Tube Amps / Music Electronics
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|8/26/2004 12:17 AM|
||Re: Myth #5|
DD, that long winded explaination is bullshit.
So there is a DC voltage on that wire along with the audio AC. All that means is that the electronis in that wire are at a higher potential (or lower, depending on it's polity WRT ground) than ground. Does this mean anything, no. Will these electrons be doing anything special because of the DC bias, nope. The DC bias on the wire does not have any current flowing though it. no current means no electron motion. no motion means the electrons in the wire don't care about which end is which(and the electrons can't "point" a certain way like little magnetic poles either). Now when the plate goes positive, electrons will move from the coupling cap through the wire and into the plate. When the voltage goes back down, the number of electrons flowing will stop (at the zero crossing of the AC wave component of the signal is when the current in the wire will b zero) and then they will go in the opposite direction as the current reverses and the plate goes negative. Therefore, the DC potential of the wire relative to ground HAS NO BEARING on what goes on it it (and what about the relation of the voltage in that wire with some other arbitrary wire??? ground is after all just anarbitrary point picked for convenience's sake)
And what about things that are NEGATIVE with respect to ground, such as the grid leads of the outputs tubes in a fixed bias amplifier??? (do I wire the wire in "the other way" to compensate?)
And if the wire gave a hoot about which way it was connected, it would be a polarized component and would inherantly have nonlinearities just like how a diode is, by definition, nonlinear. Such nonlinearities would be VERY fun in an amplifier.
BTW, what are myth's #1-4, they should prove quite amusing to debunk.
|8/26/2004 7:25 AM|
Hey Boys, cool it down a bit.
For the beginners, in his "long wind" DD is correct.
He forgot one "real" AC - in the input.
From the guitar mic to grid to ground via the grid bias resistor and back to the mic.
The currents in our amps which go through the tube's plate and cathode are "varying DC".
After the coupling caps, before a cathode biased tube we are back to real AC again.
Dr. Photon, the plate doesn't go negative, it stays positive all the time. And our triodes
are actually "controllable diodes", there's no current flowing from the cath to plate, and
they are enough linear for us like their sound. But maybe you ment the grid.
They, at least in cath biased tubes, where the grid is biased to ground level,
do go from negative to positive as you said.
Now about the Wonder Wire
IF we actually do have a wire that conducts BETTER (not a diode Bill) in one direction,
it could be used in those plate - cathode circuits, as well as in other DC circuits,
where there is no reversal of the current.
I just can't see what's the benefit of it.
Maybe if the better direction resistance is markedly smaller than that of a normal wire,
in real heavy current (kA) situations, or long cables (km), there might be some use,
but in a guitar amp, I cant see the use.
Also I have problems - like Wild Bill - figuring out how such a wire,
being pure copper, could be made.
Maybe I've been too long in the jungle,
and have not followed enough of the latest in the science.
So please DD, if you have a link, or other knowledge HOW the polarized wire works,
let us know.
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|8/26/2004 10:13 AM|
Bali, you sound like you have a little more experience than some of the others.
Polarized wire works by using a c
|8/26/2004 10:51 AM|
Sorry about that. I must have pushed the wrong button.
Polarized wire works by utilizing a perfectly crystalline conductor that reduces resistance by proper alignment of the atoms making up the wire. I don't have a link for Wonder Wire specifically but according to their advertising hype Wonder Wire is a highly pure crystalline conductor.
A good explanation of highly pure crystalline conductors can be found at the following link.
Of course, I am sure that Wonder WIre does not fall into the supercondutor catagory addressed in the link but you get the idea. In theory crystalline conductors have lower resistance.
According to the Wonder Wire (WW) manufacturer, WW is a slightly polarized to the extent that it conducts better in one direction vs the other. It has something to do with how the atoms line up crystally. The directional difference is certainly miniscule because I can't detect any difference with my ohm meter. In fact, I would not hesitate to say that the difference in conductivity is in nano-ohms for any significant length.
I'm not pushing wonder wire. Someone at the top of this thread asked me for my source for silver wire which I gladly provided. I also mentioned wonder wire because it is an alternative if you feel inclinded to use silver. And certainly silver based wires are not for everybody even though I use them extensively.
If my memory serves me correctly, I believe Wonder Wire is made by the Reliable Capacitor Company (i.e., producer of Rel-Caps) but I could be wrong.
Here is what the Wonder Wire Installation notes provided with a Wonder Wire purchase say:
"The unique design and technology of Wonder Wire gives it much better sound and also some directional properties. One end of the Wonder Wire coil you ordered was marked with a red felt marker and/or bent in a loop, from positive to negative. This is also the the input end for the positive side of a correct polarity AC music signal."
"If you have any doubts about a circuit location, simply listen to a piece of Wonder Wire in both directions. The direction with more tonal balance energy (and more distortion) in the upper midrange is the wrong direction (unless of course you happen to prefer that sound in your present system). Feel free to experiment"
Now, I have to admit that I tried a piece of wonder wire in both directions and could not tell the difference. My preference at this point is for solid silver wire instead of Wonder Wire because I just don't like the idea that accidentally putting in a piece of Wonder Wire backwards can result in potentially bad sound, even if I probably couldn't hear the difference.
Hope this helps.
|8/26/2004 1:50 PM|
Bali, I like your characterization that triodes are actually "controlable diodes" because that describes exactly what they are. Diodes produce DC. Triodes, which are variable diodes, produce varying DC. Because electrons in a triode can only flow from the cathode to the plate and not the other way around, triodes can only produce current in one direction and can therfore only produce DC, albeit variable DC where the variable portion represents the audio signal.
I'm amazed that people in this thread can't comprehend the concept. I think that many of these people must be beginners. I don't fault a beginner because we were all beginners at one time.
However, I do find it very amusing when a beginner lets themselves be blinded by their own arrogance and by their own perception that they know everything to the point of refusing to understand reality and instead clinging on to an old idea that is false.
As the saying goes, old habits are hard to break.
|8/26/2004 2:08 PM|
I'm not sure anyone has taken issue with this concept. The issue is that you seem to believe that there is no pure ac component in an amplifier signal chain. If there is only "variable dc" in the audio chain, how does it get through the coupling cap to the grid?
Dont't get all full of yourself just yet dude - explain the coupling cap question first.
Dude - the coupling cap first, we're all waiting.
|8/26/2004 6:17 PM|
You guys are really chomping at the bit for the answer aren't you. I'll be brief because if I say more than a few sentences you will jump all over me for being long winded. Also, you seem to be really irritated. I like irritation when ignorance is involved.
The coupling cap question is easy to explain. Simply put, coupling caps react to both Pure AC and the Variable portion of Variable DC as well. Variable DC has an AC component to it that can be separated out by using a coupling cap. Basically it's the change in voltage that provides the coupling and not the reverse of DC current direction. DC current doesn't reverse direction.
And the AC portion of Varying DC can only be transfered across a coupling cap if there is a way to discharge the capacitor under conditions where the current doesn't reverse direction. This is because DC is not like AC and therefore doesn't automatically discharge the coupling cap by virtue of changing direction.
The discharge mechanism is through current leaking out of the cap through the grid leak resistor on the grid side and through the plate resistor on the plate side. If the cap was not connected to these two resistors it could not discharge properly under a variable DC scenario and therefore would not couple.
Now that I answered your not-so-silly question, please answer mine. How do you propose that AC is flowing through the coupling cap. What I want to know is where does the AC come from. If you are starting to buy into a portion of my variable DC theory then tell me how you see AC being derived from the varying DC. And if I still haven't convinced you of the existance of variable DC then tell me what is there that takes it's place.
And I'll tell you what -- give me your explanation and I'll quit yanking your chain.
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