RCA to XLR or RCA to RCA

[mongobot]

In a previous setup, I was was using the Onkyo PR-SC5507 with an ATI AT525NC. I had this connected via RCA cables and was getting hum in the speakers plus some other anomalies. I switched to the Nord I currently have and went with XLR during the changeover. I had no hum after this.

It's highly likely that this improvement was due to the hardware change rather than the cable change but it gave me the notion that in some cases my system was susceptible to noise. So it seems the RCA > XLR cables may have a chance of offering some value other than audiophile frippery in my system.
We'll see how it pans out once the Denon arrives and I start hooking it up.

 

[Holmz]

In a previous setup, I was was using the Onkyo PR-SC5507 with an ATI AT525NC. I had this connected via RCA cables and was getting hum in the speakers plus some other anomalies. I switched to the Nord I currently have and went with XLR during the changeover. I had no hum after this.

If it took both you could whack the RCA in…

It's highly likely that this improvement was due to the hardware change rather than the cable change but it gave me the notion that in some cases my system was susceptible to noise. So it seems the RCA > XLR cables may have a chance of offering some value other than audiophile frippery in my system.
We'll see how it pans out once the Denon arrives and I start hooking it up.

Yes… It would be good to see if you system is susceptible to noise.

 

[rcstevensonaz]

A better example would be: a standard 2-wire STP (single twisted pair) AC power zip cord.

From Bill Whitlock (Jensen Transformer - retired)
At a distance of 10 times the conductor spacing, the magnetic field is about 1% of the close-in value.
At a distance of 2 or 3 inches, the magnetic fields from AC power cords are negligibly week.

Ok, so I think I must have completely understood what you meant by "high and low being in close proximity to each other".

I assumed that was in reference to the "hot" and "cold" wire within the balanced audio interconnect being close to each other; and therefore the balanced input device is able to cancel out the introduced noise.

But I think you might have been referring to the source of the interference rather than to the balanced cable receiving the interference? Or am I just hopelessly confused

 

[Holmz]

Ok, so I think I must have completely understood what you meant by "high and low being in close proximity to each other".

The field strength is a function of <something>/R*R.
So a wire 1cm away from a field is X, and one that is 10cm away is X/10*10.

I assumed that was in reference to the "hot" and "cold" wire within the balanced audio interconnect being close to each other; and therefore the balanced input device is able to cancel out the introduced noise.

He means do not run the power cord in parallel next to the signal cable.
And do not wrap teh signal cable around a transformer, or laying on top of one.

But I think you might have been referring to the source of the interference rather than to the balanced cable receiving the interference? Or am I just hopelessly confused

“GTS” may help alleviate confusion.

 

[rcstevensonaz]

The field strength is a function of <something>/R*R.
So a wire 1cm away from a field is X, and one that is 10cm away is X/10*10.


He means do not run the power cord in parallel next to the signal cable.
And do not wrap teh signal cable around a transformer, or laying on top of one.

I still do not know what is "high" and what is "low" in the context of @Speedskater's post.

 

[pablolie]

Yeah no.

They go to a high voltage specifically to have less current flow.
Then the voltage drop is less and less power is in the transmission from point A to point B.

The other example, and still power related, is that there is a step down transformer on the pole or substation.
Then we have a lower voltage, and a higher current.
The magnetic field is a consequence of the current.

Yawn. Current does not exist without voltage. Just let it go, man. I = U/R. They are replaceable variables in every formula.

 

[pablolie]

But it kinda does hint at something for the OP.

1. That they may want to have a construction with twisted pairs to minimize the IC picking up magnetic fields.
2. That they may want to try different routing if there are power cords, transformers, SUTs, etc. t

It will also hint at anyone else you don't know how to work with variables. Over. For good. I refuse to get into idiotic fights here, so sorry but I am blocking you and never want to see anything you post again.

 

[Holmz]

It will also hint at anyone else you don't know how to work with variables. Over. For good. I refuse to get into idiotic fights here, so sorry but I am blocking you and never want to see anything you post again.

OK sure - that’s your perogative.
But I would suggest that you try to think about without becoming emotional.

If you have 1kW on a high tension line, and run that though a 360 kV.
Now at the the house you have 120v, so that is a 3000:1 ratio.

The current at the house is 3000x greater assuming that the high tension line was just supplying that single house.

There is a reason why voltage is not a variable in the equation for the magnetic field.
And it has nothing to do with ohm’s law.
But Ohm’s law has a lot to do with why high tension lines are at a higher voltage.

Yawn. Current does not exist without voltage. Just let it go, man. I = U/R. They are replaceable variables in every formula.

I really think that you need to brush up on your physics.
Sure you got the basics of ohms law, but that is NOT any part of the magnetic field stuff.

And that is the mechanism that may influence the OP to want to use an XLR.

Sure they probably don’t need it... But some percentage of people just have the equipment placed where there is a real need for balanced lines.
One can probably work out if that is the case, but it also takes some gear and skill.


The science you’re presenting is somewhat akin to identifying the places for contracting autism or cancer, solely by looking for the presence of high tension lines.

 

[Holmz]

I still do not know what is "high" and what is "low" in the context of @Speedskater's post.

If the Send and Return (or High and Low) line are in close proximity, almost all of their fields will cancel each other.

The + would be high.
I.e. the red wire.
In an RCA there is + and ground.

In an XLR there is a “+” and “-“ or “high” and “low”, or “signal” and “inverted signal”.

If the + get wriggled then the RCA wire has signal and the wriggle.

In an XLR there is a s signal and a wriggle on “+” and on “inverted” it is -signal + wriggle.
Single + wriggle - (-signal + wriggle) = 2x signal… (and no wriggle)

And the wriggle almost always gets there from a magnetic field inducing the wriggle.

If the Send and Return (or High and Low) line are in close proximity, almost all of their fields will cancel each other.

^They^ are saying that the when the to wires are side by side, then there is not big gap (a small area) and it is hard to shove a wriggle into it.
Sort of like how metal detectors can have a big coil… which has a big area… same concept there.

 

[Speedskater]

Ok, so I think I must have completely understood what you meant by "high and low being in close proximity to each other".
I assumed that was in reference to the "hot" and "cold" wire within the balanced audio interconnect being close to each other; and therefore the balanced input device is able to cancel out the introduced noise.
But I think you might have been referring to the source of the interference rather than to the balanced cable receiving the interference? Or am I just hopelessly confused

You are not confused. It's both.
With the AC power cord, it's their radiating fields, that are canceled
With the XLR interconnect, it's that both conductors received the same interference field. Then the input stage cancels the interference.

 

[rcstevensonaz]

You are not confused. It's both.
With the AC power cord, it's their radiating fields, that are canceled
With the XLR interconnect, it's that both conductors received the same interference field. Then the input stage cancels the interference.

Thanks! I was confused at first since I thought you were referring to the AC power cable as the 2-wire twisted pair with high and low; and that the magnetic interference was being cancelled out within the AC power cable itself.

@Holmz, thank you for taking the time to add the explanation. Though one minor quibble (that everyone makes) is that the typical 2x voltage on balanced audio is irrelevant to the noise reduction (CMRR) on the balanced line — especially in the context of an RCA to XLR cable. There could just as easily be 2V (or even 4V*) on the hot (+) line and 0V on the cold (-) line. The noise cancelation is simply from the summing of the two lines, regardless of whether there is any voltage on either or both of the lines.

 

[Holmz]

…

@Holmz, thank you for taking the time to add the explanation. Though one minor quibble (that everyone makes) is that the typical 2x voltage on balanced audio is irrelevant to the noise reduction (CMRR) on the balanced line — especially in the context of an RCA to XLR cable. There could just as easily be 2V (or even 4V*) on the hot (+) line and 0V on the cold (-) line. The noise cancelation is simply from the summing of the two lines, regardless of whether there is any voltage on either or both of the lines.

Correct, but that is how the math works.
Whether it was 1/2 signal, or 2 or 4, the noise cancelling out is the important part.

As they are differenced versus being summed.

 

[Holmz]

In case I wasn't sufficiently clear - yawn to the eff degree. You're a clown that doesn't understand the formulas you throw about. You're a joke. You don't know how to work variables. I wish you didn't try to provoke me into ridiculing your pony formula trick you don't understand more. once again, no current without voltage. 101 stuff. Go back to 10th grade. Bye.

^that^ is exactly the emotional part I am referring to.
Assigning intent into the post doesn’t help.

Adults should be able to rationally discuss things to reach some mutual understanding and agreement.

 

[rcstevensonaz]

As they are differenced versus being summed.

Good correction! Just "summing" would cancel out the audio (x + -x) and double the noise (n + n)...

 

[pablolie]

^that^ is exactly the emotional part I am referring to.
Assigning intent into the post doesn’t help.

Adults should be able to rationally discuss things to reach some mutual understanding and agreement.

OK so I lost my cool and went a bit ad hominem. which truly is something I hate being driven to in a forum that is fun.I apologize for that.
But you kept claiming voltage has nothing to do with anything and presented a Maxwellish formula (actually it's other guys that created it but I forgot the names) that just said I (current), so you kept claiming voltage has nothing to do with anything and it's only about current. The most basic law of electricity by Ohm is I=U/R, so if you have a 13 year old's understanding of working with variables, you should know you can edit out I in every formula "I" is mentioned in and replace it with U/R. I even said that doesn't at all mean current doesn't matter (unlike you did with voltage). I kept repeating it, you kept ignoring it. And that is extremely frustrating at some point.
Have a great weekend.

 

[Holmz]

Ok - ^well done^.

I am not a power transmission fellow, but the voltage on the those big towers can be in the hundreds of thousands of volts.
However we cannot just replace I with V/R as the resistance of the wires have almost nothing to do with current.
If all the businesses and houses on the end away from Hoover dam are all “lights out”, then the cables are still at the same voltage, but the current has went to zero.
The power needs to go somewhere, and the cable is not going accept megawatts at Hoover dam, if it cannot get megawatts out at the far end. The current just goes to zero, irrespective of the resistance of the high tension lines wire/cable.

If we were standing underneath the line we could measure a voltage gradient, but there would be no magnetic field left to be measured.

Similarly if we replace I with V/R for say a super conductor, we see that the resistance has going to zero. The current (I) cannot go to infinity, so the only left is that the voltage drop across the super conductor must be zero volts.

The only time we can replace I with V/R is when it is a wire or resistor that has either a stiff voltage source, or a stiff current source.

The whole idea (or a lot of it) in power transmission is to get the current towards zero, as the voltage losses go down when the current goes down.
And they are not going to use large copper wires if they can use thinner and lighter steel or aluminium.
So they crank up the voltage with a transformer and get the current down. Then on the far end they reverse it to get the 110v back, and that gets to the high current back.

This is also why it is probably likely that the power cord to the amplifiers has the biggest magnetic field and the fact that it is close by only makes it increasingly worse as the ICs are probably also shoved behind a rack and the whole snake festival of ICs, cables, etc are all on each other.
Actually the speaker cable would probably have the largest magnetic fields.
And 2 and 4 ohm drivers would be worse than 8 and 16 ohm drivers.

If the OP has a hum, then they either go to XLRs, or they use a bit of cable hygiene and try to keep speaker and power cords from running parallel to RCA based ICs.
If there is no hum then there is nothing to fix.
And the twisted pair concept is ~150 years old and based upon the magnetic field understanding of the day. Which has not changed.

 

[pablolie]

Ok - ^well done^.

I am not a power transmission fellow, but the voltage on the those big towers can be in the hundreds of thousands of volts.
However we cannot just replace I with V/R as the resistance of the wires have almost nothing to do with current.

That's a tragically wrong statement. Both in DC and even more in AC high voltage transmission resistance or inductance is of vital, critical importance. Electricity travels as waves in those scenarios, meaning it can actually bounce back and unpredictably blow up stuff.

And as far as math goes, you can ALWAYS replace a variable with the variables that define it. That said, in the high voltage grid things are way more complicated that basic Ohm stuff.

You can always and every time replace I with U/R. Or U with I*R. Or R with U/I. It's the whole point of formulas and variables in math, really.

Please read a bit more about these matters before you make such statements.

If we were standing underneath the line we could measure a voltage gradient, but there would be no magnetic field left to be measured.

Wrong. again. Huge currents travel on the grid always unless you shut the lines down. That's why you can HEAR power lines, especially HVAC. Please just stop, for the love of God.

Discussion over for good, at least for me.

Similarly if we replace I with V/R for say a super conductor, we see that the resistance has going to zero. The current (I) cannot go to infinity, so the only left is that the voltage drop across the super conductor must be zero volts.

The only time we can replace I with V/R is when it is a wire or resistor that has either a stiff voltage source, or a stiff current source.

The whole idea (or a lot of it) in power transmission is to get the current towards zero, as the voltage losses go down when the current goes down.
And they are not going to use large copper wires if they can use thinner and lighter steel or aluminium.
So they crank up the voltage with a transformer and get the current down. Then on the far end they reverse it to get the 110v back, and that gets to the high current back.

This is also why it is probably likely that the power cord to the amplifiers has the biggest magnetic field and the fact that it is close by only makes it increasingly worse as the ICs are probably also shoved behind a rack and the whole snake festival of ICs, cables, etc are all on each other.
Actually the speaker cable would probably have the largest magnetic fields.
And 2 and 4 ohm drivers would be worse than 8 and 16 ohm drivers.

If the OP has a hum, then they either go to XLRs, or they use a bit of cable hygiene and try to keep speaker and power cords from running parallel to RCA based ICs.
If there is no hum then there is nothing to fix.
And the twisted pair concept is ~150 years old and based upon the magnetic field understanding of the day. Which has not changed.

 

[Holmz]

Ok I’ll defer you, and the power transmission experts.