bjoneson
Well-known member
I'm reading Doug Self's Small Signal Audio book, and in his discussion of ACN / VE summing, he suggests the coupling capacitor (feeding the inverting opamp input) be sized for a high pass corner frequency using the bus source impedance.
It seems like everything I've read indicates that you typically use in *input* impedance of the following stage when sizing coupling capacitors.
Is there some kind of voodoo magic where the input impedance of the ACN / VE amp (inverting input + feedback network) mirrors the bus source impedance?
Normally would consider an opamp input to be very high impedance, but in this case, it's treated as very low.
Can anyone help set me straight?
Thanks,
Bob
It seems like everything I've read indicates that you typically use in *input* impedance of the following stage when sizing coupling capacitors.
Is there some kind of voodoo magic where the input impedance of the ACN / VE amp (inverting input + feedback network) mirrors the bus source impedance?
Normally would consider an opamp input to be very high impedance, but in this case, it's treated as very low.
Can anyone help set me straight?
Thanks,
Bob