I wonder if a new or old grad with a BSEE, knows how to solder? 
Okay I'll be fair, you took some course's that involve passive and active components. I put that along the lines of knowing spice and not knowing how to layout a circuit board or a chip. They are all skills, either you need them or you do not or you get someone else to do it for you.
Okay I'll be fair, you took some course's that involve passive and active components. I put that along the lines of knowing spice and not knowing how to layout a circuit board or a chip. They are all skills, either you need them or you do not or you get someone else to do it for you.
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There is no need. There is only one value of the impedance at one defined time instant (time interval limited to zero duration). At this time instant, current and voltage do fulfill and must fulfill Ohm's law. This is not changed by the fact that the impedance may be temperature, light, magnetic flux, time ... whatever dependent.
Maxwell. Hmmm. Never learned it, either. But, I am still happy and well adjusted anyway.
To compensate, i do have memorized a lot of useless information and 'facts'. We have finite time to learn and then Poof... gone. So, we are selective and specialize. There is where I went off the rails... never specialized. Maybe next time around. Nah. Too many other interesting things to do. I can always hire a specialist where needed, I suppose. Then get rid of them when their specialty becomes obsolete.
But, I must admit, it is fun working with specialists. They make the magic for the rest of us.
-RNM
To compensate, i do have memorized a lot of useless information and 'facts'. We have finite time to learn and then Poof... gone. So, we are selective and specialize. There is where I went off the rails... never specialized. Maybe next time around. Nah. Too many other interesting things to do. I can always hire a specialist where needed, I suppose. Then get rid of them when their specialty becomes obsolete.
But, I must admit, it is fun working with specialists. They make the magic for the rest of us.
-RNM
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Jim kept every lead that he trimmed off of a component while making his famous breadboards for LT app notes in a pile, it was huge.
When you take the master of none approach, I would think everything seems like magic.
What a waiste of perfectly good connection material.
I should open shop as Misertronics.
That won't happen, Joe is fixated on the concept that the "imaginary" part of the current in an amplifier is "distortion" because class A/B amplifiers fundamentally can't work if the voltage and current are not in phase. Don't expect any measurements that could cast any doubt on the story being told.
It's Ed's schtick with Ohm's law, which is enough different to how it's commonly used to catch you a little off. It's ultimately no big deal but requires re-translating each time. Oh well.
Wrt the parallel resistor drama, I had to explain to someone senior to me who hasn't touched his EE degree since undergrad that his very insistent hypothesis about our chip's fan out only makes remote sense if the trace resistance is orders of magnitude higher than the component through a biological medium (and the two contact resistances). He is otherwise a pretty bright guy, but required a couple experiments to disprove his hypothesis rather than going over it on a napkin. So evidently this is not a good intuitive for everyone.
In the resistor literature there is what is called voltage coefficient. It is different than thermal changes. Thermal changes result in odd order harmonic distortion as heating and cooling occur at different rates. Attached are the distortions of a standard carbon composition resistor. It shows both thermal and voltage distortions. Input is suppressed it is 0 dB.
Here is the AP short bit on resistor distortion. From the Test Bench: Resistor noise and non-linearity - Audio Precision
Resistors intended for use as ohmic ones may have voltage coefficients of 300 ppm.
Normally the voltage coefficient becomes an issue in high resistance units intended for high voltage applications.
SiC, Se, Si and ZnO are used to make non-ohmic resistors. These are commonly used as over voltage devices. The change in resistance is not a thermal property. Although the lower voltage types may be used to stabilize an oscillator.
FYI US3663458A - Nonlinear resistors of bulk type
- Google Patents
Here is the AP short bit on resistor distortion. From the Test Bench: Resistor noise and non-linearity - Audio Precision
Resistors intended for use as ohmic ones may have voltage coefficients of 300 ppm.
Normally the voltage coefficient becomes an issue in high resistance units intended for high voltage applications.
SiC, Se, Si and ZnO are used to make non-ohmic resistors. These are commonly used as over voltage devices. The change in resistance is not a thermal property. Although the lower voltage types may be used to stabilize an oscillator.
FYI US3663458A - Nonlinear resistors of bulk type
- Google Patents
Attachments
No that's not true, it's because you heat a resistor no matter what the polarity of the voltage is. In equilibrium the final value of a resistor with +10 or -10 V on it is the same. Symmetrical distortion like soft compressive limiting = odd order distortion.
Did you ever read Barney Oliver's paper in the HP technical journal on their original oscillator? It turns out the voltage coefficient of the filament determined the distortion and settling time at most frequencies not the thermal coefficient.
Also measurements, data and products made.
"VCR is an important characteristic of high-voltage thick-film resistors.9 Typical thick-film ink consists of conductive material suspended in an insulating matrix. As the voltage across the ink is increased, new conducting paths are opened. The result is a drop in resistance. This means that the VCR is always negative in value. "
http://carlsonmfg.com/resources/military-standards-1/2331-mil-std-202g-method-309-pdf-1/file
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I don't have much to add to what has already been discussed about your case, but may I too remind that the abovementioned condition is not possible on voltage drive; i.e. the phase of current of the single driver doesn't change anywhere by adding networks in parallel to the driver. It is also not meaningful to compare your system to current drive, as they have actually nothing in common.Joe Rasmussen said:
If your parallel network or resistor really makes an audible effect, you could check your amplifiers for low-level HF oscillations using the actual speaker as a load. They can be subtle and occur only at some point along the wave.
In EE terminology, impedances and admittances have an absolute phase angle, but signals have phase shifts relative to some defined reference. In your system, there are at least three currents: amplifier current, driver current and the network current. All have their own phase shifts relative to each other and the output voltage, and it is not always clear what is meant.
Hi Esa,
Concur with Scott. I came across the title of your book already a couple of times and will order it. I know Pavel on this thread has done some experiments and he found that especially IMD can improve a lot under current drive. I did my own experiments, but they were mixed, litteraly. So, I will come back to you after having read your contribution to the improvement of sound reproduction.
Vac
Concur with Scott. I came across the title of your book already a couple of times and will order it. I know Pavel on this thread has done some experiments and he found that especially IMD can improve a lot under current drive. I did my own experiments, but they were mixed, litteraly. So, I will come back to you after having read your contribution to the improvement of sound reproduction.
Vac
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