Very detailed discussion of diodes

ctviggen · « **on:** 28 Oct 2005, 01:01 pm »

http://www.diyaudio.com/forums/showthread.php?s=&threadid=66542

lbo · « **Reply #1 on:** 22 Nov 2005, 01:44 am »

Quote from: ctviggen

http://www.diyaudio.com/forums/showthread.php?s=&threadid=66542

if rectifiers in a 50/60hz power supply, by-passed by massive amount of capacitance and snubbers, can have that much impact on a system used to amplify 20-20khz audio signal, how much attention would have to be dedicated to those power supplies used in meg hertz TV sets or Ghz microwave amplifiers?

Marketers always want you to believe that their littlest "innovations" can lift that "curtain" before you and your speakers. In reality, they are lifting your pockets and bank accounts.

ctviggen · « **Reply #2 on:** 22 Nov 2005, 02:18 am »

It's not clear how much "soft recovery" diodes help for a power supply according to that discussion. However, there's also an in depth article I can pull up on optimum snubber (typically cap + resistor) determination for diode bridges and the like. It's not clear in audio how much is hyperbole, how much is done because "it's known to do it that way" and how much is just plain dumb.

I do have to say that MHz and GHz is a whole different realm. GHz transmission gets, well, wierd. You're talking about real transmission line and skin effects; wave guides; things like that. You're also talking about generating your own clock, which an amp doesn't do.

lbo · « **Reply #3 on:** 22 Nov 2005, 12:09 pm »

soft recovery diodes are used in switching mode power supplies due to high switching frequencies (those things usually run in the 25khz - 500khz range, with some of them going to 1 or 2 mhz range) and you will need to have a soft recover diode to prevent ringing due to leakage capacitance and inductance.

That is far less of an issue for your 50hz main rectification, unless you increase your capacitance upto to the gazu so that your rectifiers conduct during just 1/1000th of a cycle - in reality, they conduct only 1/10th of a cycle.

the source of trr is due to the junction capacitance in a traditional silicone diode. the schotteky diodes don't have a "junction" so it is actually very fast and have soft recovery as well.

I think in the end, you will find that there is no audiable benefit to the use of ultra fast and soft recovery diodes in audio. All they do is to take your hard earned money away from you.