On Tue, 9 Feb 2021 15:56:15 -0000 (UTC), John Doe
wrote:
(Don Pearce) wrote:
John Doe wrote:
https://images-na.ssl-images-amazon....AC_SL1500_.jpg
Nothing is connected to that optical input DAC. No power. No signal.
Nothing. Doesn't matter whether the antenna is connected or not.
With the powered speaker (JBL LSR305, -10dVB, volume maximum) input
disconnected, with its speaker wire dangling from its input, there is
almost 0 sound from the speaker except an extremely faint wind sort of
sound with my ear up against it.
Humming begins when the speaker wire is plugged into the disconnected
DAC.
Why is that? The DAC isn't connected to anything else. Does it act as a
receiver/antenna?
The humming sound is low enough so it makes little difference, but it is
noticeable.
Why are you plugging a speaker wire into a DAC? Speakers are plugged
into amplifiers. Are you saying that your system hums, and if you unplug
the speaker the hum stops?
I don't know where to start re-explaining. I thought that was verbose.
Verbose but not even slightly clear.
It sounds like you may have a ground loop. If the speaker is grounded
at the wall plug, and the DAC has its own wall plug ground, then a hum
signal will be induced onto the signal wire by the current that flows
along the ground of the audio cable. One of those grounds needs to go.
The usual way is to keep the ground in the amplifier and disconnect
all the others, so the only ground connection through the system is
the one in the audio cable. But you need to understand what you are
doing, because this can compromise safety.
d
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