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Can You imitate the sag of rectifier tube with solid state plug-in?

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5/29/1999 1:50 PM

Can You imitate the sag of rectifier tube with solid state plug-in?

Hi everybody out there!

If I remember correctly, there once was a solid state plug-in module to imitate the sag of a rectifier tube, wasn't there?

After all, this tube is not in the signal path and it has to be changed more frequently than the others, so tube rectification is rather expensive.

What I have in mind is: use the base of an old rectifier tube and solder a circuit onto the pins that imitates the sag.

Any ideas for the circuit?

Cheers

Carsten

5/29/1999 5:18 PM
dave	The sag comes from resistance in the rectifier tube. So it sounds like it would be some combination of silocon diodes and series resistance? You'd have to use pretty hefty resistors to keep them from frying. Maybe someone else can recommend some values to try.

5/29/1999 8:35 PM

This is a quote from a post I saved on some bassman mods about a year ago. I think it was a post from Doc.

quote:
"Replace the tube rectifier with a combiation of two series pairs of
1N4007 (series pairs in normal full wave center tap rectifier config.) ,
each series pair in series with a 135ohm-10w resistor (made up of
paralleled 270-5w) to achieve a tube sound with increased reliability. "

5/30/1999 10:02 AM
Niek	Been looking into this myself. Just look at the V/I characteristics of the rectifier tube you try to emulate and determine the internal resistance from the straight part of the V/I curve. Resistance=dV/dI Niek

5/30/1999 12:51 PM
John S.	Hello Niek.There you are again buddy.Nice to see you helping once again on this great site.John S.

5/31/1999 4:47 AM
Steve A.	Jason: Good memory! I believe that quote was posted by Doc in reference to the Kevin O'Connor mods for the Fender '59 Bassman RI amp... Steve Ahola

5/30/1999 5:20 PM
Ned Carlson	My experience is that tube rectifiers generally outlast the power tubes, rather than the other way around. In typical guitar amps, the rectifier is often being run at half the rated current at idle, or less. And unless you're buying NOS 5AR4's, they're really not that expensive!

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