Power Cables

[BE718]

"CMC" may mean Common Mode Choke. Not sure what is meant by limiting to 2 Amps. Maybe that's it's failure point or maybe it adds a lot to the power line source impedance.

Thanks, that makes sense now, I was being dim. If its been designed correctly it wont at 50/60 Hz, its impedance will be very low there.




Maybe I need to get my scope and current probe out to show whats happening in an amplifier PSU.

 

[BE718]

This is all very true!
The DTCD "dynamic transient current delivery" is all rather meaningless until they test the complete system from the big power company transformer down the street to the connector on your audio component. They also claim as a virtue what others build power line filters to reduce.

You dont need to try a "full" test to know that the last metre of cable is of no significance in this respect.

 

[Speedskater]

You dont need to try a "full" test to know that the last metre of cable is of no significance in this respect.

OF course we don't need a full test, but in one of their early papers they suggested that they were going to test complete circuit and to test breaker boxes. Maybe they did test all kinds of stuff and saw that their cord didn't change anything.

 

[BE718]

OF course we don't need a full test, but in one of their early papers they suggested that they were going to test complete circuit and to test breaker boxes. Maybe they did test all kinds of stuff and saw that their cord didn't change anything.

Quite possibly. It just raises my eyebrows when they felt the need to test this when it should be obvious. So their mains cable might have 0.01 ohms lower impedance than a normal one, and they are worried about that in a circuit that might be 5 ohms or more?

people are looking in the wrong direction on this particular issue (Noise is a different issue should be discussed seperately). Its the equipments power supply performance they need to be looking at, not the mains cable.

 

[opus112]

So their mains cable might have 0.01 ohms lower impedance than a normal one, and they are worried about that in a circuit that might be 5 ohms?

Could be because its the loop (between the mains cables and ICs of the next component in the audio chain) that matters? Certainly the impedance of the loop would have an effect on CM noise.

 

[BE718]

Yes. Its why I think single ended IC is a pretty dumb idea. If you have loops or a noise issue with mains ground connections you couple this into the signal gnd. Its dumb. Whilst it can work fine you certainly have potential for lots of issues.

Go balanced and or use double insulated kit without ground connections - but one thing for sure if thats the issue messing around with mains cables isnt the answer.

 

[opus112]

I don't think double insulated solves the common-mode noise issue - mains transformers still have appreciable capacitance between primary and secondary. Split bobbins help but don't eliminate it.

Balanced is indeed the way to go but that would cut off an extremely profitable revenue stream, what with the margins on cables being what they are....

 

[Jinjuku]

I don't think double insulated solves the common-mode noise issue - mains transformers still have appreciable capacitance between primary and secondary. Split bobbins help but don't eliminate it.

Balanced is indeed the way to go but that would cut off an extremely profitable revenue stream, what with the margins on cables being what they are....

Never understood spending money on PC's when you could go balanced power.

 

[opus112]

You reckon balanced power fixes all CM noise?

Just for clarification when I said 'Balanced is the way to go' I was meaning balanced ICs, not balanced power. So we might have some crossed wires here

 

[Folsom]

DM.....

 

[BE718]

yes, talking about balanced IC.

 

[Jinjuku]

You reckon balanced power fixes all CM noise?

Just for clarification when I said 'Balanced is the way to go' I was meaning balanced ICs, not balanced power. So we might have some crossed wires here

I think you can add balanced power onto that also however. T.I. has a good white paper on signaling systems where they out the red headed step child being S.E. power.