Rectifier Tubes

At the top of rectified full wave sinewave current changes direction but rectifier is too slow to respond and keeps conducting in opposite direction for a moment then snaps back to zero current. Fast snapping back creates very narrow negative current spike, that can couple to any inductance in the circuit, inducing electrical noise (narrow pulse contains all frequencies).  Better "softer" rectifiers like Hexfred snap slower to zero producing wider (less dangerous) negative pulse.    I suspect some of this might apply to tubes as well.

In some tube pre-amps I've owned the rectifier was THE most important
tube for sound .

Ideally, a tube characteristics is less important than the filter that follows it.

The tube rectifier will determine the voltage, but ideally, the filter should eliminate noise, and is responsible for any supply sag, not the rectifier overall.
I guess this is quite variable.

Thanks for the information everyone.

I have a deep respect for those who have electrical engineering backgrounds.  They bring so much to this forum!   I do not have a background in electrical engineering, so I tend to make judgments based on empirical evaluation rather than first principle considerations.  But based on my simplistic empiricism,  I am amazed that anyone with normal hearing, especially a tube vendor, would dispute that different rectifiers, and here I mean different brands of the same type rectifier as well as different types of rectifiers, can have a profound effect on how a component sounds.  For all I know all of this may be limited to differences in sag or rise times.   I'd love it if all rectifier differences could be attributed to measurables.  I will say that I have noticed some pieces are more influenced by tube rolling than others.  Perhaps Erik's comment is relevant to that phenomenon.