I have a problem with this amplifier that has
me stumped. If I have this amp plugged directly
into a dedicated 20 amp line, I get an "electrical" fuzzy
noise/buzz in the speakers that varies in level all by itself.
It is very audible across the room from the left channel, and
present in the right channel but not as loud.
Now the weird part - if I plug an 1800W voltage
regulator into the dedicated circuit, and then
power the amp from it - no noise.
I measured the wall voltage with an averaging
meter and get 116-117 volts out of the dedicated line
and I get 126 volts out of the voltage regulator
I also have 0.3 volt DC riding on the AC
Is there a part in the amp that may be failing, making
it sensitive to the line voltage, or is my wall
voltage too low?
Steve
me stumped. If I have this amp plugged directly
into a dedicated 20 amp line, I get an "electrical" fuzzy
noise/buzz in the speakers that varies in level all by itself.
It is very audible across the room from the left channel, and
present in the right channel but not as loud.
Now the weird part - if I plug an 1800W voltage
regulator into the dedicated circuit, and then
power the amp from it - no noise.
I measured the wall voltage with an averaging
meter and get 116-117 volts out of the dedicated line
and I get 126 volts out of the voltage regulator
I also have 0.3 volt DC riding on the AC
Is there a part in the amp that may be failing, making
it sensitive to the line voltage, or is my wall
voltage too low?
Steve
That 0.3V DC on the mains might be the problem. It may saturate the transformer and cause nasty current peaks that radiate into the amplifier.
On this forum circuits circulate that remove the DC part of the mains. Some use just a few big diodes in anti parallel in series with the primary. Some add a big low voltage bipolar capacitor in parallel to these diodes. E.g. 2x 10.000u, 16V (in series, minus to minus) will make a nice bipolar cap. The diodes keep the voltage across the cap low, but you need a big capacitance to deal with the ripple current.
Steven
On this forum circuits circulate that remove the DC part of the mains. Some use just a few big diodes in anti parallel in series with the primary. Some add a big low voltage bipolar capacitor in parallel to these diodes. E.g. 2x 10.000u, 16V (in series, minus to minus) will make a nice bipolar cap. The diodes keep the voltage across the cap low, but you need a big capacitance to deal with the ripple current.
Steven
Steven,
Thank you for the reply,
The DC was my first suspect, too -
however, the DC is present at the
wall outlet, and at the output
of the voltage regulator. And the
amp is perfectly happy running off
of the voltage regulator, but not directly
from the wall outlet. I know running the
voltage regulator is the easiest answer,
however I think it is a band-aid to a
possible other problem, because all
of my other components have no problem
running with no voltage regulation.
I may send it to Krell service, but I wanted to
see if anyone had some ideas as to what is
causing this.
Steve
Thank you for the reply,
The DC was my first suspect, too -
however, the DC is present at the
wall outlet, and at the output
of the voltage regulator. And the
amp is perfectly happy running off
of the voltage regulator, but not directly
from the wall outlet. I know running the
voltage regulator is the easiest answer,
however I think it is a band-aid to a
possible other problem, because all
of my other components have no problem
running with no voltage regulation.
I may send it to Krell service, but I wanted to
see if anyone had some ideas as to what is
causing this.
Steve
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