LM4766 tiny hum/hiss is normal ?

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Nanoloop -

Outside of a metal box amplifier circuits do pick up the noises of the world. Once inside a fully screened enclosure, the situation will be much improved.
Ditto open circuit inputs - they are still technically aerials, even apparently screend RCA sockets! put a shorting plug in (old crappy phono socket with signal and earth soldered together and see if there's a marked difference. The same applies when you actually plug in a working source as the (normal) op-amp output will try to keep things quiet untill you play something.

5 cm from the speaker? You've done well! :cheers:


2013-05-21 5:04 am
I am only being a little facetious, but a very faint noise can be heard when I am closer than 5cm from a sea shell.

As others have suggested, it seems that you are well into second- and third-order effects. I will add, though, that whether it is a hum or hiss may offer some hint of the source. A hiss (white noise) could be ambient noise picked-up like little aerial antennae. A hum (50/60Hz) suggests that it originates from the power outlet or house wiring.

Overall, the results you describe do not seem so bad, especially if it is just the kit and not in a shielded enclosure like blu_glo describes.
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