• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Different cable structures for RCA interconnects

D

Deleted member 46664

Guest
So my message that coax is not the simple or normal design for RCA cables does obviously not have any reason to be challenged.

Yes it does ... because you are wrong. microphone cable, commonly used in rca patch cords is a type of coaxial cable.

The problem here is that YOU DON'T KNOW WHAT COAXIAL CABLE IS.
 

Audiofire

Addicted to Fun and Learning
Forum Donor
Joined
Feb 8, 2022
Messages
625
Likes
347
Location
Denmark
Most RCA cords are made with microphone cable ... which is a type of coaxial cable.
Demonstrably wrong, microphone cables are balanced twisted pairs in line with the design of twinaxial cables (my understanding of what generic/normal RCA cable is has now been reassessed to be coax though).
 
Last edited:

Audiofire

Addicted to Fun and Learning
Forum Donor
Joined
Feb 8, 2022
Messages
625
Likes
347
Location
Denmark
The only thing necessary to deem cable as "coax" or "coaxial" is that it has one central conductor surrounded by a shield.

Some of the more common types of coax are ... Microphone cable, patch cords, instrument cables, television cable, radio transmitter cable... and on and on.
The trick is that you have to define an arbitrary center in order to call two separate wires coaxial, since you are talking about rotation around an axis. Or I just took my thought experiment way too far, and we all agree that the middle of the two wires is the center that defines the coaxial cable.

So is it just me that doesn't know what coax is, or does it actually need to be a central conductor surrounded by the neutral conductor (that is to say not two insulated wires per channel)?
 

mansr

Major Contributor
Joined
Oct 5, 2018
Messages
4,685
Likes
10,700
Location
Hampshire
So is it just me that doesn't know what coax is, or does it actually need to be a central conductor surrounded by the neutral conductor (that is to say not two insulated wires per channel)?
Coax is short for coaxial, meaning the two conductors share a common axis. Two wires that are merely adjacent do not have this property. Does this answer your question?
 

MCH

Major Contributor
Joined
Apr 10, 2021
Messages
2,581
Likes
2,198
The trick is that you have to define an arbitrary center in order to call two separate wires coaxial, since you are talking about rotation around an axis. Or I just took my thought experiment way too far, and we all agree that the middle of the two wires is the center that defines the coaxial cable.
Unless it is circular (what doesn't make much sense if you are connecting two devices) a normal cable as we know it only has one rotation axis.
 

Audiofire

Addicted to Fun and Learning
Forum Donor
Joined
Feb 8, 2022
Messages
625
Likes
347
Location
Denmark
Unless it is circular (what doesn't make much sense if you are connecting two devices) a normal cable as we know it only has one rotation axis.
Coax is short for coaxial, meaning the two conductors share a common axis. Two wires that are merely adjacent do not have this property. Does this answer your question?
Thanks, it does. Are the two wires coax if a shield and PVC jacket are wrapped around them as suggested (above)?
 
Last edited:

Speedskater

Major Contributor
Joined
Mar 5, 2016
Messages
1,610
Likes
1,333
Location
Cleveland, Ohio USA
As the frequency increases, the roundness of the shield becomes more and more important.
As does the central axis location.
 

radix

Major Contributor
Joined
Aug 1, 2021
Messages
1,365
Likes
1,297
Coax and twinax, etc., are pretty simple, it's just the nomenclature that might trip someone up. Coax has two conductions: the center and the shield. But they are usually described as a single conductor plus drain (shield). Don't be fooled -- the drain is a conductor! And it is insulated. The only difference is the conductor is spread out on the surface of a cylinder. This can be done by using a foil, or a foil plus solid wire, or various forms of braids. Drains are also rated by how complete of coverage they provide.

Twinax is two signal conductors in the center of the drain (shield) conductor. So, there are 3 conductors, but it's usually called two conductor plus drain, as you only get two signal conductors.

For stereo, you need two coax. A typical RCA cable is two coax conductors with the outer rubber melded together for convenience. It is not twinax. As others have mentioned, RCA is the name of the connector not the cable, but consumers usually don't think of it like that. They know "RCA" for analog stereo interconnects and "coax" for spidf digital interconnect.

Pretty much all low voltage, high impedance systems (like stereo line level) wants to use coax for the shielding. That's because a fairly low power noise coupling can show up on the output. Speakers not so much, as they are driven by current, not voltage, and coupled noise will generally be low power. Of course, really long speaker wires can pick up enough noise to be audible, thus step up/down transformers....
 
Top Bottom