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O.T. Speakers static/humming



 
 
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  #1  
Old May 21st 18, 10:54 PM posted to microsoft.public.windowsxp.general
Mark Twain
external usenet poster
 
Posts: 2,402
Default O.T. Speakers static/humming

I have a Dell XPS 8500, with Windows 7 Professional, SP1,
with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

(1) TB HD
Intel (R) Core (TM) i7-33-3770 CPU @ 3.40 GHz
Ram 12.0 GB
System type : 64-bit operating system

I also have

I have a Dell Optiplex 780 Tower, with Windows 7 Professional,
SP1, with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

Intel (R) Core 2 Duo 2.93 GHz
4GB RAM, 750 GB HD
System type : 64-bit operating system

and (external hard drives)

(8500)
WD BLACK SERIES WD2003FZEX 2TB 7200
RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal
Hard Drive

(780)
Seagate Desktop HDD ST2000DM001 2TB 64MB
Cache SATA 6.0Gb/s 3.5"
Internal Hard Drive


The problem concerns the 8500; I have an intermittent problem,
for some reason when I logged on today there's a humming/buzzing
sound coming from the speakers. This has happened several times
recently. I haven't done a thing other than logging on.

I tried restarting and disconnecting and reconnecting the speaker
connections but it doesn't seem to go away until I power off/on.

So what could this be?

Thoughts/suggestions
Robert
  #2  
Old May 21st 18, 11:39 PM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 11,873
Default O.T. Speakers static/humming

Mark Twain wrote:
I have a Dell XPS 8500, with Windows 7 Professional, SP1,
with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

(1) TB HD
Intel (R) Core (TM) i7-33-3770 CPU @ 3.40 GHz
Ram 12.0 GB
System type : 64-bit operating system

I also have

I have a Dell Optiplex 780 Tower, with Windows 7 Professional,
SP1, with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

Intel (R) Core 2 Duo 2.93 GHz
4GB RAM, 750 GB HD
System type : 64-bit operating system

and (external hard drives)

(8500)
WD BLACK SERIES WD2003FZEX 2TB 7200
RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal
Hard Drive

(780)
Seagate Desktop HDD ST2000DM001 2TB 64MB
Cache SATA 6.0Gb/s 3.5"
Internal Hard Drive


The problem concerns the 8500; I have an intermittent problem,
for some reason when I logged on today there's a humming/buzzing
sound coming from the speakers. This has happened several times
recently. I haven't done a thing other than logging on.

I tried restarting and disconnecting and reconnecting the speaker
connections but it doesn't seem to go away until I power off/on.

So what could this be?

Thoughts/suggestions
Robert


Debug by section.

1) Plug headphones into the LineOut Jack of the
8500, where the speakers are currently connected.
Is the headphone sound clean ?

2) Plug a portable source (Sony Walkman, iPod, or similar)
to the speakers. Is the humming and buzzing still there,
with a driven source (that floats with respect to AC) ?
I even have a transistor radio that will serve for this
purpose (an FM radio with a synthesizer tuner).

It's possible the amplified speakers have a leaking cap in
the power supply section. Since you had a "power event" at your
place, and all your gear operated for a time at the wrong
voltage, just about anything could be wrong with it.

But first you want to separate the 8500 from the speakers,
as in (2) and verify the speakers are the author of their
own misfortune.

When my computer speakers acted up, I ended up running
a finger over the solder points inside it, until I found
a solder point that "made a difference" and the sound
started working properly again. I re-soldered that point
(it was a cold solder joint).

Trouble is though, some computer speakers are *glued*
shut, so this is not as easy as it seems. They can be very
hard to open up. I actually used a saw on mine, and sawed a
slot where I could get prying tools jammed into the
seam and used brute strength to separate the
glue. And the speaker still works :-) It no longer
looks all that nice though. I won't be selling it
on Ebay ("slightly used, some scratches").

Paul
  #3  
Old May 22nd 18, 09:38 AM posted to microsoft.public.windowsxp.general
Mark Twain
external usenet poster
 
Posts: 2,402
Default O.T. Speakers static/humming

I don't have headphones, a walkman
or iPod etc. to test and the speakers
are brand new Harman Kardon (after the
electrician fried all my components)

https://www.google.com/search?q=Harm...lboe9gT-etK1M:

When I logged on later everything is back
to normal. As I say, it's intermittent.

Robert

  #4  
Old May 22nd 18, 10:04 AM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 11,873
Default O.T. Speakers static/humming

Mark Twain wrote:
I don't have headphones, a walkman
or iPod etc. to test and the speakers
are brand new Harman Kardon (after the
electrician fried all my components)

https://www.google.com/search?q=Harm...lboe9gT-etK1M:

When I logged on later everything is back
to normal. As I say, it's intermittent.

Robert


Does the Harmon Kardon have a two or three prong plug ?

Computer speakers should have a two prong plug. This
prevents ground loops from forming. The 1/8" plug has
the only ground between the two units, so there's no
ground loop.

If the audio equipment has three prongs, it *might* need
a hum-breaker, which is a form of transformer coupling
between units. These require precisely constructed
transformers for best results (some of these have
a bandwidth of 10KHz or so, not that impressive).

You can also solve hum problems, by using stuff
like TOSLink between units (optical interconnect,
red LED light flowing over plastic large aperture
dental fiber). You would have to look at the input
options on the HK speakers, to see if there's another
way to get there (a way that avoids this stuff).

I've never really owned any "spectacular" audio gear,
and 1/8" audio input is about as fancy as anything
I've had on my gear here. I didn't even have S'PDIF
to play with.

*******

I've had your problem, between my Mac G4 and the stereo
I used for other sources. And the Mac G4 was the only
one with funny radio station noises, hum and other
garbage. I never managed to fix that. While it's
possible to couple radio station signals into audio
cables, and have them rectified by the front end of
the speaker or stereo, it's hard to say why
this happens. I could use the same cable between
two different audio sources, have the problem on
one source and not the other.

Lots of devices in the room with you, use capacitors
on input and output for DC blocking. This is supposed
to prevent one device from applying a DC input to
a transistor on the input of another device, and driving
it into a non-linear area of operation. If you look
at the sound chip on the computer motherboard, it
uses capacitors on all inputs and outputs for this
reason. A defective capacitor might cause a problem,
but when it happens identically on both left and
right channel, you have to wonder whether it's
a design issue.

You could also move audio with something like Bluetooth,
but the default profile for audio isn't all that good.
And that would also add latency, which might upset lip sync
while watching movies.

Paul
  #5  
Old May 22nd 18, 07:47 PM posted to microsoft.public.windowsxp.general
Mark Twain
external usenet poster
 
Posts: 2,402
Default O.T. Speakers static/humming

The Harmon Kardon speakers use a
two prong.

Here's the setup connections:

https://www.google.com/search?biw=17...u-MK58fLu9ONM:

It's odd that it's intermittent, you would
think if it were a capacitor it would happen
all the time.

Well, I guess I'll just live with it
and just power off/on when it happens.

Thanks,
Robert
  #6  
Old May 22nd 18, 10:21 PM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 11,873
Default O.T. Speakers static/humming

Mark Twain wrote:
The Harmon Kardon speakers use a
two prong.

Here's the setup connections:

https://www.google.com/search?biw=17...u-MK58fLu9ONM:

It's odd that it's intermittent, you would
think if it were a capacitor it would happen
all the time.

Well, I guess I'll just live with it
and just power off/on when it happens.

Thanks,
Robert


So that looks to me, like a 2.1 amplified computer
speaker, with LineOut for the satellites and CenterSub
connector for the larger speaker in the base unit ?

Are both audio connectors plugged into the computer ?

Do you have a center-sub connector on the 8500 ? I
presume so.

According to the standard colors table here, black
is "Surround" and lime-green is "front left and front right".
You would think they'd want an orange connector for
a center-sub (so the computer can send a "sub" signal
to make the larger speaker in the base unit work).

https://en.wikipedia.org/wiki/PC_System_Design_Guide

If you leave the second connector "floating", it might
pick up hum. Especially as the Sub probably extends
to 60Hz for the hum (the Sub would normally be band-limited
as to which frequencies it could reproduce).

You also want the computer audio settings in the 8500,
set to a setting which "matches" the wiring you're
using. If your speakers are 2.1, and two plugs are
used, you want to select "2.1" in some output selection
panel to match.

You have a bunch of stuff to check.

I thought originally, this was a simple 2-channel setup,
with a single green plug to plug in. If you left a
plug unplugged, that could well explain the extraneous
noises.

Paul
 




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