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Old 11th February 2013, 05:20 PM   #34811
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Christophe,
I have assumed perhaps incorrectly up to now that some of the very expensive interconnects and speaker cables have a ferrite included in their construction? Little round plastic coated traps as part of the assembly. Now I for one am not going to pay $1,000 per meter foot for a speaker cable or interconnect, exaggerating perhaps here, but not by much, but it appears that the boutique manufacturers are already doing this. To any effect I won't conjecture, I do not know anything in the RF field to understand what is supposed to be happening between a speaker and an amplifier where I am worrying about any RF injection unless they are in the audio band.
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Old 11th February 2013, 05:30 PM   #34812
qusp is offline qusp  Australia
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with depleted uranium shielded ferrite cores perhaps Christophe? that has that super secret allure
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Old 11th February 2013, 05:36 PM   #34813
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Quote:
Originally Posted by Kindhornman View Post
To any effect I won't conjecture, I do not know anything in the RF field to understand what is supposed to be happening between a speaker and an amplifier where I am worrying about any RF injection unless they are in the audio band.
Blocking some RF to go back in the feedback loop of the amp, reason why it is better to set the ferrite near the outputs.
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Old 11th February 2013, 05:46 PM   #34814
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Thanks Christophe,
I guess we would have more to worry about with some of the new wi-fi enabled speakers with unwanted RF.

Qusp,
You forgot the Di-lithium crystals on the cables.
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Old 11th February 2013, 05:49 PM   #34815
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Anything witch can bring happiness in the life of an audiophile satisfies the altruism of the snake oil merchant.

Joke apart, as asserted Bonsai, we do not think often enough to use little ferrite in our electronics boards, like in the gates of power FETS, when we chase instability.
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Last edited by Esperado; 11th February 2013 at 05:53 PM.
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Old 11th February 2013, 06:06 PM   #34816
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true, interesting you mention them really, i'm playing with some of the newer compound common and differential mode SMD filters in some regulators at the moment to isolate and filter noise. its pretty mad science though... particularly common mode.

Kindhornman: thats correct, I think the crystals add too much upper treble energy though... or was that the pipe crystal?

Last edited by qusp; 11th February 2013 at 06:09 PM.
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Old 11th February 2013, 06:11 PM   #34817
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Christophe, that might be because, for people like me at least, who are inexperienced with them, they are somewhat mysterious and there is what seems like such a bewildering array of available ferrite beads, and different ways to use them (e.g. wire or pin through once, wire wrapped around and through more than once).

How often is it critical to use exactly the ferrite with certain characteristics? And how would we predict which ones would be suitable?

Can we model them as a series component with some impedance versus frequency curve? How would we calculate or simulate with them, and how would we design such that we arrived at the requirements for the bead? Or are they simpler to think of as just low-pass filters with a relatively-high cutoff frequencies? Or as tiny inductors?
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Old 11th February 2013, 06:13 PM   #34818
DF96 is online now DF96  England
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Quote:
Originally Posted by Esperado
Of course, they will be VERY expensive, and w'll have to pretend their improvements only reach the top on HI-FI (not MID-FI) equipments around.
We will tell our customers that if they can't hear any improvement then either their equipment or their ears are not sufficiently discriminating. That guarantees no complaints.

The sort of ferrites used for RF suppression essentially add a lossy inductor to the cable. In some cases it can be so lossy that it is more resistive than inductive.

Last edited by DF96; 11th February 2013 at 06:16 PM. Reason: comment on ferrites
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Old 11th February 2013, 06:20 PM   #34819
qusp is offline qusp  Australia
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gootee, i've found the reading materials, application and selection guide at the murata website to be very helpful in sifting through the myriad choices. this article noise counter-measures has been very useful. luckily it relates to some excellent parts too.

common mode choke coils would seem the better choice on cables as well

Last edited by qusp; 11th February 2013 at 06:27 PM.
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Old 11th February 2013, 06:37 PM   #34820
DF96 is online now DF96  England
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On cables carrying non-trivial currents (e.g. power or speaker cables) you need common-mode chokes. For small signals other options are possible.
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