from DF96:
In some cases this can raise the supply impedance, especially if low ESR electrolytics have been used. Of course, if the resultant sound degradation is audible it may be misperceived as an improvement.[/QUOTE]
Can you explain in which way the impedance can be raised?
in addition
"I am considering whatever takes charge out of the capacitor. As a general rule if a capacitor is big enough to have low ripple voltage at 100Hz then it will be big enough to have even lower signal voltage at 1kHz."
the supply capacitors are in the signal path and in every case they must be a short for ac signals (this is the goal) from low end to the upper limit
Walter
In some cases this can raise the supply impedance, especially if low ESR electrolytics have been used. Of course, if the resultant sound degradation is audible it may be misperceived as an improvement.[/QUOTE]
Can you explain in which way the impedance can be raised?
in addition
"I am considering whatever takes charge out of the capacitor. As a general rule if a capacitor is big enough to have low ripple voltage at 100Hz then it will be big enough to have even lower signal voltage at 1kHz."
the supply capacitors are in the signal path and in every case they must be a short for ac signals (this is the goal) from low end to the upper limit
Walter
Bypass caps can raise impedance because they can form a parallel tuned circuit with the inductance of the larger capacitor. Fortunately the ESR damps the resonance so sometimes you can get away with it; it does no good but does no harm either.
The "signal path" is not always a helpful concept as it can mislead people. Supply caps are never a "short"; they do have to be sufficiently low in impedance. If they are big enough for low ripple then they are likely to be big enough for audio. One of the techniques of 'audio gurus' is to take a real effect which is almost always not a problem and claim that it is a major problem if you don't listen to the guru.
The "signal path" is not always a helpful concept as it can mislead people. Supply caps are never a "short"; they do have to be sufficiently low in impedance. If they are big enough for low ripple then they are likely to be big enough for audio. One of the techniques of 'audio gurus' is to take a real effect which is almost always not a problem and claim that it is a major problem if you don't listen to the guru.
some points:
1- if you connect to a large cap a bypass that has ( is an example) the same parasitic you have lower Z ( in this case the half), it is logic because it is in parallel.
2- the cap is in the signal path and this is clear written in every theory of circuits, the goal is to use the best components close to ideal cap to have a short, that's all. In some test in lab is possible to see that from low freq to 200KHz ( on Ap1) you have close to zero the residual.
The "audio guru" are the people that after the theory does't show the test.
Walter
1- if you connect to a large cap a bypass that has ( is an example) the same parasitic you have lower Z ( in this case the half), it is logic because it is in parallel.
2- the cap is in the signal path and this is clear written in every theory of circuits, the goal is to use the best components close to ideal cap to have a short, that's all. In some test in lab is possible to see that from low freq to 200KHz ( on Ap1) you have close to zero the residual.
The "audio guru" are the people that after the theory does't show the test.
Walter
Due to the inductance of the larger capacitor, there will be an impedance peaking effect
from resonance with the smaller parallel capacitor.
https://electronics.stackexchange.com/questions/295989/bypass-capacitor-vs-low-pass-filter
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In fact I put, on monos, p.e. 8 x 470 uF /550 vdc + 4x 0,22 uF in parallel.
"Due to the inductance of the larger capacitor, there will be an impedance peaking effect
from resonance with the small parallel capacitor. "
No, in my opinion, because the bypass ( intended as pp, high quality) acting as an ideal cap for the frequency where the big caps can have a L
Walter
"Due to the inductance of the larger capacitor, there will be an impedance peaking effect
from resonance with the small parallel capacitor. "
No, in my opinion, because the bypass ( intended as pp, high quality) acting as an ideal cap for the frequency where the big caps can have a L
Walter
The parasitic L in the circuit causes impedance peaking, even if the bypass capacitor is perfect.
The right damping resistor(s) in the right place(s) can help to reduce the peak(s).
For a simple parallel LC, the resonance peaking f = 1/2Pi.sqrt(LC). Parallel Resonant Circuits
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The values of the parasitic components would then need to "just happen" to be correct
for proper damping of the resonance. In practice, it would be necessary to add actual
lumped inductance and resistance in series with the large capacitor to properly tune the circuit.
This assumes that the bypass capacitor is "perfect".
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The film bypass capacitor must be of extended foil construction to have relatively low inductance.
Otherwise, it will have its own resonant impedance peaking.
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