bridge rectifier questions


2002-01-25 9:28 pm
What are the pros & cons of using monolithic bridge rectifiers vs a bridge composed of discrete diodes? Specifically, for relatively high current applications (triode filaments, aleph ps, ect)

Also, I noticed on some high voltage tube ps schematics, that each leg of the bridge is composed of two diodes in series. What is the purpose of such a configuration?

Thanks in advance for any answers.
Normally there is no electrical diference. Both do fine.

If you need fast diodes, you can find them easier in discrete form.

If you need just a normal high current bridge, a block bridge is better. Its easier to mount it somewhere for cooling. Not so many connections to make and relatively cheap. a 35 amp one is so cheap.

diodes in series are use in higher voltages. Two diodes in series can handle double more voltage than each one alone, also you might see diodes in parallel, this is for higher current control.
Some say discrete bridges are better because you can use special diodes like ultra-soft recovery or ultra-fast recovery diodes. I've tried replacing a monolithic bridge rectifier with discrete ultra-fast diodes, and I didn't notice anything. Although I'm going to try using some ultra-soft recovery diodes in my tube circuit I'm working on instead of the normal 1N4007s (just because I have the ultra-soft recovery diodes lying around).

But for high current a monolithic bridge works just fine, after all they're made for high currents, and if that's what you need, use them.

The caps across the diodes (or corners of a bridge) may do something in a PS for signal processing - an active XO, a phono amp etc.

In a power amp, I doubt it. I've tried it in a power amp and found nothing I could hear. That doesn't mean it can't be measured, of course. Or that next time it will make a difference. In any future amps I'll probably still put the snubbers in since it's cheap and does no harm. Also gives me something to opine about and feel cool!