Posted by Lew on December 28, 2004 at 08:43:10:
In Reply to: Sparks posted by Donut on December 27, 2004 at 08:25:45:
First, if you saw a spark it is indicative of "arc-ing" or the jumping of a static electricity discharge
from stator to diaphragm. This is NOT due to your amplifier OR to setting the bias too high per
se. Most likely it is due to a dust particle on either the stator or diaphragm which is providing a
pathway for the discharge. However, if you took note of the approximate location of the spark,
you should now examine that area closely with a flashlight or other light source to determine
whether there is a hole in the diaphragm in the area where you observed the spark. A hole in the
diaphragm is another cause of arc-ing, if the loose flap of the torn mylar is too near to the
stator. If you do have a hole, and if the sparking is recurrent, you will eventually want to/have to
repair the hole. This can be done at home with factory verbal assistance, usually, but
unfortunately it is a pain in the butt. (I wish the factory would make it easier to remove and
replace the Spandex grille cloth to facilitate such repairs. A zipper would be nice, ha-ha.)
You also report that your owner's manual states that there is no harm done by setting the bias
too high. This may be a matter of semantics, as in how does one define "too high", but others on
this forum have been told by the factory that their speakers were damaged by prolonged use
with the bias set too high, meaning set so that one can hear a "crackling" or "crinkling" sound
when not playing music. Some of these folks have had to have their speakers re-built. You
might want to ask the factory for clarification on that issue, but right now the spark you have
observed is not due to setting the bias too high (as stated above) except in the sense that setting
the bias lower might alleviate the problem (but it also reduces the efficiency of the speaker in
transducing the amplifier output into sound). If the sparking recurs and is not due to a hole in
the diaphragm, it might help to vacuum your panels and in future remove dust from the
environment as much as possible. Disconnect the bias supply for at least 12 hours prior to
vacuuming.