Koss Model 1 Problem (?)

[zab...@my-deja.com]

I just purchased a pair of Koss Model 1-A's (Which sound absolutely
amazing). One odd aspect of them is that they have a gel cell battery
that is constantly trickle charging, and produces a quiet hum. The
problem I have with them, is that because the stator's (or plates) are
constantly polarized, there is an audiable crackling sound that comes
from the speakers when they are not being used. I'd guess it is that
field breakdown between the stators - it sounds a little like a bowl of
rice krispies. Its not really loud - the crackling can only be heard
when the speakers aren't being used, or during extremely quiet passages
in music.
Is this a common 'feature' of electrostatic speakers, or might it be a
result of the speakers not having been used much for the last five years.
Could the crackling sound be due to dust and other 'grime' on the
diaphragms? Is it advisable to clean the diaphragms? How does one go
about this? Does anyone out there have a pair of these speakers - It
would be cool to chat about their sound with someone who is familiar with
them.
Thanks,
Kevin

Sent via Deja.com http://www.deja.com/
Before you buy.

[Barry Waldron]

In article <8aodpa$r84$1...@nnrp1.deja.com>,

zab...@my-deja.com wrote:
> I just purchased a pair of Koss Model 1-A's (Which sound absolutely
> amazing). One odd aspect of them is that they have a gel cell battery
> that is constantly trickle charging, and produces a quiet hum. The
> problem I have with them, is that because the stator's (or plates) are
> constantly polarized, there is an audiable crackling sound that comes
> from the speakers when they are not being used. I'd guess it is that
> field breakdown between the stators - it sounds a little like a bowl
> of rice krispies. Its not really loud - the crackling can only be
> heard when the speakers aren't being used, or during extremely quiet
> passages in music.

> Is this a common 'feature' of electrostatic speakers, or might it be a
> result of the speakers not having been used much for the last five
> years. Could the crackling sound be due to dust and other 'grime' on
> the diaphragms? Is it advisable to clean the diaphragms? How does one
> go about this? Does anyone out there have a pair of these speakers -

Hello Kevin,
Given the history of the speakers, it is very likely that the panels
could stand to be cleaned. There are two approaches that can be used.
The first is to use a vacuum with an upholstry brush attachment. Place
the brush against each stator (front and rear) and move the brush
slowly from left to right, top to bottom. Dust particles between the
stator and diaphragm can cause the panels to arc. A large piece of
lint trapped between the two elements will create a path to ground
resulting in either a single arc, or, reduced output.

The second method is to use a can of compressed air, however, I reserve
this method for the large pieces of lint that occasionally become
lodged inside.

If ths does not fix the motorboating, then look for a bias voltage
adjustment. It is possible that the voltage is higher than it should
be. Now, having said that, how many and which panels are motorboating?
If it is one panel in one speaker, then the problem could be, as above,
or, the fact that the diaphragm has become relaxed and can no longer
tollerate the design voltage. If it is all or most of the panels, the
diagnosis becomes more complex. I would lean toward a higher than
normal voltage rather than "all" the diaphragms becoming less taut.

If you are unable to solve the problem, call Koss and ask to speak with
their repair department--and then someone who is familiar with this
model.

(As an aside, I talked with a Koss technician four years ago who told
me that they no long have any replacement panels.)

I hope this helps,
Barry

ESL Information eXchange
http://www.jps.net/eslinfo

[zab...@my-deja.com]

In article <8ap4kv$dlv$1...@nnrp1.deja.com>,

I realized I forgot to mention one other problem. The two speakers have
different sensitivities: One is dramatically louder than the other.
Simply adjusting the power amp trim knobs (its an Audio Research D-250)
fixed this problem with no weird side-effects like imageing problems. Am
I correct in guessing that the bias voltage of the quieter speaker is
lower than that of the louder speaker? I've connected two different amps
to the speakers, and in both cases one speaker was louder than the other.
Are there other potential sources of this level difference?
One bad aspect of the Koss's is that you have to dis-assemble the cabinet
in order to remove the grill cloth. So I'll have to take them apart to
clean the diaphragms.
Thanks for your help,

[zab...@my-deja.com]

[bope...@my-deja.com]

You might want to try here:
http://www.electrostaticdoc.com/
and see if they can help you

> I just purchased a pair of Koss Model 1-A's (Which sound absolutely
> amazing). One odd aspect of them is that they have a gel cell battery
> that is constantly trickle charging, and produces a quiet hum. The
> problem I have with them, is that because the stator's (or plates) are
> constantly polarized, there is an audiable crackling sound that comes
> from the speakers when they are not being used. I'd guess it is that
> field breakdown between the stators - it sounds a little like a bowl
of
> rice krispies. Its not really loud - the crackling can only be heard
> when the speakers aren't being used, or during extremely quiet
passages
> in music.
> Is this a common 'feature' of electrostatic speakers, or might it be a
> result of the speakers not having been used much for the last five
years.
> Could the crackling sound be due to dust and other 'grime' on the
> diaphragms? Is it advisable to clean the diaphragms? How does one go

> about this? Does anyone out there have a pair of these speakers - It
> would be cool to chat about their sound with someone who is familiar
with
> them.
> Thanks,