Maybe I was unclear. A bad throw out bearing makes noise when the clutch is depressed (IE to shift gears). This is because when you push the clutch pedal in the clutch fork moves the throw out bearing into the fingers of the clutch to release it (in simple terms at least). The throw out bearing has to spin when this happens. (I've attached a video below).
I've also found this website. Really helpful for diagnosing bad throw out bearings. The OP could look at this to diagnose whether it is a bad throw out bearing.
https://wheelzine.com/symptoms-of-bad-throwout-bearing
If he is hearing a noise while sitting in neutral at idle, then there is a very small chance it is the throw out bearing. If he doesn't here a noise when pushing the clutch in then I would basically guarantee it isn't the throw out bearing.
The NV3550's are just loud transmissions and take some getting used to. This question is asked all the time because of how unnerving the noise is. But the true answer is that it is just normal.