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Old 30th December 2011, 09:31 PM   #381
Pano is offline Pano  United States
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Don't be so hard on 1968 engineering. We went to the moon in '68, you know.
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Old 30th December 2011, 09:33 PM   #382
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Tvr, I have been designing complementary differential jfet input stages for about 40 years now. NO, they are NOT mosfets. Mosfets are fragile, not jfets. One of my clients just bought 120,000 of them for future products. We use them at a rate of many hundreds per month or more. My other client has 50,000 in storage. My greatest competitor, Ayre, as about 1 million in reserve. I have thousands, myself. We use them every day.
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Old 30th December 2011, 09:50 PM   #383
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Anatoliy, I've done it once or twice. And my tube power amps have almost universally used feedback as well.
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Old 30th December 2011, 09:53 PM   #384
SY is offline SY  United States
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Quote:
Originally Posted by Pano View Post
Don't be so hard on 1968 engineering.
Quite the opposite- I was pointing out that this was well-known at that time in general electronics, and was a non-issue in commercial hifi amps shortly thereafter.
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Old 30th December 2011, 09:53 PM   #385
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Quote:
Originally Posted by SY View Post
Anatoliy, I've done it once or twice. And my tube power amps have almost universally used feedback as well.
Now, it is time to design your own SS amp that sounds close to your tube projects!

There is big difference: to ride a bike, and to read a book about riding bikes, when driving a car.
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Old 30th December 2011, 10:02 PM   #386
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I would like to pose a thought problem. What is 'propagation delay'? Are we referring to CLOSED LOOP propagation delay, or OPEN LOOP propagation delay?
Second, think of a black box with a bandwidth of 10 Hz, before it starts to roll off at 6dB/oct. What is ITS propagation delay?
My best guess is that it is 1/8 of .1 sec or 1/80 of a second, or 12.5 milliseconds.
It seems a lot to me. Where did I go wrong?
Because a typical op amp should have a similar OPEN LOOP delay.
SY, PMA, T, Wave? Show me my error, please. 'Enquiring minds need to know'.
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Old 30th December 2011, 10:27 PM   #387
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Propagation delay? Nanoseconds. Group delay is perhaps what you mean?
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Old 30th December 2011, 10:29 PM   #388
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Quote:
Originally Posted by Wavebourn View Post
Now, it is time to design your own SS amp that sounds close to your tube projects!
Zero interest in that. There's plenty of guys out there (John included) who design excellent SS amps. Excellent tube amps are quite a bit rarer.
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Old 30th December 2011, 10:32 PM   #389
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Real delay.
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Old 30th December 2011, 10:44 PM   #390
SY is offline SY  United States
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Real delay? That's an engineering term that I'm unfamiliar with. Could you define it?
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