Question about plate load resistor with slight change in value

[Tubenstein]

Hello!
If a tube circuit has a plate load resistor there, say 19.6K, what will happen if replacing with 20K?

Thanks!

 

[JonSnell Electronic]

Absolutely nothing. It won't make any difference.

 

[kevinkr]

Pretty much as Jon relates, in theory perhaps a minute increase in gain depending on rp and other factors.

 

[RJM1]

That is about 2% difference, Most tube amps were built with 10 or 20% resistors and occasionally 5%. So it is well within the design specification. Not to mention that today 1% resistors are usually cheaper than 5% resistors. Tubes are much more forgiving to bias levels and occasional overload than transistors, tubes distort more, transistors explode.

 

[Osvaldo de Banfield]

I have seen tenth's of old radios working with resistors of the very early types: a carbon bar with a color body, one central color dot and one in the end. Sometimes, the guy who assembled the radio, hasn't the proper value, then he "trimmed" it filing the body of the carbon bar. The tolerance, then, may be ±100% :-D, and most of them had maintained their value reasonably well during several decades. I believe I still have some of this old kind of resistors.