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An ultra Low Shunt Capacitance way for audio interconnections (LSC configuration)
An ultra Low Shunt Capacitance way for audio interconnections (LSC configuration)
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Old 28th June 2010, 11:37 AM   #21
jan.didden is offline jan.didden  Europe
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Originally Posted by neazoi View Post
[snip]But at microwave frequencies capacitor B is not formed because the shield reflects the RF even if it is not grounded, like a dish reflects microwaves.[snip]..
I don't think that is how it works. RF or EMI causes a field that sets up current into the cable (screen) which couples into the signal conductors.
That is usually much lower in freq than microwave signals used with dishes, afaik.

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Old 28th June 2010, 11:49 AM   #22
neazoi is offline neazoi  Greece
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So, in either frequencies RF is coupled...
Thus there is no good of using coaxials this way...?
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Old 28th June 2010, 11:54 AM   #23
AndrewT is offline AndrewT  Scotland
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it's down to that loop area.
To minimise interference the loop areas must be minimised. This applies to receiving system and transmitting systems.
The AC cable coming into your amplifier should have the flow and return closely coupled together to minimise the radiated field that will affect surrounding equipment.
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Old 28th June 2010, 11:55 AM   #24
AndrewT is offline AndrewT  Scotland
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Originally Posted by neazoi View Post
This is not a technical answer, we are trying to improve things or at least to explore the possibilities.
so you cannot accept the simple answer. Then go and look at how everyone does it? And then try to explain to yourself why they do it that way.
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Old 28th June 2010, 11:58 AM   #25
neazoi is offline neazoi  Greece
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so you cannot accept the simple answer. Then go and look at how everyone does it? And then try to explain to yourself why they do it that way.
Or ask at the diyaudio...
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Last edited by neazoi; 28th June 2010 at 12:00 PM.
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Old 28th June 2010, 12:02 PM   #26
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by neazoi View Post
So, in either frequencies RF is coupled...
Thus there is no good of using coaxials this way...?
I think what you want to do is to insure that the coupling in both the hot and gnd is identical so there is no net interference signal. It's not realistic to expect 100% screening.

jd
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Old 28th June 2010, 12:19 PM   #27
neazoi is offline neazoi  Greece
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Since we are talking about coaxials a bit..
the cost of a silver plated twisted cable is very high. RG223 coaxial can be found in low cost and it's internal conductor and shields are silver plater copper. It has a 100pf/m shunt capacitance.

Does it make sense to use coaxial for the speaker cables, the standard way, central conductor positive, shield grounded.
Alternativelly I could rip the shield off and twist the central conductors (and also their insulation) together, to form a twisted cable.

Which one should I prefer for better characteristics?
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Last edited by neazoi; 28th June 2010 at 12:22 PM.
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Old 28th June 2010, 12:34 PM   #28
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by neazoi View Post
Since we are talking about coaxials a bit..
the cost of a silver plated twisted cable is very high. RG223 coaxial can be found in low cost and it's internal conductor and shields are silver plater copper. It has a 100pf/m shunt capacitance.

Does it make sense to use coaxial for the speaker cables, the standard way, central conductor positive, shield grounded.
Alternativelly I could rip the shield off and twist the central conductors (and also their insulation) together, to form a twisted cable.

Which one should I prefer for better characteristics?
Unless you are living nextdoor to a radio transmitter, and unless your power amp has the output termination wrong, you won't here a difference either way. So I would go for lowest cost

jd
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Old 28th June 2010, 12:47 PM   #29
neazoi is offline neazoi  Greece
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I am lucky enough to live in an underground.
I have no idea of the twisted cables shunt capacitance though to compare it with 100pf/m coaxial one
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Old 28th June 2010, 05:48 PM   #30
neazoi is offline neazoi  Greece
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After your useful advices I have decided to make the speaked cables like this shown in the photo.
They are composed of a pair of RG223 central conductors with thei insulations, twisted together. This ensures minimum dielectric contact and at the same time noise won't affect the cable..?

Is the way I have done it right?


Also, can I use the same configuration for interconnections? Will this impose a gain in relation to the coaxial?
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