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Re: What Are the Cylyndrical Objects You Often See on Audio, USB, etc, Cables?
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petrus bitbyter
Nov 9, 2011, 10:43:41 AM11/9/11
to
"Nelson" <nel...@nowhere.com> schreef in bericht
news:0001HW.CAE0073A...@news.astraweb.com...
> What are those cylindrical objects you often see surrounding the cable
> on USB, Audio, Firewire, etc cables? I am assuming they are some kind
> of passive RF interference filter. How do they work? How effective are
> they?
>
> I am having trouble with interference with an audio cable connected
> from a computer to a TV and was wondering if a cable with one of these
> doo-dads would be worth the $.
>
> --
> Nelson
>
They are ferrites and used for RF suppression. You can buy types that can be
clamped on existing cables and they usually are effective. Nor that
expensive too so it's worthwhile to give it a try.
petrus bitbyter
Jeffrey Angus
Nov 9, 2011, 10:44:02 AM11/9/11
to
On 11/9/2011 9:32 AM, Nelson wrote:
> What are those cylindrical objects you often see surrounding the cable
> on USB, Audio, Firewire, etc cables? I am assuming they are some kind
> of passive RF interference filter. How do they work? How effective are
> they?
>
> I am having trouble with interference with an audio cable connected
> from a computer to a TV and was wondering if a cable with one of these
> doo-dads would be worth the $.
>
Ferrite cores
> What are those cylindrical objects you often see surrounding the cable
> on USB, Audio, Firewire, etc cables? I am assuming they are some kind
> of passive RF interference filter. How do they work? How effective are
> they?
>
> I am having trouble with interference with an audio cable connected
> from a computer to a TV and was wondering if a cable with one of these
> doo-dads would be worth the $.
>
Jeff
--
"Everything from Crackers to Coffins"
Jeff Liebermann
Nov 9, 2011, 12:10:06 PM11/9/11
to
On Wed, 9 Nov 2011 10:32:26 -0500, Nelson <nel...@nowhere.com> wrote:
>What are those cylindrical objects you often see surrounding the cable
>on USB, Audio, Firewire, etc cables?
Regulatory repellents. They're attached by the manufacturer to keep
>What are those cylindrical objects you often see surrounding the cable
>on USB, Audio, Firewire, etc cables?
the FCC off their back by limiting the amount of RFI/EMI sprayed by
their equipment.
>I am assuming they are some kind
>of passive RF interference filter.
of powdered oxidized iron.
>How do they work?
Quite well. If an FCC Enforcement Burro inspector approached, all one
needs to do is wave the lumpy cable at the inspector, and he will
vanish into a smog of legalese.
>How effective are they?
100% successful. I haven't seen an FCC inspector for many years.
>I am having trouble with interference with an audio cable connected
>from a computer to a TV and was wondering if a cable with one of these
>doo-dads would be worth the $.
accomplish, so I guess I'll have to provide a reasonable answer.
I assume the computah generated interference is trashing the picture
on the TV or is being heard on the TV audio. What channel is the TV
watching? If it's channel 3/4 from some kind of set top box, you
might find it more useful to simply avoid the RF problem and rewire
your TV setup to use a non-RF input. HDMI, DVI, component video,
S-video, and component video inputs should all be present on the back
of your unspecified model TV.
If you're only using the TV for computer audio, you could also
eliminate the problem by purchasing a set of "computah speakers" for
about $30. The speakers inside most TV's are fairly disgusting.
If none of these alternatives seem useful, you can purchase clamp on
ferrite filters.
<http://www.delevan.com/web/PDF/Suppressors/Cable/BFseries/Page%20118_120_BF.pdf>
Radio Shock carries some:
<http://www.radioshack.com/product/index.jsp?productId=3012599>
<http://www.radioshack.com/product/index.jsp?productId=2103222>
or you can just cannibalize the ferrite beads off an old cable. For
audio, just about anything will work. Bigger is better and running
multiple turns through the core is even better:
<http://www.stevelarkins.freeuk.com/computer_interference.htm>
Gotta run... good luck.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
hrho...@att.net
Nov 9, 2011, 5:02:18 PM11/9/11
to
> Radio Shock carries some:
> <http://www.radioshack.com/product/index.jsp?productId=3012599>
> <http://www.radioshack.com/product/index.jsp?productId=2103222>
> or you can just cannibalize the ferrite beads off an old cable. For
> audio, just about anything will work. Bigger is better and running
> multiple turns through the core is even better:
> <http://www.stevelarkins.freeuk.com/computer_interference.htm>
>
> Gotta run... good luck.
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> <http://www.radioshack.com/product/index.jsp?productId=3012599>
> <http://www.radioshack.com/product/index.jsp?productId=2103222>
> or you can just cannibalize the ferrite beads off an old cable. For
> audio, just about anything will work. Bigger is better and running
> multiple turns through the core is even better:
> <http://www.stevelarkins.freeuk.com/computer_interference.htm>
>
> Gotta run... good luck.
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Skype: JeffLiebermann AE6KS 831-336-2558
Do what Jeff says. As past predident of the IEEE EMC Society, I have
used many ferrite beads to reduce interference levels to meet FCC
requirements. There are cylidrical beads for round cables and flat
beads for ribbon cables. If you scrap almost any piece of electronic
equipment, you can scrounge a ferrite bead or several.
But, there are different compositions of ferrite to cover the whole
frequency band, so the first bead you try might not be the one you
need. If you told us a little bit more about what your setup is and
what the interference is and where and what you turn off to clear the
problem, we might be able to give you a lot more help
Message has been deleted
Jeff Liebermann
Nov 11, 2011, 11:37:37 AM11/11/11
to
On Fri, 11 Nov 2011 05:01:44 -0500, Nelson <nel...@nowhere.com> wrote:
>I have a MacBook Pro set up as an entertainment center feeding an
>analog TV. Video is out of the mini-display port through an S-Video
>adapter. Audio is out of the headphone port into the RCA audio-in on
>the TV. There is a constant hiss which modulates with screen changes.
<http://www.htmblog.com/2010/01/macbook-pro-audio-hissing-in-sound-card.html>
>Since I don't hear the hiss if I just connect earphones to the port, my
>assumption is that it is RF pickup from the S-Video cable or the TV
>being fed back through the audio cable. If any of my classes ever
>covered RF interference, I must have slept through them :-)
Fix your earphones. I've heard the hiss on several Macbooks.
>I posted this problem here a while back. One suggestion was to buy a
>usb or firewire sound adapter... but my insurance premium is due :-)
I remember. Same problem, same suggestion. The MacBook audio output
is noisy. Ferrites are not going to fix it.
As for the cost, is $1.30 too much for you?
<http://www.ebay.com/itm/360385369541>
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
>I have a MacBook Pro set up as an entertainment center feeding an
>analog TV. Video is out of the mini-display port through an S-Video
>adapter. Audio is out of the headphone port into the RCA audio-in on
>the TV. There is a constant hiss which modulates with screen changes.
<http://www.htmblog.com/2010/01/macbook-pro-audio-hissing-in-sound-card.html>
>Since I don't hear the hiss if I just connect earphones to the port, my
>assumption is that it is RF pickup from the S-Video cable or the TV
>being fed back through the audio cable. If any of my classes ever
>covered RF interference, I must have slept through them :-)
Fix your earphones. I've heard the hiss on several Macbooks.
>I posted this problem here a while back. One suggestion was to buy a
>usb or firewire sound adapter... but my insurance premium is due :-)
I remember. Same problem, same suggestion. The MacBook audio output
is noisy. Ferrites are not going to fix it.
As for the cost, is $1.30 too much for you?
<http://www.ebay.com/itm/360385369541>
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann
Nov 11, 2011, 11:46:45 AM11/11/11
to
On Fri, 11 Nov 2011 08:37:37 -0800, Jeff Liebermann <je...@cruzio.com>
wrote:
><http://www.htmblog.com/2010/01/macbook-pro-audio-hissing-in-sound-card.html>
More on the hiss problem.
<http://forums.macrumors.com/showthread.php?p=13200418>
My guess(tm) is some manner of internal grounding problem. The his is
probably coming from processor switching noise, some of which is going
through the audio circuitry. Ferrites are not going to fix that.
Spend the $1.30 and get an external USB or firewire sound thing.
wrote:
><http://www.htmblog.com/2010/01/macbook-pro-audio-hissing-in-sound-card.html>
More on the hiss problem.
<http://forums.macrumors.com/showthread.php?p=13200418>
My guess(tm) is some manner of internal grounding problem. The his is
probably coming from processor switching noise, some of which is going
through the audio circuitry. Ferrites are not going to fix that.
Spend the $1.30 and get an external USB or firewire sound thing.
Message has been deleted
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Jeff Liebermann
Nov 11, 2011, 11:44:50 PM11/11/11
to
On Fri, 11 Nov 2011 14:09:36 -0500, Nelson <nel...@nowhere.com> wrote:
>OK, OK, I spent the $ 1.30 :P I'll let you know when the slow boat
>from China gets it here.
There are others available from domestic sources on eBay. I happened
to find the absolute cheapest.
>But I thought you said earlier that you tried
>USB and it didn't work.
Correct. Thanks for reading what I previously posted. However, you
missed or forgot an important point. We were trying to use the
MacBook for recording a music festival. The hiss was also present
with USB on record as well as playback. For playback, I doubt if you
could hear hiss that was more then -30dB down from the peak audio
level. That's 1/1000th of the peak volume. However, the recording
engineer wanted absolutely no buzz or hiss at any level. I couldn't
do that with the USB dongle. I got close with fancy USB external
sound card. However, when someone air dropped (literally) a firewire
sound card, the noise was almost totally gone on the spectrum
analyzer.
Note that in a previous URL, various users offered different
grounding, ungrounding, configuration, and equipment changes to fix
the hiss problem. Reading further, most came back indicating that the
fix was not permanent.
>Do you have any $1.30 firewire solutions up
>your sleeve? :-)
No. I'm wearing short sleeves.
Do your own shopping:
<http://search.reviews.ebay.com/Firewire_Sound-Cards_W0QQftsZ2QQsubmitZGoQQucatZ5781QQufmZ1QQugatZ2QQuqtZrQQusopZ1003>
These look like the cheapest and can probably be found used somewhere:
<http://www.atpm.com/10.02/ifire.shtml>
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
>OK, OK, I spent the $ 1.30 :P I'll let you know when the slow boat
>from China gets it here.
There are others available from domestic sources on eBay. I happened
to find the absolute cheapest.
>But I thought you said earlier that you tried
>USB and it didn't work.
Correct. Thanks for reading what I previously posted. However, you
missed or forgot an important point. We were trying to use the
MacBook for recording a music festival. The hiss was also present
with USB on record as well as playback. For playback, I doubt if you
could hear hiss that was more then -30dB down from the peak audio
level. That's 1/1000th of the peak volume. However, the recording
engineer wanted absolutely no buzz or hiss at any level. I couldn't
do that with the USB dongle. I got close with fancy USB external
sound card. However, when someone air dropped (literally) a firewire
sound card, the noise was almost totally gone on the spectrum
analyzer.
Note that in a previous URL, various users offered different
grounding, ungrounding, configuration, and equipment changes to fix
the hiss problem. Reading further, most came back indicating that the
fix was not permanent.
>Do you have any $1.30 firewire solutions up
>your sleeve? :-)
No. I'm wearing short sleeves.
Do your own shopping:
<http://search.reviews.ebay.com/Firewire_Sound-Cards_W0QQftsZ2QQsubmitZGoQQucatZ5781QQufmZ1QQugatZ2QQuqtZrQQusopZ1003>
These look like the cheapest and can probably be found used somewhere:
<http://www.atpm.com/10.02/ifire.shtml>
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Message has been deleted
Jeff Liebermann
Nov 12, 2011, 2:05:21 PM11/12/11
to
On Sat, 12 Nov 2011 04:37:38 -0500, Nelson <nel...@nowhere.com> wrote:
>On Fri, 11 Nov 2011 23:44:50 -0500, Jeff Liebermann wrote
>(in article <altrb75q38tlutaml...@4ax.com>):
>I think I'll hold off until I see how the Chinese USB dongle works,
>assuming the company actually exists :-)
As I vaguely recall, the USB dongle didn't have much noise when the
laptop was running off battery, but was slightly noisy with the AC
adapter attached. I had 2 or 3 different USB audio dongles, which
were about the same.
You might try ordering from a USA vendor for faster delivery:
<http://www.ebay.com/sch/i.html?LH_PrefLoc=1&rt=nc&LH_BIN=1&_nkw=usb+sound&_sc=1&_sop=15&_sticky=1&_trksid=p3286.c0.m301>
>It's hard for me to imagine
>how they can even afford to ship it at that price. No wonder they are
>killing us.
Agreed. If you purchase such a dongle retail in the USA, my guess is
that it would cost about $15. As long as we have enough money to
purchase such underpriced products, we will benefit from the low
prices. When we run out of money, China will own us.
>I am still struggling to explain why the hiss is very loud when the
>audio output is connected to the TV and inaudible when connected to
>earphones or the external speakers. I'm thinking that maybe the
>S-Video ground and the audio ground are at different levels. But then
>you had the problem with no video output involved, right?
It doesn't require video to produce the hiss. My guess(tm) is that
it's coming from the processor, not the video. Changes in operating
configuration and wiring produce a different path to ground for the
processor. It it happens to go through or near the audio circuitry,
you get hiss. If I knew which ground path, it might be possible to do
something to fix it. However, the easiest fix is to insert something
that isolates the audio ground from the laptop ground. I don't know
if the USB dongle or the other devices do this, but it would make
sense to prevent ground loops.
>On Fri, 11 Nov 2011 23:44:50 -0500, Jeff Liebermann wrote
>(in article <altrb75q38tlutaml...@4ax.com>):
>I think I'll hold off until I see how the Chinese USB dongle works,
>assuming the company actually exists :-)
As I vaguely recall, the USB dongle didn't have much noise when the
laptop was running off battery, but was slightly noisy with the AC
adapter attached. I had 2 or 3 different USB audio dongles, which
were about the same.
You might try ordering from a USA vendor for faster delivery:
<http://www.ebay.com/sch/i.html?LH_PrefLoc=1&rt=nc&LH_BIN=1&_nkw=usb+sound&_sc=1&_sop=15&_sticky=1&_trksid=p3286.c0.m301>
>It's hard for me to imagine
>how they can even afford to ship it at that price. No wonder they are
>killing us.
Agreed. If you purchase such a dongle retail in the USA, my guess is
that it would cost about $15. As long as we have enough money to
purchase such underpriced products, we will benefit from the low
prices. When we run out of money, China will own us.
>I am still struggling to explain why the hiss is very loud when the
>audio output is connected to the TV and inaudible when connected to
>earphones or the external speakers. I'm thinking that maybe the
>S-Video ground and the audio ground are at different levels. But then
>you had the problem with no video output involved, right?
It doesn't require video to produce the hiss. My guess(tm) is that
it's coming from the processor, not the video. Changes in operating
configuration and wiring produce a different path to ground for the
processor. It it happens to go through or near the audio circuitry,
you get hiss. If I knew which ground path, it might be possible to do
something to fix it. However, the easiest fix is to insert something
that isolates the audio ground from the laptop ground. I don't know
if the USB dongle or the other devices do this, but it would make
sense to prevent ground loops.
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