I know that one [raising hand].
If you set the US ANSI C16.5 VU meter…
… to “zero” tone and put show through it, the readings, given natural sounds (and not special effects) were almost always about 10dB or so louder than the meter reading. This gave you a good idea how to set the electronics, clipping, and noise floor for the rest of the system.
It was sloppy, and we’re the only ones using this system. Other countries went with variations on the peak-reading meter such as the British PPM that didn’t have this difference, but the idea stuck, mostly because of the need to exchange shows between countries. As is pointed out frequently, you can produce a very nice show using either one given that you’re paying attention.
If you’re producing live work, the number goes up. Most musicians or voice performers can blow right past 10dB headroom without breathing hard, so they take higher numbers like 15 or 20.
Broadcast video “tone” level is -20 in the US. 20dB of increased level before you have to worry about overloading the channel. In Europe, it’s -18.
Clip Fix, like Noise Removal should not be taken literally. Each one only works well on a very strict, tiny subset of problems. Most of what you would naturally consider noise and clipping is far outside the abilities of either of these tools.
As a result, you can’t actually recover from most noise and clipping. Clipping in particular is one of the four deadly horsemen. Few people recover shows with severe clipping or peak distortion.
the Clip Fix plugin generates some excessively loud (32dB above signal) interpolations
The tool isn’t actually fixing clipping. It’s guessing that any signal close to or actually at 0 is probably damage and it tries to guess what the peak signal probably should have been given the work, frequencies and rise and fall times before and after. What people really want is a tool that intelligently analyses the instruments and singing and generates a whole new voice or trumpet or bass guitar to fill in the hole left by the overload.
I’m not shocked that this simple tool doesn’t work like that. Like most Audacity tools, this one is a math function, not a musical one.