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Old 13th April 2008, 03:30 AM   #31
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Quote:
Originally posted by Zen Mod
talking about Profet ;
NFB is bloody different
Much of the difference is due to the high degeneration of their
input JFETs, the lower transconductance of Laterals and their relatively
high output gain. This means a lot less feedback, as seen by the
output impedance and distortion specs.

For Common Source topologies, damping factor = feedback.
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Old 13th April 2008, 05:11 AM   #32
EUVL is offline EUVL  Europe
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I guess you won't be showing us any measurements of distortion or bandwidth until the article is out ?


Patrick
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Old 13th April 2008, 05:13 AM   #33
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Wow! This F5 doesn't have any C!

Get well soon, Nelson.

Wachara C.
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Old 13th April 2008, 05:24 AM   #34
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Quote:
Originally posted by EUVL
I guess you won't be showing us any measurements of distortion or bandwidth until the article is out ?
You can look at posts #1740 and 1741 in DIY Progress Report, and
here earlier I posted a 2 ohm distortion curve. Here's an 8 ohm
curve, this with a regulated supply.
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Old 13th April 2008, 05:33 AM   #35
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Hmmm... I see that I didn't post the 2 ohm curve. I guess that
was just the Vicodin talking.

Oh well, they're pretty good too.
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Old 13th April 2008, 11:04 AM   #36
EUVL is offline EUVL  Europe
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> And yes, "current feedback" is pretty fast.

I must be still asleep.

I am not sure which part of the circuit you are referring to is current feedback.

For global current feedback, e.g., I would expect the feedback signal be derived from a sensing resistor in series with the load. Since the output current does not go through the 2x 50R feedback resistors, at least the global loop is voltage feedback, be it with a twist.

Anyone care to explain to me, Tino ?


Patrick
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Old 13th April 2008, 11:41 AM   #37
EUVL is offline EUVL  Europe
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I think I got it now.

Thanks anyway,
Patrick
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Old 13th April 2008, 01:25 PM   #38
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Location: Italy
Quote:
Originally posted by Nelson Pass


You can look at posts #1740 and 1741 in DIY Progress Report, and
here earlier I posted a 2 ohm distortion curve. Here's an 8 ohm
curve, this with a regulated supply.

Does the F5 have a regulator for each rail ?
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Old 13th April 2008, 01:32 PM   #39
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Quote:
Originally posted by Nelson Pass


...............

Now I've done it. The F5 isn't even out and some of you will
already be scrambling to build the two balanced versions.










...are you kidding me? The group buy started this morning
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Old 13th April 2008, 04:32 PM   #40
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Quote:
Originally posted by EUVL
> And yes, "current feedback" is pretty fast.

I am not sure which part of the circuit you are referring to is current feedback.

For global current feedback, e.g., I would expect the feedback signal be derived from a sensing resistor in series with the load. Since the output current does not go through the 2x 50R feedback resistors, at least the global loop is voltage feedback, be it with a twist.
You are quite right, and that's why "current feedback" is in quotes.

As I have previously pointed out elsewhere and in the F5 write-up,
this term probably came from the marketing departments at the
chip companies when they began selling high speed op amps using
this approach.
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