Twisting the field away...
RobM,
I can't see why your approach should improve things
... but I'm eager to learn.
The way I see it, a conductor should be twisted with it's "mate", meaning that a signal and it's return path should be twisted.
For signal lines, it's a matter of shielding them to obtain immunity against radiated noise.
In the case of a power conductor, it's to minimise the emission of noise.
The most powerful noise source in terms of radiation is between your mains transformer and the bridge rectifier, and between the rectifiers and the power supply capacitors. They're charged at high currents over short time in bursts, and it's the current that creates this field we want to minimize. The way to do this would be to
1) lower the current, which isn't really an option...
2) have the conductor and it's return path run in a tight parallel.
The resulting field of two wires carrying a current in opposite directions is ideally zero. (Not in reality, but it's close)
The twisting is a practical way of keeping them together while the fources of nature (laws of magnetism) try to push them away from each other.
In terms of the high order harmonics, it's basically the same concept, except that we're talking about the voltage drops from one end to the other which creates an antenna. Again, the vecor sum of two opposite antennas is ideally zero.
In other words, it's a matter of keeping a conducted current and it's return path close.
If you have a design where the ground is truely not carrying any current, you can leave it out. Then again, you will then no longer have a useful amplifier.
Imagine the amp turned on, and no signal applied.
Your output will be at ground potential (roughly), and the supply current/bias runs from the positive supply through the amp and output stage (especially for class A designs) to the negative supply rail and back to the supply's negative part. Then, your ground is not participating.
When a positive signal is applied to a non-inverting class B amp, the current runs from the positive supply rail through part of the output stage, then to the speaker, and back to the speakers negative terminal. This terminal is a ground line. NOW the ground is "actively" participating as is conducts current
The concept is basicallt the same for class A amps, except the entire output stage is conducting at all times.
The SUM of currents is constant (zero), and now you'll need to include the ground in your twisting of supply conductors, to avoid creating electric and magnetic fields in your amp.
I'm not native to english, but I hope this all makes sense (somehow
)
Jens
RobM,
I can't see why your approach should improve things
... but I'm eager to learn.The way I see it, a conductor should be twisted with it's "mate", meaning that a signal and it's return path should be twisted.
For signal lines, it's a matter of shielding them to obtain immunity against radiated noise.
In the case of a power conductor, it's to minimise the emission of noise.
The most powerful noise source in terms of radiation is between your mains transformer and the bridge rectifier, and between the rectifiers and the power supply capacitors. They're charged at high currents over short time in bursts, and it's the current that creates this field we want to minimize. The way to do this would be to
1) lower the current, which isn't really an option...
2) have the conductor and it's return path run in a tight parallel.
The resulting field of two wires carrying a current in opposite directions is ideally zero. (Not in reality, but it's close)
The twisting is a practical way of keeping them together while the fources of nature (laws of magnetism) try to push them away from each other.
In terms of the high order harmonics, it's basically the same concept, except that we're talking about the voltage drops from one end to the other which creates an antenna. Again, the vecor sum of two opposite antennas is ideally zero.
In other words, it's a matter of keeping a conducted current and it's return path close.
If you have a design where the ground is truely not carrying any current, you can leave it out. Then again, you will then no longer have a useful amplifier.
Imagine the amp turned on, and no signal applied.
Your output will be at ground potential (roughly), and the supply current/bias runs from the positive supply through the amp and output stage (especially for class A designs) to the negative supply rail and back to the supply's negative part. Then, your ground is not participating.
When a positive signal is applied to a non-inverting class B amp, the current runs from the positive supply rail through part of the output stage, then to the speaker, and back to the speakers negative terminal. This terminal is a ground line. NOW the ground is "actively" participating as is conducts current
The concept is basicallt the same for class A amps, except the entire output stage is conducting at all times.
The SUM of currents is constant (zero), and now you'll need to include the ground in your twisting of supply conductors, to avoid creating electric and magnetic fields in your amp.
I'm not native to english, but I hope this all makes sense (somehow
)Jens
Jennice, that was a good explanation about twisting wires.
Would you mind if I copied it for use on Decibel Dungeon? I would of course give you full credit for it.
I want to gather enough material for another page of slightly more advanced hi-fi subjects and this is the sort of item that I am looking for.
Would you mind if I copied it for use on Decibel Dungeon? I would of course give you full credit for it.
I want to gather enough material for another page of slightly more advanced hi-fi subjects and this is the sort of item that I am looking for.
How about Shielded Coax?
Something I read in Kevin O'Connor's book "The Ultimate Tone" might be applicable here...
In his discussion of the wires supplying heater filaments for tubes, he suggests twisting the wires together very tightly to reduce stray 60Hz hum from getting into signal wires, but he then suggests an even better solution would be to use shielded coaxial cable for power runs. You would connect the shield to chassis ground, connecting the twisted pair as you would normally do.
Belden makes a several different twisted pair coax cables with a seperate shield/ground that would fill the bill nicely. It might be overkill, but I've always believed that overengineered projects are better than underengineered ones. As Peter Daniel has said, it's all in the listening, though. So, I may be wrong.
Cheers.
-Erik.
Something I read in Kevin O'Connor's book "The Ultimate Tone" might be applicable here...
In his discussion of the wires supplying heater filaments for tubes, he suggests twisting the wires together very tightly to reduce stray 60Hz hum from getting into signal wires, but he then suggests an even better solution would be to use shielded coaxial cable for power runs. You would connect the shield to chassis ground, connecting the twisted pair as you would normally do.
Belden makes a several different twisted pair coax cables with a seperate shield/ground that would fill the bill nicely. It might be overkill, but I've always believed that overengineered projects are better than underengineered ones. As Peter Daniel has said, it's all in the listening, though. So, I may be wrong.
Cheers.
-Erik.
Nuuk,
You're welcome to use my description ;-)
MatttCattt:
I surely hope your signal wires are the "normal" coaxial (shielded) signal cables.
In that case there's no twisting to so there. (signal cable as in signal from input terminal to PCB).
In your PSU, twist the wires from the transformer to each rectifier bridge, and the wires from the bridge to the capacitors.
The wires from the capacitors to your PCB / output stage can be twisted (together with the ground conductor which would most likely be going to your bridge rectifiers as well). This length would then include 3 wires twisting along (V+, V- and GND).
Some of the PSU wires can be done in the "stiff" conductor used in fixed household installations. They're flexible enough to twist, but stiff enough to remain together and make a nice routing inside your amp.
No, they're not Oxygen Free Copper, No they don't have a fancy name on them,
No, they are never mentioned in any High end reviews,
But they make the world turn, and should be fine for the PSU purpose.
Happy twisting
Jens
You're welcome to use my description ;-)
MatttCattt:
I surely hope your signal wires are the "normal" coaxial (shielded) signal cables.
In that case there's no twisting to so there. (signal cable as in signal from input terminal to PCB).
In your PSU, twist the wires from the transformer to each rectifier bridge, and the wires from the bridge to the capacitors.
The wires from the capacitors to your PCB / output stage can be twisted (together with the ground conductor which would most likely be going to your bridge rectifiers as well). This length would then include 3 wires twisting along (V+, V- and GND).
Some of the PSU wires can be done in the "stiff" conductor used in fixed household installations. They're flexible enough to twist, but stiff enough to remain together and make a nice routing inside your amp.
No, they're not Oxygen Free Copper, No they don't have a fancy name on them,
No, they are never mentioned in any High end reviews,
But they make the world turn, and should be fine for the PSU purpose.
Happy twisting
Jens
Hi Nuuk,
I dropped by dB dungeon, and it looks interesting.
I've thought about setting up something similar, but never found the time and suitable online space for it.
I also have my own oppinions about cable quality - whether or not there's more to it than L, C and R (which I claim there is not; not to a level of relevance that is).
However, I'd be stoned to death by most of the people in the debate thread about this subject...
Feel free to email me at
jens@sylvestREMOVE_THIS.net
to discuss articles for your site.
Regards,
Jens
I dropped by dB dungeon, and it looks interesting.
I've thought about setting up something similar, but never found the time and suitable online space for it.
I also have my own oppinions about cable quality - whether or not there's more to it than L, C and R (which I claim there is not; not to a level of relevance that is).
However, I'd be stoned to death by most of the people in the debate thread about this subject...
Feel free to email me at
jens@sylvestREMOVE_THIS.net
to discuss articles for your site.
Regards,
Jens
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