Are you talking about a BJT input stage? If so the BJTs draw a small base current. This will cause a voltage drop across input resistors and feedback resistors. To keep the input balanced, and thus the output with minimal dc offset, the voltage drops caused by the base currents need to be the same. The way to ensure this is to check that the DC resistance to gnd on both inverting and non-inverting inputs is the same. To achieve the same dc resistance it is usually necessary to put a dc blocking cap on the input too.
well I have seen custom made polypropylene caps of 220uF in the feedback that are very small. The should be not more then 20Volts. A friend of mine ordered a few from a commercial company for service. When you see the polypropylene caps at 400 or 630 volts its impossible to use 220u in an amp. They are just TOO big.
Polypropylene caps are just not made in that size, they would be to darn big. Solen, make a 100uf Polypropylene cap, however I am not a big fan of their caps the quality is only fair and the material they use is very thin. They caps are normally used in speakers..
Polypropylene caps, 10uf is about the biggest size that most manufactures will make.
Polystyrene or even bigger. You might want to look at a Black Gate cap.
😉
Polypropylene caps, 10uf is about the biggest size that most manufactures will make.
Polystyrene or even bigger. You might want to look at a Black Gate cap.
😉
Actually, SCR polypropylenes 250V 330uF are available here,
but they cost over $100 and the size can almost compete
with a can of Coke. 🙂
but they cost over $100 and the size can almost compete
with a can of Coke. 🙂
10uF are not the biggest
Audyn go up to 200uF.
BUT I have seen 220uF for around 30-50 Volts and they are small.
Audyn go up to 200uF.
BUT I have seen 220uF for around 30-50 Volts and they are small.
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