Effective OP-AMP Input Impedance, JFET vs. BiPolar

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matt239
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Post by matt239 »

I'm curious about the effective input impedance of various op-amps, in various circuits.

Consider, as an example a TL072 vs. an LM833, -the LM833 has better specs overall. -The selling point for the TL072 (in a guitar stompbox..) is the bi-FET input's ultra-high input impedance,
-but, configured as a non-inverting amplifier, won't the LM833 have very high input impedance also?

Is an LM833 a good choice for a guitar level input?
- such as in a buffer-less screamer type circuit?
Or, will it require a buffer before?

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matt239
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Post by matt239 »

For an ideal non-inverting op-amp the input impedance is infinite, so for a real LM833 it should still be at least a couple MegaOhms yes?

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Post by DrNomis »

matt239 wrote:For an ideal non-inverting op-amp the input impedance is infinite, so for a real LM833 it should still be at least a couple MegaOhms yes?

Probably more like 10 Megaohms.... :hmmm:
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