if replace stock kt88 to el34 tubes , help

For all tubes. Turn bias down, turn off amp, remove old tubes, replace with new tubes, let warm up, set correct bias, check again in one half hour. 

to remove also preamp tubes?

If you're asking whether you need to also remove the preamp tubes to be able to set the bias, the answer is no. The preamp tubes are not affected by the bias process.

on what amp??? on some you may not switch from one to the other...

also, this post is in the analog section.... doesn't belong here

tubes= analog , what section tubes digital?! w*f?!

Analogue means turntables, tonearms, cartridges. The moderator can move this thread if necessary.

@russ69 has provided the proper procedure to bias power tubes. My question is what amp do you have and does it work with both those tube types?

op a noob with 3 posts, but plenty cocky, despite asking dumb-ass question without providing knowledgeable people here with critical info to properly answer

off to a really nice start 👍