Express 5:25 Bias Mod

[wagdog]

@rolandibus - those are some interesting values your seeing on the cathodes as well as some very different idle bias values as a result.

I agree that separate thread might get you some input on it. I’m sorry I’m not more help!

 

[wagdog]

It's imperfectly fine to use the 5 watt mode that is what it is there for and it has a great class A tweedy blues tone that is still plenty loud and can even be miked for a small gig. Don't be put off because only one tube is being used, it's not going to break it, and if you are that worried about it just rotate them once a year.

That’s the one of the beautiful things about music; soundscapes that don’t do much for one person can make amazing music in the hands of another.

In my case those single ended tones just don’t do much for me, hence I don’t use them. I’ve built single ended amps, and while they sound like they’re supposed to, those tones just don’t work well with my style of playing. In the hands of someone who seeks, appreciates, and understands them; amazing.

Anyway, I do feel that using the class a single-ended mode in the express will cause one tube to wear faster than the other. As you said, if that’s a mode that’s used often, swapping the output tubes would mitigate the impact of it.