Full wave bridge rectifier usage?

[Rick]

I'm just wondering why full wave bridge rectifiers aren't used much? You usually see just the full wave with capacitor input load type. You'd maybe think that a full wave bridge would make it much easier for the capacitors to smooth the ripple.

[David Root]

It's a matter of history, when it comes to musical instrument amplification. The industry has always used full wave half bridge rectification, basically because it made tube rectification very simple.

Full wave full bridge rectification is more efficient (but not a lot) and the transformers can be a bit lower VA rating.

But when silicon diodes came in, it was easier just to replace the tube with diodes (big $$ saving) but not go thru the hassle of respecifying PTs and getting stuck with a bazillion of old stock PTs you couldn't use.

Marshall sort of recognized this, and on their 100W amps did change to a four way bridge, BUT, they used it in a dual complementary arrangement, ie they split the plate cap into two equal halves in series and connected the PT centertap between the two. So they didn't have to obsolete their PT stocks either.

For solid state rectification, full bridge rectification makes sense, but I think you'd have to have one custom spec'd for full wave full bridge use (or use a hi-end audio PT, which might not be a good idea for an MI amp). I'd kind of like to be proven wrong on that point, as I too would like to do it in an MI design.

[mhuss]

The Hiwatt DR103 100-watter used a conventional four diode full-wave bridge. They coupled that with an unconventional stacked capacitors filter: http://mhuss.com/Hiwatt/Schematics/DR_100wPS.pdf

Of course, until recently getting a 350v high current PT was a bit of an issue, but Heyboer is now making these and Andy at Mojo sells them.

--mark

[David Root]

Mark, that's much easier to read than the DR103 schematic I have! I should have known Mr. Reeves would have done something like that.