Re: EMG Retro Active pickups
Most noise from any pickup has more to do with how "hot" the pickup is and how much gain is used. Hotter pickups will seem noisier because the pickup is more sensitive and the same is true in a higher gain amp. The noise is not generated by the pickup itself but picked up by the pickup. Very similar to how a mic gets more sensitive when the gain is turned up. Most noise floor ratings on active pickups are the noise floor of the pre-amp and has nothing to do with anything but that. The pre-amps in actives are extremely quiet. Now if the pre-amp is the issue, it usually results in "white noise" or hiss
Electro magnetic interference with power lines or powerful radio stations nearby has nothing to do with pickup noise or quality. The strings on your guitar and pickups become transducers and amplify any thing they can detect. Hotter pickups = better ability to pickup noise.
The reason you will see that actives are touted as quieter is because the signal leaving the pickup is Low impedance. In simple terms low impedance means higher current flow, higher current flow is less susceptible to interference because the signal is stronger than the interfering signals around and less susceptible to capacitance. Passive pickups are high impedance, meaning very low current flow, and the signal is fairly weak, thus the need for shielded cable. So actives are less likely to have noise issues generated by lower quality cables.
But most pickup noise is not pickup noise, it is noise around you amplified by the pickup.