I have a pair of Sonus Faber Amati's connected to a Krell 400cx and KCT.
The right speaker's tweeter no longer works (no sound comes out of it
whatsoever). It worked the day before with normal sound pressure levels
(jazz/classical). The next day it stopped working. I bought the
components brand new 2.5 years ago.

Sumiko (Sonus Faber) are going to repair the tweeter - no problem, but
my question is why did it happen in the first place? I was advised to
have the amplifier checked for 'oscillaitons', but the amp works
great....effortlessly in fact. Any speaker I connect to it sounds
fabulous (for the quality speaker).

It makes me wonder about the quality of the tweeter. Anyone else
experience a blown speaker without doing anything (high volume) to cause
it yourself?

"have the amplifier checked for 'oscillaitons', but the amp works"

They are often supersonic and not heard so listening might not detect
them but they are heating up the voice coil all the same.

Michael wrote:

I have a pair of Sonus Faber Amati's connected to a Krell 400cx and KCT.
The right speaker's tweeter no longer works (no sound comes out of it
whatsoever). It worked the day before with normal sound pressure levels
(jazz/classical). The next day it stopped working. I bought the
components brand new 2.5 years ago.

Sumiko (Sonus Faber) are going to repair the tweeter - no problem, but
my question is why did it happen in the first place? I was advised to
have the amplifier checked for 'oscillaitons', but the amp works
great....effortlessly in fact. Any speaker I connect to it sounds
fabulous (for the quality speaker).

It makes me wonder about the quality of the tweeter. Anyone else
experience a blown speaker without doing anything (high volume) to cause
it yourself?

To check for an ultrasonic oscillation, which is what they were trying
to tell you, you need to hook up an oscilloscope to the speaker leads.

Even a transient oscillation, like when turning on or off one or more
components, amplified by ur Krell would be quite sufficient to render
your tweeter's voice coil leads into blown fuses...

Of course, tweeter leads are fragile and *can* open all by themselves.
Given that only one channel is blown, it makes it *more likely* that the
problem is not in the supporting equipment, but it is still possible.

You need to find someone with a scope and look very carefully at the
system during turn on/off and with various switching going on, and even
when playing...

Or just replace the tweeter and see if it happens again - if it doesn
then it is a fault in the system. :- )

_-_-bear

BEAR wrote:
Michael wrote:

I have a pair of Sonus Faber Amati's connected to a Krell 400cx and
KCT. The right speaker's tweeter no longer works (no sound comes out
of it whatsoever). It worked the day before with normal sound
pressure levels (jazz/classical). The next day it stopped working. I
bought the components brand new 2.5 years ago.

Sumiko (Sonus Faber) are going to repair the tweeter - no problem, but
my question is why did it happen in the first place? I was advised to
have the amplifier checked for 'oscillaitons', but the amp works
great....effortlessly in fact. Any speaker I connect to it sounds
fabulous (for the quality speaker).

It makes me wonder about the quality of the tweeter. Anyone else
experience a blown speaker without doing anything (high volume) to
cause it yourself?


To check for an ultrasonic oscillation, which is what they were trying
to tell you, you need to hook up an oscilloscope to the speaker leads.

Even a transient oscillation, like when turning on or off one or more
components, amplified by ur Krell would be quite sufficient to render
your tweeter's voice coil leads into blown fuses...

Of course, tweeter leads are fragile and *can* open all by themselves.
Given that only one channel is blown, it makes it *more likely* that the
problem is not in the supporting equipment, but it is still possible.

You need to find someone with a scope and look very carefully at the
system during turn on/off and with various switching going on, and even
when playing...

Or just replace the tweeter and see if it happens again - if it doesn
then it is a fault in the system. :- )

_-_-bear

Thanks - The Tweeter was replaced and the system is working fine again.
I am looking into getting a used scope on E-bay or somewhere to check
the oscillations as you pointed out during turn on/off of the system.
As you might expect, the Krell has all sorts of safe guards built in
during on and off. I have had numerous thunderstorms rumble through
here which would flicker the lights causing power shut down and power up
of the Krell and never has there been even a hint of problem. The
system just re-cycles.

It is as others have said, probably just 'one of those things'. I do
know that the Tweeter is a modified Scan-Speak in that there is no
Ferrofluid in the Amati's version and there is in the standard driver
that Scan-Speak sells. Perhaps the lack of Ferrofluid (which dampens
and cools the driver) creates a weaker Tweeter structurally, but I am
just speculating and don't know.

I will find out next week what caused the tweeter to fail. I hope it is
just a mechanical failure (those little wires separated or something)
and not a burn out.