In Reply to: RE: As you might imagine, I'm having a problem with this posted by cpotl on January 14, 2015 at 12:57:08:
We're actually in agreement on this but the term 'output impedance' as you are using it (and for that matter, most of the audio industry) is not actually the output impedance of the amp. This is why I stated
Of course, what is meant by the term 'output impedance' must then be under question
-because in most cases its really a measure of the servo gain of the feedback loop, and not an actual measure of the impedance of the output section. However, I tend to work with the Power Paradigm rules (which predate the Voltage Paradigm rules, see link below) which measure the impedance of the output section rather than the 'output impedance'. A lot of people are confused by this topic, especially if the Voltage Paradigm is their only source of the terms.
My contention is simply that the term as it is usually seen is misleading, because so many people use the concept to suggest that if you add feedback to an amplifier, its output impedance goes down therefore it can drive lower impedance loads. As you correctly point out, there is a current limit involved which was what I was referring to with Kirchoff's Law. We just have different ways of expressing it is all :)
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Follow Ups
- RE: more on output impedance - Ralph 13:30:09 01/14/15 (10)
- RE: more on output impedance - cpotl 19:53:44 01/14/15 (9)
- RE: more on output impedance - Ralph 10:08:07 01/15/15 (8)
- RE: more on output impedance - cpotl 05:15:27 01/17/15 (3)
- There's gotta be a bug somewhere - Ralph 10:05:05 01/19/15 (2)
- RE: There's gotta be a bug somewhere - cpotl 05:33:40 01/21/15 (1)
- Sounds/looks like we are on the same page here - Ralph 08:28:21 01/21/15 (0)
- RE: more on output impedance - cpotl 07:51:54 01/16/15 (3)
- RE: more on output impedance - Ralph 09:21:42 01/16/15 (2)
- RE: more on output impedance - cpotl 09:29:35 01/16/15 (1)
- Yes. nt - Ralph 09:38:55 01/16/15 (0)