Liquid inside a tweeter

Archived from groups: rec.audio.high-end (More info?)

I own a Moudaunt-Short MS10i Classic bookshelf loudspeaker. Recently
one of the tweeters stop working. I was able to fix it since it was a
broken wire in the coil connection. However, in this disassembling
process I found (in the two tweeters) a dark brown liquid inside the
circular groove in the magnet where the coil is supposed to stay. Is
this liquid part of the tweeter mechanism (and the coil is dipped on
it) or is just moisture accumulated over the years? I am afraid to dry
it up. Any help would be very welcome. Thanks very much. Jose Carlos
Brunelli

Archived from groups: rec.audio.high-end (More info?)

It's called Ferro Fluid. It's a magnetic fluid that dissapates the heat and
increases the power handling of the tweeter. The amount is supposed to be
the same in both tweeters as it has an effect on the physical response of
the tweeters.

Mark T.
"JCBrunelli" <brunelli@amja.org.br> wrote in message
news:cjpvdh02bjc@news1.newsguy.com...
> I own a Moudaunt-Short MS10i Classic bookshelf loudspeaker. Recently
> one of the tweeters stop working. I was able to fix it since it was a
> broken wire in the coil connection. However, in this disassembling
> process I found (in the two tweeters) a dark brown liquid inside the
> circular groove in the magnet where the coil is supposed to stay. Is
> this liquid part of the tweeter mechanism (and the coil is dipped on
> it) or is just moisture accumulated over the years? I am afraid to dry
> it up. Any help would be very welcome. Thanks very much. Jose Carlos
> Brunelli

Archived from groups: rec.audio.high-end (More info?)

JCBrunelli wrote:

> I own a Moudaunt-Short MS10i Classic bookshelf loudspeaker. Recently
> one of the tweeters stop working. I was able to fix it since it was a
> broken wire in the coil connection. However, in this disassembling
> process I found (in the two tweeters) a dark brown liquid inside the
> circular groove in the magnet where the coil is supposed to stay. Is
> this liquid part of the tweeter mechanism (and the coil is dipped on
> it) or is just moisture accumulated over the years? I am afraid to dry
> it up. Any help would be very welcome. Thanks very much. Jose Carlos
> Brunelli

That sounds like Ferrofluid. It is supposed to help conduct heat from
the voice coil to the surrounding magnet structure; and perhaps to
provide some mechanical damping to the voice coil.

-Gene Poon

Archived from groups: rec.audio.high-end (More info?)

brunelli@amja.org.br (JCBrunelli) wrote in message news:<cjpvdh02bjc@news1.newsguy.com>...
> I own a Moudaunt-Short MS10i Classic bookshelf loudspeaker. Recently
> one of the tweeters stop working. I was able to fix it since it was a
> broken wire in the coil connection. However, in this disassembling
> process I found (in the two tweeters) a dark brown liquid inside the
> circular groove in the magnet where the coil is supposed to stay. Is
> this liquid part of the tweeter mechanism (and the coil is dipped on
> it) or is just moisture accumulated over the years? I am afraid to dry
> it up. Any help would be very welcome. Thanks very much. Jose Carlos
> Brunelli

This is the famous "ferrofluid" that you have undoubtedly heard of. It
floats around in the magnetic gap but does get on the voicecoil if you
remove it. What's best is to not dry it up and just put it back. Most
likely what you see represents a minority of the total fluid still
present in the gap, although this is not absolutely certain as some
tweeters tend to scoop out more than others. If by doing the surgury
you did some FF got smeared in other places you can wipe this off. It
should be on or very nearby the coil, nowhere else. After
investigating this a quite few times I found that there are ussually
no audible or significant measurable differences after doing something
like this. You should be just fine.

You should avoid potential generic audiophile advice from some who say
that ferrofluid doesn't sound better etc and to remove it. It's true
that you see much less of it these days in the upper range drivers.
The tweeter was designed to have it in there so if you would remove
it, the chances are good the frequency response will be linear, but no
longer neutral (flat). I like your tenacity to do this, it's fun to do
that kind of stuff isn't it?

Wessel

Archived from groups: rec.audio.high-end (More info?)

On 4 Oct 2004 23:51:02 GMT, Dalibor Bauernfrajnd <mmx181@vip.hr>
wrote:

>In article <cjqhpq01c7e@news4.newsguy.com>, ldmnews1@netassoc.net says...
>> "JCBrunelli" <brunelli@amja.org.br> wrote in message news:cjpvdh02bjc@news1.newsguy.com...
>> > I own a Moudaunt-Short MS10i Classic bookshelf loudspeaker. Recently
>> > one of the tweeters stop working. I was able to fix it since it was a
>> > broken wire in the coil connection. However, in this disassembling
>> > process I found (in the two tweeters) a dark brown liquid inside the
>> > circular groove in the magnet where the coil is supposed to stay. Is
>> > this liquid part of the tweeter mechanism (and the coil is dipped on
>> > it) or is just moisture accumulated over the years? I am afraid to dry
>> > it up. Any help would be very welcome. Thanks very much. Jose Carlos
>> > Brunelli
>> >
>> I think it's called "ferrofluid". It's main purpose is to conduct heat
>> away from the voice coil. If you remove it, you'll have to replace it.
>
>Not really.
>The tweeter will work fine without it; actually, most sound better without
>it.

That is *very* bad advice. While many will argue that tweeters which
do not use ferrofluid sound better than those which do, this is a very
different matter from *removing* ferrofluid from a tweeter which was
designed to use it. At best, you'll get a ragged frequency response
with a severe resonance peak (which had been damped by the
ferrofluid). At worst, because the fluid is largely a heat conductor,
you'll fry the tweeter voice coil.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Archived from groups: rec.audio.high-end (More info?)

JCBrunelli wrote:

>...I do not understand how this thin wire (to the tweeter voice coil) broke...

Probably just flexing over a long period of time, perhaps helped along
by extreme excursions of the tweeter dome. It is not that uncommon a
fault, and splicing or soldering the wire occasionally is necessary to
fix a speaker at all, if the tweeter is no longer available from its
manufacturer. It does take good eyes and steady hands.

-Gene Poon