RCA, XLR or DIN Connectors - Which is Best?
28/02/12 09:04 *HELIX USB CableInterconnect Connectors
Please note: this post is an introduction only and does not cover everything pertaining to this subject, which can get very complex.
Before looking at the actual performance of these connectors I must first explain that RCA can only support a “single ended” electrical interface, DIN typically supports a single ended electrical interface and XLR typically supports a “balanced” interface.
A Single Ended Interface:
A Balanced Interface:
What does Balanced buy me?
When the balanced signals are processed at the receiving component (e.g. the amp) they are combined by a process referred to as “subtraction”, which effectively retrieves the original signal.
The subtraction process however has a couple of additional benefits:
Alas - the circuitry in balanced components is more complex and in turn more expensive to manufacture.
There is also the possibility that the circuitry in the sending component is not perfectly matched in the receiving component - which can result in performance that is in fact lower quality than a single ended approach
So what are the actual connector differences - the obvious...
RCA
What is IACS? — it’s a measure of the conductivity of various metals relative to “Pure Copper”, a standard developed for copper wire producers, having a rating of 100%
- See IACS Conductivity Ratings PDF for further details.
Have XLR connectors been used on components using a single ended design?
Can you connect a balanced output to a single ended input?
Can you connect a single ended output to a balanced input?
XLR's have always been a better "quality" connector that uses plated copper for the pins. But it has more component parts, resulting in it being more expensive to manufacture. Whereas RCA connectors were generally made from more "cost effective" materials like brass and far less complicated to manufacture.
Having said that there are many RCA connectors that are very highly priced - some, for no apparent reason.
A Better RCA Interconect...
To elevate the performance of interconnects using RCA connectors, i.e. from a noise perspective, in place of using a a coax cable, you can use a balanced cable (two identical centre conductors + shield) by connecting the two centre conductors to the signal and neutral, but connecting the shield to the neutral side of the RCA at only one end of the cable.
But there remains a serious problem with the RCA in that pure copper, because of it’s softness, is difficult to machine. Copper alloys were developed, but even those fall below the conductivity of pure copper, or even silver.
A Better RCA Connector...
KLE Innovations, had the foresight to develop a quality RCA connector that did not require the same manufacturing processes that in turn allowed pure copper and silver to be used. There is also more to the science of these connectors in that they focus the transmission of the electron flow resulting in a much improved transmission of the electrical signal and minimize electrical reactance within the RCA itself, resulting in improved dynamics, details and spacial image.
The performance of many RCA interconnect cables are now comparable to XLR interconnects
Because of the improved performance of high quality RCA interconnects and the development of the floating shield approach, the choice of which type of interconnect to use on components that have both types of connector implemented is not quite so clear cut these days, i.e. for shorter cable lengths.
So which interconnect type do you buy?
So right about now you may be thinking that perhaps to move to the "next level" in performance you have to sell off all your RCA connected components and buy only those components with XLR Connectors!
Well, you can implement floating shield grounding strategy using interconnects with RCA connectors and balanced cables that will deal very effectively with RF interference in a system.
If you utilize the "Floating Shield" design for interconnects and power cables - and implement the component grounding strategy identified in Hi-Fi & Grounding - the effectiveness at removing RF interference from the next level of amplification is second only to that of systems where every component adopts a balanced design.
Most RCA Interconnects are NOT constructed using floating shield techniques. Those that do will indicate this fact by a ground-end marking sticker on the actual cable (e.g. Van Den Hul cables are marked in this manner) - this end ALWAYS connects to the source component
CAUTION: I have seen interconnects out there that have a little arrow indicating a "direction" - this is NOT always an indication that the cable has a floating shield, but more often indicates the direction in which the wire was extruded. Always ensure that both left and right channel cables are connected in the same direction.
UPDATE: since writing the original posting, I now use my own DIY interconnects
Before looking at the actual performance of these connectors I must first explain that RCA can only support a “single ended” electrical interface, DIN typically supports a single ended electrical interface and XLR typically supports a “balanced” interface.
A Single Ended Interface:
- has a conductor for the signal and
- a second conductor for the neutral (or ground)
- with a “Coax cable” the shield performs double duty as the neutral conductor
- A “balanced cable” having two identical conductors + shield can also be used for single ended cables
- an RCA connector will carry the signal for the left or right channel only
- a DIN connector can carry both left and right channels
A Balanced Interface:
- has a conductor for the signal - referred to as "+", or "non-inverted",
- a second identical conductor for an inverted copy of the signal - referred to as “-“, or "inverted"
- a conductor for the neutral (or ground)
- an XLR connector will carry the signal for the left or right channel only
- the neutral or ground is not used for signal transfer - so ground loop hums are eliminated
What does Balanced buy me?
When the balanced signals are processed at the receiving component (e.g. the amp) they are combined by a process referred to as “subtraction”, which effectively retrieves the original signal.
The subtraction process however has a couple of additional benefits:
- it effectively doubles the strength of the signal, which allows for much longer cable runs to be used, and
- cancels out any hum or noise picked up by the cables themselves
Alas - the circuitry in balanced components is more complex and in turn more expensive to manufacture.
There is also the possibility that the circuitry in the sending component is not perfectly matched in the receiving component - which can result in performance that is in fact lower quality than a single ended approach
So what are the actual connector differences - the obvious...
RCA
- only has the ability to connect two conductors - a signal and a neutral/ground
- originally used with Coax type cables - one centre conductor and a shield conductor
- RF Noise will flow through the neutral side of the circuit
- the barrel (i.e. the neutral side) is generally made from materials having a lower IACS conductivity rating, hence does not perform as well
- use on cables longer than 30 ft can affect performance
- has the ability to connect three conductors - signal, inverted signal and ground
- generally used with "balanced cables" that have two centre conductors of the same gauge and a separate shield conductor
- RF Noise is generally contained in completely separate shield/ground circuit
- the pins are generally made from pure copper - with a superior IACS conductivity rating
- can be used on cables longer that 30ft without an issue
- is normally used in single ended designs
- because it uses very small pins, then materials that have a high IACS conductivity rating are often used while keeping costs low
- performance is better than many RCA connector designs
What is IACS? — it’s a measure of the conductivity of various metals relative to “Pure Copper”, a standard developed for copper wire producers, having a rating of 100%
- See IACS Conductivity Ratings PDF for further details.
Have XLR connectors been used on components using a single ended design?
- There are companies that have used XLR connectors on their components utilizing a single ended design
- The manufacturer adapts the internal wiring such that it does not present a problem when connecting to components using balanced circuits
Can you connect a balanced output to a single ended input?
- Yes, but you should only connect the non-inverted signal pin on the XLR to the signal pin on the RCA
- you may experience additional noise and/or possibly a lower output level
Can you connect a single ended output to a balanced input?
- NOT directly!
- A conversion circuit would be required.
XLR's have always been a better "quality" connector that uses plated copper for the pins. But it has more component parts, resulting in it being more expensive to manufacture. Whereas RCA connectors were generally made from more "cost effective" materials like brass and far less complicated to manufacture.
Having said that there are many RCA connectors that are very highly priced - some, for no apparent reason.
A Better RCA Interconect...
To elevate the performance of interconnects using RCA connectors, i.e. from a noise perspective, in place of using a a coax cable, you can use a balanced cable (two identical centre conductors + shield) by connecting the two centre conductors to the signal and neutral, but connecting the shield to the neutral side of the RCA at only one end of the cable.
- This end would always be connected to the component that was the origin, or source of the signal.
- Provided that component was correctly grounded, any noise in the shield is not conveyed to the next level of amplification in the chain
- This technique is called “floating shield” and it brought a very respectable level of performance back to the RCA connector
But there remains a serious problem with the RCA in that pure copper, because of it’s softness, is difficult to machine. Copper alloys were developed, but even those fall below the conductivity of pure copper, or even silver.
A Better RCA Connector...
KLE Innovations, had the foresight to develop a quality RCA connector that did not require the same manufacturing processes that in turn allowed pure copper and silver to be used. There is also more to the science of these connectors in that they focus the transmission of the electron flow resulting in a much improved transmission of the electrical signal and minimize electrical reactance within the RCA itself, resulting in improved dynamics, details and spacial image.
The performance of many RCA interconnect cables are now comparable to XLR interconnects
Because of the improved performance of high quality RCA interconnects and the development of the floating shield approach, the choice of which type of interconnect to use on components that have both types of connector implemented is not quite so clear cut these days, i.e. for shorter cable lengths.
So which interconnect type do you buy?
- The obvious - If you have two components that have both types of connector - Buy XLR!
- But you no longer need to limit you component choice to only those components with XLR connectors only
- XLR to RCA cables are also available
So right about now you may be thinking that perhaps to move to the "next level" in performance you have to sell off all your RCA connected components and buy only those components with XLR Connectors!
Well, you can implement floating shield grounding strategy using interconnects with RCA connectors and balanced cables that will deal very effectively with RF interference in a system.
If you utilize the "Floating Shield" design for interconnects and power cables - and implement the component grounding strategy identified in Hi-Fi & Grounding - the effectiveness at removing RF interference from the next level of amplification is second only to that of systems where every component adopts a balanced design.
Most RCA Interconnects are NOT constructed using floating shield techniques. Those that do will indicate this fact by a ground-end marking sticker on the actual cable (e.g. Van Den Hul cables are marked in this manner) - this end ALWAYS connects to the source component
CAUTION: I have seen interconnects out there that have a little arrow indicating a "direction" - this is NOT always an indication that the cable has a floating shield, but more often indicates the direction in which the wire was extruded. Always ensure that both left and right channel cables are connected in the same direction.
UPDATE: since writing the original posting, I now use my own DIY interconnects
DIY Interconnect Cables - The "Helix Mark V"
These utilize an advanced helix architecture and can resolve to an extremely high level due to the materials used and their unconventional cable geometery.