Inductance mainly comes from wire spacing, not wire size. In any case, for most audio purposes inductance is swamped by resistance.cogeniac said:
The real issue for audio is that a speaker has an impedance which varies with frequency, in a quite lumpy way, so any significant resistance in the feed directly causes a lumy frequency response. This will be noticeable long before you get anywhere near melting wires.
Irrelevant to audio. That is speaking about RF transmission lines i.e. the frequency region where L and C dominate over R and G.
Never mind that, can my cousin borrow your submarine repeater network?
Canada is a wavelength at 20Hz away
Very old!!!
Some time ago, in the last generation of PC CRT monitors, I changed all electrolytics in the video signal (some monitors have a bunch of them, specially the Asian ones) for some mini-polyester or polypropilene ones. Always resulting in more sharpy images, and with more constant and stable white/gray scale. Some people blamed the CRT. But why? The high-end CRT operates with >100MHz clock pixel, a very fast switching one. And we know that the electrolytics have a bad manner with fast signals (not the drums in recordings, please!!!
Even the expensive Sony ones have these bad engineering practice (caps are caps, after all, and not distorts like active components, so...
Ahhh, good (recent) times. Now with these HDMI DC-coupled digital stream, why bother
LATE EDIT: the modded monitors resulting image have less overshoot and better pixel sharpness, without "ghosting" or ripples (better defined)
The elcaps original are more blurred and with some overshoot.
Yes but CRTs had an analogue signal, modern flat screen monitors the signal is digital... Spent years getting my C&'s for CRT televisions... not that useful these days.
Exactly, but for clarifiyng the "fast", if people without experience with analog video read this, some examples: one pixel black with a white background is a short/fast unidirectional pulse, and a group of black/white alternating pixels represent a very fast square wave, except at retrace time. Very fast with eg. 1600x1200@85Hz, at 2~3ns equivalent pulse time. Some video amplifiers are made for that bandwidth
The modern digital link killed my re-cap fun
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Canada is a wavelength at 20Hz away
In the electromagnetic domain, yes. 20 Hz has a wavelength of 15K kilometers.
Lambda=Vel/Freq
For electromagnetic waves, Vel=3e10^8, so the wavelength ON A WIRE, is very large.
For sound, Vel=340 m/sec (about 1M times slower than the corresponding EM wave), and the wavelength is only about 17 meters.
The self inductance of a wire is based on the ratio of the diameter of the wire and the length of the wire. Here is the formula.
A 1 meter length of #32 wire has a self inductance of about 1.8 uH. A 1 meter length of #10 wire has a self inductance of 1.3 uH.
For parallel wires the inductance predominantly depends on the spacing of the wires. Although I am not certain if this is relevant here. It depends on the wire arrangement. Once the spacing is more than a few wire diameters it will look pretty much like a single wire.
In general, this inductance is not going to play a large role since it is presumably much lower than the inductance of the speaker.
For copper wire*:
A #32 wire has a resistance of 0.54 ohms per meter. This wire can support a maximum current of 0.53 Amps.
A #10 wire has a resistance of .003 ohms per meter. The maximum current for this wire is 55 Amps.
At 8 Ohms, .5 Amps corresponds to 2 watts of audio power; 55 amps corresponds to 24kW of power!
So, while I do not disagree that any system would sound terrible with, say 2 meter #32 speaker wires (which would add 2 ohms of resistance-round trip), I suspect that at any significant listening level, the problem would also not last very long, because the wires would fuse.
Cheers!
Scott
*Handbook of Electronic Tables and Formulas for American Wire Gauge
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Inductance may seem to have little importance for audio and be swamped by resistance, but this does not apply to the internals of an amplification device where it comes to the power rails. Its is the inductance of the rails which necessitates decoupling caps, not their resistance.
I know we are discussing speaker wire, but no opportunity to start an argument will be left unused.
I know we are discussing speaker wire, but no opportunity to start an argument will be left unused.
Out of cusiosity, a flat cable, like a rectangle with very low side and very large, like ones used for "non-invasive" electric home installations, will show less inductance-to-resistance ratio than a equivalent cross-sectional area of common round wire?The self inductance of a wire is based on the ratio of the diameter of the wire and the length of the wire. Here is the formula.
A 1 meter length of #32 wire has a self inductance of about 1.8 uH. A 1 meter length of #10 wire has a self inductance of 1.3 uH.
For parallel wires the inductance predominantly depends on the spacing of the wires. Although I am not certain if this is relevant here. It depends on the wire arrangement. Once the spacing is more than a few wire diameters it will look pretty much like a single wire.
In general, this inductance is not going to play a large role since it is presumably much lower than the inductance of the speaker.
For copper wire*:
A #32 wire has a resistance of 0.54 ohms per meter. This wire can support a maximum current of 0.53 Amps.
A #10 wire has a resistance of .003 ohms per meter. The maximum current for this wire is 55 Amps.
At 8 Ohms, .5 Amps corresponds to 2 watts of audio power; 55 amps corresponds to 24kW of power!
So, while I do not disagree that any system would sound terrible with, say 2 meter #32 speaker wires (which would add 2 ohms of resistance-round trip), I suspect that at any significant listening level, the problem would also not last very long, because the wires would fuse.
Cheers!
Scott
*Handbook of Electronic Tables and Formulas for American Wire Gauge
Is a kind of newbie question, but I curious to know about the formula/theory about it.
I have a 1mm² of these wire, and maybe I purchase same lenght of 1mm² normal wire, for comparisions.
Some time ago, I measured some lenght of wire in LIMP/ARTA, and with a normal tweeter the inductance is far less tha the coil inductance for normal home use, but if we short the wire at tweeter terminals, the measured phase is 45° (inductive) at HF, since the inductance will dominate over the low wire resistance. A short wire measures 0º, and varied lenghts measure proportionally. Interesting, for a zero ohm "load" the inductance is important, but for normal loads is swamped by normal driver inductance, or even if compared to driver resistance. One will wonder about these shorted conditions...
When I tried to measure a high-feedback amp this manner, I also found this difficulty.
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Exactly, but for clarifiyng the "fast", if people without experience with analog video read this, some examples: one pixel black with a white background is a short/fast unidirectional pulse, and a group of black/white alternating pixels represent a very fast square wave, except at retrace time. Very fast with eg. 1600x1200@85Hz, at 2~3ns equivalent pulse time. Some video amplifiers are made for that bandwidth
The modern digital link killed my re-cap fun
I never really thought of it that way, but they were temperamental signals. I remember that one way of stopping videos being copied was having a pretty crappy time base signal, so when they were copied the time base signal was so bad the copy was almost unplayable...
That may be so, but it is still true that most inductance is not self-inductance but loop inductance.cogeniac said:
It is relevant, in the sense that this inductance will probably dominate over the self-inductance. It is irrelevant in the sense that resistance usually dominates at audio frequency.
Not sure what you mean here. As the loop gets bigger the inductance gets bigger.
0.5 amps into 8 ohms is 2W. This is probably well above normal listening level unless very inefficient speakers are used.
Just got that.
I hope my spoken grammar is better than my written grammar.
Or at least more gooder.��
Thanks for all the explanations, everyone.
I may have a hard time not using this ref in several diyaudio threads:
BBC - Future - The man who studies the spread of ignorance
BBC - Future - The man who studies the spread of ignorance
Not to open a political can of worms (or is that snakes?) but the Orange Turd here in America used FUD/Agnotology to his advantage on the recent election...and I see this point was not lost in the article!
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Given that as far back as 1920 cigarettes where called Coffin nails in popular press . This study is more a look at self dilution than miss information. They believed what they wanted in the face of knowledge widely told. Brown and Williamson and others just gave people who wanted to smoke an excuse to do so . More a spread of excuses than ignorance.
I have become rather sanguine in the face of such fine research.
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