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Ultimate HDMI Cable Noise Test

Hello,

In this HDMI cable noise test the following was done:

PC connected to power box. Monitor connected to same power box. Receiver connected to same power box.

Powerbox connected to wall socket (no earth grounding/wire)

PC Monitor PC Keyboard PC Mouse PC Receiver Receiver Speakers

Everything else disconnected.

The test was recorded on video/audio and placed on youtube:

HDMI cable noise test video:

formatting link

During this test a very clear NOISE signal can be heard coming from the HDM I cable when the PC is ON.

When the PC is OFF and/or disconnected there is no NOISE signal.

I think this video is very clear evidence that there is some kind of NOISE signal being transmitted across this HDMI cable.

Perhaps friday I may repeat this test with a high quality/expensive HDMI ca ble to see if it makes any difference. (If the other person agrees to provi de this cable).

What is the source and why is there noise ?

I think it might be the excessive voltage/power being dumped on the chasis by the PC's power supply since it's not grounded and entering the HDMI cabl e connectors/plugs.

Let me know your thoughts, do you still believe it's a ground loop ?

Do you still believe HDMI cables are not capable of transmitting noise ? ;)

Also an analog cable noise test was done as well, different kind of humming noise, but also coming from PC.

Analog cable noise test video:

formatting link

One question could be: Why is the humming different for analog ? My hunch i s it's the receiver's analog inputs, it's being noise-filtered or so, but a pperently it does not do the same for HDMI. Perhaps an oversight in the DEN ON manufacturer's design, believing HDMI does not transmit noise, just spec ulation though, it could also be the Creative X-Fi Elite Pro 7.1 soundblast er filtering out these signals before transmission over analog cables.

Bye, Skybuck.

Reply to
skybuck2000
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On Wednesday, December 19, 2018 at 6:04:18 PM UTC+1, snipped-for-privacy@hotmail.com w rote:

DMI cable when the PC is ON.

E signal being transmitted across this HDMI cable.

cable to see if it makes any difference. (If the other person agrees to pro vide this cable).

s by the PC's power supply since it's not grounded and entering the HDMI ca ble connectors/plugs.

;)

ng noise, but also coming from PC.

is it's the receiver's analog inputs, it's being noise-filtered or so, but apperently it does not do the same for HDMI. Perhaps an oversight in the D ENON manufacturer's design, believing HDMI does not transmit noise, just sp eculation though, it could also be the Creative X-Fi Elite Pro 7.1 soundbla ster filtering out these signals before transmission over analog cables.

Somebody on another newsgroup mentioned "pin 1 problem".

What you electronics guys think of the "pin 1 problem".

Try googling that.

Bye for now, Skybuck.

Reply to
skybuck2000

The "pin 1 problem" relates to a completely different technology which is analogue audio transmitted over shielded twisted-pair cables using 3-pin XLR connectors. Pin 1 is the cable shield connection in XLR connectors.

The idea behind it (when adapted to HDMI) is that if a large current is flowing in the cable shield this will cause a voltage drop in the internal wiring of the connected devices, depending on how the shield is grounded internally. If that voltage drop occurs within the audio signal path after digital to analogue conversion then it could be audible.

However, you are powering everything from a single power distribution block, so large ground currents seem unlikely. The most likely source of ground currents is the leakage capacitances of the various power supplies. Leakage of radio frequency noise from switching power supplies is a possibility, as this could be demodulated by non-linearities of components in the analogue circuits inside your equipment.

There are certain things you could try:

1) Connect the chassis of each item of equipment to all the others with a short thick wire. This would cause some of the unwanted current (if any) to flow by a different route. 2) Use an HDMI cable with a lump. This is a ferrite absorber which will reduce the amount of radio frequency current flowing in the HDMI cable shield.

John

Reply to
jrwalliker

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