When You Replace Tubes...

[Josh Koropchak]

When you replace old tubes with new tubes that are the same, but different manufacturer, do you have to get the amp biased?

[Josh Koropchak]

Josh,

What type tubes are you replacing, and in what amp. There are many answers to your question.
El-84's in my Hughes & Kettner Tube Edition.

[Phil Macino]

When you replace old tubes with new tubes that are the same, but different manufacturer, do you have to get the amp biased?I would say anytime you replace Power Tubes that are not matched to the spec's of your original tubes by the same manufacturer...Yes. It's even a good idea to do it when they are "matched".

Manufacturers all use different rating systems for their tubes, that have no real baseline. So for example, EL-34's from Eurotubes, and EL-34's from Groovetubes will be rated differently even though they could have the same spec's as each other.

If you are thinking about this for your Mesa, the easiest thing you could do would be to see what the matching code for your 6L6 STR430s is. Mesa uses a color coding scheme (ie: Yellow, etc).

[Josh Koropchak]

How do you tell the difference between cathode-biased and fixed-biased. Sorry, but I'm a guitar guy, not an amp guy. If it sounds good, I'll buy it without knowing anything about it!