Do not cover the transducers! - you can damage your headphones !!!

[liamk]

Senhheiser's HD580 user guide include information that covering the tranductors with your hands will damage the headphones.
Is this true ?
Unfortunately i've covered my hd580 for 4-5 seconds : / but i don't hear andy difference in sound. Is this possible that i've already damaged it ?

 

[JohnRich]

unless you were listening to ear shattering volumes I doubt 4-5 seconds of obstructing the grills would do any damage; if they don't sound any different then you don't have a problem

 

[JaZZ]

Impossible to damage the drivers that way. That's a joke.

 

[gsferrari]

Actually he is quite right and this is NOT a joke.

I amnot willing to experiment with my headphones but my engineering background tells me that this is like a diaphragm of a capacitive pressure sensor of the "relative" and not "absolute" kind. The absolute version will hold true for closed cans.

I have built several relative pressure sensors and I can tell you with authority that if operating conditions demand these to perform as absolute pressure sensors then the diaphragms will fail because of the damping.

I expect the same to hold true for headphones. In fact - Stax headphones are quite delicate and easy to damage if you dont follow proper operating procedures. Grado headphones are more susceptible than sennheiser headphones because it is far more easy to cover the driver housing of a grado headphone than it is to reliably cover that of a senn headphone. The senn headphone also has many leak points in its chassis that make "covering" it difficult.

It may not be an "instantaneous" process because the diaphragm is definitely tougher than my pressure sensor diaphragm but on a "scale" level it actually equates pretty well.

Stax HIGHLY recommends that you DONT burn in the headphone without having them on your head or against some kind of damping where the head should be - the pressure differences can damage the drivers.

 

[ixeo]

then i believe the following will most likely destroy your headphones...

 

[hugz]

i never let my graddos sit grill down on a table when i'm just using them as mini speakers (at normal listening levels of course.. they're open enough to let me enjoy the quiet sound and give my ears a rest) just in case of something like this

 

[gsferrari]

Quote:

Originally Posted by ixeo then i believe the following will most likely destroy your headphones...

No - like I said - there are plenty of leakage points on the sennheiser chassis to release pressure buildup. The sennheisers are the least "open" dependent "open" headphones I have seen.

Besides - there is enough volume inside those wooden housings to theoretically keep the headphone diaphragms free of pressure buildup. The only problem in this case would be reflected waves but I dont see owners complaining.

The woody senns will not damage the drivers.

Woody grados on the other hand - with a closed driver housing is not something I would recommend.

Cheers!

 

[gsferrari]

[size=small]An explanation of how this works :-[/size]

Grado / Sennheiser explanation :

Take a subwoofer and start playing a bass track on it. Now take a ring of rubber/towel/cloth and place it on the diaphragm. Slowly push down on this (the ring should be on the cone and not on the joint/suspension/center.

After some time the coil will detatch from the cone (the cone will rip around the central portion.

Either that OR the electrical dynamics (you know how a coil works right? Interaction between electric and magnetic fields produces motion by Faradays laws of electromagnetism) Now if you DONT allow the coil to move the way it is designed to move - you have interaction between electric and magnetic fields BUT the effect is being damped. Now the energy has to go somewhere...results in heat buildup (Lentz Law and Eddy Current have roles here) and damage to the driver and subsequently to the subwoofer.

Stax Explanation :

A stax headphone is a "damped" design. which means that you need external damping for the driver to perform at its optimum. This damping is provided by the head when the headphones are placed on the head.

Without this damping - its like a car with suspension but no damper springs. A wallowy ride with plenty of roll. Unstable. Suspension bottoms out and eventually gets damaged.

In a stax driver the suspension is provided by the electrode elements point of attachment to the frame. Without adequate damping, if the headphones are used - it places ENORMOUS stress on these joints and they WILL break.

 

[setmenu]

I very much doubt headphone transducers are likely to fail when unloaded
using normal signal levels.
As for the stax drivers over excursion is more likely to slap the electrodes [definitely to be avoided] during over high signal levels before the actual membrane becomes over stressed.
I would guess any recommendation by stax about unloading the phones
is to reduce the risk of the above rather than membrane damage at the attachment periphery.

So I would guess the best advice would be to have some mechanical sympathy for ones transducers and err on the side of caution by reducing the
volume a bit if choosing to run them unloaded.


Setmenu

 

[Xanadu777]

Quote:

Originally Posted by ixeo then i believe the following will most likely destroy your headphones...

Just as Beyer DT770's have a pressure release hole, so do the Senn Woodies at the bottom of the cups

No worries...

 

[taymat]

Quote:

Originally Posted by ixeo then i believe the following will most likely destroy your headphones...

Lol yes I think headphone transducers are all going to be damaged just by being closed! Seriously headhpone transducers don't move a lot at all and even if they did move a lot, how do you explain speaker designs where the driver pushes against air (in either direction) in a sealed box. I mean unless you don't allow the driver to move hardly at all, I don't see a risk IMO.

 

[gsferrari]

Quote:

Originally Posted by taymat Lol yes I think headphone transducers are all going to be damaged just by being closed! Seriously headhpone transducers don't move a lot at all and even if they did move a lot, how do you explain speaker designs where the driver pushes against air (in either direction) in a sealed box. I mean unless you don't allow the driver to move hardly at all, I don't see a risk IMO.

You are obviously not an engineer. When I design a pressure sensor it is a few microns (micro-meters) across and a 10th/100th less microns in thickness. They barely move...yet they produce sufficient output and work very well.

How much a driver moves is all a matter of scale. In fact - the lesser is the scale of motion and the higher the rate of change of direction...it is a stressful life...to be a headphone driver

 

[JaZZ]

Quote:

Originally Posted by gsferrari Actually he is quite right and this is NOT a joke. I amnot willing to experiment with my headphones but my engineering background tells me that this is like a diaphragm of a capacitive pressure sensor of the "relative" and not "absolute" kind. The absolute version will hold true for closed cans. I have built several relative pressure sensors and I can tell you with authority that if operating conditions demand these to perform as absolute pressure sensors then the diaphragms will fail because of the damping. I expect the same to hold true for headphones. In fact - Stax headphones are quite delicate and easy to damage if you dont follow proper operating procedures. Grado headphones are more susceptible than sennheiser headphones because it is far more easy to cover the driver housing of a grado headphone than it is to reliably cover that of a senn headphone. The senn headphone also has many leak points in its chassis that make "covering" it difficult. It may not be an "instantaneous" process because the diaphragm is definitely tougher than my pressure sensor diaphragm but on a "scale" level it actually equates pretty well. Stax HIGHLY recommends that you DONT burn in the headphone without having them on your head or against some kind of damping where the head should be - the pressure differences can damage the drivers.

No.

Increased damping will not damage the drivers. You can even apply excessive damping to speaker chassis without damaging them. Bose has lanched the 901 system years ago, which is based on extremely low-volume cabinets forming a very stiff air cushion for the membranes and shifting the bass resonance up to unusually high frequencies. Even worse: the whole system has been equalized at low frequencies, meaning the membranes have been driven by brute force to travel by millimeters against enormous air pressure. I've experimented myself with this bass principle and several bass drivers, with even smaller housings, and none of the drivers has ever been damaged.

Now you can say headphone drivers are much more delicate systems. However, you won't be able to create an airtight seal with your hands on the HD 600's rear grill.

Quote:

Besides - there is enough volume inside those wooden housings to theoretically keep the headphone diaphragms free of pressure buildup.

Indeed! And the same applies to the original housing. There's not much difference in terms of enclosed volume between it and the woodies, if at all. But if any of the two variants is more dangerous according to your hypothesis, then it's the woodies -- they do provide an airtight seal; whereas a hand on the grill doesn't.

Actually none of these scenarios are reality. Because of the fact that the Sennheiser's drivers are mounted on an open baffle. Any possible excessive air pressure will immediately be equalized through the air- and sound-permeable baffle.

So: no, putting your hands on the rear grill can't damage the drivers.

With electrostats on the other hand the scrupulousness has a real background. Theoretically it's possible to overstretch the foil membranes without the default acoustic resistance of a human head between the drivers. Anyway, I'm not sure if the qualms are really justified. I guess not. There are fully open electrostats such as the Jecklin Float and the Purtscheller with no damping through acoustic resistance at all. Although one can still argue that those drivers are designed for this specific operation.

 

[gsferrari]

Quote:

Originally Posted by JaZZ No. Increased damping will not damage the drivers. You can even apply excessive damping to speaker chassis without damaging them. Bose has lanched the 901 system years ago, which is based on extremely low-volume cabinets forming a very stiff air cushion for the membranes and shifting the bass resonance up to unusually high frequencies. Even worse: the whole system has been equalized at low frequencies, meaning the membranes have been driven by brute force to travel by millimeters against enormous air pressure

This is because the drivers have been designed to work in these conditions. Drivers are designed to work according to what is required of them. A tweeter does not have the same material / suspension / coil as a subwoofer because the demands on it are significantly different from the physical demands of being a subwoofer.

Quote:

Now you can say headphone drivers are much more delicate systems. However, you won't be able to create an airtight seal with your hands on the HD 600's rear grill

I agree and have posted to that effect in my earlier posts. This damage to a sennheiser driver is simply not possible using your hands. You have to seal the driver in to do this.

It is, however, possible to damage a Grado driver in this fashion.





Quote:

Although one can still argue that those drivers are designed for this specific operation.

I can assure you that this is a fact and driver optimization for targeted applications is a HUGE field in the audio world. I have applied for several positions in several audio companies like Bose, Sony etc. and my process engineering background will most likely get me into this area of work.

 

[JaZZ]

Quote:

Originally Posted by gsferrari This is because the drivers have been designed to work in these conditions. Drivers are designed to work according to what is required of them.

Of course. A HD 600 driver wouldn't survive in a Bose 901 system.

But you have to consider that also the occuring forces -- even in the worst-case scenario of a tight seal -- are overproportionally smaller in the case of a closed-baffled HD 600.

And don't forget the Senns' open baffle! It finally makes all those fears obsolete.

Quote:

...my process engineering background will most likely get me into this area of work.

This would be an interesting job I guess.