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First cycle distortion - Graham, what is that?
First cycle distortion - Graham, what is that?
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Old 23rd April 2004, 09:01 AM   #41
subwo1 is offline subwo1  United States
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Last I looked, loudspeaker drivers were passive as well. And they also store energy.
You are correct here.

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Actively convert? What's the active element in a loudspeaker driver?
It is the cone assembly including the voice coil which are coupled to the permanent magnetic field, which traderbam mentioned.

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How does calling it a motor change its fundamental electrical behavior?
It doesn't, really.

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But we're not talking about it moving in response to sound or being pushed with fingers. We're talking about it being driven by an amplifier.
But it is also pushed by the sound reflecting around inside the enclosure.

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But if you want to look at it in that context, then would you also call an inductor which is being impinged upon by a time varying magnetic field a "generator" as well?
Yes.

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Sure. So if we're talking about it being driven by an amplifier, then where does the "AC generator" come into it?
It comes in when the physical movement in the system is converted back to electrical energy.
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Old 23rd April 2004, 09:15 AM   #42
subwo1 is offline subwo1  United States
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Oh no. The resonant circuit in the speaker electric diagram is really the what you are speaking about (exchange of the energy).
The resonant circuits you show are good for our purposes to approximate the behavior of a speaker driven by an amp. In fact, the circuit values of some of the elements should be changed if any element of the physical set-up is changed, like cabinet volume or damping material, for example. I am not trying to imply that the models do not work or anything like that.
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Old 23rd April 2004, 09:24 AM   #43
runebivrin is offline runebivrin  Sweden
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On the topic of knowing what you're talking about, and in loose connection with the topic at hand:

Are step response and transient response different things?

My thinking is that a transient in the musical sense very rarely means the signal goes from zero to full amplitude in a microsecond. It's rather a question of an instrument (or several) suddenly striking a very loud note. That note would still consist of several sinusoidal ccomponents, wouldn't it?

If this is true, why would a transient be noticably harder to reproduce than the same spectrum played continously?

If the power bandwidth of the amplifier is sufficient (whatever that means...), the only thing I can think of is the power supply somehow not being instantly able to deliver the required power. As if more power requires a phone call to the power company, telling them to crank the generators.

Rune
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Old 23rd April 2004, 10:36 AM   #44
sreten is offline sreten  United Kingdom
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Originally posted by peranders
Nice explanations (but I don't understand a thing....) but how can you measure this new distortion and how does is relate to music reproduction? It seems that noone knows really what Graham is talking about.
No.

IM0 your last sentence needs rearranging.

I'm tempted to quote Barnum at this point, IMO your
assumption that FCD is a new distortion is misguided.

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Old 23rd April 2004, 10:39 AM   #45
peranders is offline peranders  Sweden
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First cycle distortion - Graham, what is that?
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Originally posted by sreten
The implication for your last sentence is the other way round.
Yeah, becuase that I think this is a product of simulation which is not the real world.

Has anyone heard it before?

What is the defenition of FCD?

Anyone who knows how FCD is measured?
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Old 23rd April 2004, 10:41 AM   #46
millwood is offline millwood  United States
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Originally posted by runebivrin
My thinking is that a transient in the musical sense very rarely means the signal goes from zero to full amplitude in a microsecond. It's rather a question of an instrument (or several) suddenly striking a very loud note. That note would still consist of several sinusoidal ccomponents, wouldn't it?

Rune

yes it would. And it stands to argue that physical instruments are less likely to produce a Dirac-like spike (you need infinite amount of force to move a mass suddenly, however small the mass is). so to produce an electronic step function, you need infinite bandwidth. But to produce anything less, you don't need infinite bandwidth.

The "first cycle distortion" is nothing but a gimic for marketing purposes, a problem created by those marketing types.
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Old 23rd April 2004, 10:53 AM   #47
traderbam is offline traderbam  Canada
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My thinking is that a transient in the musical sense very rarely means the signal goes from zero to full amplitude in a microsecond. It's rather a question of an instrument (or several) suddenly striking a very loud note. That note would still consist of several sinusoidal ccomponents, wouldn't it?
As an aside, try not to think of a step waveform as the same thing as a collection of harmonic sinusoids. It most certainly isn't. It is a step waveform.

Representing things as a sine series is just a mathematical convenience which works under special circumstances. Don't lose sight of reality.
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Old 23rd April 2004, 11:02 AM   #48
runebivrin is offline runebivrin  Sweden
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Oh, I'm not sure it's just a marketing thing. As a software developer, I do recognize a general pattern. Once the audio designers of this world arrived at designs that were essentially distortion free (in the traditional sense), and with flat frequency response, it's rather unlikely there would be consensus, and all designers would stop improving their designs.

It's certainly turned in to a game of finding problems, such that they may then be solved.

I think this is what Graham is trying do do. Whether it will prove to be real is another issue, and if it's relevant to reproduction of audio is yet another - completely different - issue, and much harder to determine.

It would make sense that Graham can hear a difference, since he wants to hear it. I don't see the point in flogging him for that, but I also don't see the point in not realizing the dangers that lie in judging the results of your own efforts.

Rune
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Old 23rd April 2004, 11:18 AM   #49
phase_accurate is online now phase_accurate
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It's certainly turned in to a game of finding problems, such that they may then be solved.
Could indeed be, but not necessarily. If a system is getting more transparent in one domain it might reveal problems in other ones that otherwise have been masked.

It is also clear that for a 100% accurate reproduction the WHOLE chain has to be able to reproduce from DC to infinity in terms of frequency response. And this is only one requirement out of many ! While the upper cutoff frequency of the amp should be quite high in order to not generate too much transient distortion one has to be aware that the real culprits in this respect are the speakers, microphones and storage media.

Regards

Charles
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Old 23rd April 2004, 11:26 AM   #50
runebivrin is offline runebivrin  Sweden
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Quote:
Originally posted by phase_accurate


Could indeed be, but not necessarily. If a system is getting more transparent in one domain it might reveal problems in other ones that otherwise have been masked.

Certainly. That's pretty much what I meant to say, with that added caveat that can be quite hard to find the problem that causes the unmasked artifacts. Several candidates may exist. You find a problem, solve it (you think), and analyze the results. Either way, you go on to uncover the next problem...

And the beat goes on, so to speak.

Rune
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