Reply
 
Thread Tools Display Modes
  #1   Report Post  
Posted to rec.audio.pro
John Doe[_2_] John Doe[_2_] is offline
external usenet poster
 
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.
  #2   Report Post  
Posted to rec.audio.pro
Don Pearce[_3_] Don Pearce[_3_] is offline
external usenet poster
 
Posts: 2,417
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

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

  #3   Report Post  
Posted to rec.audio.pro
John Doe[_2_] John Doe[_2_] is offline
external usenet poster
 
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   Report Post  
Posted to rec.audio.pro
Tobiah[_6_] Tobiah[_6_] is offline
external usenet poster
 
Posts: 22
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   Report Post  
Posted to rec.audio.pro
John Doe[_2_] John Doe[_2_] is offline
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.



  #6   Report Post  
Posted to rec.audio.pro
geoff geoff is offline
external usenet poster
 
Posts: 1,812
Default Where does the hum come from?

On 10/02/2021 4:58 am, 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.



How about 'the LST305 is a powered speaker' !

If one didn't already know, or couldn't have guessed that from the
context of the question (-10dBV into a passive speaker ?!!!), looking it
up before asking such a dumb question normally unbecoming of Don, would
have been appropriate.

geoff
  #7   Report Post  
Posted to rec.audio.pro
[email protected] palli...@gmail.com is offline
external usenet poster
 
Posts: 125
Default Where does the hum come from?

Tobiah the Idiot Troll puked:
-----------------------------

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


** There are no questions.
The OP has no clue what he is talking about.
Nor do you.


...... Phil
  #8   Report Post  
Posted to rec.audio.pro
Don Pearce[_3_] Don Pearce[_3_] is offline
external usenet poster
 
Posts: 2,417
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

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

  #9   Report Post  
Posted to rec.audio.pro,free.spam
John Doe[_2_] John Doe[_2_] is offline
external usenet poster
 
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
Content-Transfer-Encoding: 7bit
Injection-Info: reader02.eternal-september.org; posting-host="169e1115689465ad10ea04c0d672053b"; logging-data="13171"; "; posting-account="U2FsdGVkX186TrmBBPly5TE+TPrCW4aJeKT8SiETv j8="
Cancel-Lock: sha1:t38Yfe1D0hIbjNJEmMGFwGD+1mo=
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




  #10   Report Post  
Posted to rec.audio.pro
Scott Dorsey Scott Dorsey is offline
external usenet poster
 
Posts: 16,853
Default Where does the hum come from?

John Doe wrote:

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


Speaker wire is unshielded zip cord or SO line. There is no speaker wire
involved in your configuration. Your use of the word "speaker wire" has
confused people into thinking that you actually have speaker wire somewhere.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."


  #11   Report Post  
Posted to rec.audio.pro,free.spam
Don Pearce[_3_] Don Pearce[_3_] is offline
external usenet poster
 
Posts: 2,417
Default Where does the hum come from?

On Tue, 9 Feb 2021 16:59:09 -0000 (UTC), John Doe
wrote:

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...


Here's the problem. Your description is confused and confusing. You
talk about speaker wire when you mean phono cable. And why are you
talking about a DAC when it isn't plugged in? It is clearly not a part
of the problem.

Now let's try to sort out what you really mean. Are you saying that
when your amplifier has an open circuit input, there is a low level
hum? If so, that is absolutely fine. That's what they do. As long as
it goes away when something is plugged in all is well. Get a phono
plug and short the live to the ground. Now plug that in. Is the noise
still there?

d

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

  #12   Report Post  
Posted to rec.audio.pro
Scott Dorsey Scott Dorsey is offline
external usenet poster
 
Posts: 16,853
Default Where does the hum come from?

I am -assuming- that the original poster is plugging a DAC that has a TRS
1/4" output into a powered speaker with a TRS input, using a proper
TRS-TRS patch cable and that no speaker wire is involved.

If unshielded speaker wire is used for line level connections, there will
be a hum.

Now.... a thing can hum for two reasons: either something is grounded in
two places (causing a ground loop) or something is not grounded at all
(causing something to be unshielded).

We know the problem is not a ground loop because there is no connection
to the DAC other than the speaker, and there is no connection to the
speaker other than to the DAC and power.

It's quite possible the DAC does not have a pin 1 connection to chassis and
that therefore it is effectively unshielded until an input or power is
connected to it. A multimeter will very quickly show if this is the case.

If so, the hum will disappear when the system is configured for actual use.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #13   Report Post  
Posted to rec.audio.pro
[email protected] palli...@gmail.com is offline
external usenet poster
 
Posts: 125
Default Where does the hum come from?

Scott Dorsey wrote:
================

If unshielded speaker wire is used for line level connections, there will
be a hum.


** Certainly, but this can also happen with cheap RCA leads.

I found this out when repairing a Fender tube amp with a faulty reverb.
The connecting RCA leads were bad so I fitted a new pair that were the right length and had stubby plugs.
The result was buzzing noise and loud squealing if you turned up the reverb gain pot.

When cut open, the cable used was NOT co-axial !!
The ground wires just ran alongside the core in a tight bunch providing no ES shielding.

Soon as I fitted known, well shielded leads - all problems vanished.


...... Phil
  #14   Report Post  
Posted to rec.audio.pro
geoff geoff is offline
external usenet poster
 
Posts: 1,812
Default Where does the hum come from?

On 11/02/2021 12:53 pm, Scott Dorsey wrote:
I am -assuming- that the original poster is plugging a DAC that has a TRS
1/4" output into a powered speaker with a TRS input, using a proper
TRS-TRS patch cable and that no speaker wire is involved.

If unshielded speaker wire is used for line level connections, there will
be a hum.

Now.... a thing can hum for two reasons: either something is grounded in
two places (causing a ground loop) or something is not grounded at all
(causing something to be unshielded).

We know the problem is not a ground loop because there is no connection
to the DAC other than the speaker, and there is no connection to the
speaker other than to the DAC and power.

It's quite possible the DAC does not have a pin 1 connection to chassis and
that therefore it is effectively unshielded until an input or power is
connected to it. A multimeter will very quickly show if this is the case.

If so, the hum will disappear when the system is configured for actual use.
--scott




Look at the picture in the OP link. RCA unbal outputs.

geoff
  #15   Report Post  
Posted to rec.audio.pro
John Williamson John Williamson is offline
external usenet poster
 
Posts: 1,753
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.


  #16   Report Post  
Posted to rec.audio.pro
UnsteadyKen UnsteadyKen is offline
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
  #17   Report Post  
Posted to rec.audio.pro,free.spam
John Doe[_2_] John Doe[_2_] is offline
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



  #18   Report Post  
Posted to rec.audio.pro,free.spam
John Williamson John Williamson is offline
external usenet poster
 
Posts: 1,753
Default Where does the hum come from?

On 09/02/2021 16:50, John Doe wrote:
Please don't do hard drugs and post at the same time...

Those of us that are familiar with and use professional audio equipment
have no trouble understanding Unsteady Ken's post.

--
Tciao for Now!

John.
  #19   Report Post  
Posted to rec.audio.pro,free.spam
John Williamson John Williamson is offline
external usenet poster
 
Posts: 1,753
Default Where does the hum come from?

Also, top posting is deprecated on usenet.

On 09/02/2021 16:50, John Doe wrote:
Please don't do hard drugs and post at the same time...



--
Tciao for Now!

John.
  #20   Report Post  
Posted to rec.audio.pro,free.spam
John Doe[_2_] John Doe[_2_] is offline
external usenet poster
 
Posts: 36
Default Where does the hum come from?

Depreciated?

--
John Williamson wrote:

Path: eternal-september.org!reader02.eternal-september.org!news.szaf.org!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: John Williamson
Newsgroups: rec.audio.pro,free.spam
Subject: Where does the hum come from?
Date: Tue, 9 Feb 2021 17:24:47 +0000
Lines: 11
Message-ID:
References:
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: individual.net 1c7TA6dnnNBVKBPfXAc/RAYt0CF+DPVp7q+alWHBI/7d6BN1Xd
Cancel-Lock: sha1:x+WVMgdyeP2oZb0PffPSqLuwNHQ=
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:50.0) Gecko/20100101 Thunderbird/50.0
In-Reply-To:
Content-Language: en-GB
Xref: reader02.eternal-september.org rec.audio.pro:91969 free.spam:14177

Also, top posting is deprecated on usenet.

On 09/02/2021 16:50, John Doe wrote:
Please don't do hard drugs and post at the same time...



--
Tciao for Now!

John.





  #21   Report Post  
Posted to rec.audio.pro,free.spam
John Williamson John Williamson is offline
external usenet poster
 
Posts: 1,753
Default Where does the hum come from?

On 09/02/2021 17:36, John Doe wrote:
Depreciated?

Nope. Deprecated, depreciated means something entirely different.

The definitions of both words are in all good dictionaries. Is English,
be that British, Australian, American or some other dialect, not your
first language?

--
Tciao for Now!

John.
  #22   Report Post  
Posted to rec.audio.pro
[email protected] palli...@gmail.com is offline
external usenet poster
 
Posts: 125
Default Where does the hum come from?

John Dope wrote:
==============

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.

** There is no "speaker wire" involved.

What you have is an RCA signal lead - get the name right, you arrogant ****head.

Some cheap RCA leads have little or no shielding, so try a good quality one and you problem may disappear.

....... phil
Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT +1. The time now is 12:47 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"