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Negative feedback - right or wrong to use?
Negative feedback - right or wrong to use?
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Old 5th December 2017, 08:41 PM   #41
banat is offline banat  Serbia
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Hi sottomano ,thanks but I`m not interested .
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Old 6th December 2017, 04:51 PM   #42
cbdb is offline cbdb  Canada
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Is a class D (PWM) amp even possible without feedback?
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Old 6th December 2017, 05:38 PM   #43
banat is offline banat  Serbia
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Good question !
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Old 6th December 2017, 07:50 PM   #44
PRR is offline PRR  United States
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Quote:
Originally Posted by cbdb View Post
Is a class D (PWM) amp even possible without feedback?
Yes.

If fast (>1MHz) devices are available, it may be more linear than most simple baseband amplifiers, avoiding device nonlinearity by bang-bang on/off conduction.
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Old 6th December 2017, 09:58 PM   #45
jan.didden is offline jan.didden  Europe
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Originally Posted by banat View Post
Hi Jan
-Cutting vinyl with cutterhead powered from GNFB-free amp is possible , our DIY member Atmasphere already is doing that for many years
Yes I am sure it is possible, you probably can build a whole audio system with no GNFB. But what is your point?

Jan
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Old 6th December 2017, 10:09 PM   #46
traderbam is offline traderbam  Europe
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Quote:
Originally Posted by cbdb View Post
Is a class D (PWM) amp even possible without feedback?
I designed and built one in about 1979! I was just a teenager with no formal electronics education but I made a PWM using a lateral MOSFET. It worked. It had no feedback. It did not sound so good but worked ok at low volumes. I thought I had invented something new until later on when I found out what a switch mode power supply was.

It is evident that Hypex thinks that an awful lot of NFB is required to make a good enough sound. Class D reduces power dissipation. That's where it excels.
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Old 6th February 2018, 12:01 PM   #47
Mikelandjelo is offline Mikelandjelo  Serbia
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I am finishing my current development about this....I achieved pure linear response without any negative feedback.Output power is 200W and i am finalizing this with 2x2000W amplifier design which i will make in next month or two.If i dont sell the design (project) i will offer to sell it to public and i will show a demo video of it.No matter whats written till now that doesnt mean that things cant be improved further.
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Old 6th February 2018, 02:48 PM   #48
DF96 is offline DF96  England
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No feedback? Not even an emitter follower sneaked in somewhere?
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Old 6th February 2018, 03:54 PM   #49
traderbam is offline traderbam  Europe
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An emitter follower doesn't use feedback (at low f) any more than a potentiometer.
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Old 6th February 2018, 04:27 PM   #50
scottjoplin is offline scottjoplin  Wales
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I was handed a feedback form by a tutor, I told them that purely on principle I never fill them in because I only give negative feedback and from past experience they invariably take it the wrong way (because the questions refer to them) and ignore the fact that it is the only positive thing to do
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