I have not directly measured it, but years ago I started with in-line commercial filters. Later, I decided that most of these filters were not made with high enough quality components, and I started just using common mode filters with other quality components, because they were small and convenient, yet offered some real series impedance at high frequencies that must help reduce RFI. Still, I can't actually prove it, at the moment. All of my latest power supply designs have common mode filters added, however. Better safe than sorry.
Now that's irony. Sending away the guy that gets continously affronted by Steve Eddy.
While I highly respect Steve Eddys posts, I would wish that you relax a bit. I envy you honestly for your persistance and all the energy you put into barking at John Curl. I do not say your posts contain no interesting points, it's the way you argue. It's more like a bombardment and not a respectfull discussion.
I can only kindly ask you to relax a bit, open a can of your favourite lager and see the discussion here as relaxation. Man, that's a hobby and that should be fun! All those blood pressure levels! Nobody wants to see the headline 'xxx died of a heart attack in front of his computer, arguing in DIYAudio' (xxx being the participant with the weaker heart).
With that aggressive undertone it more looks like trying to establish credibility by a forced search for errors in the posts of a well known and respected designer. I do not think that you are in need of this.
This is not meant as offence, if it appears as that I'm sorry for my improper english, as I'm not a native speaker.
All the best and have fun! Hannes
PS: as I believe I speak for many, I'm wondering that nobody says so. Is it really only the fact that John Curl is here in the forum less known than Nelson Pass? Because I imagine that Steve Eddy would get immediately stoned in the Pass Labs forum.
Steve will never be happy with what John is describing, no matter what is said. He wants to pick up an individual electron with a pair of nano-tweezers and name it Bob, then force John to admit that the specific electron "Bob" does not cross between the primary and the secondary. To Steve, this will count as victory. To me it is pointless arguing about how many angels can dance on the head of a pin because it's irrelevant whether the specific electron makes it from one side of the transformer to the other--the magnetic coupling is sufficient that its doppleganger Bob' carries the same characteristics on the other side. Steve sees this as a discontinuity proving his point. No one else agrees.
As for high quality filters, consider something like a cap. A perfect cap will respond mathematically perfectly at all frequencies. Real caps have a bandwidth limitation. For example, the lowly ceramic disc capacitor happens to work nicely at very high frequencies, like RF. An electrolytic ceases to exist as a capacitor well below that level. That's not to say it wouldn't filter lower frequencies, but it would hardly work at all above a few tens of thousands of Hz, if it even managed that much. It used to be that electrolytics started rolling off at just a few kHz. I confess that I haven't looked at that in a while. Hopefully they're better now, though they still won't go very high. At any rate, to look in a power line filter (separate and distinct from a power supply filter in a preamp or amp) and see an electrolytic in a position clearly intended to filter RF would tell you that the filter was of poor quality.
John,
You mentioned common mode chokes. How do you feel about about a straight choke for the ground line?
Grey
As for high quality filters, consider something like a cap. A perfect cap will respond mathematically perfectly at all frequencies. Real caps have a bandwidth limitation. For example, the lowly ceramic disc capacitor happens to work nicely at very high frequencies, like RF. An electrolytic ceases to exist as a capacitor well below that level. That's not to say it wouldn't filter lower frequencies, but it would hardly work at all above a few tens of thousands of Hz, if it even managed that much. It used to be that electrolytics started rolling off at just a few kHz. I confess that I haven't looked at that in a while. Hopefully they're better now, though they still won't go very high. At any rate, to look in a power line filter (separate and distinct from a power supply filter in a preamp or amp) and see an electrolytic in a position clearly intended to filter RF would tell you that the filter was of poor quality.
John,
You mentioned common mode chokes. How do you feel about about a straight choke for the ground line?
Grey
Thank you Grey for explaining what the question was, and the 'trick' to it. I suspected to be so, but I could not be sure.
Yes, Bob the single electron, (if he even exists
) will probably never get to the other side, but he, with the help of his comrades (or all they the same electron?) will impart whatever information he carries to the 'other side' of the transformer.
Electrons were not even discovered when Ohm, Faraday, Maxwell, and Kirchhoff were alive, and they wrote the rule book. How did they get away with it?
Yes, Bob the single electron, (if he even exists
) will probably never get to the other side, but he, with the help of his comrades (or all they the same electron?) will impart whatever information he carries to the 'other side' of the transformer.Electrons were not even discovered when Ohm, Faraday, Maxwell, and Kirchhoff were alive, and they wrote the rule book. How did they get away with it?
Grey, I don't understand your question completely, but I have experimented with air coil chokes in series with the center tap, and with full dual choke input power supplies. Both work.
The common mode choke is convenient, because you can get relatively high dual inductance in a relatively small case size and cost, and adequate working current.
PI or CLC input filters are a favorite of mine as well.
If we had Charles Hansen of Ayre, here, and he was inclined to give his personal info and experience, you would learn even more. He goes even further than I do in addressing these issues.
The common mode choke is convenient, because you can get relatively high dual inductance in a relatively small case size and cost, and adequate working current.
PI or CLC input filters are a favorite of mine as well.
If we had Charles Hansen of Ayre, here, and he was inclined to give his personal info and experience, you would learn even more. He goes even further than I do in addressing these issues.
john curl said:
John,
I don't understand this. The common mode chokes rely on the fact that both currents are of opposite phase but equal; that way you can get a high L in a small box. Like in a mains filter where you always are sure that the currents *are* equal and in opposite phase.
But in +/- power supplies the two currents are not equal, almost by definition not, not even in a class-A amp. So how would that work then?
Edit: I think in a class-A amp it *would* work though.
Jan Didden
john curl said:
John,
I wish he (Bybee) wouldn't insult my intelligence with the absurd hubris on his web site. He does after all claim to change the velocity of light in a cable an easily verifyable claim.
But one thing I've learned from our customers is that people easily agree on quality issues in video. It's a whole different ball game than audio, and furthermore quick A/B switching makes even the subtlest differences obvious.
Sooooo. where can I see the Bybee conditioners 'purifying' my HD image or even changing it. Do I put them on the power line or on the HDMI cable?
Steve will never be happy with what John is describing, no matter what is said. He wants to pick up an individual electron with a pair of nano-tweezers and name it Bob, then force John to admit that the specific electron "Bob" does not cross between the primary and the secondary. To Steve, this will count as victory. To me it is pointless arguing about how many angels can dance on the head of a pin because it's irrelevant whether the specific electron makes it from one side of the transformer to the other--the magnetic coupling is sufficient that its doppleganger Bob' carries the same characteristics on the other side. Steve sees this as a discontinuity proving his point. No one else agrees.
_ GRollins
Yes, Bob the single electron, (if he even exists ) will probably never get to the other side
_ john curl
Hmmmmmmmm, well at least Mr. Curl somewhat agrees.
P.S. Grey, angels don't dance on pins.
BC
_ GRollins
Yes, Bob the single electron, (if he even exists ) will probably never get to the other side
_ john curl
Hmmmmmmmm, well at least Mr. Curl somewhat agrees.
P.S. Grey, angels don't dance on pins.
BC
Hi Scott, once again your conservatism is showing.
For DVD and CD, I meant AUDIO, not video. They have audio connections too, please remember.
Soon, I am told, a review of the newer Bybee devices will be put forth in 'The Absolute Sound' by a physicist who has the clearances to be told HOW the Bybee actually works, and who has signed a non-disclosure agreement with Jack Bybee so that he won't 'let the cat out of the bag' so to speak. I hope it will come out and will reveal greater insight than we have now.
Personally, I don't have to know WHY something works, only that it works for me. Jack doesn't care to tell you or anyone else exactly why his stuff works, but I have never seen a direct lie coming from him or his website. Just a confusion of information.
Jack doesn't need further business, he is already overwhelmed by orders. I don't know why he still bothers, as he is independently wealthy already from previous endeavors, such as re-chipping auto computers for better performance. He did all this more than 20 years ago. He does the audio thing, because he likes audio, himself, and likes to help his friends and other audiophiles.
For DVD and CD, I meant AUDIO, not video. They have audio connections too, please remember.
Soon, I am told, a review of the newer Bybee devices will be put forth in 'The Absolute Sound' by a physicist who has the clearances to be told HOW the Bybee actually works, and who has signed a non-disclosure agreement with Jack Bybee so that he won't 'let the cat out of the bag' so to speak. I hope it will come out and will reveal greater insight than we have now.
Personally, I don't have to know WHY something works, only that it works for me. Jack doesn't care to tell you or anyone else exactly why his stuff works, but I have never seen a direct lie coming from him or his website. Just a confusion of information.
Jack doesn't need further business, he is already overwhelmed by orders. I don't know why he still bothers, as he is independently wealthy already from previous endeavors, such as re-chipping auto computers for better performance. He did all this more than 20 years ago. He does the audio thing, because he likes audio, himself, and likes to help his friends and other audiophiles.
MikeBettinger said:
But common mode chokes don't work there, because the two currents are unequal. One reason CM chokes can be built so small is that the differential current - the differences between the two - are small to non-existing, so the fields cancel to a great extend, allowing a core that is small.
But as soon as you put in a differential current, which is the case before or after the rectifiers, you have a large differential current, your core saturates, the L collapses and the CM choke doesn't do diddly. So it isn't true that "the common mode choke is convenient, because you can get relatively high dual inductance in a relatively small case size and cost, and adequate working current".
Jan Didden
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