Hello Folks,
>
> In a really sensitive sub-audio application we are experiencing cell
> phone pickup.
In a really sensitive sub-audio application you use LM833 despite of all your complaints :-)
It got a lot worse when switching from the LT1112 to the
> LM833 in order to lower the sub-audio noise (and yeah, reduce cost...).
> Anyhow, this surprised me because the LM833 doesn't even have the input
> protectors like the LT1112 so the chances of something clipping and
> demodulating should be lower. How could this be? Older process with
> larger patterns and thus more pickup loop area?
It could be some resonance affected by the parasitics of the opamp.
VLV