Actually, I found DUP to be incredibly ignorant on almost any technical area you can name.

But, I think the main reason he was booted was that he would enter a discussion of subwoofers and spew out 4000 words about the 3rd chapter of "War and Peace" or computer hard drives before he was momentarily finished....

The people who need to know my name here, whom I respect and have something in common with do know it. I shant give it to the likes of you though, pal. Why would I possibly do that? It makes no difference whatsoever..

Post yours if it gets your rocks off.

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It would also be nice if you would finally give your name and where you work, since you claim to be a recording engineer.

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Check out this as one easy source: http://en.wikipedia.org/wiki/Slew_rate

Yes, I know how to take the derivative of a sine wave. That's freshman calculus. What I said was that slew rate and bandwidth are not in general related. I'm referring to the bandwidth of the amplifier here, not the frequency of the signal.

Let's take the example of an op-amp or op-amp-like circuit with Miller frequency compensation, whose output stage has a gain of 1.

The gain-bandwidth product of such an op-amp in rad/sec is gm/C where gm is the input stage transconductance and C is the Miller compensation capacitor value. Also, the slew rate in Volts/sec is Imax/C, where Imax is the maximum output current of the input stage. You can easily see from the above that one can keep the gain-bandwidth product (and thus the bandwidth of the amplifier at a fixed gain) constant by multiplying gm and C by the same factor, call it K. Let's say K=0.5. If the input stage bias current is not changed, then the maximum output current of the input stage has not changed either. However, because K=0.5, the compensation capacitor has been cut in half, along with the input stage transconductance.

So what we've done in this case is keep the bandwidth of the amplifier constant, yet doubled the slew rate (because we've cut the compensation capacitor in half). That's what I meant by the amplifier bandwidth and slew rate being unrelated in general.

There are examples such as the AD797 in which the gain-bandwidth product is very large (100 MHz in this case), yet the slew rate is quite modest (20 V/uS in this case). You'll also find other op-amps whose GBW is not nearly as large, yet their slew rate is much larger. FET input op-amps have this property exactly because of the reduced input stage transconductance as mentioned in the example above.

It has been a long time since studying this in depth and the math. In fact, we did not have ICs in college. I also wonder how this applies with regards to tube circuits?

From Semiconductor and tube electronics, by James Frazee (college textbook), page 281

"For a given amplifier,

Av BW = Gm/Cs in radians/sec

equation states that the gain-bandwidth product is a constant, meaning that any attempt to increase the gain must be done at the expense of bandwidth. And conversely, an increase in bandwidth may be achieved only by a similar decrease in gain."

(For newbies, if the gain is increased then the bandwidth must be decreased in order to maintain the same gain bandwidth product. Conversely, if the bandwidth is increased then the gain must be decreased to maintain the same gain bandwidth product.)

If one reduces the miller compensation capacitor, has not the rise time changed because of less miller capacitance?

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The people who need to know my name here, whom I respect and have something in common with do know it. I shant give it to the likes of you though, pal. Why would I possibly do that? It makes no difference whatsoever..

Post yours if it gets your rocks off.

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It would also be nice if you would finally give your name and where you work, since you claim to be a recording engineer.

I always have to question the motives of those who have to hide and refuse to identify themselves. Yes it makes a difference considering your past posts. Is "southeastern sector" accurate? We know it does not necessarily mean southeastern usa.

It could mean southeastern sector of NY considering your job description. That is right, you claim to be a recording engineer while working for the government. My name is right there in my profile, for the public to see, or at my website.

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If one reduces the miller compensation capacitor, has not the rise time changed because of less miller capacitance?

If only C is cut in half, then the rise time will indeed be cut in half as well. But in my example above, gm was cut in half along with C. This keeps GBW constant, and therefore the rise time will be the same when the amp is not in slew rate limiting. That's the advantage of FET input op-amps as opposed to those with undegenerated BJT inputs - the transconductance is less for a FET input stage, so a smaller C can be used for the same GBW, giving a higher slew rate.

I don't know how this relates to tube amps, as I'm from the solid-state world. But if the rise time is always constant with changes in signal amplitude, that's a good thing, as the amp is acting linearly and not in slew rate limiting. An input LPF to a SS power amp is often used to ensure the amp has that property (and for RFI protection as well).

Anyway, I'm getting way off topic here.

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There are a few problems with that notion. For one thing, if all equipment is subjective, then there is no such thing as bad piece of gear because no matter how subjectively bad something may be, there will always be someone who likes it.

Secondly, if measurements are irrelevant and it's all subjective anyway, then, there is no reason to strive to make objectively better equipment. All that one has to do is provide different syrup flavors.

Finally, if there is no objective definition of "good" or "reference", then there is no such thing as snake oil. Anyone can sell you anything, no matter how ludicrous and there will always be someone who claims that a particular piece of poop placed in a particular bowl at a particular time of day made their music sound (place your favorite adjective here).

By getting down to the factors that matter most, we can place an objective definition of "good" and we can place a value, whether monetary or enjoyment value on a particular component. This allows us to develop an objective reference and to strive to improve components to equal or surpass the reference.

Alex-

Very eloquently stated please let ncdrawl know so that he can promptly set you straight by blowing you off by saying how obvious it is that you are wrong.

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If one reduces the miller compensation capacitor, has not the rise time changed because of less miller capacitance?

If only C is cut in half, then the rise time will indeed be cut in half as well. But in my example above, gm was cut in half along with C. This keeps GBW constant, and therefore the rise time will be the same when the amp is not in slew rate limiting. That's the advantage of FET input op-amps as opposed to those with undegenerated BJT inputs - the transconductance is less for a FET input stage, so a smaller C can be used for the same GBW, giving a higher slew rate.

I don't know how this relates to tube amps, as I'm from the solid-state world. But if the rise time is always constant with changes in signal amplitude, that's a good thing, as the amp is acting linearly and not in slew rate limiting. An input LPF to a SS power amp is often used to ensure the amp has that property (and for RFI protection as well).

Anyway, I'm getting way off topic here.

Thanks for the information Andy. I was looking at it from a tube standpoint.

It is interesting since tubes (no feedback) really have little problem with distortion at higher frequencies, no slew rate problem (say -3db point or less). Yet slew rate figures are given with tube components.

That is why I mention that one can simply raise the B+ voltage in order to publish a higher slew rate, or raise the frequency and get a higher slew rate figure. The formula I posted can be used for any frequency as long as it is not distorting severely, which shows a correlation when using that formula.

If an output capacitor is going to charge faster from a pulse, 1/2 the capacitance and transconductance, and same .5 amps, then haven't we actually changed the frequency response since the slope is more vertical?

I get the feeling that two different formulas and criteria are being used for ss and tubes.

That is it for tonight. Thanks Andy.

haha... ncdrawl makes me laugh. Of course everything is subjective to a guy who collects SS Nazi memorabilia. Maybe that's also the reason why you keep refusing to answer my question, nc, when I ask you why you went back on your word to be appalled about a certain member of this forum saying that Holocaust never happened, if that were true? Three times now already. Whatever. Just stop the verbal diarrha please.

On the subjectivist notion: to a point I agree because it's just an obvious point. Of course we are our own ultimate judges, because we have our own preferences. But to believe that there isn't some kind of a standard in any literary, visual or musical arts is to ignore the centuries of cultural history. I'm sure there were asses who thought Clementi was the bigger talent than Beethoven back in the day, because that's what their ears told them so... and guess what, according to your standards, they were fricking right! Of course, because their own ears told them so, and they were subjectively right, huh?

Undoubtedly, critics get it wrong SO many times. But there are critics who get it, and establish a cultural heritage. I'm thinking of Walter Benjamin's championing of Proust and Kafka. etc. etc. Same with audio critics. These people get it wrong a lot of times, but also get it right a lot of times, and not only that, by the fervor of their belief and writing, cultivate a way of listening and encourage the designers who build.

So it offends that they write so unequivocally? Umm, they are PAID to voice their opinions. They offer their opinions for people to agree or disagree with. Why you view their opinions as some mind-washing vendetta against you or some person is beyond me, ncdrawl. From some of the recent posts you've written in this forum, your pomposity is reaching beautiful new heights.

Bravo.

you describing my posts as arrogant makes me laugh, Mao.

you've been at this "hifi" thing all of what, a year and some change? yet you constantly shoot off as if you were anything other than a wet behind the ears don't know dick kid..... now THAT is pompous. and deluded.

the Nazi references-- nice touch. made me smile.

oh yeah, I hate to mention this again, but there is a wonderful spell check feature built right into firefox.

Bis Bald!

Der Doppelg

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Very eloquently stated please let ncdrawl know so that he can promptly set you straight by blowing you off by saying how obvious it is that you are wrong.

tsk tsk..run-on sentence!! outside of that, the damned thing is so disjointed..well , it doesn't make any sense.

First of all, you don't see me here beating someone over the head that his ideas about audio are wrong, do you? No. Because I respect something called civility, Mr. Nazi-memorabilia-collecting-audio-pomeranian-from-hell. And again: the evasion with the Nazi thing. For a guy who supposedly values straight talk and no-nonsense philosophy about everything, you sure love that cowardly retreat. Face it. I saw it, a lot of other people saw it, when you said you'd be disgusted if DUP did indeed say Holocaust didn't happen. You accused me of actually making shit up. Then when it surfaced that I was actually right, you disappeared behind your wall of silence. And how amusing that you pleasantly divulge that you collect SS-Nazi collectibles. Kant wrote that the aesthetic ability to appreciate the sublime in art was related to one's moral sense. You're the living proof that he was right.

Just stop your ugly barking.

pretentious name dropping: proust, kant, checkov- check

talking a lot without saying anything: check

accusing those with opposing viewpoints of being "Nazis"- check

it has just dawned on me. you are a perfect sidekick for KBK. you two could wax "intellectual" and name drop dead people endlessly! a merging of two great minds..oh the potential!

"You got to have smelt a lot of mule shit before you can sing like a hillbilly.

Yeah, yeah, shut your hole. Go shine your Hitler bobble-head... I didn't accuse you of being a Nazi, pomeranian. You're the one who offered up the info that you collect SS Nazi memorabilia, and you're the one who refuses to answer re: Holocaust denial. Again, others have seen you dodge that question, it's not just me. Get a backbone, all right?

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checkov- check

lol, for someone who hallucinates correct spelling, this is a laugher. And when did I mention Chekhov? Are you making shit up again, ncdrawl?

haven't heard from you in a while self. too bad you picked this one to come back on. some of these guys make me long for dup to return. better the devil you know right? at least he made you laugh. these guys are much worse and are not funny. don't sink to their level man.

hey, I just return the love im given, killer.
and for Mao,

my bad, it was Kafka. getting my dead russians mixed up. I dont name-drop them endlessly you see..

Die F

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my bad, it was Kafka. getting my dead russians mixed up. I dont name-drop them endlessly you see..

Die F

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haven't heard from you in a while self. too bad you picked this one to come back on. some of these guys make me long for dup to return. better the devil you know right? at least he made you laugh. these guys are much worse and are not funny. don't sink to their level man.

You're right, Tom. There were many moments when DUP did have that weird sense of humor that worked for him... sorry about 'sinking down' to this level, but it's just too fun watching ncdrawl dig his own grave!

Sorry, Ethan. Apologies.

Ethan,

Did you notice how there is a hate triangle going on these forums. A hates B who hates C who hates D who hates E who hates Z who hates A.

Seems as though there is not a single person on these forums who can get along with everyone else.

you are a liar, Mao.

verbal diarrhea? I may be an asshole, but id much rather live with that than to be a pretentious, wet behind the ears know it all. All bombast, no substance. Have you considered being an audio reviewer?

off to the range! Got a new handgun today, gonna go break er in..

Bis Morgen

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Ethan,

Did you notice how there is a hate triangle going on these forums. A hates B who hates C who hates D who hates E who hates Z who hates A.

Seems as though there is not a single person on these forums who can get along with everyone else.

I dont "hate" anyone. I do hate how some present themselves here.. I can get along just fine with anyone, provided they aren't too sensitive, uppity, fake, or stupid.

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you are a liar, Mao.

verbal diarrhea? I may be an asshole, but id much rather live with that than to be a pretentious, wet behind the ears know it all. All bombast, no substance. Have you considered being an audio reviewer?

off to the range! Got a new handgun today, gonna go break er in..

Bis Morgen

Wait, remind me what I lied about? All the shit that you couldn't back up, all the times you hid behind the wall of silence is documented in this forum. Are you playing with your imaginary friends or something? What the hell...

I guess all that proof about you having no integrity or the balls to admit the truth DOES bother you. Congratulations on having human feelings. Have you read all the threads you've posted on? And you can accuse anyone of bombast? Let's not even talk about substance. We'll go there when you're man enough to own up to your words.

According to your own personal standards of what is too "sensitive, uppity (now THERE'S a nice, precise term), fake, or stupid."

Great, ncdrawl. If only you were King. Then you could have everyone who doesn't measure up to your standards summarily hanged.

nah, i prefer execution style(mit firing squad) or stoning.

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Then you could have everyone who doesn't measure up to your standards summarily hanged.

Figures. I suppose I ought to be grateful for the honesty.

Not.