Bridge Rectifier for the heater 300b tube amp

No.... Don't do that. If you're looking to truly upgrade your rectifiers with discreet parts go get some boards and build them out right. I've got a couple of nice rectifier boards I'd be happy to give you, but I've only got 2. 

Just get 35amp bridges. I had 25amp ones but after 2 years they cracked.
Make sure you mount them on the chassis with paste for some heat sinking.
http://www.mouser.com/Semiconductors/Discrete-Semiconductors/Diodes-Rectifiers/Bridge-Rectifiers/_/N-ax1mf?P=1yzxhyxZ1yuo9ua


Cheers George

Kosst what would be the difference?

A fully discreet rectifier can be built to smooth and filter the power. Is it worth the hassle? A lot of people think not. It's the way to go if you want the most ideal rectification possible. Some like fast diodes. Some like slow. Some want to tune and filter the stage. That's how to do it. I did what George suggested; 250V, 35A Vishay bridge rectifiers. The heatsinks alone are more expensive than the Vishay parts. 

George... would it be better to custom your own bridge rectifier using 4 diodes?   Besides the fact that a bridge is more convenient and easy to install ( less of a hassle) a custom bridge will give you more reliability and better performance?  

If i custom my own bridge for the heater, do you recommend fred, hexfred or Schottky?  Will be for the 300b heater, the unit came with 4 bridges Rs802 (8amp 100v).   Please advise??

George... would it be better to custom your own bridge rectifier using 4 diodes?

Same, same. Except the bridge has a nice metal plate that can be bolted to the chassis to keep it cool, 4 diodes don't.

Cheers George 

Using heftier diodes (and the bridge), as George suggested, is always a good thing.  The problem with rectifiers is that at the peak of the voltage they should stop conducting (being suddenly polarized in opposite direction), but in reality current will rapidly drop to zero and will keep going (diode conducts in opposite direction) for a short moment, then snapping back to zero.  This extremely short current spike (triangle) can induce noise in any circuit inductance (any loop).   Good diode should be fast, but snap back slowly.  They are called "Soft Recovery Diodes" and Hexfred is example of that.  Softness of the diode is often measured as the ratio of recovery time after the peak of the spike to time before (two sides of triangle)
https://www.jedec.org/standards-documents/dictionary/terms/reverse-recovery-softness-factor-rrsf

Can I just point out that if you need to ask the questions posed you probably shouldn't be building rectifiers? 
In all reality, if you want the best, most stable rectification, you want tube rectifiers.