janneman said:Agreed. I thought you said earlier that because an emitter follower uses feedback, it is a regulator.
Your posts are sometimes very sparse
Jan Didden
Is this a new defintion of the term 'negative feedback' thread
I thought it was about Lumba Ogir super shunt regulator.
Maybe I was wrong ...
We have seen such 'feedback' topics many times.
To me, it is only like splitting hair and a waste of time
... as there is almost never any doubt
when we use one real example and talk about 'feedback' or emitter degeneration resistors.
Come on
Let us attack Lumba's circuit.
Think he deserves to get feedback from us.
Negative or positive FB .. is upto anyone posting.
Lineup regards
quote
it could be mentioned in parentheses that the sonic performance of shunt regulators cannot be compared to the 15kHz IC types, which have an immense circuit complexity and suffer from devastating GNF effects and other anomalies in audio use. Yet many seriously meant attempts for "improvement" have been made over the years. What a waste of resources.
unquote.
No b.s. please.
it could be mentioned in parentheses that the sonic performance of shunt regulators cannot be compared to the 15kHz IC types, which have an immense circuit complexity and suffer from devastating GNF effects and other anomalies in audio use. Yet many seriously meant attempts for "improvement" have been made over the years. What a waste of resources.
unquote.
No b.s. please.
Hi,
the importance of good quality power supply cannot be overrated. My main goal is low output impedance over a large frequency range, clean voltage concerning ripple, noise, various harmonic and intermodulation products. I personally don`t bother much with achieving meticulous regulation accuracy, usually the fluctuations are thermal related so better provide adequate heat sink (than applying feedback), also to keep thermal distortions low.
Most types of electrolytics have especially poor linearity and frequency range. The capacitor bank in many power amplifiers is barely sufficient to supply flashing bulbs or things like that.
the importance of good quality power supply cannot be overrated. My main goal is low output impedance over a large frequency range, clean voltage concerning ripple, noise, various harmonic and intermodulation products. I personally don`t bother much with achieving meticulous regulation accuracy, usually the fluctuations are thermal related so better provide adequate heat sink (than applying feedback), also to keep thermal distortions low.
Most types of electrolytics have especially poor linearity and frequency range. The capacitor bank in many power amplifiers is barely sufficient to supply flashing bulbs or things like that.
The task of the cap bank in supplies is to give out charge as fast and as much as possible if the load wants it. Therefore, what you want is low ESR. Linearity (whatever THAT is) or dielectric absorbtion is irrelevant.
I agree that regulation in the absolute sense is also unimportant.
Jan Didden
I agree that regulation in the absolute sense is also unimportant.
Jan Didden
BTW, the TL431 configured for 2.5V in the schematic of the first post of this thread will be unstable with 1uF across it. See the TI or OnSemi datasheets for more data on this. There is a graph of unstable regions for various voltages and capacitance values. The adjustable one may or may not be stable depending on voltage, but even if it is, it will be on the hairy edge. The TL431 needs either very small or very large parallel capacitance for stability.
Jan,
Linearity means absence of distortion. Distortion in pure audio could be defined as any departure (except magnitude) of the output signal waveform from the input signal waveform.
Electrolytic capacitors are markedly nonlinear, most characteristics being very far from the ideal, small operating frequency range, considerable dielectric losses, strongly increasing with increasing frequency. The problem is that they cannot be easily discarded.
ESR should be low all right, ideally zero at all frequencies, but it says nothing about linearity and most types are made for applications where it is not an issue. Low ESR and good linearity can be combined at the expense of design and manufacturing complications.
In a compromise situation I would chose good linearity.
You have a somewhat simplified view on this. Dielectric absorption should indeed be considered highly relevant Power supply capacitors behave not just as energy storage, but constitute an important filter component having major impact on amplifier linearity (sound).
Linearity means absence of distortion. Distortion in pure audio could be defined as any departure (except magnitude) of the output signal waveform from the input signal waveform.
Electrolytic capacitors are markedly nonlinear, most characteristics being very far from the ideal, small operating frequency range, considerable dielectric losses, strongly increasing with increasing frequency. The problem is that they cannot be easily discarded.
ESR should be low all right, ideally zero at all frequencies, but it says nothing about linearity and most types are made for applications where it is not an issue. Low ESR and good linearity can be combined at the expense of design and manufacturing complications.
In a compromise situation I would chose good linearity.
PMA,
Jan,
all materials distort when an electric current (like the delicate and precious audio signal) passes through them. Electrolyte distorts heavily due to its miserable electrical properties. It`s a material we would gladly avoid in audio.
I`m not able to define "linearity" without comprehensiveness.
I meant PSU capacitors, their task is far more complex and demanding.
Jan,
all materials distort when an electric current (like the delicate and precious audio signal) passes through them. Electrolyte distorts heavily due to its miserable electrical properties. It`s a material we would gladly avoid in audio.
I`m not able to define "linearity" without comprehensiveness.
Lumba Ogir said:
So what? What does that do to the audio that comes out of the speaker? I think you may have fallen victim to the notion that 'the output cap is part of the audio circuit'. It is and is not. The audio return current from the speaker does indeed pass through the supply cap. But that does not impact the audio *signal* at the amp output.
Look at it this way. If we have a cap that distorts 10%, and if it is true that it is 'part of the signal', how could we then ever build amps with 0.001% distortion.
The audio signal current also goes through the rectifiers and the xformer. Compared with their (non)linearity, caps are perfect!
Jan Didden
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