Michael A. Terrell wrote in message
m...

N_Cook wrote:

Michael A. Terrell wrote:

Poor quality control, or a defective manufacturing process.

Its more than that.
In both Mackie cases the main active coils showed absolutely no
overheating
let alone burning. In all other odd o/c speakers I've poked my nose in,
have
had large sections of charring or completely burnt and broken coil
formers.
Not failure in the tail sections because they are usually different /
larger
conductors soldered or welded to the main coil. These Mackie tails are
acting as fuses, protecting the voice coil, which is ridiculous.


No, it isn't. Who would manufacture speakers that way for Mackie? If
they did, all of them would fail. They would have to pay extra, and get
no warranty. It sounds like the tinsel wire was the wrong type for the
power level and was likely got through due to poor QC. Poor quality
tinsel wire also suffers from work hardening, and broken strands. When
enough break, the rest burn. Also, if they are a few percent too short,
they get more mechanical abuse, which destroys them. Since you didn't
see them when they were brand new, you have absolutely no idea what
really happened.

I have worked in failure analysis in electronics manufacturing, and I
can tell you that production people can be some of the biggest idiots in
the world. Monday mornings they have hangovers, and Fridays they don't
give a damn what they do, as long as they can leave on time to drink
their paychecks.


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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

The problem is not at the tinsel wire, ie the flexible bridge. But before
that, a flattening of the voice coil wire into ribbon. Production seems to
be a precise length of say 2.5m with the ends squashed giving some precise
run of round voice coil wire. One end has the ribbon fixed to the tinsel in
the ideal spot but the other end arrives at maybe half a turn from ideal and
has to make a half turn to join the tinsel for the other termination.
Tinsel ribbon is presumably higher current carying than the crresponding
voice coil wire, so no problems there.
This Mackie problem is something to do with a run of same gauge but
squashed wire.
Remember the whole half-turn of ribbon disintegrated so not due to a nick or
rubbing on metalwork.


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