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.

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.

Depreciated?

--
John Williamson > wrote:

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> Subject: Where does the hum come from?
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> 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.
>
>

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.

On Tuesday, February 9, 2021 at 10:23:42 AM UTC-8, John Williamson wrote:
> 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.

Ah, yet another thread run amok! After reviewing all the useful information whilst trying to disregard the flames, I speculate that the output circuitry of the DAC presents some kind of "RLC" network that, indeed, makes the "speaker wire" into a somewhat tuned antenna that is in the faint AC environment we all experience. The JBL LSR305 at maximum gain boosts and outputs some of that as hum.

Roy W. Rising "If you notice the *sound*, it's wrong!"

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

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

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

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."

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."