Replacing JCA20H vacuum tubes, need to bias?

[pschwind]

Hi all,

Tube amp noob question here...

I want to replace the tubes in my JCA20H. My JCA currently has stock tubes and the amp is 3 years old. The amp takes 3 - 12AX7 and 2 - EL84 Power tubes if I’ve done my homework correctly.

My question, without getting off topic, is in regards to biasing tubes. I’d like to believe I can buy new tubes, stick them in and be done. That seems too easy. Do I need to bias new tubes and is it something you can do yourself? I plan to use JJ Electronics tubes, if that matters.

Thanks,
Pete

[K-Bizzle]

You should bias but when I replaced the tubes in mine I did not because I didn't want to spend the cash on a probe for the amp.

I literally just turned it down all the way then turned it back up all the way to get an idea of the high and low end and then set it to an area somewhere towards the lower middle that looked ok visually.

This is a stupid way to do it but my tubes are fine so far months later.