I’ve sound treated my studio with acoustic panels and I turn off my air conditioning while recording but my Shure SM7B recordings still contain a lot of low level noise. I’m comparing the noise level to the noise that my condenser mics pick up. I’m also recording into a Scarlett 2i2. Is this microphone just super noisy or is something else going on?
This is normal for a Shure SM7B. It requires a significant amount of gain to sufficiently separate your recordings from the noise floor. The most effective way to do this involves purchasing a Cloudlifter, which provides a significant amount of clean gain to low output dynamic mics. Connect your SM7B to the Cloudlifter and then plug the Cloudlifter into your interface. Also, make sure to provide the Cloudlifter with phantom power; it’s required for operation.
Even if you own an interface with high gain preamps, you should still experience less noise with a Cloudlifter.
I usually treat my dialogue recordings with some light de-noising using Accusonus’s de-noiser at around 8-10%. This cleans up the little bit of noise that’s still present.
If you’re recording vocals for a song, that low-level noise probably won’t be noticeable at all when layered with instruments so de-noising likely won’t be required.
The likely source of the problem is a hum field in your studio caused by the AC power lines. There are only two causes of hiss in your context: electronic noise from the mic/preamp, and/or the ambient acoustic noise or ‘room tone’ . The SM7b is a pretty insensitive mic so needs a lot of gain