[John Casler]

This is something I should know

Does anyone know if there is any advantage to having a single ended source, run to an XLR available Component, via a cable terminated with RCA on one end and XLR on the other???

[audioengr]

No advantage.  I do this for some cable customers because their source component does not have Balanced outs and thats all their designation component has for inputs.  The XLR should have pin 3 tied to pin 1. (- to gnd)

[John Casler]

No advantage.  I do this for some cable customers because their source component does not have Balanced outs and thats all their designation component has for inputs.  The XLR should have pin 3 tied to pin 1. (- to gnd)

Thanks much,

But to carry this one step further, the Son of Ampzilla has a connector that will accept either phono plugs or XLR.

In your opinion, which of the two termination options would be the best, considering the cable will originate from "single ended" RCA?

[eico1]

I'm not sure if I understand your question or Steve's response correctly, but a balanced input can improve performance even when using a single ended output to drive it. You still have common mode rejection and chassis ground isolation due to the balanced input.

steve

[8thnerve]

No.  

If the source is not balanced, there is no advantage to using an XLR connector on the other end, in fact it may be worse.  A single ended signal has two paths, 1) signal and 2) ground.  A balanced signal has three, 1) signal, 2) signal in opposite polarity, and 3) ground.  The idea of balanced is that path one and two can be used to reject noise that entered the cable.

Lets say for example (very simplified) that airborne noise causes a +3db rise at 3KHz.  This would affect both the 1) signal and 2) opposite signal.  At the end of the cable, the device (preamp, amp, whatever) will put together the 1) signal and then invert the 2) opposite signal to be the correct polarity.  Ideally the two signals should now be identical, but since the noise caused a +3db rise at 3KHz, and since the polarity of 2) the opposite signal was inverted, that signal now has a -3db drop at 3KHz.  Put them together and they cancel out, no more noise.  The magic of this process is called common mode rejection.

This is why there is also no advantage to running a Balanced cable to a component that is not truly "balanced".

Hope that helps!

[8thnerve]

I'm not sure if I understand your question or Steve's response correctly, but a balanced input can improve performance even when using a single ended output to drive it. You still have common mode rejection and chassis ground isolation due to the balanced input.

steve

I don't think that is true.  You can't get the common mode rejection if you don't have the cold signal (opposite polarity).  And to properly connect a single ended source to an XLR output, like audioengnr stated, the ground needs to be connected to the cold signal pin on the XLR, not the ground, which is what provides the chassis ground isolation.

[John Casler]

the Son of Ampzilla has a connector that will accept either phono plugs or XLR.

In your opinion, which of the two termination options would be the best, considering the cable will originate from "single ended" RCA?

Anyone have any feelings on the second part of the question?

Phono plugs vs XLR with an RCA termination on the other end??

[eico1]

You can't get the common mode rejection if you don't have the cold signal (opposite polarity).

The noise needs to be common mode, not the signal! What is more important is a balanced impedence as seen by the noise looking back into the source.

ground needs to be connected to the cold signal pin on the XLR...

this is the correct hook-up, but it sounds like that is what provides the ground isolation.

steve

[8thnerve]

You can't get the common mode rejection if you don't have the cold signal (opposite polarity).

The noise needs to be common mode, not the signal! What is more important is a balanced impedence as seen by the noise looking back into the source.

I think you are misunderstanding me.  The common mode rejection is achieved by having two identical signal out of polarity with each other so that any change in the signal cancels itself out when the inverted signal is reversed and joined with the signal with the original polarity.  Without two signals in opposite polarity, no gains from common mode rejection can be realized.

John,

Unless the RCA inputs have been compromised from an engineering standpoint, the RCA inputs should give you the best sound.  Using an adaptor is more points of contact and introduces the possibility for more loss in the chain.

[Wayne1]

John,

As with all connectors, it depends on how well the connector is built. In general, a good XLR will sound better than most standard 1/4" phone plugs.

The Neutrik gold 1/4" phone is about the best sounding one. That is what I terminated Brian Cheney's single ended Nitros with.

[John Casler]

John,

Unless the RCA inputs have been compromised from an engineering standpoint, the RCA inputs should give you the best sound ...

The problem is, I don't have that option.

One end is RCA - output from the preamp

Other end has to be either XLR or Phono (1/4"), there is no RCA option on this (the amp) end.

So my question was relating to which (amp end) termination would be best, given those circumstances.

[John Casler]

John,

As with all connectors, it depends on how well the connector is built. In general, a good XLR will sound better than most standard 1/4" phone plugs.

The Neutrik gold 1/4" phone is about the best sounding one. That is what I terminated Brian Cheney's single ended Nitros with.

Hi Wayne,

So if I'm reading you right, going with a "high quality" XLR on the amp end would be better than the 1/4" phono, but a very good phono plug works pretty good?

[Charles Calkins]

Hey Guys:
  I thought that I read somewhere that the only time XLR connections were needed was when you had to run very long lengths of cable.

                    Cheers
                    Charlie

[Wayne1]

Hi Wayne,

So if I'm reading you right, going with a "high quality" XLR on the amp end would be better than the 1/4" phono, but a very good phono plug works pretty good?

That is correct, IMHO.

There is less metal involved in the contacts with "audiophile grade" XLRs than with the 1/4" phone plugs. To my ears, the less metal, the better it sounds.  The Neutrik Gold XLRs are very good sounding connectors. Some folks seem to really like the Furutech XLRs, but they ARE a bit on the pricey side.

[eico1]

I think you are misunderstanding me.  The common mode rejection is achieved by having two identical signal out of polarity with each other so that any change in the signal cancels itself out when the inverted signal is reversed and joined with the signal with the original polarity.  Without two signals in opposite polarity, no gains from common mode rejection can be realized...

It seems I understand what you are saying, I just don't know why you think it's so. The common mode signal will be rejected regardless of if the signal is on the hot, cold, or both(opposite polarity). There is online literature to describe this better that me.

John, XLR connectors are considered gas tight connections, so over time the connection won't degrade as a crappy phono connector will.  

steve