Consensus on ferrite cores? - AVS Forum
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post #1 of 14 Old 08-28-2014, 05:31 PM - Thread Starter
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Consensus on ferrite cores?

After doing some research on ferrite cores to HDMI, power cables, audio cables etc? I've read that they'll help reduce interference to them degrading picture quality. I currently have one attached to the HDMI cable that is connected to my Blu-ray player and some for the power cable to my receiver. From what I understand is that ferrite cores should help clear up the picture in a sense by reducing the slight noise that may be present on the screen caused by RF waves. Has anyone here dealt with ferrite cores long enough to get a better idea of how they might help? I suppose if it does help, even slightly, I'll pick up a few more as they are quite inexpensive.
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post #2 of 14 Old 08-28-2014, 08:19 PM
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Snake oil. Especially on an HDMI cable. Their most practical application is to keep the signals that are in the cable from 'leaking' out and causing interference with things like transistor radios.
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post #3 of 14 Old 08-29-2014, 08:54 AM
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Digital signal is either there or not. It is not like Analog, where it could be there, partially there, sometimes there, or not there at all.

Ferrite cores for digital are no different than muffler bearings and halogen blinker fluid that a car shop may offer for sale.

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #4 of 14 Old 08-29-2014, 11:39 AM
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Quote:
Originally Posted by blueiedgod View Post
Ferrite cores for digital are no different than muffler bearings and halogen blinker fluid that a car shop may offer for sale.
Depends on the weight of the fluid.

CIAO!

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post #5 of 14 Old 09-08-2014, 05:28 AM
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Ferrite cores are used to absorb Radio-Frequency noise that is flowing on the outside of the cable (usually the shield).
They are made of different mixes of metal powders, and are selected by the general frequency "band" that the interference is in.
They can be handy when you are getting interference from an outside source, such as a radio transmitter, which can flow in to the particular piece of equipment.
They are also handy to stop RF Interference from radiating out of a cable, or the attached equipment, getting in to an antenna of a receiver.

I wish they were more universally required ("permanently attached") on cables that are used in A/V equipment and computer stuff. The Noise Floor is getting way too high nowadays.

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post #6 of 14 Old 09-08-2014, 10:51 AM
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Quote:
Originally Posted by kenglish View Post
Ferrite cores are used to absorb Radio-Frequency noise that is flowing on the outside of the cable (usually the shield).
They are made of different mixes of metal powders, and are selected by the general frequency "band" that the interference is in.
They can be handy when you are getting interference from an outside source, such as a radio transmitter, which can flow in to the particular piece of equipment.
They are also handy to stop RF Interference from radiating out of a cable, or the attached equipment, getting in to an antenna of a receiver.

I wish they were more universally required ("permanently attached") on cables that are used in A/V equipment and computer stuff. The Noise Floor is getting way too high nowadays.

Is RF interference prevalent in digital transmission over copper?

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #7 of 14 Old 09-10-2014, 06:18 AM
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RFI can radiate from cables that are carrying digital signals, and RFI can also get in to cables carrying digital....the RFI can "blur" the waveform (eye-pattern) of a Digital signal, although the effects may not be noted except on weak signals.
Worst, though, is what radiates out from the cables, which can interfere with TV, Radio, and other wireless devices. It's that ever-increasing "noise-floor" thing.

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post #8 of 14 Old 09-10-2014, 09:51 AM
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Quote:
Originally Posted by kenglish View Post
RFI can radiate from cables that are carrying digital signals, and RFI can also get in to cables carrying digital....the RFI can "blur" the waveform (eye-pattern) of a Digital signal, although the effects may not be noted except on weak signals.
Worst, though, is what radiates out from the cables, which can interfere with TV, Radio, and other wireless devices. It's that ever-increasing "noise-floor" thing.
Wouldn't shielding take care of that?

I am thinking in terms of HDMI cables. They are supposed to be made of 4 twisted pairs and shielded.

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #9 of 14 Old 09-10-2014, 11:46 AM
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Here's my thought:
If the cable(s) you purchased have ferrite chokes. Super. Won't hurt.
Do you need to use them? Probably not.
Do you have a problem? It's probably due to something other than the lack of ferrite chokes.
If you want to purchase them to add to other cables, use them if it helps you to sleep at night. It won't hurt (nor probably help) and they are inexpensive.

I have a bag full in my basement "box o' junk".

In a commercial environment, they may be needed. In a home environment, it's a non-issue IMHO.
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post #10 of 14 Old 09-15-2014, 06:56 AM
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Depends on whether you (and your neighbors) want to listen to radio, or watch OTA TV on certain channels .
Shielding, if it is continuous and well designed, works. Problem is, if the noise gets out of the "box" and on to the outside of the shield, then that shielded cable can act like a long-wire antenna.
That often happens where there is a crack or a small hole in the enclosure.
Worst offenders, though, are power supplies and computer-gizmos. They make a huge racket.
Plasma TV sets cause lots of noise, too.....often from their power supply circuits, and radiation from the screen.

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post #11 of 14 Old 09-15-2014, 09:10 AM
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Well, the next time I hear radio over my TV, I'll pass out ferrite cores to my neighbors.

As I said... in a residential environment, it's not usually necessary. If you have a problem with ingress, then perhaps some ferrite may be beneficial. If my neighbors experience radio problems, it's going to be tough for them to identify the problematic cable/egress from my home. Even if it's not from my home, I'll provide them to my neighbor(s) for free from the bag 'o crap in my basement.

IMO, if they were that beneficial, every cable, wire, power cord sold would have/provide one. And some vendors would be selling them at a 1000% profit margin, because their ferrite would be superior due a special manufacturing process.
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post #12 of 14 Old 09-16-2014, 06:45 AM
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I wish the FCC would require them on everything. Maybe it will happen one day.
Probably won't happen until it interferes with the precious cell-phones, though.

Ken English, Sr. Engineer, KSL-TV.
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post #13 of 14 Old 10-24-2014, 01:47 AM
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I don't think suppose too wrap hdmi cable through ferrite core as it bends hdmi cable too much and damages it.So the ferrite cores they give you with a new tv are probably meant too go on the power cord,but I'm guessing this.
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post #14 of 14 Old 10-24-2014, 08:12 PM
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There was another thread(s) on this very exact same subject. ...I don't remember where it went exactly.
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