Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Brian

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Try lifting the ground on the subwoofer. Use a cheater or a cheap extension
cord. If the hum disappears you have found the culprit. If not, ask and
we'll make more suggestions, but this is the first (and simplest) thing to
check.

Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Try lifting the ground on the subwoofer. Use a cheater or a cheap extension
cord. If the hum disappears you have found the culprit. If not, ask and
we'll make more suggestions, but this is the first (and simplest) thing to
check.

Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Try lifting the ground on the subwoofer. Use a cheater or a cheap extension
cord. If the hum disappears you have found the culprit. If not, ask and
we'll make more suggestions, but this is the first (and simplest) thing to
check.

Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Try lifting the ground on the subwoofer. Use a cheater or a cheap extension
cord. If the hum disappears you have found the culprit. If not, ask and
we'll make more suggestions, but this is the first (and simplest) thing to
check.

Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

In , on 02/17/04
at 07:00 PM, (Brian) said:

Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

This seems like a ground loop issue to me. (read on)

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

There is always a small amount of hum. It's difficult for us to decide
if it is normal or not unless we hear it or interpret a measurement
that we trust. In a very quiet room, close to the speaker, the hum is
usually audible. In most homes, with all the heaters, appliances,
computers, etc. that are running, the hum is not significant.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

The plug on the end of the cable fell apart? The jack on the receiver
separated?

It is possible that you damaged the jack on the receiver. Obviously,
replacing the subwoofer cable will cure a damaged cable issue. You can
quickly check for a damaged jack by using a screwdriver to short the
shield (outside) of the subwoofer cable to the shield on a nearby jack.
If the problem cures, the the jack must be replaced.

Plugging the subwoofer into another outlet can easily cause ground
loops. You can test for this situation by using a power extension cord
to temporarily use the same outlet for everything in the system.

Also, disconnect the cable TV feed if you have one.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 02/17/04
at 07:00 PM, (Brian) said:

Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

This seems like a ground loop issue to me. (read on)

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

There is always a small amount of hum. It's difficult for us to decide
if it is normal or not unless we hear it or interpret a measurement
that we trust. In a very quiet room, close to the speaker, the hum is
usually audible. In most homes, with all the heaters, appliances,
computers, etc. that are running, the hum is not significant.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

The plug on the end of the cable fell apart? The jack on the receiver
separated?

It is possible that you damaged the jack on the receiver. Obviously,
replacing the subwoofer cable will cure a damaged cable issue. You can
quickly check for a damaged jack by using a screwdriver to short the
shield (outside) of the subwoofer cable to the shield on a nearby jack.
If the problem cures, the the jack must be replaced.

Plugging the subwoofer into another outlet can easily cause ground
loops. You can test for this situation by using a power extension cord
to temporarily use the same outlet for everything in the system.

Also, disconnect the cable TV feed if you have one.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 02/17/04
at 07:00 PM, (Brian) said:

Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

This seems like a ground loop issue to me. (read on)

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

There is always a small amount of hum. It's difficult for us to decide
if it is normal or not unless we hear it or interpret a measurement
that we trust. In a very quiet room, close to the speaker, the hum is
usually audible. In most homes, with all the heaters, appliances,
computers, etc. that are running, the hum is not significant.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

The plug on the end of the cable fell apart? The jack on the receiver
separated?

It is possible that you damaged the jack on the receiver. Obviously,
replacing the subwoofer cable will cure a damaged cable issue. You can
quickly check for a damaged jack by using a screwdriver to short the
shield (outside) of the subwoofer cable to the shield on a nearby jack.
If the problem cures, the the jack must be replaced.

Plugging the subwoofer into another outlet can easily cause ground
loops. You can test for this situation by using a power extension cord
to temporarily use the same outlet for everything in the system.

Also, disconnect the cable TV feed if you have one.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 02/17/04
at 07:00 PM, (Brian) said:

Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

This seems like a ground loop issue to me. (read on)

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

There is always a small amount of hum. It's difficult for us to decide
if it is normal or not unless we hear it or interpret a measurement
that we trust. In a very quiet room, close to the speaker, the hum is
usually audible. In most homes, with all the heaters, appliances,
computers, etc. that are running, the hum is not significant.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

The plug on the end of the cable fell apart? The jack on the receiver
separated?

It is possible that you damaged the jack on the receiver. Obviously,
replacing the subwoofer cable will cure a damaged cable issue. You can
quickly check for a damaged jack by using a screwdriver to short the
shield (outside) of the subwoofer cable to the shield on a nearby jack.
If the problem cures, the the jack must be replaced.

Plugging the subwoofer into another outlet can easily cause ground
loops. You can test for this situation by using a power extension cord
to temporarily use the same outlet for everything in the system.

Also, disconnect the cable TV feed if you have one.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

just sticking the 3 light tester into an outlet doesnt mean the GROUNDS are
connected correctly. in a perfect world, all the grounds only make contact
with the neutral at one point, and that is in the panel OUTSIDE YOUR HOUSE.
often electritians connect the neutral to the ground inside the panel, and
its also contacting inside the meter box. depending on how far this is and
other circumstances this alone can create a hum. and this is just one
example of where the tester says yes, but its not quite right. you may not
have proper ground rods installed, there may be a water meter that breakes
the electrical connection in the plumbing which was being used for the
ground. etc...

but i would first try this. disconnect any cable tv sources you have and
see if it goes away. if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

just sticking the 3 light tester into an outlet doesnt mean the GROUNDS are
connected correctly. in a perfect world, all the grounds only make contact
with the neutral at one point, and that is in the panel OUTSIDE YOUR HOUSE.
often electritians connect the neutral to the ground inside the panel, and
its also contacting inside the meter box. depending on how far this is and
other circumstances this alone can create a hum. and this is just one
example of where the tester says yes, but its not quite right. you may not
have proper ground rods installed, there may be a water meter that breakes
the electrical connection in the plumbing which was being used for the
ground. etc...

but i would first try this. disconnect any cable tv sources you have and
see if it goes away. if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

just sticking the 3 light tester into an outlet doesnt mean the GROUNDS are
connected correctly. in a perfect world, all the grounds only make contact
with the neutral at one point, and that is in the panel OUTSIDE YOUR HOUSE.
often electritians connect the neutral to the ground inside the panel, and
its also contacting inside the meter box. depending on how far this is and
other circumstances this alone can create a hum. and this is just one
example of where the tester says yes, but its not quite right. you may not
have proper ground rods installed, there may be a water meter that breakes
the electrical connection in the plumbing which was being used for the
ground. etc...

but i would first try this. disconnect any cable tv sources you have and
see if it goes away. if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

just sticking the 3 light tester into an outlet doesnt mean the GROUNDS are
connected correctly. in a perfect world, all the grounds only make contact
with the neutral at one point, and that is in the panel OUTSIDE YOUR HOUSE.
often electritians connect the neutral to the ground inside the panel, and
its also contacting inside the meter box. depending on how far this is and
other circumstances this alone can create a hum. and this is just one
example of where the tester says yes, but its not quite right. you may not
have proper ground rods installed, there may be a water meter that breakes
the electrical connection in the plumbing which was being used for the
ground. etc...

but i would first try this. disconnect any cable tv sources you have and
see if it goes away. if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

"Brian" wrote in message
om

Apologies to the group if this has been discussed prior:

No problem, if you keep an open mind. Grounding problems with subwoofers are
very common, and have been discussed many times. Try searching using words
like subwoofer and hum at www.google.com .

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

That makes about as much sense as having a short-term cough and sniffles and
not suspecting that you might have a cold.

It's probably a ground loop issue or another kind of grounding issue called
a "grounding potential difference".

Probably, the first thing to do is to eliminate the fact that you have the
sub and the receiver grounded at separate points as a potential source of
problem. IOW plug the receiver and the subwoofer into the same outlet or
plug strip, and see what happens.

Also, eliminate the rest of your system as a potential source of problems.
Remove all connections from your receiver but power, speakers, and the
connection to the subwoofer.

Once you get reasonably hum-free operation, add things back one at a time
and see if any of them are causing grounding problems.

"Brian" wrote in message
om

Apologies to the group if this has been discussed prior:

No problem, if you keep an open mind. Grounding problems with subwoofers are
very common, and have been discussed many times. Try searching using words
like subwoofer and hum at www.google.com .

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

That makes about as much sense as having a short-term cough and sniffles and
not suspecting that you might have a cold.

It's probably a ground loop issue or another kind of grounding issue called
a "grounding potential difference".

Probably, the first thing to do is to eliminate the fact that you have the
sub and the receiver grounded at separate points as a potential source of
problem. IOW plug the receiver and the subwoofer into the same outlet or
plug strip, and see what happens.

Also, eliminate the rest of your system as a potential source of problems.
Remove all connections from your receiver but power, speakers, and the
connection to the subwoofer.

Once you get reasonably hum-free operation, add things back one at a time
and see if any of them are causing grounding problems.

"Brian" wrote in message
om

Apologies to the group if this has been discussed prior:

No problem, if you keep an open mind. Grounding problems with subwoofers are
very common, and have been discussed many times. Try searching using words
like subwoofer and hum at www.google.com .

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

That makes about as much sense as having a short-term cough and sniffles and
not suspecting that you might have a cold.

It's probably a ground loop issue or another kind of grounding issue called
a "grounding potential difference".

Probably, the first thing to do is to eliminate the fact that you have the
sub and the receiver grounded at separate points as a potential source of
problem. IOW plug the receiver and the subwoofer into the same outlet or
plug strip, and see what happens.

Also, eliminate the rest of your system as a potential source of problems.
Remove all connections from your receiver but power, speakers, and the
connection to the subwoofer.

Once you get reasonably hum-free operation, add things back one at a time
and see if any of them are causing grounding problems.

"Brian" wrote in message
om

Apologies to the group if this has been discussed prior:

No problem, if you keep an open mind. Grounding problems with subwoofers are
very common, and have been discussed many times. Try searching using words
like subwoofer and hum at www.google.com .

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

That makes about as much sense as having a short-term cough and sniffles and
not suspecting that you might have a cold.

It's probably a ground loop issue or another kind of grounding issue called
a "grounding potential difference".

Probably, the first thing to do is to eliminate the fact that you have the
sub and the receiver grounded at separate points as a potential source of
problem. IOW plug the receiver and the subwoofer into the same outlet or
plug strip, and see what happens.

Also, eliminate the rest of your system as a potential source of problems.
Remove all connections from your receiver but power, speakers, and the
connection to the subwoofer.

Once you get reasonably hum-free operation, add things back one at a time
and see if any of them are causing grounding problems.

(Brian) writes:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum.

The receiver and the subwoofer are configured to plug into different
grounded outlets. Both outlets are properly wired.

Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system.

You appear to have every symptom of a ground loop problem. If
possible, plug the receiver and subwoofer into the same outlet, and
I'll betcha a quarter the issue goes away. :-)

If plugging them into the same outlet is not feasible, seek out an
audio isolation transformer for the line level signal that feeds your
subwoofer. This isolates the grounds of the two affected component
and often eliminates the hum.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

(Brian) writes:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum.

The receiver and the subwoofer are configured to plug into different
grounded outlets. Both outlets are properly wired.

Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system.

You appear to have every symptom of a ground loop problem. If
possible, plug the receiver and subwoofer into the same outlet, and
I'll betcha a quarter the issue goes away. :-)

If plugging them into the same outlet is not feasible, seek out an
audio isolation transformer for the line level signal that feeds your
subwoofer. This isolates the grounds of the two affected component
and often eliminates the hum.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

(Brian) writes:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum.

The receiver and the subwoofer are configured to plug into different
grounded outlets. Both outlets are properly wired.

Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system.

You appear to have every symptom of a ground loop problem. If
possible, plug the receiver and subwoofer into the same outlet, and
I'll betcha a quarter the issue goes away. :-)

If plugging them into the same outlet is not feasible, seek out an
audio isolation transformer for the line level signal that feeds your
subwoofer. This isolates the grounds of the two affected component
and often eliminates the hum.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

(Brian) writes:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum.

The receiver and the subwoofer are configured to plug into different
grounded outlets. Both outlets are properly wired.

Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system.

You appear to have every symptom of a ground loop problem. If
possible, plug the receiver and subwoofer into the same outlet, and
I'll betcha a quarter the issue goes away. :-)

If plugging them into the same outlet is not feasible, seek out an
audio isolation transformer for the line level signal that feeds your
subwoofer. This isolates the grounds of the two affected component
and often eliminates the hum.

Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice."

A couple other things that can cause hum are cheap cable (or a cable gone
bad),and speaker cables tangled in power cables.Try another cable of high
quality and clean up around the back of your system.Have all power cables
away from speaker cables.Make sure you are running everything out of one
outlet,if needed buy a good power bar.

Good Luck




Brian wrote in message
om...
Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Brian

A couple other things that can cause hum are cheap cable (or a cable gone
bad),and speaker cables tangled in power cables.Try another cable of high
quality and clean up around the back of your system.Have all power cables
away from speaker cables.Make sure you are running everything out of one
outlet,if needed buy a good power bar.

Good Luck




Brian wrote in message
om...
Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Brian

A couple other things that can cause hum are cheap cable (or a cable gone
bad),and speaker cables tangled in power cables.Try another cable of high
quality and clean up around the back of your system.Have all power cables
away from speaker cables.Make sure you are running everything out of one
outlet,if needed buy a good power bar.

Good Luck




Brian wrote in message
om...
Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Brian

A couple other things that can cause hum are cheap cable (or a cable gone
bad),and speaker cables tangled in power cables.Try another cable of high
quality and clean up around the back of your system.Have all power cables
away from speaker cables.Make sure you are running everything out of one
outlet,if needed buy a good power bar.

Good Luck




Brian wrote in message
om...
Apologies to the group if this has been discussed prior:

When I plug my subwoofer into my receiver and turn on the receiver, I
hear a hum. The sound is similar to putting a finger across the
subwoofer cable lead.

I am trying to understand if there is an obvious cause for this hum,
other than a problem with the receiver's subwoofer output jack. I do
not believe this is a ground loop issue.

My equipment is an Onkyo TX-SR500 receiver and Sony SA-WM20 subwoofer.
(I know, not the greatest - but it's what I have.) I tested the
subwoofer on a friend's Onkyo, and it worked properly. I swapped
subwoofer cables and the hum still occurs.

I have disconnected all input/output leads from the receiver other
than the subwoofer cable. When the receiver is not plugged in, there
is a low hum. When the subwoofer is plugged in, the volume of the hum
increases, even with the receiver power off. When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

The system was working properly before I pulled it apart to install a
wall unit. Other than upgrading some RCA cables and changing the
outlets into which some components plug, no changes were made to the
system. When I disconnected the system, the subwoofer cable was very
difficult to remove from the receiver, In fact, the head came apart
in my hand, and I needed to use needlenose pliers to pull the casing
off the receiver output jack. I am wondering if I somehow damaged
whatever is hooked to the backside of this jack, and whether that
might cause the hum.

Any advice before I cart the receiver off to a shop is gratefully
accepted.

Brian

"xrongor" wrote in message news:HeDYb.212095$U%5.1223717@attbi_s03...
When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

(snip)

but i would first try this. disconnect any cable tv sources you have and
see if it goes away.

A cable TV connection somewhere in the system (such as connected to
your TV or VCR) is often the problem, although other posts in this
thread may also be useful.

If you have cable TV, try disconnecting the cable from your system. If
that solves the problem, then go to www.google.com and search web and
newsgroups for fixes. Search terms such as:

cable TV
hum
ground loop
subwoofer

A few searches will probably lead you to more info and simple fixes.
Fixes for this sort of problem are often cheap or free.

If the cable TV is the problem, also call cable TV company and ask for
advice.

If you can't fix the problem, here's another resource:

rec.audio.tech

But I think your problem should be easy to fix, although it may
involve a little trial and error and plugging in your gear a few
different ways until you find something that makes the hum go away.

if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

"xrongor" wrote in message news:HeDYb.212095$U%5.1223717@attbi_s03...
When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

(snip)

but i would first try this. disconnect any cable tv sources you have and
see if it goes away.

A cable TV connection somewhere in the system (such as connected to
your TV or VCR) is often the problem, although other posts in this
thread may also be useful.

If you have cable TV, try disconnecting the cable from your system. If
that solves the problem, then go to www.google.com and search web and
newsgroups for fixes. Search terms such as:

cable TV
hum
ground loop
subwoofer

A few searches will probably lead you to more info and simple fixes.
Fixes for this sort of problem are often cheap or free.

If the cable TV is the problem, also call cable TV company and ask for
advice.

If you can't fix the problem, here's another resource:

rec.audio.tech

But I think your problem should be easy to fix, although it may
involve a little trial and error and plugging in your gear a few
different ways until you find something that makes the hum go away.

if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

"xrongor" wrote in message news:HeDYb.212095$U%5.1223717@attbi_s03...
When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

(snip)

but i would first try this. disconnect any cable tv sources you have and
see if it goes away.

A cable TV connection somewhere in the system (such as connected to
your TV or VCR) is often the problem, although other posts in this
thread may also be useful.

If you have cable TV, try disconnecting the cable from your system. If
that solves the problem, then go to www.google.com and search web and
newsgroups for fixes. Search terms such as:

cable TV
hum
ground loop
subwoofer

A few searches will probably lead you to more info and simple fixes.
Fixes for this sort of problem are often cheap or free.

If the cable TV is the problem, also call cable TV company and ask for
advice.

If you can't fix the problem, here's another resource:

rec.audio.tech

But I think your problem should be easy to fix, although it may
involve a little trial and error and plugging in your gear a few
different ways until you find something that makes the hum go away.

if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

"xrongor" wrote in message news:HeDYb.212095$U%5.1223717@attbi_s03...
When the receiver is
powered on, the hum's volume increases more. The receiver and the
subwoofer are configured to plug into different grounded outlets.
Both outlets are properly wired.

(snip)

but i would first try this. disconnect any cable tv sources you have and
see if it goes away.

A cable TV connection somewhere in the system (such as connected to
your TV or VCR) is often the problem, although other posts in this
thread may also be useful.

If you have cable TV, try disconnecting the cable from your system. If
that solves the problem, then go to www.google.com and search web and
newsgroups for fixes. Search terms such as:

cable TV
hum
ground loop
subwoofer

A few searches will probably lead you to more info and simple fixes.
Fixes for this sort of problem are often cheap or free.

If the cable TV is the problem, also call cable TV company and ask for
advice.

If you can't fix the problem, here's another resource:

rec.audio.tech

But I think your problem should be easy to fix, although it may
involve a little trial and error and plugging in your gear a few
different ways until you find something that makes the hum go away.

if that doesnt work, do what robert bass said. either
isolate the ground plug, or put em both in the same exact outlet and see
what happens. you also didnt say if the different outlets are on the same
circuit..

lastly, before taking it back to the shop, take it down to bare bones, and i
mean bare. just plug in the sub, and use the radio on the receiver and
disconnect everything else. if this fixes it, bring it up one at a time
until the hum returns.

randy

A couple other things that can cause hum are
cheap cable (or a cable gone bad),and speaker
cables tangled in power cables...

I disagree. You will not get audible hum from defective speaker cables.
You also will not get it from wrapping them around power cables. Defective
interconnect cables can allow noise to enter the system but the SNR on the
speaker cables -- after all of the amplification -- is so great that any
induced AC there will not be audible.

In all probability this is a ground loop problem.
--
Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

A couple other things that can cause hum are
cheap cable (or a cable gone bad),and speaker
cables tangled in power cables...

I disagree. You will not get audible hum from defective speaker cables.
You also will not get it from wrapping them around power cables. Defective
interconnect cables can allow noise to enter the system but the SNR on the
speaker cables -- after all of the amplification -- is so great that any
induced AC there will not be audible.

In all probability this is a ground loop problem.
--
Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

A couple other things that can cause hum are
cheap cable (or a cable gone bad),and speaker
cables tangled in power cables...

I disagree. You will not get audible hum from defective speaker cables.
You also will not get it from wrapping them around power cables. Defective
interconnect cables can allow noise to enter the system but the SNR on the
speaker cables -- after all of the amplification -- is so great that any
induced AC there will not be audible.

In all probability this is a ground loop problem.
--
Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

A couple other things that can cause hum are
cheap cable (or a cable gone bad),and speaker
cables tangled in power cables...

I disagree. You will not get audible hum from defective speaker cables.
You also will not get it from wrapping them around power cables. Defective
interconnect cables can allow noise to enter the system but the SNR on the
speaker cables -- after all of the amplification -- is so great that any
induced AC there will not be audible.

In all probability this is a ground loop problem.
--
Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================

"Robert L. Bass" said:

I disagree. You will not get audible hum from defective speaker cables.

Depends on the circuit.
There's a feedback loop in most amps from output to input, and said
input is out of phase with the source signal.
Hence, there's no attenuation from feedback for signals intruding in
the feedback loop. Because of the high open loop gain in that case,
hum and other undesired rubble may well be audible.
It can even be demodulated, in case of strong RF signals.

I've actually seen amps humming and even oscillating due to
interference that came in through the speaker outputs.

Some small caps across the outputs and gnd, as well as chokes in the
output circuit may well prevent this, shielded speaker cables may help
too.

--
Sander deWaal
Vacuum Audio Consultancy

"Robert L. Bass" said:

I disagree. You will not get audible hum from defective speaker cables.

Depends on the circuit.
There's a feedback loop in most amps from output to input, and said
input is out of phase with the source signal.
Hence, there's no attenuation from feedback for signals intruding in
the feedback loop. Because of the high open loop gain in that case,
hum and other undesired rubble may well be audible.
It can even be demodulated, in case of strong RF signals.

I've actually seen amps humming and even oscillating due to
interference that came in through the speaker outputs.

Some small caps across the outputs and gnd, as well as chokes in the
output circuit may well prevent this, shielded speaker cables may help
too.

--
Sander deWaal
Vacuum Audio Consultancy

"Robert L. Bass" said:

I disagree. You will not get audible hum from defective speaker cables.

Depends on the circuit.
There's a feedback loop in most amps from output to input, and said
input is out of phase with the source signal.
Hence, there's no attenuation from feedback for signals intruding in
the feedback loop. Because of the high open loop gain in that case,
hum and other undesired rubble may well be audible.
It can even be demodulated, in case of strong RF signals.

I've actually seen amps humming and even oscillating due to
interference that came in through the speaker outputs.

Some small caps across the outputs and gnd, as well as chokes in the
output circuit may well prevent this, shielded speaker cables may help
too.

--
Sander deWaal
Vacuum Audio Consultancy

"Robert L. Bass" said:

I disagree. You will not get audible hum from defective speaker cables.

Depends on the circuit.
There's a feedback loop in most amps from output to input, and said
input is out of phase with the source signal.
Hence, there's no attenuation from feedback for signals intruding in
the feedback loop. Because of the high open loop gain in that case,
hum and other undesired rubble may well be audible.
It can even be demodulated, in case of strong RF signals.

I've actually seen amps humming and even oscillating due to
interference that came in through the speaker outputs.

Some small caps across the outputs and gnd, as well as chokes in the
output circuit may well prevent this, shielded speaker cables may help
too.

--
Sander deWaal
Vacuum Audio Consultancy

(Brian) wrote in message . com...
Thanks to the group for all the excellent advice. I am clearly
trolling in the right waters.

This is an update on my progress: I disconnected ALL leads from the
receiver other than the subwoofer cable. I unplugged the receiver's
powercord from the AC outlet. I removed the receiver to a new room,
away from all other wires and hardware. I place the receiver in the
middle of the floor (still not plugged to AC), connected the subwoofer
and turned on the subwoofer. Hmmm? Hummm! Touching the receiver's
case slightly altered the pitch of the hum. When I plugged the
received into the same outlet as the subwoofer, the hum increased in
volume, and loudened again when I powered on the receiver.

(All: Is it possible that a ground loop is being set up between the
receiver's subwoofer output jack and the receiver's case? With a
receiver that isn't even plugged into an electrical outlet?)
(Robert B: Wish I knew how to lift the ground using an extension
cord. You all are too smart for me.)
(Troy: hope its not speaker wire interference, because the speaker
wires are 30 feet away.)
(Todd, Neil and Arny: I am using same outlet. I've removed about all
I can remove from the system, including tv cable in. What I have
configured is: electric
outlet-to-power-cord-to-subwooder-to-cable-to-receiver to an electric
cord either (a)laying on the floor or (b) plugged back into the same
outlet as the subwoofer.
(Randy: I take your meaning about the 3 light tester not being the
end-all. Beyond that, you're beyond me. But I stripped down pretty
much to my skivvies here.)
(Barry: this is more than a little hum. It overpowers the other 5
speakers, even with the gain on the subwoofer fairly low. The jack of
the receiver didn't separate, but the plug end of the connecting cable
came apart. The sheath, pin and some plastic stayed on the receiver
jack, while a small metallic clip and some more plastic stayed on the
wire. And yes, I am thinking that maybe I did damage the receiver
jack. I'm trying the eliminate other potentials before taking my
Onkyo into the shop.)

Sometimes sniffles and a cough aren't a cold. Sometimes it's an
pneumonia.

Brian

(Brian) wrote in message . com...
Thanks to the group for all the excellent advice. I am clearly
trolling in the right waters.

This is an update on my progress: I disconnected ALL leads from the
receiver other than the subwoofer cable. I unplugged the receiver's
powercord from the AC outlet. I removed the receiver to a new room,
away from all other wires and hardware. I place the receiver in the
middle of the floor (still not plugged to AC), connected the subwoofer
and turned on the subwoofer. Hmmm? Hummm! Touching the receiver's
case slightly altered the pitch of the hum. When I plugged the
received into the same outlet as the subwoofer, the hum increased in
volume, and loudened again when I powered on the receiver.

(All: Is it possible that a ground loop is being set up between the
receiver's subwoofer output jack and the receiver's case? With a
receiver that isn't even plugged into an electrical outlet?)
(Robert B: Wish I knew how to lift the ground using an extension
cord. You all are too smart for me.)
(Troy: hope its not speaker wire interference, because the speaker
wires are 30 feet away.)
(Todd, Neil and Arny: I am using same outlet. I've removed about all
I can remove from the system, including tv cable in. What I have
configured is: electric
outlet-to-power-cord-to-subwooder-to-cable-to-receiver to an electric
cord either (a)laying on the floor or (b) plugged back into the same
outlet as the subwoofer.
(Randy: I take your meaning about the 3 light tester not being the
end-all. Beyond that, you're beyond me. But I stripped down pretty
much to my skivvies here.)
(Barry: this is more than a little hum. It overpowers the other 5
speakers, even with the gain on the subwoofer fairly low. The jack of
the receiver didn't separate, but the plug end of the connecting cable
came apart. The sheath, pin and some plastic stayed on the receiver
jack, while a small metallic clip and some more plastic stayed on the
wire. And yes, I am thinking that maybe I did damage the receiver
jack. I'm trying the eliminate other potentials before taking my
Onkyo into the shop.)

Sometimes sniffles and a cough aren't a cold. Sometimes it's an
pneumonia.

Brian

(Brian) wrote in message . com...
Thanks to the group for all the excellent advice. I am clearly
trolling in the right waters.

This is an update on my progress: I disconnected ALL leads from the
receiver other than the subwoofer cable. I unplugged the receiver's
powercord from the AC outlet. I removed the receiver to a new room,
away from all other wires and hardware. I place the receiver in the
middle of the floor (still not plugged to AC), connected the subwoofer
and turned on the subwoofer. Hmmm? Hummm! Touching the receiver's
case slightly altered the pitch of the hum. When I plugged the
received into the same outlet as the subwoofer, the hum increased in
volume, and loudened again when I powered on the receiver.

(All: Is it possible that a ground loop is being set up between the
receiver's subwoofer output jack and the receiver's case? With a
receiver that isn't even plugged into an electrical outlet?)
(Robert B: Wish I knew how to lift the ground using an extension
cord. You all are too smart for me.)
(Troy: hope its not speaker wire interference, because the speaker
wires are 30 feet away.)
(Todd, Neil and Arny: I am using same outlet. I've removed about all
I can remove from the system, including tv cable in. What I have
configured is: electric
outlet-to-power-cord-to-subwooder-to-cable-to-receiver to an electric
cord either (a)laying on the floor or (b) plugged back into the same
outlet as the subwoofer.
(Randy: I take your meaning about the 3 light tester not being the
end-all. Beyond that, you're beyond me. But I stripped down pretty
much to my skivvies here.)
(Barry: this is more than a little hum. It overpowers the other 5
speakers, even with the gain on the subwoofer fairly low. The jack of
the receiver didn't separate, but the plug end of the connecting cable
came apart. The sheath, pin and some plastic stayed on the receiver
jack, while a small metallic clip and some more plastic stayed on the
wire. And yes, I am thinking that maybe I did damage the receiver
jack. I'm trying the eliminate other potentials before taking my
Onkyo into the shop.)

Sometimes sniffles and a cough aren't a cold. Sometimes it's an
pneumonia.

Brian