Tweakers' Asylum

bridge rectifier question

132.208.134.14

driver8

I'll be building my first tube amp (The Zapper 911), which calls for a 6A, 200V bridge rectifier for the heaters. I would like to use a fast/soft recovery type which I could not find in those values. Is it ok to use larger values? Here's a link. Any downsides (beside cost)? Cheers.
http://www.partsconnexion.com/rectifier_bridge_hex.html (Open in New Window)

Follow Ups:

Why not use Schottky's? - wheezer 21:20:06 12/17/10 (4)
3x the rms voltage for the diode V rating.
No reason to use a 200V noisy fred unless you're heating a toaster. :-)
- Something like this? - driver8 13:24:34 12/18/10 (3)
  Is it worth the cost?
  - http://www.partsconnexion.com/rectifier_bridge_schottky.html (Open in New Window)
  - Nope... - wheezer 13:42:05 12/18/10 (2)
    Use these.
    Is there some reason for a 200V bridge when the heaters are 6.3Vdc?
    Four diodes can easily be wired into the four holes in place of a single bridge. I can send you pics offline if you wish.
    - 50V 5A Schottky (Open in New Window)
    - RE: Nope... - driver8 06:39:02 12/20/10 (1)
      I'm building a single ended EL84 amp from a project in Audio Xpress. It seems pretty simple (which is an absolute prerequisite, this being my first amp) and quite honestly, I'm going on faith. Yes, the diode bridge is for a 6.3V 12AX7 filament. Is 200V overkill? If I can safely use the 50V Schottkys, I'd be happy to (here I am going on faith again). Cheers.
      - I run four 6dj8's from them..... - wheezer 08:48:16 12/20/10 (0)
        
        In Reply to: RE: Nope... posted by driver8 on December 20, 2010 at 06:39:02
        
        Do you have the schematic for the heaters?
        NTC's are a must as well.Preferably on the PT's secondary winding.
        If it's multi stages, try to make the first C considerably smaller then the rest.
        The voltage is not the issue. It's the current spike(s) with heaters.
        6.3Vdc you'll have something like 9-11VacRMS. (RMS x 3) - you're fine.
Larger is better with fancy rectifiers. - Al Sekela 15:02:56 12/16/10 (0)
These typically have less overload capacity than conventional junction diode rectifiers. There will be a current surge upon cold start, and the rectifiers have to be able to withstand the surge without damage.

I would install the largest bridge that will fit.

Beware, though, that the forward voltage drop through the rectifiers may also be higher and the filament voltage may be reduced as a consequence. It is not clear to me that the filament voltage service generates enough electrical noise to make the fancy rectifiers worthwhile.

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