I had the exact same response when I received my Centaur last
December. I documented the problem and exchanged letters with Ten-Tec
about it. Worse, you will hear a lot of abuse from folks who have never
heard the amp and will tell you "real men (or hams)" can live with the
noise. But they've never heard it! By the way, if you remove the covers
you'll notice the fan makes almost no noise. The "pure tone" noise you
are hearing is caused by the fan being mounted almost directly against
the side of the cabinet with about 50% restriction in front of it.
Acoustic engineers where I work suggested one of two possible solutions:
1. Use a 1" or so hole punch and remove material from in front
of the fan intake.
. . .if that doesn't reduce the noise enough, then,
2. Punch a hole the same diameter as the fan intake through the
With my work schedule I have not had the opportunity to give that a
try. I had planned to perform the surgery, then write it up for others
to do. The best laid plans of mice & overworked hams . . . ! So, if
anyone has the chance to try this on their Centaur, I'm sure there are
many of us who would like to know how much the noise was reduced. Of
course, there are other options like installing a light dimmer on the
fan, or removing the fan and installing a DC (variable speed) fan.
Like you, I decided to keep mine and struggle with the problem. After
all, maybe it will build character, and, everyone says I'm a character .
Duane (he's not foolin' folks, the Centaur is LOUD!)
Duane A. Calvin, AC5AA
ac5aa@Juno.com -or- firstname.lastname@example.org
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