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Grounding a turntable with a PC hookup.

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Anonymous
July 30, 2004 3:53:59 AM

Archived from groups: rec.audio.tech (More info?)

I just hooked my turntable to my PC, and I'm getting a low bassy hum noise.
I'm sure that it's more than likely a grounding problem. However, I have
no idea how to ground a turntable to a PC. I currently have a ground cable
going from my turntable to my preamp, but it isn't taking care of the hum.
Any suggestions?

Thanks,
Dan
Anonymous
July 30, 2004 8:30:17 AM

Archived from groups: rec.audio.tech (More info?)

The ground to the receiver should have done it. Is the receiver across the
room, or is there a cable TV or outside antenna hooked up anywhere in the
system?

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns9535C041B60D0nospamspamcom@216.168.3.44...
> I just hooked my turntable to my PC, and I'm getting a low bassy hum
noise.
> I'm sure that it's more than likely a grounding problem. However, I have
> no idea how to ground a turntable to a PC. I currently have a ground
cable
> going from my turntable to my preamp, but it isn't taking care of the hum.
> Any suggestions?
>
> Thanks,
> Dan
Anonymous
July 30, 2004 3:40:55 PM

Archived from groups: rec.audio.tech (More info?)

madcow1515 wrote:
> I just hooked my turntable to my PC, and I'm getting a low bassy hum noise.
> I'm sure that it's more than likely a grounding problem. However, I have
> no idea how to ground a turntable to a PC. I currently have a ground cable
> going from my turntable to my preamp, but it isn't taking care of the hum.
> Any suggestions?
>
> Thanks,
> Dan
If you have any doubts on the grounding, just connect the preamp chassis
directly to the PC chassis at the point where the turntable wire connects.
Related resources
Anonymous
July 30, 2004 6:15:18 PM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2muip7FqvuomU1@uni-berlin.de:

> The ground to the receiver should have done it. Is the receiver across
> the room, or is there a cable TV or outside antenna hooked up anywhere
> in the system?
>
> Mark Z.
>

I went to Radio Shack, and the guy there told me to try running a ground
from the turntable to the preamp, one from the preamp to the PC, and one
from the turntable to the PC. It still didn't take care of it. Would a
ground loop isolator do anything to help?
Anonymous
July 30, 2004 6:28:47 PM

Archived from groups: rec.audio.tech (More info?)

Robert Gault <robert.gault@worldnet.att.net> wrote in
news:btqOc.353011$Gx4.108175@bgtnsc04-news.ops.worldnet.att.net:

> If you have any doubts on the grounding, just connect the preamp
> chassis
> directly to the PC chassis at the point where the turntable wire
> connects.
>

What is the proper way to connect a ground wire to a PC chassis though? Do
I just need to twist the wires around anything metal back there?
Anonymous
July 30, 2004 7:49:42 PM

Archived from groups: rec.audio.tech (More info?)

madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
news:Xns9535C041B60D0nospamspamcom@216.168.3.44:

> I just hooked my turntable to my PC, and I'm getting a low bassy hum
> noise. I'm sure that it's more than likely a grounding problem.
> However, I have no idea how to ground a turntable to a PC. I
> currently have a ground cable going from my turntable to my preamp,
> but it isn't taking care of the hum. Any suggestions?
>
> Thanks,
> Dan
>

Problem fixed! I went to Radio Shack and bought a ground loop isolator,
and it did the trick!
Anonymous
July 30, 2004 7:51:31 PM

Archived from groups: rec.audio.tech (More info?)

madcow1515 <danner1515@NOSPAMyahoo.com> wrote in message news:<Xns9536606DBEA19nospamspamcom@216.168.3.44>...
> Robert Gault <robert.gault@worldnet.att.net> wrote in
> news:btqOc.353011$Gx4.108175@bgtnsc04-news.ops.worldnet.att.net:
>
> > If you have any doubts on the grounding, just connect the preamp
> > chassis
> > directly to the PC chassis at the point where the turntable wire
> > connects.
> >
>
> What is the proper way to connect a ground wire to a PC chassis though? Do
> I just need to twist the wires around anything metal back there?

....probably.

Had exactly this at start of my LP recording project. Found it to be
poorly grounded audio coax from the preamp to PC; somehow it'd got
wired to be grounded at one end only. Swapping the preamp > PC cable
for another immediately made the problem go away.

So... check the grounding on the circuit / swap out the cable.

IF you do need to improve the grounding then try a circuit from the
preamp chassis to the PC chassis as close to the PC soundcard as
possible; if not then just loosen one of the PC's PSU screws and
secure grounding wire under the screw head & retighten. Nice & tidy
with no loose ends.


But that would really do no more then a properly wired audio circuit.

satayeen
Anonymous
July 31, 2004 8:36:09 AM

Archived from groups: rec.audio.tech (More info?)

"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns95366E26026CDnospamspamcom@216.168.3.44...
> madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
> news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
>
> > I just hooked my turntable to my PC, and I'm getting a low bassy hum
> > noise. I'm sure that it's more than likely a grounding problem.
> > However, I have no idea how to ground a turntable to a PC. I
> > currently have a ground cable going from my turntable to my preamp,
> > but it isn't taking care of the hum. Any suggestions?
> >
> > Thanks,
> > Dan
> >
>
> Problem fixed! I went to Radio Shack and bought a ground loop isolator,
> and it did the trick!

Heaven forefend I would be too picky, but fixing the ground loop, now that
it's been established this is your problem, would be preferable.
The "ground loop isolator" is transformer-coupling your audio signal. Not
ideal. I fixed this problem on my system by putting a similar isolator on
the antenna cable. I'd lots rather have a slight insertion loss there than
in the signal path.

Mark Z.
Anonymous
August 1, 2004 8:41:56 AM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2n17g4Fs0r9sU1@uni-berlin.de:

>
> "madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> news:Xns95366E26026CDnospamspamcom@216.168.3.44...
>> madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
>> news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
>>
>> > I just hooked my turntable to my PC, and I'm getting a low bassy
>> > hum noise. I'm sure that it's more than likely a grounding
>> > problem. However, I have no idea how to ground a turntable to a PC.
>> > I currently have a ground cable going from my turntable to my
>> > preamp, but it isn't taking care of the hum. Any suggestions?
> Heaven forefend I would be too picky, but fixing the ground loop, now
> that it's been established this is your problem, would be preferable.
> The "ground loop isolator" is transformer-coupling your audio signal.
> Not ideal. I fixed this problem on my system by putting a similar
> isolator on the antenna cable. I'd lots rather have a slight insertion
> loss there than in the signal path.
>
> Mark Z.
>
>

Please pardon my ignorance (I'm really new with this grounding stuff),
but how would I go about fixing the ground loop? What item other item
would I run the isolator through? I tried pretty much every grounding
connection I could think of: one from the turntable to the preamp, one
from the preamp to the PC, and one from the turntable to the PC. I still
kept hearing a hum. I tried disconnecting my cable internet line, and it
made no difference.
August 1, 2004 9:01:52 AM

Archived from groups: rec.audio.tech (More info?)

Mark D. Zacharias wrote:
> "madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> news:Xns95366E26026CDnospamspamcom@216.168.3.44...
>
>>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
>>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
>>
>>
>>>I just hooked my turntable to my PC, and I'm getting a low bassy hum
>>>noise. I'm sure that it's more than likely a grounding problem.
>>>However, I have no idea how to ground a turntable to a PC. I
>>>currently have a ground cable going from my turntable to my preamp,
>>>but it isn't taking care of the hum. Any suggestions?
>>>
>>>Thanks,
>>>Dan
>>>
>>
>>Problem fixed! I went to Radio Shack and bought a ground loop isolator,
>>and it did the trick!
>
>
> Heaven forefend I would be too picky, but fixing the ground loop, now that
> it's been established this is your problem, would be preferable.
> The "ground loop isolator" is transformer-coupling your audio signal. Not
> ideal. I fixed this problem on my system by putting a similar isolator on
> the antenna cable. I'd lots rather have a slight insertion loss there than
> in the signal path.
>
> Mark Z.
>
>

That's easier said than done. The loop might be among the PC, pre-amp
and turntable rather than involving the "antenna cable" (not sure which
you mean by that) at all. This is probably consumer stereo gear, not
pro balanced stuff.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
August 1, 2004 10:40:22 AM

Archived from groups: rec.audio.tech (More info?)

I need a good description of your system, including any cable tv or antenna
stuff. Sorry if this is redundant.

It's not usually a matter of connecting a ground wire, except for the
turntable ground of course, but disconnecting or isolating a source of hum,
such as a cable tv connection.

I recently had a problem like this, and was appalled that the guy at Radio
Shack had no clue. Their isolator was transformer-coupled audio cables.
Yick. RS didn't even sell what I was looking for - but MCM did - at way too
high a price. The female to male version they had was way overpriced. I
bought a female to female for about 5.00 and used a short cable to give me
the needed male end to connect to the system. No more hum problem, and I
felt I could live with any slight reception issues caused by the isolator
(none noticed).

Your problem is likely to fall into this type of category - not connecting
another ground, but eliminating a ground path already existing.


Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns9537F112E8F8Fnospamspamcom@216.168.3.44...
> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> news:2n17g4Fs0r9sU1@uni-berlin.de:
>
> >
> > "madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> > news:Xns95366E26026CDnospamspamcom@216.168.3.44...
> >> madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
> >> news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
> >>
> >> > I just hooked my turntable to my PC, and I'm getting a low bassy
> >> > hum noise. I'm sure that it's more than likely a grounding
> >> > problem. However, I have no idea how to ground a turntable to a PC.
> >> > I currently have a ground cable going from my turntable to my
> >> > preamp, but it isn't taking care of the hum. Any suggestions?
> > Heaven forefend I would be too picky, but fixing the ground loop, now
> > that it's been established this is your problem, would be preferable.
> > The "ground loop isolator" is transformer-coupling your audio signal.
> > Not ideal. I fixed this problem on my system by putting a similar
> > isolator on the antenna cable. I'd lots rather have a slight insertion
> > loss there than in the signal path.
> >
> > Mark Z.
> >
> >
>
> Please pardon my ignorance (I'm really new with this grounding stuff),
> but how would I go about fixing the ground loop? What item other item
> would I run the isolator through? I tried pretty much every grounding
> connection I could think of: one from the turntable to the preamp, one
> from the preamp to the PC, and one from the turntable to the PC. I still
> kept hearing a hum. I tried disconnecting my cable internet line, and it
> made no difference.
Anonymous
August 1, 2004 5:11:13 PM

Archived from groups: rec.audio.tech (More info?)

"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns9537F112E8F8Fnospamspamcom@216.168.3.44
>
> Please pardon my ignorance (I'm really new with this grounding stuff),
> but how would I go about fixing the ground loop?

Do you really understand the isssue?

Here's your reading assignment, if you haven't done it already:

http://www.smr-home-theatre.org/Ground-Loops/

http://www.epanorama.net/documents/groundloop/index.htm...


> What item other item would I run the isolator through? I tried pretty
much every grounding
> connection I could think of: one from the turntable to the preamp, one
> from the preamp to the PC, and one from the turntable to the PC. I
> still kept hearing a hum. I tried disconnecting my cable internet
> line, and it made no difference.

Ground loops are due to redundant grounds and other redundant, which can
come through power cords, signal cables, actual ground connections, and
antenna lines, among other things.
Anonymous
August 1, 2004 8:22:18 PM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2n4350Fsp7b7U1@uni-berlin.de:

> I need a good description of your system, including any cable tv or
> antenna stuff. Sorry if this is redundant.

Let's see here. I'm not sure what all details you're looking for, so
tell me if you need more.

I have my turntable on a table left of the workstation where my PC is,
with the preamp mounted under the table. The preamp is connected to the
line-in jack of the PC. I have a subwoofer on the bottom of my
workstaton between the turntable and the PC. I don't have a TV or
anything near the setup, just a cable internet line. Here's a little
visual aid:

__L-speaker--monitor--R-speaker__
| |
| |
__turntable__ | keyboard/mouse ____|
| | | | | |
| -preamp |----| | PC |
| | | subwoofer | |
------------- ---------------------------------
Anonymous
August 1, 2004 8:32:11 PM

Archived from groups: rec.audio.tech (More info?)

madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
news:Xns953873ADEAEABnospamspamcom@216.168.3.44:

> __L-speaker--monitor--R-speaker__
> | |
> | |
> __turntable__ | keyboard/mouse ____|
>| | | | | |
>| -preamp |----| | PC |
>| | | subwoofer | |
> ------------- ---------------------------------
>

Well, that didn't work very well, now did it? Look here:
http://img.photobucket.com/albums/v193/madcow1515/setup...
Anonymous
August 2, 2004 8:02:46 AM

Archived from groups: rec.audio.tech (More info?)

In article <410C7940.1010406@prodigy.net>, CJT <abujlehc@prodigy.net>
wrote:

> Mark D. Zacharias wrote:
> > "madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> > news:Xns95366E26026CDnospamspamcom@216.168.3.44...
> >
> >>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
> >>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
> >>
> >>
> >>>I just hooked my turntable to my PC, and I'm getting a low bassy hum
> >>>noise. I'm sure that it's more than likely a grounding problem.
> >>>However, I have no idea how to ground a turntable to a PC. I
> >>>currently have a ground cable going from my turntable to my preamp,
> >>>but it isn't taking care of the hum. Any suggestions?
> >>>
> >>>Thanks,
> >>>Dan
> >>>
> >>
> >>Problem fixed! I went to Radio Shack and bought a ground loop isolator,
> >>and it did the trick!
> >
> >
> > Heaven forefend I would be too picky, but fixing the ground loop, now that
> > it's been established this is your problem, would be preferable.
> > The "ground loop isolator" is transformer-coupling your audio signal. Not
> > ideal. I fixed this problem on my system by putting a similar isolator on
> > the antenna cable. I'd lots rather have a slight insertion loss there than
> > in the signal path.
> >
> > Mark Z.
> >
> >
>
> That's easier said than done. The loop might be among the PC, pre-amp
> and turntable rather than involving the "antenna cable" (not sure which
> you mean by that) at all. This is probably consumer stereo gear, not
> pro balanced stuff.

See what happens if you put a "ground isolator" on the PC power cord --
one of those two-prong to three-prong adapters, but *don't* connect the
ground wire.

Isaac
Anonymous
August 2, 2004 9:42:42 AM

Archived from groups: rec.audio.tech (More info?)

Any hardware store would sell a 2-prond to 3-prong adapter for the computer
power cord, you could use that, simply not connecting the pigtail. This is
less than ideal.
You need an isolator for the cable internet cable. I don't believe it would
compromise your internet performance.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns953873ADEAEABnospamspamcom@216.168.3.44...
> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> news:2n4350Fsp7b7U1@uni-berlin.de:
>
> > I need a good description of your system, including any cable tv or
> > antenna stuff. Sorry if this is redundant.
>
> Let's see here. I'm not sure what all details you're looking for, so
> tell me if you need more.
>
> I have my turntable on a table left of the workstation where my PC is,
> with the preamp mounted under the table. The preamp is connected to the
> line-in jack of the PC. I have a subwoofer on the bottom of my
> workstaton between the turntable and the PC. I don't have a TV or
> anything near the setup, just a cable internet line. Here's a little
> visual aid:
>
> __L-speaker--monitor--R-speaker__
> | |
> | |
> __turntable__ | keyboard/mouse ____|
> | | | | | |
> | -preamp |----| | PC |
> | | | subwoofer | |
> ------------- ---------------------------------
August 2, 2004 10:48:36 AM

Archived from groups: rec.audio.tech (More info?)

Isaac Wingfield wrote:

> In article <410C7940.1010406@prodigy.net>, CJT <abujlehc@prodigy.net>
> wrote:
>
>
>>Mark D. Zacharias wrote:
>>
>>>"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
>>>news:Xns95366E26026CDnospamspamcom@216.168.3.44...
>>>
>>>
>>>>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
>>>>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
>>>>
>>>>
>>>>
>>>>>I just hooked my turntable to my PC, and I'm getting a low bassy hum
>>>>>noise. I'm sure that it's more than likely a grounding problem.
>>>>>However, I have no idea how to ground a turntable to a PC. I
>>>>>currently have a ground cable going from my turntable to my preamp,
>>>>>but it isn't taking care of the hum. Any suggestions?
>>>>>
>>>>>Thanks,
>>>>>Dan
>>>>>
>>>>
>>>>Problem fixed! I went to Radio Shack and bought a ground loop isolator,
>>>>and it did the trick!
>>>
>>>
>>>Heaven forefend I would be too picky, but fixing the ground loop, now that
>>>it's been established this is your problem, would be preferable.
>>>The "ground loop isolator" is transformer-coupling your audio signal. Not
>>>ideal. I fixed this problem on my system by putting a similar isolator on
>>>the antenna cable. I'd lots rather have a slight insertion loss there than
>>>in the signal path.
>>>
>>>Mark Z.
>>>
>>>
>>
>>That's easier said than done. The loop might be among the PC, pre-amp
>>and turntable rather than involving the "antenna cable" (not sure which
>>you mean by that) at all. This is probably consumer stereo gear, not
>>pro balanced stuff.
>
>
> See what happens if you put a "ground isolator" on the PC power cord --
> one of those two-prong to three-prong adapters, but *don't* connect the
> ground wire.
>
> Isaac

and watch for smoke

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
August 2, 2004 10:48:37 AM

Archived from groups: rec.audio.tech (More info?)

"CJT" <abujlehc@prodigy.net> wrote in message
news:410DE3C5.5080605@prodigy.net...
> Isaac Wingfield wrote:
>
> > In article <410C7940.1010406@prodigy.net>, CJT <abujlehc@prodigy.net>
> > wrote:
> >
> >
> >>Mark D. Zacharias wrote:
> >>
> >>>"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> >>>news:Xns95366E26026CDnospamspamcom@216.168.3.44...
> >>>
> >>>
> >>>>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
> >>>>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
> >>>>
> >>>>
> >>>>
> >>>>>I just hooked my turntable to my PC, and I'm getting a low bassy hum
> >>>>>noise. I'm sure that it's more than likely a grounding problem.
> >>>>>However, I have no idea how to ground a turntable to a PC. I
> >>>>>currently have a ground cable going from my turntable to my preamp,
> >>>>>but it isn't taking care of the hum. Any suggestions?
> >>>>>
> >>>>>Thanks,
> >>>>>Dan
> >>>>>
> >>>>
> >>>>Problem fixed! I went to Radio Shack and bought a ground loop
isolator,
> >>>>and it did the trick!
> >>>
> >>>
> >>>Heaven forefend I would be too picky, but fixing the ground loop, now
that
> >>>it's been established this is your problem, would be preferable.
> >>>The "ground loop isolator" is transformer-coupling your audio signal.
Not
> >>>ideal. I fixed this problem on my system by putting a similar isolator
on
> >>>the antenna cable. I'd lots rather have a slight insertion loss there
than
> >>>in the signal path.
> >>>
> >>>Mark Z.
> >>>
> >>>
> >>
> >>That's easier said than done. The loop might be among the PC, pre-amp
> >>and turntable rather than involving the "antenna cable" (not sure which
> >>you mean by that) at all. This is probably consumer stereo gear, not
> >>pro balanced stuff.
> >
> >
> > See what happens if you put a "ground isolator" on the PC power cord --
> > one of those two-prong to three-prong adapters, but *don't* connect the
> > ground wire.
> >
> > Isaac
>
> and watch for smoke
>

Nonsense.

Mark Z.
Anonymous
August 3, 2004 3:19:39 AM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2n6k4qFtapvbU1@uni-berlin.de:

> Any hardware store would sell a 2-prond to 3-prong adapter for the
> computer power cord, you could use that, simply not connecting the
> pigtail. This is less than ideal.
> You need an isolator for the cable internet cable. I don't believe it
> would compromise your internet performance.
>
> Mark Z.
>

What kind of isolator would I need for the cable line? I searched Radio
Shack's web page and couldn't really find anything that looked suitable for
the job. Besides, I tried unplugging the cable line from the wall and
still heard a hum. Would I still get interference from the cable even with
it unplugged?
Anonymous
August 3, 2004 3:19:40 AM

Archived from groups: rec.audio.tech (More info?)

I guess I missed the part where you mentioned you had unplugged the cable.
We're going to have to start from the beginning. Exactly WHEN do you get the
hum, and is it on all sources?

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
news:Xns9539BA6E1763nospamspamcom@216.168.3.44...
> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> news:2n6k4qFtapvbU1@uni-berlin.de:
>
> > Any hardware store would sell a 2-prond to 3-prong adapter for the
> > computer power cord, you could use that, simply not connecting the
> > pigtail. This is less than ideal.
> > You need an isolator for the cable internet cable. I don't believe it
> > would compromise your internet performance.
> >
> > Mark Z.
> >
>
> What kind of isolator would I need for the cable line? I searched Radio
> Shack's web page and couldn't really find anything that looked suitable
for
> the job. Besides, I tried unplugging the cable line from the wall and
> still heard a hum. Would I still get interference from the cable even
with
> it unplugged?
Anonymous
August 3, 2004 5:19:41 AM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2n83vpFtitaeU1@uni-berlin.de:

> I guess I missed the part where you mentioned you had unplugged the
> cable. We're going to have to start from the beginning. Exactly WHEN
> do you get the hum, and is it on all sources?
>
> Mark Z.
>

I only get the hum when the line from the preamp is plugged into the PC.
When I unplug or mute the "line-in" channel, the hum goes away. The hum
goes away when I unplug the power plug from the preamp though. Could it be
a matter of a cheap preamp causing trouble?
Anonymous
August 3, 2004 5:19:42 AM

Archived from groups: rec.audio.tech (More info?)

"madcow1515" <danner1515@yahoo.com> wrote in message
news:Xns9539CEC7F3E99nospamspamcom@216.168.3.44...
> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> news:2n83vpFtitaeU1@uni-berlin.de:
>
> > I guess I missed the part where you mentioned you had unplugged the
> > cable. We're going to have to start from the beginning. Exactly WHEN
> > do you get the hum, and is it on all sources?
> >
> > Mark Z.
> >
>
> I only get the hum when the line from the preamp is plugged into the PC.
> When I unplug or mute the "line-in" channel, the hum goes away. The hum
> goes away when I unplug the power plug from the preamp though. Could it
be
> a matter of a cheap preamp causing trouble?

If the hum also went away when using the stereo isolator from Radio Shack,
then I don't think the preamp is the problem. If the preamp power cord is in
the same outlet as the computer, maybe reversing the preamp power plug in
the outlet might help. Unlikely but worth a try. Did you ever try lifting
the computer power cord ground with the 3-prong to 2 prong adapter? Don't
worry about the guy who posted that this was dangerous. It could only be
dangerous under certain unusual conditions. The computer power supply would
have to fail in such a way as to put 110v on the chassis. Otherwise the
chassis is just a metal box with the case tied to an isolated internal DC
ground, just like any stereo system you've ever used. I'm not saying it's an
ideal solution - a surge suppressor might not work correctly, but they
usually don't anyway. I would prefer this approach to the Radio Shack
isolators for sound quality reasons.


Mark Z.
Anonymous
August 3, 2004 5:19:43 AM

Archived from groups: rec.audio.tech (More info?)

BTW I am assuming the entire computer system would be ungrounded, not just
the box. A chassis ground would carry through from a monitor, printer, etc.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Mark D. Zacharias" <mzacharias@yis.us> wrote in message
news:2n8ao2Fucpu4U1@uni-berlin.de...
> "madcow1515" <danner1515@yahoo.com> wrote in message
> news:Xns9539CEC7F3E99nospamspamcom@216.168.3.44...
> > "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> > news:2n83vpFtitaeU1@uni-berlin.de:
> >
> > > I guess I missed the part where you mentioned you had unplugged the
> > > cable. We're going to have to start from the beginning. Exactly WHEN
> > > do you get the hum, and is it on all sources?
> > >
> > > Mark Z.
> > >
> >
> > I only get the hum when the line from the preamp is plugged into the PC.
> > When I unplug or mute the "line-in" channel, the hum goes away. The hum
> > goes away when I unplug the power plug from the preamp though. Could it
> be
> > a matter of a cheap preamp causing trouble?
>
> If the hum also went away when using the stereo isolator from Radio Shack,
> then I don't think the preamp is the problem. If the preamp power cord is
in
> the same outlet as the computer, maybe reversing the preamp power plug in
> the outlet might help. Unlikely but worth a try. Did you ever try lifting
> the computer power cord ground with the 3-prong to 2 prong adapter? Don't
> worry about the guy who posted that this was dangerous. It could only be
> dangerous under certain unusual conditions. The computer power supply
would
> have to fail in such a way as to put 110v on the chassis. Otherwise the
> chassis is just a metal box with the case tied to an isolated internal DC
> ground, just like any stereo system you've ever used. I'm not saying it's
an
> ideal solution - a surge suppressor might not work correctly, but they
> usually don't anyway. I would prefer this approach to the Radio Shack
> isolators for sound quality reasons.
>
>
> Mark Z.
>
>
August 3, 2004 5:26:55 AM

Archived from groups: rec.audio.tech (More info?)

Mark D. Zacharias wrote:

> "CJT" <abujlehc@prodigy.net> wrote in message
> news:410DE3C5.5080605@prodigy.net...
>
>>Isaac Wingfield wrote:
>>
>>
>>>In article <410C7940.1010406@prodigy.net>, CJT <abujlehc@prodigy.net>
>>>wrote:
>>>
>>>
>>>
>>>>Mark D. Zacharias wrote:
>>>>
>>>>
>>>>>"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
>>>>>news:Xns95366E26026CDnospamspamcom@216.168.3.44...
>>>>>
>>>>>
>>>>>
>>>>>>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
>>>>>>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>I just hooked my turntable to my PC, and I'm getting a low bassy hum
>>>>>>>noise. I'm sure that it's more than likely a grounding problem.
>>>>>>>However, I have no idea how to ground a turntable to a PC. I
>>>>>>>currently have a ground cable going from my turntable to my preamp,
>>>>>>>but it isn't taking care of the hum. Any suggestions?
>>>>>>>
>>>>>>>Thanks,
>>>>>>>Dan
>>>>>>>
>>>>>>
>>>>>>Problem fixed! I went to Radio Shack and bought a ground loop
>
> isolator,
>
>>>>>>and it did the trick!
>>>>>
>>>>>
>>>>>Heaven forefend I would be too picky, but fixing the ground loop, now
>
> that
>
>>>>>it's been established this is your problem, would be preferable.
>>>>>The "ground loop isolator" is transformer-coupling your audio signal.
>
> Not
>
>>>>>ideal. I fixed this problem on my system by putting a similar isolator
>
> on
>
>>>>>the antenna cable. I'd lots rather have a slight insertion loss there
>
> than
>
>>>>>in the signal path.
>>>>>
>>>>>Mark Z.
>>>>>
>>>>>
>>>>
>>>>That's easier said than done. The loop might be among the PC, pre-amp
>>>>and turntable rather than involving the "antenna cable" (not sure which
>>>>you mean by that) at all. This is probably consumer stereo gear, not
>>>>pro balanced stuff.
>>>
>>>
>>>See what happens if you put a "ground isolator" on the PC power cord --
>>>one of those two-prong to three-prong adapters, but *don't* connect the
>>>ground wire.
>>>
>>>Isaac
>>
>>and watch for smoke
>>
>
>
> Nonsense.
>
> Mark Z.
>
>
It's not called a "safety ground" for nothing.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
August 3, 2004 5:26:56 AM

Archived from groups: rec.audio.tech (More info?)

It is simply unnecessary for most equipment. We have power transformers for
isolation.


Mark Z.

>It's not called a "safety ground" for nothing.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"CJT" <abujlehc@prodigy.net> wrote in message
news:410EE9DE.10100@prodigy.net...
> Mark D. Zacharias wrote:
>
> > "CJT" <abujlehc@prodigy.net> wrote in message
> > news:410DE3C5.5080605@prodigy.net...
> >
> >>Isaac Wingfield wrote:
> >>
> >>
> >>>In article <410C7940.1010406@prodigy.net>, CJT <abujlehc@prodigy.net>
> >>>wrote:
> >>>
> >>>
> >>>
> >>>>Mark D. Zacharias wrote:
> >>>>
> >>>>
> >>>>>"madcow1515" <danner1515@NOSPAMyahoo.com> wrote in message
> >>>>>news:Xns95366E26026CDnospamspamcom@216.168.3.44...
> >>>>>
> >>>>>
> >>>>>
> >>>>>>madcow1515 <danner1515@NOSPAMyahoo.com> wrote in
> >>>>>>news:Xns9535C041B60D0nospamspamcom@216.168.3.44:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>I just hooked my turntable to my PC, and I'm getting a low bassy
hum
> >>>>>>>noise. I'm sure that it's more than likely a grounding problem.
> >>>>>>>However, I have no idea how to ground a turntable to a PC. I
> >>>>>>>currently have a ground cable going from my turntable to my preamp,
> >>>>>>>but it isn't taking care of the hum. Any suggestions?
> >>>>>>>
> >>>>>>>Thanks,
> >>>>>>>Dan
> >>>>>>>
> >>>>>>
> >>>>>>Problem fixed! I went to Radio Shack and bought a ground loop
> >
> > isolator,
> >
> >>>>>>and it did the trick!
> >>>>>
> >>>>>
> >>>>>Heaven forefend I would be too picky, but fixing the ground loop, now
> >
> > that
> >
> >>>>>it's been established this is your problem, would be preferable.
> >>>>>The "ground loop isolator" is transformer-coupling your audio signal.
> >
> > Not
> >
> >>>>>ideal. I fixed this problem on my system by putting a similar
isolator
> >
> > on
> >
> >>>>>the antenna cable. I'd lots rather have a slight insertion loss there
> >
> > than
> >
> >>>>>in the signal path.
> >>>>>
> >>>>>Mark Z.
> >>>>>
> >>>>>
> >>>>
> >>>>That's easier said than done. The loop might be among the PC, pre-amp
> >>>>and turntable rather than involving the "antenna cable" (not sure
which
> >>>>you mean by that) at all. This is probably consumer stereo gear, not
> >>>>pro balanced stuff.
> >>>
> >>>
> >>>See what happens if you put a "ground isolator" on the PC power cord --
> >>>one of those two-prong to three-prong adapters, but *don't* connect the
> >>>ground wire.
> >>>
> >>>Isaac
> >>
> >>and watch for smoke
> >>
> >
> >
> > Nonsense.
> >
> > Mark Z.
> >
> >
> It's not called a "safety ground" for nothing.
>
> --
> The e-mail address in our reply-to line is reversed in an attempt to
> minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
August 3, 2004 8:47:08 AM

Archived from groups: rec.audio.tech (More info?)

In article <2n6k4qFtapvbU1@uni-berlin.de>,
"Mark D. Zacharias" <mzacharias@yis.us> wrote:

--snip--

> You need an isolator for the cable internet cable. I don't believe it would
> compromise your internet performance.

That might work, but make sure it's a *broadband* isolator. An ordinary
TV isolator might be 50-1000 MHz, and that won't work. For the cable
modem upstream signal, the isolator must go down to maybe 5 MHz (depends
on where your cable company found a quiet spot in the spectrum).

5-1000 MHz isolators are not hard to find; check Radio Shack, but also
check the specs.

Isaac
Anonymous
August 3, 2004 8:53:39 AM

Archived from groups: rec.audio.tech (More info?)

In article <Xns9539CEC7F3E99nospamspamcom@216.168.3.44>,
madcow1515 <danner1515@yahoo.com> wrote:

> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
> news:2n83vpFtitaeU1@uni-berlin.de:
>
> > I guess I missed the part where you mentioned you had unplugged the
> > cable. We're going to have to start from the beginning. Exactly WHEN
> > do you get the hum, and is it on all sources?
> >
> > Mark Z.
> >
>
> I only get the hum when the line from the preamp is plugged into the PC.
> When I unplug or mute the "line-in" channel, the hum goes away. The hum
> goes away when I unplug the power plug from the preamp though. Could it be
> a matter of a cheap preamp causing trouble?

More likely it's due to bad grounding practice in the computer. There's
no reason why the manufacturer of it would pay any attention to
groundloops or audio noise.

Try ground isolators on one or both of the preamp and the PC.

If the preamp power cord is two-prong, try flipping it over to reverse
the power connections.

Try running the audio from a battery-powered radio (no AC cord) into the
PC. If that hums, something's wrong with the audio input circuitry of
the PC.

Isaac
Anonymous
August 3, 2004 9:31:34 AM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> wrote in
news:2n8ao2Fucpu4U1@uni-berlin.de:

> "madcow1515" <danner1515@yahoo.com> wrote in message
> news:Xns9539CEC7F3E99nospamspamcom@216.168.3.44...
>> "Mark D. Zacharias" <mzacharias@yis.us> wrote in
>> news:2n83vpFtitaeU1@uni-berlin.de:
>>
>> > I guess I missed the part where you mentioned you had unplugged the
>> > cable. We're going to have to start from the beginning. Exactly
>> > WHEN do you get the hum, and is it on all sources?
>> >
>> > Mark Z.
>> >
>>
>> I only get the hum when the line from the preamp is plugged into the
>> PC. When I unplug or mute the "line-in" channel, the hum goes away.
>> The hum goes away when I unplug the power plug from the preamp
>> though. Could it
> be
>> a matter of a cheap preamp causing trouble?
>
> If the hum also went away when using the stereo isolator from Radio
> Shack, then I don't think the preamp is the problem. If the preamp
> power cord is in the same outlet as the computer, maybe reversing the
> preamp power plug in the outlet might help. Unlikely but worth a try.
> Did you ever try lifting the computer power cord ground with the
> 3-prong to 2 prong adapter? Don't worry about the guy who posted that
> this was dangerous. It could only be dangerous under certain unusual
> conditions. The computer power supply would have to fail in such a way
> as to put 110v on the chassis. Otherwise the chassis is just a metal
> box with the case tied to an isolated internal DC ground, just like
> any stereo system you've ever used. I'm not saying it's an ideal
> solution - a surge suppressor might not work correctly, but they
> usually don't anyway. I would prefer this approach to the Radio Shack
> isolators for sound quality reasons.

I'll try to find a two-to-three prong adapter tomorrow morning (I
couldn't find one at Home Depot tonight). I'll give it a shot though.

BTW, I REALLY appreciate all you guys helping me out with this stuff.
!