B&D wrote:
On 8/26/04 7:17 PM, in article , "chung"
wrote:
B&D wrote:
On 8/24/04 11:13 PM, in article , "Dave Platt"
wrote:
The whole NAD silverline is zero negative feedback.
I doubt that... at least, not as it's written there.
They may very well have no _global_ negative feedback.
They almost certainly have _local_ negative feedback, in each
individual stage. You need at least some local feedback in order to
make each stage (e.g. input, driver, output) linear enough to deliver
acceptable performance.
Not to mention to maintain stability into all kinds of loads!!
Uhh, a circuit with no feedback will be stable. Feedback is not used to
provide stability. Instability is the result of incorrectly applying
feedback.
Negative Feedback can and is used to stabilize amplifiers - if you apply it
in some ways, it certainly can make an amplifier unstable (such as use of
positive feedback in regenerative circuitry) - negative feedback properly
applied does make amplifiers more stable.
You failed to understand that an amplifier with no feedback cannot be
unstable. You were saying feedback was used to maintain stability.
Local feedback may be something as simple as
an emitter or source resistor.
Yes - but I think they were talking about loop feedback, not ballasting
resistors.
Uhh, using emitter resistor or source resistor *is* applying feedback.
You should be able to clearly visualize the feedback loop.
Chung - you misunderstood what I was saying - the folks claiming "Zero
feedback" most certainly mean they are not feeding back signal from the
output to the input, but applying things like what we were talking about
(ballasting resistors - on the source, or emitter to provide localized
negative feedback is not taking the output signal and applying it to the
input of an amplifier)
But then why were you arguing with Mr. Platt? Please re-read what he
wrote. He already said that some of these amps may very well have no
global feedback, but instead have local feedback.