Tube amp bias adjustment advice

Have you try swap the tube from left to right?

Have you try swap the tube from left to right?

Don’t do this as then you will have to re-bias both of the the amps.
Just swap the amp whole from left to right first, and say which side is louder.
(it could be the source or the speakers) that has to be ascertained first before doing any re-biasing, and a 211 biasing is not a very safe area to be fiddling with if your not confident, with the HT around that area.)
  
Cheers George

Swapping tubes,then cables is a start.Oftentimes it's sound waves building up on one side/ corner of the room. My room for instance has bass build up in two corners diagonal to each other. Behind the right speaker and behind me to my left. I solved my problem with room treatment and a *swarm* of subs.Not saying that's the case, but just something to check out.

@mmporsche 

you are biasing 'the first' set of tubes?

so new amp, or just new tubes in amp you have used for some time?  no channel imbalance before as you have been using this amp?

you need to clarify these critical contextual parameters to get any useful advice

You do not measure from the back of the speaker to the wall behind it. You measure from the front of the speaker to your nose at the sitting position.