Egnater Rebel 20 Head - Re-Bias Question

[longjaw]

Hi fellas, first time poster here as I've just bought a Rebel 20 Head!

I've only been able to test it at bedroom levels but it sounds pretty darn good.
However it does give off a few pops and static sounds so I've done the pencil tap test on the valves and it appears one or both of the EL84s are microphonic. Luckily enough I have a couple of matched EL84s spare which I have chucked in for a quick test and this has cleared the problem and improved the tone but the amp instructions states it should be re-biased when the valves are replaced
So (finally!) my question is - the amp sounds better with the new valves in, am I ok to leave them as they are or will the amp or valves be damaged without a re-bias?

Cheers

 

[Len Rabinowitz]

It always best to check the biasing- You don't want to run the tubes too hot, for example. If it sounds good you are probably OK, but you don't want to wear the tubes out prematurely. It is good to check the biasing every now and again anyway even if yoy don't change the tubes as it can drift over time.

 

[Steedee]

Yeah like Len said.... Just check to make sure your not to hot as to lower the life of the tubes.
Tone wise I think Bias is a little over rated, I've just started to run my 6V6's a little cold and they sound awesome that way.
I dont know the procedure for the R20, maybe someone else can chime in.

 

[longjaw]

Thanks guys, guess its time to learn how to bias! From a quick check on this forum it looks pretty simple for the Rebel 20.

Will check it out when I get time!

 

[Ian Egnater]

You should always check the bias when you change tubes. Running tubes too hot will shorten their life. How much it will shorten them is obviously not something you can tell, but the best balance of tone and reliability for the bias is usually what the manufacturer suggests. If you've got any questions, I check in here usually every day.