Sennheiser and Aluminum Voice Coil
Feb 3, 2009 at 10:11 PM Thread Starter Post #1 of 10

mbd2884

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Why do they use aluminum voice coil? From what little I have read so far, Aluminum only recommended in speakers due only when you have high power source. If not its still recommended to use Copper.

Basically what I read it doesn't make sense to use aluminum voice coils in headphones, and probably why Sennheiser seems to be the only one to do so, and rest of industry either use copper bobbin or copper clad aluminum voice coil. Did notice that the K701 and K702 use flat wire aluminum, another headphone that doesn't truly shine until driven by an amp well above its own value.

My impression so far is copper used to conteract the limitations of aluminum which conducts too much heat and burning the speakers. Instead of using some sort of polymer, copper is used instead.

Seems AKG and Bose turned to using flat wire or flat ribbon aluminum to address the same issue above and to avoid dialectric breakdowns.

So I can find good reasons why AKG and Bose use flat wire aluminum and other uses copper cladded aluminum voice coil, but can't find any good reason why Sennheiser uses the voice coils they do. Its also the reason why I suspect they have a veiled sound unless powered by expensive amps/tubes and why their signature sound that many find unimpressive is pervasive in their entire line of audiophile/personal headphones.

Love to read some input and discussion about this. The pros cons of aluminum, copper and aluminum flat wire or ribbon. I'm sure I am correct on everything, but would shed some light into why some headphones are so hard to drive and why they maintain a veiled sound until used with powerful amps. And for those of us who are not as knowledgeable on this subject.

Also more interesting to read than another suggest me a headphone because I can't use the "search" button. That was in jest right there if you happen to miss it.
 
Feb 3, 2009 at 10:41 PM Post #2 of 10

John Willett

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Sennheiser use aluminium ribbon because it's light.

It makes the weight of the diaphragm much lighter than using a copper coil and therefore it's faster and more responsive.

Yes, the downside of aluminium is that it has a lower melting point than copper and is more easily damaged by the switch-on surge of some amplifiers.

But this is more than made up by the speed and responsiveness of the capsule.
 
Feb 3, 2009 at 10:49 PM Post #3 of 10

Kees

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Halfway your post you switched from Sennheiser to Bose!?!?!
Is this Freud-Fi or what?
evil_smiley.gif


Quote:

Why do they use aluminum voice coil? From what little I have read so far, Aluminum only recommended in speakers due only when you have high power source. If not its still recommended to use Copper.

Basically what I read it doesn't make sense to use aluminum voice coils in headphones, and probably why Sennheiser seems to be the only one to do so, and rest of industry either use copper bobbin or copper clad aluminum voice coil. Did notice that the K701 and K702 use flat wire aluminum, another headphone that doesn't truly shine until driven by an amp well above its own value.

My impression so far is copper used to conteract the limitations of aluminum which conducts too much heat and burning the speakers. Instead of using some sort of polymer, copper is used instead.

Seems AKG and Bose turned to using flat wire or flat ribbon aluminum to address the same issue above and to avoid dialectric breakdowns.

So I can find good reasons why AKG and Bose use flat wire aluminum and other uses copper cladded aluminum voice coil, but can't find any good reason why Sennheiser uses the voice coils they do. Its also the reason why I suspect they have a veiled sound unless powered by expensive amps/tubes and why their signature sound that many find unimpressive is pervasive in their entire line of audiophile/personal headphones.

Love to read some input and discussion about this. The pros cons of aluminum, copper and aluminum flat wire or ribbon. I'm sure I am correct on everything, but would shed some light into why some headphones are so hard to drive and why they maintain a veiled sound until used with powerful amps. And for those of us who are not as knowledgeable on this subject.

Also more interesting to read than another suggest me a headphone because I can't use the "search" button. That was in jest right there if you happen to miss it.


 
Feb 4, 2009 at 9:16 PM Post #5 of 10

ericj

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I don't think the aluminum is substantially less durable than copper. Not in the voice coil scenario at least.

Thinking about it now, I'm not sure I've heard of a detached / broken voice coil lead that was aluminum. Unless the HD600 was aluminum.

But I've heard of a number of copper AKG and Beyerdynamic voice coil leads - that's the wire from the coil to the solder lug - breaking or otherwise getting severed.
 
Feb 4, 2009 at 10:07 PM Post #6 of 10

Kees

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Quote:

Originally Posted by ericj /img/forum/go_quote.gif
I don't think the aluminum is substantially less durable than copper. Not in the voice coil scenario at least.

Thinking about it now, I'm not sure I've heard of a detached / broken voice coil lead that was aluminum. Unless the HD600 was aluminum.

But I've heard of a number of copper AKG and Beyerdynamic voice coil leads - that's the wire from the coil to the solder lug - breaking or otherwise getting severed.



Voice coils ought to be cryo treated!
wink.gif
 
Feb 4, 2009 at 10:52 PM Post #7 of 10

John Willett

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Quote:

Originally Posted by ericj /img/forum/go_quote.gif
I don't think the aluminum is substantially less durable than copper. Not in the voice coil scenario at least.


It's not the durability - it's the melting point.

If you overheat the coil, an aluminium coil will burn through before a copper one; that's all.

The melting point of aluminium is 660.25° Celsius (933.40° Kelvin).

The melting point of copper is 1,084.60° C (1,357.80° K).

That's the payment for making it light. But you can see how hot it has to get before you get to the melting point.

In normal use it's no problem at all - only with equipment (normally the cheaper stuff) that puts a big switching surge through the headphones and speakers when it's switched on and off.

Hence I normally advise to not have headphones plugged in and turned up when you switch on and off.
 
Feb 4, 2009 at 11:07 PM Post #9 of 10

ericj

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Quote:

Originally Posted by John Willett /img/forum/go_quote.gif
It's not the durability - it's the melting point.

If you overheat the coil, an aluminium coil will burn through before a copper one; that's all.

The melting point of aluminium is 660.25DEG Celsius (933.40DEG Kelvin).

The melting point of copper is 1,084.60DEG C (1,357.80DEG K).

That's the payment for making it light. But you can see how hot it has to get before you get to the melting point.

In normal use it's no problem at all - only with equipment (normally the cheaper stuff) that puts a big switching surge through the headphones and speakers when it's switched on and off.

Hence I normally advise to not have headphones plugged in and turned up when you switch on and off.



Right. But every headphone I've heard of that lost a voice coil due to such a surge had a copper voice coil.

Primarily full-size beyers and mainly 250 and 600 ohm which have thinner wire. Some AKGs with dkk45 drivers as well. The old dkk32 akg drivers appear to be almost bulletproof.

What I'm saying is that the physical properties of the metal are not necessarily or even often a major factor in this type of failure. It's the overall design.
 
Feb 5, 2009 at 12:44 AM Post #10 of 10

Fitz

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Quote:

Originally Posted by ericj /img/forum/go_quote.gif
Primarily full-size beyers and mainly 250 and 600 ohm which have thinner wire. Some AKGs with dkk45 drivers as well. The old dkk32 akg drivers appear to be almost bulletproof.


The vast majority of the time the damage is caused by a recable or repair attempt rather than from a surge, too. AKGs sound great, but the way they attach the voice coil to the solder tabs/posts is just stupid, and Beyer isn't that much better. I think the only time I've managed to fully kill a driver (where the damage was in the coil itself and unrepairable) was on a Beyerdynamic.
 

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