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Where does the hum come from?



 
 
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  #1  
Old February 9th 21, 12:29 PM posted to rec.audio.pro
John Doe[_2_]
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Posts: 36
Default Where does the hum come from?

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.

Thanks.
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  #2  
Old February 9th 21, 04:40 PM posted to rec.audio.pro
Don Pearce[_3_]
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Posts: 2,377
Default Where does the hum come from?

On Tue, 9 Feb 2021 11:29:15 -0000 (UTC), 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.
>
>Thanks.


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?

d

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  #3  
Old February 9th 21, 04:56 PM posted to rec.audio.pro
John Doe[_2_]
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Posts: 36
Default Where does the hum come from?

(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.
  #4  
Old February 9th 21, 04:58 PM posted to rec.audio.pro
Tobiah[_6_]
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Posts: 10
Default Where does the hum come from?

>> 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.
>


I'd like to hear the answers to Don's questions.
  #5  
Old February 9th 21, 05:23 PM posted to rec.audio.pro
John Williamson
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Posts: 1,738
Default Where does the hum come from?

On 09/02/2021 15:40, Don Pearce wrote:

>
> 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?
>

The speaker mentioned has an amplifier built in, so will work when
connected to a DAC which provides a line out connection.

--
Tciao for Now!

John.
  #6  
Old February 9th 21, 05:35 PM posted to rec.audio.pro
UnsteadyKen
external usenet poster
 
Posts: 180
Default Where does the hum come from?

In article >,

John Doe says...

> Why is that?
>

The DAC has single ended audio output on RCA sockets.
The loudspeakers expect balanced audio input on XLR or TRS connetions.

How are you converting from SE to balanced working?
And what do you mean by "Speaker wire"?



--
Ken
  #7  
Old February 9th 21, 05:45 PM posted to rec.audio.pro
John Doe[_2_]
external usenet poster
 
Posts: 36
Default Where does the hum come from?

Tobiah > wrote:

>>> 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.


> I'd like to hear the answers to Don's questions.


It wasn't a question, it was an erroneous statement.

Please properly introduce USENET authors and avoid deleting relevant text.

  #8  
Old February 9th 21, 05:50 PM posted to rec.audio.pro,free.spam
John Doe[_2_]
external usenet poster
 
Posts: 36
Default Where does the hum come from?

Please don't do hard drugs and post at the same time...

--
Unsteadyken > wrote:

> Path: eternal-september.org!reader02.eternal-september.org!weretis.net!feeder8.news.weretis.net !3.eu.feeder.erje.net!feeder.erje.net!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
> From: Unsteadyken >
> Newsgroups: rec.audio.pro
> Subject: Where does the hum come from?
> Date: Tue, 9 Feb 2021 16:35:20 -0000
> Organization: Home
> Lines: 16
> Message-ID: >
> References: >
> Mime-Version: 1.0
> Content-Type: text/plain; charset="us-ascii"
> Content-Transfer-Encoding: 7bit
> X-Trace: individual.net 5wTsT2pbVLnDEZbs1wsxcgrDoQoeWEzXLSC7TABYLssQFp+gOl
> Cancel-Lock: sha1:8LtwzCXQsaNm8dv75svlgnHFu6c=
> User-Agent: MicroPlanet-Gravity/3.0.4
> Xref: reader02.eternal-september.org rec.audio.pro:91963
>
> In article >,
>
> John Doe says...
>
>> Why is that?
>>

> The DAC has single ended audio output on RCA sockets.
> The loudspeakers expect balanced audio input on XLR or TRS connetions.
>
> How are you converting from SE to balanced working?
> And what do you mean by "Speaker wire"?
>
>
>
> --
> Ken
>
>


  #9  
Old February 9th 21, 05:51 PM posted to rec.audio.pro
Don Pearce[_3_]
external usenet poster
 
Posts: 2,377
Default Where does the hum come from?

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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  #10  
Old February 9th 21, 05:59 PM posted to rec.audio.pro,free.spam
John Doe[_2_]
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Posts: 36
Default Where does the hum come from?

Obviously "the DAC having its own wall plug ground" has absolutely nothing
to do with it SINCE I EXPLICITLY STATED THAT THE THING IS DISCONNECTED
FROM EVERYTHING.

Do you want to know what a "speaker wire" is, too, you illiterate moron?

That's why I said to ask questions after the relevant part of what I said.
You can't even count the number of fingers on your hand...

--
(Don Pearce) wrote:

> Path: eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail
> From:
(Don Pearce)
> Newsgroups: rec.audio.pro
> Subject: Where does the hum come from?
> Date: Tue, 09 Feb 2021 16:51:21 GMT
> Organization: A noiseless patient Spider
> Lines: 48
> Message-ID: >
> References: > > >
> Mime-Version: 1.0
> Content-Type: text/plain; charset=us-ascii
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> X-Antivirus-Status: Clean
> X-Newsreader: Forte Agent 1.5/32.451
> X-Antivirus: Avast (VPS 210207-2, 07/02/2021), Outbound message
> Xref: reader02.eternal-september.org rec.audio.pro:91966
>
> 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
>
> --
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
>
>


 




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