apply, as significant cone excursion on a single wide-bandwidth driver (loud bass) can modulate the higher frequencies it produces. Likewise the voice-coil / magnetic gap geometry may not be linear for large excursions, which will not only create intermodulation distortion but also harmonic distortion. In contrast, electrostatic driver excursion is usually small over a very large area, and the electrostatic field is very linear, resulting in much less distortion (unless played at excessive volume, by which time you may be burning / arcing holes in the diaphragm).

 

[Kjuiss]

Hello fellow HD540-lovers...(sorry for my English)
just got mine from a fleamarket in Germany (2 Euro)  and had the opportunity to compare them to many different other older Sennheisers AKGs and Beyer Dynamics, hooked to an Anedio D2 DAC.... As for now I think I will keep them. Like the HD800 the spacious stage the 540 produce is fantastic. Its the older grey 300 Version with original cable and Mesh-Pads. For the price you can normaly find them on ebay they are fantastic. Its really mindblowing... 
 
What i think is very important for these Headphones are the original MESH-Pads !! ... Only the original pads help producing the  fantastic spacious stage. Forget about the cheap ebay-china pads... they are crap.. to small to flat... really bad quality.
What I found fits the HD540 perfectly are the leather-Pads of my HifiMan He400 in matter of size. The only problem is the change of sound. The stage is dramatically reduced. 
I know there is also a velours-version of these hifiman-pads perhaps someone would like to give them a try =) ... size fits perfectly... since the reference II had velourpads and some of you guys  think they sound even better than the meshpads its perhaps worth it.
 
Since the foam of the original pads is flatened i tried some DIY. I cut the pads open on the backside and took out the foam. The foam consists of 2 foamrings divided by some kind of stiff fabric. I think this fabric is also important... thats why I tried to reproduce these foamrings with some round foampieces you can find in Watchboxes from Casio Edifice and G-Shock =). I did the best I could and it looks like new now... but still doesnt sound exactly like the original pads. So the kind of foam is perhaps also important.
 
Next thing I will try are the velourspads from hifiman perhaps... 

 

[o0CosmoMemory0o]

The pads that I think sound best on the HD540 are the HD540II velour pad skins with my fresh stock foam tucked into them but the skin NOT stitched up. Stitching up the pad makes the pad look better but typically compresses the inner foam a little, making them slimmer and therefore bringing the drivers closer to the ears. This reduced volume of space inside the earcup reduces stereo imaging IMO. The HD540II velour pad that has the backing pleather on its reverse face is a bit too slim in stitched up thickness so I recommend using these unstitched for extra thickness. This also makes foam replacement easy...