ground-loop problems

[William Sommerwerck]

This posting isn't intended to provoke hundreds of responses. Rather, I'm
looking for insights I've missed, that might be of use to both me and
others.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio signal
to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but didn't
reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder box
through an HDMI cable. Disconnecting the decoder from AC, and the HDMI from
the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check the
buzz level, the buzz comes in abruptly at one point. Then, to get rid of the
hum, you have to turn the volume well below that point. This might be a
psychoacoustic illusion, but I doubt it. It seems more like some weird sort
of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the buzz
is to disconnect the HDMI cable that connects the Blu-ray player to the
Pioneer plasma. Of course, you can't do that when watching Blu-ray movies!

It would be nice if I could simply leave everything connected all the time.
I've thought of connecting the plasma's AC to the main audio system's power
outlet with a very heavy (12ga) cord. But I'm not sure I want to add 400+
watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm drawing
less than 300 watts, so there's "room".

 

[msg]

William Sommerwerck wrote:


<audio buzzing description snipped>

I would like to read opinions on how to work around protective ground
electrical codes which in my opinion are a bane to proper RFI and
EMI suppression. I have needed to provide separate grounds (copper
rods in soil close to the power and RF connections) for various receivers,
audio systems, and instruments and have disconnected bypass capacitors
inside the chassis(s) that were connected to the protective ground
(third wire). In my experience, with so many smps and other switch
mode devices on common AC circuits, the third wire is a noisy, un-
redeemable nuisance, and is best eschewed for proper grounding
schemes, but this often defies the electrical codes. Fortunately
for me, I have located much of the sensitive gear in outbuildings
that are not part of the common protective grounding requirement, and
use proper grounding methods to reduce noise. In instances where the
AC third wire ground is directly connected to the metal chassis, the
only remedy has been to remove it and ground the device to a better
ground and where possible, connect its satellite devices to the same
ground or one nearby (in moist, highly conductive soil) to avoid
serious ground loops. Sometimes, it is necessary to use heavy copper
strap between ground rods.

If you have double insulated devices with only two-wire AC connections,
then you are free to engineer a proper grounding system to prevent
interference; perhaps using isolation transformers, in steel cases that
are third-wire grounded, and disconnecting all downstream grounds from
the third wire is worth a shot and still complies with codes (be sure
that there are no bypass capacitors connected to the third wire).

Michael

 

[Jeff Liebermann]

On Sun, 7 Jun 2009 12:31:18 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

I'm
looking for insights I've missed, that might be of use to both me and
others.

One must suffer before enlightenment.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio signal
to mask them.

Buzz or hum? Measure the frequency. If you don't have any test
equipment, use a PC software oscilloscope. I suggest:
<http://www.sillanumsoft.org/prod01.htm>
If it's 60 or 120Hz, you might really have a ground loop. However, if
it's some other frequency, then you might be picking up junk from some
other source, such as a switching power supply, CCFL inverter, wall
wart, or something similar.

I had a nasty buzz in my hi-fi stack that turned out to be the
switching supply in my cheapo DVD player, coupling to the FM tuner
through the plastic case (no shielding). I also fixed a low level
buzz problem on my MIDI synthesizer when I replaced a switcher type
wall wart, with a linear power supply. Later, I found that the power
filtering in the synthesizer was inadequate.

Most home electronics get their case ground to the green (ground) wire
of the 117VAC plug. If your home wiring system does not have a proper
common (green) ground, then this line will have some 60Hz noise on it.
By connecting the hi-fi to 2 seperate AC lines, you might be creating
such a condition. Try everything on one AC line and see if fixes the
problem. If it does, check your outlet and house wiring.

A really sloppy way to find the buzz source is to take an unterminated
phono cable connected to a high gain Mic input, and save it around
your equipment stack. If the noise source is radiating junk, the tiny
end of the phono cable should pickup something.

I suggest that you:
1. Identify the buzz/hum characteristics.
2. Play with the grounds.
3. Attempt to identify the source.
4. Disconnect cables and boxes until the buzz goes away. (Diagnosis
by substitution and elimination).
5. Sniff for a possible source.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Charles]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:h0h4is$crr$1@news.eternal-september.org...

Sometimes it is instructive to "unground" a shielded audio cable at one end.

 

[Dave Plowman (News)]

In article <h0h4is$crr$1@news.eternal-september.org>, William Sommerwerck
<grizzledgeezer@comcast.net> wrote:

This posting isn't intended to provoke hundreds of responses. Rather,
I'm looking for insights I've missed, that might be of use to both me
and others.

Everything in my main audio system _except_ the power amps are on the
same circuit. This hasn't caused problems, because the audio connections
to the power amps are balanced.

Good grief. ;-) A bit OTT for the sort of runs involved in domestic
situations.

When I added a Sony BDP-550 Blu-ray player to the audio system (its
analog audio outputs feeding a Parasound C2 controller), plus a Pioneer
plasma TV on another AC circuit (or at least an outlet some distance
away), I started hearing a buzz in the speakers at "ordinary" gain
levels. It was particularly noticeable in the rear speakers when there
was no audio signal to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but
didn't reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder
box through an HDMI cable. Disconnecting the decoder from AC, and the
HDMI from the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check
the buzz level, the buzz comes in abruptly at one point. Then, to get
rid of the hum, you have to turn the volume well below that point. This
might be a psychoacoustic illusion, but I doubt it. It seems more like
some weird sort of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the
buzz is to disconnect the HDMI cable that connects the Blu-ray player to
the Pioneer plasma. Of course, you can't do that when watching Blu-ray
movies!

It would be nice if I could simply leave everything connected all the
time. I've thought of connecting the plasma's AC to the main audio
system's power outlet with a very heavy (12ga) cord. But I'm not sure I
want to add 400+ watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm
drawing less than 300 watts, so there's "room".

I'm not sure about how the US does things mains wise - but in the UK
pretty all equipment has an isolating transformer in the PS and is double
insulated so no safety ground is needed - apart on usually the main amp or
AV centre. So the only ground audio path is via the screen on the
interconnect. Which should prevent any earth loops.
However, I well remember some Japanese 'separates' where they did have
(obviously at that time) transformers in the PS but also had all the cases
earthed via the power cord - and that ground was the same as the audio
one. Plug it all up using the supplied leads and you got earth loop hum...

However, if you've tried a proper mains isolating transformer, an earth
loop is unlikely.

--
*Don't byte off more than you can view *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[CJT]

hr(bob) hofmann@att.net wrote:
<snip>

Have you tried putting everything on the same isolation transformer
and running everything on long extension cords from the isolation
transformer to the individual units. That way, you have eliminated
ground loops.
snip

Huh? That does not necessarily eliminate ground loops
(except perhaps in an ideal world). The devil is in the
details (e.g. bypass capacitors, inter-device connections
and their associated shields, downstream power strips,
cable TV connections, etc.). Every system must be considered
on its own merits.

--
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.

 

[hr(bob) hofmann@att.net]

On Jun 7, 2:31 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

This posting isn't intended to provoke hundreds of responses. Rather, I'm
looking for insights I've missed, that might be of use to both me and
others.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio signal
to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but didn't
reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder box
through an HDMI cable. Disconnecting the decoder from AC, and the HDMI from
the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check the
buzz level, the buzz comes in abruptly at one point. Then, to get rid of the
hum, you have to turn the volume well below that point. This might be a
psychoacoustic illusion, but I doubt it. It seems more like some weird sort
of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the buzz
is to disconnect the HDMI cable that connects the Blu-ray player to the
Pioneer plasma. Of course, you can't do that when watching Blu-ray movies!

It would be nice if I could simply leave everything connected all the time.
I've thought of connecting the plasma's AC to the main audio system's power
outlet with a very heavy (12ga) cord. But I'm not sure I want to add 400+
watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm drawing
less than 300 watts, so there's "room".

Have you tried putting everything on the same isolation transformer
and running everything on long extension cords from the isolation
transformer to the individual units. That way, you have eliminated
ground loops. Then if that works ok, try bypassing the isolation
transformer and run everything from the outlet the isolation
transformer was plugged into, T way the ground loops still cannot
occur, but you are pluggged into the house wiring. Then start moving
things back into their normal mode and see if it is the blu-ray or
maybe something else. Then play detective.

 

On Jun 7, 12:31 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

This posting isn't intended to provoke hundreds of responses. Rather, I'm
looking for insights I've missed, that might be of use to both me and
others.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio signal
to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but didn't
reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder box
through an HDMI cable. Disconnecting the decoder from AC, and the HDMI from
the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check the
buzz level, the buzz comes in abruptly at one point. Then, to get rid of the
hum, you have to turn the volume well below that point. This might be a
psychoacoustic illusion, but I doubt it. It seems more like some weird sort
of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the buzz
is to disconnect the HDMI cable that connects the Blu-ray player to the
Pioneer plasma. Of course, you can't do that when watching Blu-ray movies!

It would be nice if I could simply leave everything connected all the time.
I've thought of connecting the plasma's AC to the main audio system's power
outlet with a very heavy (12ga) cord. But I'm not sure I want to add 400+
watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm drawing
less than 300 watts, so there's "room".

I ran into an audio hum problem but in my case it was 2 computers (1
to the TV) with antenna connection being the culprit. I also needed a
'float' on the cable feed. Here is what fixed it.

http://www.rmscommunications.net/pdf/MI2120VPG69&70.pdf

I bought 2 of those at $5 a pop. Money well spent.

G˛

 

[Trevor Wilson]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:h0h4is$crr$1@news.eternal-september.org...

This posting isn't intended to provoke hundreds of responses. Rather, I'm
looking for insights I've missed, that might be of use to both me and
others.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I
started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio
signal
to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but
didn't
reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder box
through an HDMI cable. Disconnecting the decoder from AC, and the HDMI
from
the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check
the
buzz level, the buzz comes in abruptly at one point. Then, to get rid of
the
hum, you have to turn the volume well below that point. This might be a
psychoacoustic illusion, but I doubt it. It seems more like some weird
sort
of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the
buzz
is to disconnect the HDMI cable that connects the Blu-ray player to the
Pioneer plasma. Of course, you can't do that when watching Blu-ray movies!

It would be nice if I could simply leave everything connected all the
time.
I've thought of connecting the plasma's AC to the main audio system's
power
outlet with a very heavy (12ga) cord. But I'm not sure I want to add 400+
watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm
drawing
less than 300 watts, so there's "room".

**Disconnect the antenna/cable connection from the system. That should do
the trick. If it does, you need an isolator for the antenna/cable system.


--
Trevor Wilson
www.rageaudio.com.au

 

[Blarp]

On Sun, 7 Jun 2009 12:31:18 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

It's worth noting that, as you turn up the controller's volume to check the
buzz level, the buzz comes in abruptly at one point

Apart from other good suggestions - if the buzzing sets in abruptly
and shows hysteresis, I would suspect oscillation on above hearing
frequencies. The loaded power supply would provide the hum (which is
normally masked by very loud sound from the speakers).



--
- Blarp the Enigmatic

 

[Meat Plow]

On Sun, 7 Jun 2009 12:31:18 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net>wrote:

This posting isn't intended to provoke hundreds of responses. Rather, I'm
looking for insights I've missed, that might be of use to both me and
others.

Everything in my main audio system _except_ the power amps are on the same
circuit. This hasn't caused problems, because the audio connections to the
power amps are balanced.

When I added a Sony BDP-550 Blu-ray player to the audio system (its analog
audio outputs feeding a Parasound C2 controller), plus a Pioneer plasma TV
on another AC circuit (or at least an outlet some distance away), I started
hearing a buzz in the speakers at "ordinary" gain levels. It was
particularly noticeable in the rear speakers when there was no audio signal
to mask them.

The first thing I did was to put the Blu-ray player on an isolation
transformer (that just happened to be lying around). That helped, but didn't
reduce the buzz as much as I would have liked.

For cable reception, the Pioneer plasma is fed from a Motorola decoder box
through an HDMI cable. Disconnecting the decoder from AC, and the HDMI from
the Pioneer plasma further reduces the buzz.

It's worth noting that, as you turn up the controller's volume to check the
buzz level, the buzz comes in abruptly at one point. Then, to get rid of the
hum, you have to turn the volume well below that point. This might be a
psychoacoustic illusion, but I doubt it. It seems more like some weird sort
of hysteresis. Is it a symptom that points to a cause?

It should come as no surprise that the only way to really suppress the buzz
is to disconnect the HDMI cable that connects the Blu-ray player to the
Pioneer plasma. Of course, you can't do that when watching Blu-ray movies!

It would be nice if I could simply leave everything connected all the time.
I've thought of connecting the plasma's AC to the main audio system's power
outlet with a very heavy (12ga) cord. But I'm not sure I want to add 400+
watts load to that outlet. *

Thoughts, please. Thank you.

* Even with the controller and several other components running, I'm drawing
less than 300 watts, so there's "room".

I take it the Blue device doesn't have component out that you could
try instead of HDMI?

 

[William Sommerwerck]

I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.

 

[bg]

William Sommerwerck wrote in message ...

I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.


Keep in mind that your balanced amps will not be balanced unless whatever

drives them has balanced outputs.
Your cable TV is a common culprit for introducing hum, etc. Use a 75 ohm to
75 ohm transformer or back to back 75 to 300 ohm matching transformers if
the cable is adding hum when connected.
For your unbalanced audio, a ground loop forms when current flows from one
chassis to another chassis through the shield of your cable.
You can use line level audio isolation transformers in those connections
which will break the chassis to chassis connection. This will eliminate the
need for swapping grounds or isolation transformers at the power side of
things.
Another option is to connect a heavy gauge ground strap from chassis to
chassis in a star grounding scheme. The ground strap will hopefully provide
a lower resistance path for the chassis to chassis ground currents rather
than through the shields. This can work and is cheaper than converting to
balanced, or using audio isolation transformers.

 

[AZ Nomad]

On Tue, 9 Jun 2009 12:44:48 -0600, bg <bg@nospam.com> wrote:

William Sommerwerck wrote in message ...
I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.


Keep in mind that your balanced amps will not be balanced unless whatever
drives them has balanced outputs.
Your cable TV is a common culprit for introducing hum, etc. Use a 75 ohm to
75 ohm transformer or back to back 75 to 300 ohm matching transformers if
the cable is adding hum when connected.

Keep in mind that most 'matching transformers' are autotransformers
and supply no isolation.

 

[bg]

AZ Nomad wrote in message ...

On Tue, 9 Jun 2009 12:44:48 -0600, bg <bg@nospam.com> wrote:

William Sommerwerck wrote in message ...
I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.


Keep in mind that your balanced amps will not be balanced unless whatever
drives them has balanced outputs.
Your cable TV is a common culprit for introducing hum, etc. Use a 75 ohm
to
75 ohm transformer or back to back 75 to 300 ohm matching transformers if
the cable is adding hum when connected.

Keep in mind that most 'matching transformers' are autotransformers
and supply no isolation.


Good point, I forgot about that!

bg

 

[William Sommerwerck]

Keep in mind that your balanced amps will not be balanced unless
whatever drives them has balanced outputs.

<extreme sarcasm>Gee. I never knew.</extreme sarcasm> The amps and the
controller are from the same company, and the balanced outputs of the
controller feeds the power amps.

Your cable TV is a common culprit for introducing hum, etc. Use a 75 ohm
to
75 ohm transformer or back to back 75 to 300 ohm matching transformers if
the cable is adding hum when connected.

I am aware of this. I discovered it by myself 25 years ago.

 

[AZ Nomad]

On Tue, 9 Jun 2009 13:08:50 -0600, bg <bg@nospam.com> wrote:

AZ Nomad wrote in message ...
On Tue, 9 Jun 2009 12:44:48 -0600, bg <bg@nospam.com> wrote:

William Sommerwerck wrote in message ...
I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.


Keep in mind that your balanced amps will not be balanced unless whatever
drives them has balanced outputs.
Your cable TV is a common culprit for introducing hum, etc. Use a 75 ohm
to
75 ohm transformer or back to back 75 to 300 ohm matching transformers if
the cable is adding hum when connected.

Keep in mind that most 'matching transformers' are autotransformers
and supply no isolation.


Good point, I forgot about that!

I've had good luck with jensen isolators. However I just now went
to look them up and see the price is now $49. Too damn high. I
had remembered paying too much, but it was around $25-30.

 

[Meat Plow]

On Tue, 9 Jun 2009 08:48:55 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net>wrote:

I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did, I'd
still have a common ground, would I not?

This is not a major problem, just an irritation.

It supports 1080p why else would it be there.

 

[William Sommerwerck]

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2snkbb.hfl.17.4@news.alt.net...

On Tue, 9 Jun 2009 08:48:55 -0700, "William Sommerwerck"
grizzledgeezer@comcast.net>wrote:

I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did,
I'd still have a common ground, would I not?

It supports 1080p, why else would it be there?

Because not everyone with a Blu-ray player necessarily has an HD set with
HDMI. By that reasoning, Blu-ray players should have only HDMI outputs. They
don't. They have a variety of outputs, to support varying resolutions and
"connectivity".

The component outputs on my Sony BDP-S550 DO NOT support 1080p.

http://www.sonystyle.com/wcsstore/SonyStyleStorefrontAssetStore/pdf/BDPS550_OM.pdf

They support 480p, 480i, 720p, 1080i. No higher. (See page 14.)

 

[Meat Plow]

On Thu, 11 Jun 2009 07:14:41 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net>wrote:

"Meat Plow" <meat@petitmorte.net> wrote in message
news:2snkbb.hfl.17.4@news.alt.net...
On Tue, 9 Jun 2009 08:48:55 -0700, "William Sommerwerck"
grizzledgeezer@comcast.net>wrote:

I take it the Blue device doesn't have a component out
that you could try instead of HDMI?

It does, but... I don't think it supports 1080p. And even if it did,
I'd still have a common ground, would I not?

It supports 1080p, why else would it be there?


Because not everyone with a Blu-ray player necessarily has an HD set with
HDMI. By that reasoning, Blu-ray players should have only HDMI outputs. They
don't. They have a variety of outputs, to support varying resolutions and
"connectivity".

The component outputs on my Sony BDP-S550 DO NOT support 1080p.

http://www.sonystyle.com/wcsstore/SonyStyleStorefrontAssetStore/pdf/BDPS550_OM.pdf

They support 480p, 480i, 720p, 1080i. No higher. (See page 14.)

Ok then give it a try in 1080i and see if you still have the loop.