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#42
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Do loudspeaker inductors have audible polarity?
"Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. |
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#43
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Do loudspeaker inductors have audible polarity?
"Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. |
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#44
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Do loudspeaker inductors have audible polarity?
"Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. |
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#45
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Do loudspeaker inductors have audible polarity?
"Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. |
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#46
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Do loudspeaker inductors have audible polarity?
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#47
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Do loudspeaker inductors have audible polarity?
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#48
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Do loudspeaker inductors have audible polarity?
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#49
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Do loudspeaker inductors have audible polarity?
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#50
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Do loudspeaker inductors have audible polarity?
"Nousaine" wrote in message ... "citronzx" wrote: "Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. And properly scented to mask the odor of the bull**** too :-[ I thought they liked the smell |
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#51
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Do loudspeaker inductors have audible polarity?
"Nousaine" wrote in message ... "citronzx" wrote: "Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. And properly scented to mask the odor of the bull**** too :-[ I thought they liked the smell |
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#52
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Do loudspeaker inductors have audible polarity?
"Nousaine" wrote in message ... "citronzx" wrote: "Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. And properly scented to mask the odor of the bull**** too :-[ I thought they liked the smell |
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#53
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Do loudspeaker inductors have audible polarity?
"Nousaine" wrote in message ... "citronzx" wrote: "Richard Crowley" wrote in message ... "citronzx" wrote ... I like your posts on 'audiophile' hogwash, keep it up! I had roommates using a green marker on their cds and trying to hear a difference. I thought that they were nuts; I had never heard of this story. Long story shot, they believed that they could hear a difference and were not interested in learning about things like studies showing very poor hearing 'memory' in people. These were not audiophile types, just regular music listeners. If you have anymore stories like this that hasn't yet been turned into a product then let's get together and make ourselves a fortune. My buddies and I joked for years about selling a line of gold-plated fuses. But then someone actually came out with them and they are making MY fortune from gullible customers. Oh, what about some sort of spray that treats the air in a listening room to make it ready to accept sound, softens it perhaps. And properly scented to mask the odor of the bull**** too :-[ I thought they liked the smell |
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#54
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Do loudspeaker inductors have audible polarity?
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#56
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Do loudspeaker inductors have audible polarity?
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#57
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Do loudspeaker inductors have audible polarity?
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#58
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Do loudspeaker inductors have audible polarity?
Parts Express sells gold plated audio grade receptacles for $154.80 each, and also gold plated cord ends for $84.80 each, the cord is cheap though, only $8.30 for 25 feet of 14 AWG, but its only 99.9 % pure copper, no gold.......good thing this is not code...... |
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#59
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Do loudspeaker inductors have audible polarity?
Parts Express sells gold plated audio grade receptacles for $154.80 each, and also gold plated cord ends for $84.80 each, the cord is cheap though, only $8.30 for 25 feet of 14 AWG, but its only 99.9 % pure copper, no gold.......good thing this is not code...... |
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#60
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Do loudspeaker inductors have audible polarity?
Parts Express sells gold plated audio grade receptacles for $154.80 each, and also gold plated cord ends for $84.80 each, the cord is cheap though, only $8.30 for 25 feet of 14 AWG, but its only 99.9 % pure copper, no gold.......good thing this is not code...... |
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#61
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Do loudspeaker inductors have audible polarity?
Parts Express sells gold plated audio grade receptacles for $154.80 each, and also gold plated cord ends for $84.80 each, the cord is cheap though, only $8.30 for 25 feet of 14 AWG, but its only 99.9 % pure copper, no gold.......good thing this is not code...... |
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#62
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Do loudspeaker inductors have audible polarity?
John Fields wrote in message . ..
On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: CJT wrote in message ... Wessel Dirksen wrote: "CJT" wrote in message ... snip Nobody commented on my observation earlier in the thread that the Earth's magnetic field could bias the hysteresis curve in certain orientations. g I personally thought you were making a joke. I was. But that sort of thing is similar to other audiophile legends. Skin effect comes to mind; nobody denies its existence, but to claim an audible effect exceeds credibility. Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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#63
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Do loudspeaker inductors have audible polarity?
John Fields wrote in message . ..
On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: CJT wrote in message ... Wessel Dirksen wrote: "CJT" wrote in message ... snip Nobody commented on my observation earlier in the thread that the Earth's magnetic field could bias the hysteresis curve in certain orientations. g I personally thought you were making a joke. I was. But that sort of thing is similar to other audiophile legends. Skin effect comes to mind; nobody denies its existence, but to claim an audible effect exceeds credibility. Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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#64
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Do loudspeaker inductors have audible polarity?
John Fields wrote in message . ..
On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: CJT wrote in message ... Wessel Dirksen wrote: "CJT" wrote in message ... snip Nobody commented on my observation earlier in the thread that the Earth's magnetic field could bias the hysteresis curve in certain orientations. g I personally thought you were making a joke. I was. But that sort of thing is similar to other audiophile legends. Skin effect comes to mind; nobody denies its existence, but to claim an audible effect exceeds credibility. Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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#65
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Do loudspeaker inductors have audible polarity?
John Fields wrote in message . ..
On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: CJT wrote in message ... Wessel Dirksen wrote: "CJT" wrote in message ... snip Nobody commented on my observation earlier in the thread that the Earth's magnetic field could bias the hysteresis curve in certain orientations. g I personally thought you were making a joke. I was. But that sort of thing is similar to other audiophile legends. Skin effect comes to mind; nobody denies its existence, but to claim an audible effect exceeds credibility. Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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#66
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
m John Fields wrote in message . .. On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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#67
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
m John Fields wrote in message . .. On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
m John Fields wrote in message . .. On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
m John Fields wrote in message . .. On 11 Feb 2004 08:11:15 -0800, (Svante) wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). Thx |
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Do loudspeaker inductors have audible polarity?
"Arny Krueger" wrote in message ...
"Svante" wrote in message m Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). |
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Do loudspeaker inductors have audible polarity?
"Arny Krueger" wrote in message ...
"Svante" wrote in message m Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). |
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#72
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Do loudspeaker inductors have audible polarity?
"Arny Krueger" wrote in message ...
"Svante" wrote in message m Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). |
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#73
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Do loudspeaker inductors have audible polarity?
"Arny Krueger" wrote in message ...
"Svante" wrote in message m Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Looks like there may be some capacitance in parallel with the coil. This would be the capacitance between the turns of wire in the coil. The capacitcance would make the coil parallel self-resonant at some frequency above the highest frequency tested. At resonance, the impedance of the coil could be far higher than that predicted by just series inductance and resistance. Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). |
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Do loudspeaker inductors have audible polarity?
On 12 Feb 2004 00:15:25 -0800, (Svante)
wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. --- ??? I wasn't aware that you were making a point... I was just reponding with a posible reason for your problem. :-) --- In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. --- You haven't described what you mean by a "match" or how the circuit is implemented, so it's difficult to keep from guessing about what you're trying to accomplish. Be that as it may, at resonance the reactances of the inductor and capacitor will be equal, but opposite in sign, and in a series circuit will cancel, leaving behind only the resistance of the circuit as the impedance. If, then, you connect the resonant circuit in series with your load: Vin----[R]--[L]--[C]--+ | [Rl] | Vret------------------+ And your load is totally resistive, the voltage across the load will peak at the resonant frequency of the LC, whe 1 f = ------------ 2pi(sqrt LC) and will fall away from the peak value on either side of resonance, with the result being that the LC will form a bandpass filter. With the circuit in parallel with the load: Vin----+-----+ | | [R] | | | [L] [Rl] | | [C] | | | Vret----+-----+ The voltage across the load will be at a minimum at the resonant frequency of the LC and will rise on either side of resonance, making the response that of a band-reject, or notch, filter. In a parallel resonant circuit (a "tank"), however, the cancellation of the reactances will give rise to circulating currents in the tank which will only be limited by the series resistance of the elements comprising the tank and the impedance will rise to a very high value. Such being the case, a parallel resonant circuit connected in parallel with a purely resistive load will be a bandpass filter, and connected in series with the load will look like a notch at resonance; exactly the opposite of the series tuned circuit. Since the inductive and capacitive reactances will be equal at resonance, for 0.22µF and 20kHz we have: Xc = 1/2piFc = 1/6.28*2.0E4*2.2E-6 ~ 3.6 ohms Then, for the inductance to have a reactance of 3.6 ohms, we have: Xl = 2pifL so, rearranging to solve for L, L = Xl/2pif = 3.6/6.28*2.0E4 ~ 2.9E-5H ~ 29µH Is that what the inductance of the coil at 20kHz is supposed to be? --- I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? --- There shouldn't be. --- The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). --- Rather than trust a simulator, I'd actually _measure_ the self-resonant frequency of the coil to determine what its distributed capacitance is or, failing that, at the very least measure the resonant frequency at a couple of places using known parallel and series capacitances in order to determine what its true inductance is at different frequencies. -- John Fields |
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Do loudspeaker inductors have audible polarity?
On 12 Feb 2004 00:15:25 -0800, (Svante)
wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. --- ??? I wasn't aware that you were making a point... I was just reponding with a posible reason for your problem. :-) --- In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. --- You haven't described what you mean by a "match" or how the circuit is implemented, so it's difficult to keep from guessing about what you're trying to accomplish. Be that as it may, at resonance the reactances of the inductor and capacitor will be equal, but opposite in sign, and in a series circuit will cancel, leaving behind only the resistance of the circuit as the impedance. If, then, you connect the resonant circuit in series with your load: Vin----[R]--[L]--[C]--+ | [Rl] | Vret------------------+ And your load is totally resistive, the voltage across the load will peak at the resonant frequency of the LC, whe 1 f = ------------ 2pi(sqrt LC) and will fall away from the peak value on either side of resonance, with the result being that the LC will form a bandpass filter. With the circuit in parallel with the load: Vin----+-----+ | | [R] | | | [L] [Rl] | | [C] | | | Vret----+-----+ The voltage across the load will be at a minimum at the resonant frequency of the LC and will rise on either side of resonance, making the response that of a band-reject, or notch, filter. In a parallel resonant circuit (a "tank"), however, the cancellation of the reactances will give rise to circulating currents in the tank which will only be limited by the series resistance of the elements comprising the tank and the impedance will rise to a very high value. Such being the case, a parallel resonant circuit connected in parallel with a purely resistive load will be a bandpass filter, and connected in series with the load will look like a notch at resonance; exactly the opposite of the series tuned circuit. Since the inductive and capacitive reactances will be equal at resonance, for 0.22µF and 20kHz we have: Xc = 1/2piFc = 1/6.28*2.0E4*2.2E-6 ~ 3.6 ohms Then, for the inductance to have a reactance of 3.6 ohms, we have: Xl = 2pifL so, rearranging to solve for L, L = Xl/2pif = 3.6/6.28*2.0E4 ~ 2.9E-5H ~ 29µH Is that what the inductance of the coil at 20kHz is supposed to be? --- I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? --- There shouldn't be. --- The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). --- Rather than trust a simulator, I'd actually _measure_ the self-resonant frequency of the coil to determine what its distributed capacitance is or, failing that, at the very least measure the resonant frequency at a couple of places using known parallel and series capacitances in order to determine what its true inductance is at different frequencies. -- John Fields |
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#76
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Do loudspeaker inductors have audible polarity?
On 12 Feb 2004 00:15:25 -0800, (Svante)
wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. --- ??? I wasn't aware that you were making a point... I was just reponding with a posible reason for your problem. :-) --- In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. --- You haven't described what you mean by a "match" or how the circuit is implemented, so it's difficult to keep from guessing about what you're trying to accomplish. Be that as it may, at resonance the reactances of the inductor and capacitor will be equal, but opposite in sign, and in a series circuit will cancel, leaving behind only the resistance of the circuit as the impedance. If, then, you connect the resonant circuit in series with your load: Vin----[R]--[L]--[C]--+ | [Rl] | Vret------------------+ And your load is totally resistive, the voltage across the load will peak at the resonant frequency of the LC, whe 1 f = ------------ 2pi(sqrt LC) and will fall away from the peak value on either side of resonance, with the result being that the LC will form a bandpass filter. With the circuit in parallel with the load: Vin----+-----+ | | [R] | | | [L] [Rl] | | [C] | | | Vret----+-----+ The voltage across the load will be at a minimum at the resonant frequency of the LC and will rise on either side of resonance, making the response that of a band-reject, or notch, filter. In a parallel resonant circuit (a "tank"), however, the cancellation of the reactances will give rise to circulating currents in the tank which will only be limited by the series resistance of the elements comprising the tank and the impedance will rise to a very high value. Such being the case, a parallel resonant circuit connected in parallel with a purely resistive load will be a bandpass filter, and connected in series with the load will look like a notch at resonance; exactly the opposite of the series tuned circuit. Since the inductive and capacitive reactances will be equal at resonance, for 0.22µF and 20kHz we have: Xc = 1/2piFc = 1/6.28*2.0E4*2.2E-6 ~ 3.6 ohms Then, for the inductance to have a reactance of 3.6 ohms, we have: Xl = 2pifL so, rearranging to solve for L, L = Xl/2pif = 3.6/6.28*2.0E4 ~ 2.9E-5H ~ 29µH Is that what the inductance of the coil at 20kHz is supposed to be? --- I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? --- There shouldn't be. --- The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). --- Rather than trust a simulator, I'd actually _measure_ the self-resonant frequency of the coil to determine what its distributed capacitance is or, failing that, at the very least measure the resonant frequency at a couple of places using known parallel and series capacitances in order to determine what its true inductance is at different frequencies. -- John Fields |
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Do loudspeaker inductors have audible polarity?
On 12 Feb 2004 00:15:25 -0800, (Svante)
wrote: Hmm. Pardon me if I am drifting off topic here, but I and a collegue of mine recently noticed a quite noticeable deviance from the Z=wL in the impedance of inductors in the HF range. These inductors were made of standard ~0.3mm (I'll have to check this) wires and no iron core (for loudspeaker crossovers). Any explanation to this, apart from skin? http://www.tolvan.com/coil.gif Note that I don't claim big *audible* effects from this in most applications, though. --- Probably because Z does _not_ equal wL, inductive reactance (Xl) does. That is, Xl = wL = 2pi*f*L OK, you are right, but you got my point. --- ??? I wasn't aware that you were making a point... I was just reponding with a posible reason for your problem. :-) --- In a series circuit containing resistance, inductance, and capacitance, the impedance (Z) of the circuit will be equal to the square root of the sums of the squares of the resistance and the square of the difference between the inductive and capacitive reactance. That is, Z = sqrt (R² + (Xl - Xc)²) Of course, in a circuit containing only inductance, the inductive reactance and impedance will be equal. However, such a scenario is impossible and the effects of capacitance and resistance must always be considered if accuracy is important. Looking at just the inductor, since there is a voltage difference between turns and the turns are dielectrically isolated from each other, that gives rise to an inherent capacitance and since there is resistance in the wire used to wind the inductor, that's also part of the inductor and can't be separated from it. There are winding techniques used to minimize the capacitance (which appears to be in _parallel_ with the inductance) but in the case of coils wound for loudspeaker crossovers, I'd seriously doubt whether the slightest consideration was given to them. Just to test the possibility of a parallel capacitance I entered it into the program (it's another coil now, I could not find the first one again). It turns out that I can get a pretty good match if I parallel the coil (0.22mH, 0.7 ohm) with a (capacitor in series with a resistor) of 0.22 uF and 33 ohm. However, the resonance frequency of this circuit will be just above 20 kHz (the limit of the soundcard) and I get the feeling that the match will be very poor at higher frequencies. Also, a stray capacitance of 0.22 uF appears very much, so I don't beleive in it. --- You haven't described what you mean by a "match" or how the circuit is implemented, so it's difficult to keep from guessing about what you're trying to accomplish. Be that as it may, at resonance the reactances of the inductor and capacitor will be equal, but opposite in sign, and in a series circuit will cancel, leaving behind only the resistance of the circuit as the impedance. If, then, you connect the resonant circuit in series with your load: Vin----[R]--[L]--[C]--+ | [Rl] | Vret------------------+ And your load is totally resistive, the voltage across the load will peak at the resonant frequency of the LC, whe 1 f = ------------ 2pi(sqrt LC) and will fall away from the peak value on either side of resonance, with the result being that the LC will form a bandpass filter. With the circuit in parallel with the load: Vin----+-----+ | | [R] | | | [L] [Rl] | | [C] | | | Vret----+-----+ The voltage across the load will be at a minimum at the resonant frequency of the LC and will rise on either side of resonance, making the response that of a band-reject, or notch, filter. In a parallel resonant circuit (a "tank"), however, the cancellation of the reactances will give rise to circulating currents in the tank which will only be limited by the series resistance of the elements comprising the tank and the impedance will rise to a very high value. Such being the case, a parallel resonant circuit connected in parallel with a purely resistive load will be a bandpass filter, and connected in series with the load will look like a notch at resonance; exactly the opposite of the series tuned circuit. Since the inductive and capacitive reactances will be equal at resonance, for 0.22µF and 20kHz we have: Xc = 1/2piFc = 1/6.28*2.0E4*2.2E-6 ~ 3.6 ohms Then, for the inductance to have a reactance of 3.6 ohms, we have: Xl = 2pifL so, rearranging to solve for L, L = Xl/2pif = 3.6/6.28*2.0E4 ~ 2.9E-5H ~ 29µH Is that what the inductance of the coil at 20kHz is supposed to be? --- I suspect the resistance of the wire is what's causing the deviation from "ideal" inductance, and I also suspect that skin effect has _nothing_ to do with it since that's an effect which starts to become significant at radio frequencies. You say that you suspect the resistance to be responsible for the increased impedance. Is there another effect than the skin effect that could cause the resistance to increase with frequency? --- There shouldn't be. --- The new curve fittings can be seen at: http://www.tolvan.com/coil1.gif blue curve is the impedance of a model (0.22mH 0.7 ohm), red curve is the same model paralleled with 0.22uF+33ohm, black is measured data. Don't pay too much attention to the measured phase curve, I have a delay between channels that ruins the HF phase response. A photo of this particular coil is available at: http://www.tolvan.com/coil1.jpg wire diameter 0.9mm, inner diameter 28 mm, outer diameter 38 mm, height 13 mm. Could you or someone else verify that coils really do like this? I have used different soundcards and differenct coils for the measurements, but the same home-brewed program, so it would be nice with a verification from someone else. A 10 ohm resistor produces a straight line within 0.2 ohm using the same equipment (phase is -130 degrees at 20kHz due to the delay I mentioned :-( ). --- Rather than trust a simulator, I'd actually _measure_ the self-resonant frequency of the coil to determine what its distributed capacitance is or, failing that, at the very least measure the resonant frequency at a couple of places using known parallel and series capacitances in order to determine what its true inductance is at different frequencies. -- John Fields |
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
om Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). How many feet of wire in that coil? There might be something like 30 pF of stray capacitance per foot of wire in the coil. |
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#79
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
om Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). How many feet of wire in that coil? There might be something like 30 pF of stray capacitance per foot of wire in the coil. |
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#80
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Do loudspeaker inductors have audible polarity?
"Svante" wrote in message
om Do you think that a 0.22 uF stray capacitance is likely in this case? That is what the red curve is (+ 33 ohm in series with the capacitance for best fit, modeled). How many feet of wire in that coil? There might be something like 30 pF of stray capacitance per foot of wire in the coil. |
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