Wow how profound, a normalized to f=1 plot of any RC network (45 degrees at -3db). What on earth does this have to do with amplifier stability/"delay"?
John, Seems like the recent rumble has 'em hiding in the alleys. Since I don't know math very well I just watch in amazement when these "my math is better than yours" arguments ramp up to chest bumping. Electronics is like plumbing to me.
Edit: Oh wait! it is starting again! where is my popcorn?
Edit: Oh wait! it is starting again! where is my popcorn?
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Actually, it is a very good explanation for a digital IIR (infinite impulse response) recursion filter topology.
But it's kinda incorrect when dealing with discrete analog circuits.
jn
The 'wires as pipes' analogy is meant to get complete newbies starting on the basics of wiring a simple battery-switch-lamp circuit.morinix said:
Would you hire a lawyer who was only semi-literate? Or a composer who couldn't read music? So why is maths regarded as an optional extra (or even a handicap!!) for audio engineers?
Validity of the mathematical statement of the problem is not a matter of opinion. I am curious, I assume positron's A,A1...An are the A term in the standard textbook form of Black's equation. I would like to see a text that describes the signal going round and round with a delay each time.
Save your popcorn, TROLLHUNTER (Official Movie Site) - John M. Jacobsen presents A Film by Andre Ovredal - Available on DVD and Blu-ray? - Trailers, Pictures & More
A story for another day, amazing compactness of expression compared to FIR or overlapped FFT filters. I assume folks here are looking for input on the behavior of analog contiuous time systems. On that note a good test vector is a raised cosine pulse (for audio 20kHz will do), one will notice the distortion there immediately in the residual. We just did this at 2 and 5MHz for an ultrasound customer.
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The third is using results of works of others to draw conclusions and design own products based on them. It can be quite effective.
Gee, and I was hoping for some 'peace'. Oh well, forward we go!
I think that anyone out there who was not able (or willing) to learn calculus can still get a practical grasp of the subject, easiest, by a video course, that you can learn 'online' these days. Of course, you will not, because don't need to do ALL the drudgery of solving all kinds of problems, become 'proficient' or expert like many here claim to be, BUT you can understand the ESSENCE of calculus, which is a different way of looking at things, and worthwhile.
I think that anyone out there who was not able (or willing) to learn calculus can still get a practical grasp of the subject, easiest, by a video course, that you can learn 'online' these days. Of course, you will not, because don't need to do ALL the drudgery of solving all kinds of problems, become 'proficient' or expert like many here claim to be, BUT you can understand the ESSENCE of calculus, which is a different way of looking at things, and worthwhile.
Yes, but it is non-issue in analog audio design, because it is way beyond throughput of an amplifier.
In this particular case it is used as the result of gross misunderstanding of feedback. As Scott suspected, thrown here for trolling purposes by a team with popcorn.
Is it rhetoric question about speed of light and "length of signal path" in wires as pipes?
Tote them metaphors! Lift that barge!
Very nice.
Thank you, but my analogy is incomplete. For analog system equivalent some additional hysteresis is required, to add one more loss of an information. Like in oscillator on 555 timer, for example.
We used a TEK arb generator in this case because its 12bits was more than the 10bit answer we were looking for. I think to illustrate a point, i.e. an amplifier with known crossover distortion you could use a 24/96 sound card and a good buffer. Averaging is fair to use here. In our case we could see the crossover at 2MHz and then some slew problems kicked in at 5MHz. There were only three-four cycles but first and last were the same, the important point is that for this closed loop amplifier the very first 1/2 cycle zero crossing contained all the harmonics of the crossover distortion.
So there, another anyone can do this at home experiment, de-bias a simple DIY class A/B amplifier and see it yourself.
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Just to help the unfamiliar, newbies. Another example of the relationship between gain and phase from a simple RC network. Is that so wrong to help people? The text with the graph was benign, and I posted later that it was not confrontational or "teaching" you as I was falsely accused of twice.
Moderator, I thought the attacks have stopped, but I see now. They are not helpful to the discussions.
Cheers.
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It is a reasonable approximation to a signal that is somewhat BW limited and can have a high crest factor. The purpose is to provide counter evidence for things like first cycle distortion and other proposed phenomena. Our use this time had nothing to do with audio but I thought it might be of use there. A suddenly applied sine wave has a confusing amount of out of band signal.
So does a suddenly discontinued sine wave. Remember Hawksford's essex echo paper?
A sinx/x running 20 khz would be a very interesting stimulus when the output stage has multiple paralleled devices each with their own emitter resistors. I wonder how the current will share at that freq given R's about 100 to 300 milliohms with self inductances from geometry...
jn
ps. Personally, I'd superimpose that on a high power 20 hz sinewave to see how each output half responds when driving a reactive load through all 4 quadrants.
A conceptual example of time delay vs. phase shift is the transit time of electrons in a vacuum tube (valve), time delay, as opposed to their charging of capacitances at the anode, phase shift. (At and way above audio frequencies the transit time is negligible, but it comes into play at VHF).
Thanks,
Chris
Thanks,
Chris
That was not me saying that, but throwing in a simple RC plot does not seem to move forward. The statement of a "typical" audio PA having 20usec "delay" was made, the counter example was provided in the form of a plain old chip amp. Still waiting for a bonafide text that teaches the feedback looping around with a path delay.
Getting ahead a little aren't we? For the purpose at hand the raised cosine pulse has enough BW limiting to demonstrate the basic principle. BTW in your abve example wouldn't a doublet kernel (raised sine) have more symmetry for class A/B outputs?
EDIT - Sorry if I wasn't clear by raised I meant a cosine pulse with gaussian envelope.
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Yes, real. Yes, measurable- you subtract the minimum phase delay from the frequency response from the output. Order of magnitude in practical amplifiers is a few dozen nanoseconds or less (much less for IC amps). It's something you have to pay attention to in video amps, but not audio. Its invocation as the somehow neglected factor in audio amplifier feedback (like the "round and round" argument) is a sure indicator that there's a fundamental non-understanding of how electronics works.
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