nomad 100 tube question

[wilson]

i have a nomad 100 head that i just got recently. i'm new to tube amps, this is my first one. i'm playing at a very low volume since i'm in an apartment. i haven't really got the chance to crank this thing up yet.
i'm only using the 60w mode. if you're looking at the back of the amp the two left tubes are the ones that get warm when i turn the high volts on. the two on the right stay cool. all four are mesa tubes. the left two are marked 6L6 GC STR420 and the right two are marked 6L6 GC STR 430. after moving them around to different locations i found that the STR 430's stay cool everywhere and the STR 420's get warm.
is this just a difference in the two types of tubes? is it ok to have these two different tubes running together? also the 430's have a purpleish glow to them. is this normal? which tubes are being used when i am in 60w mode? do i need to make sure i'm using tubes with the same number in those spots?
i know this is a lot of questions but i'm new to all this. thanks!

 

[fishyfishfish]

Well, power tubes run in pairs, so make sure that the two outside are the same, and the two inside are the same IE: XOOX, or OXXO. The reason that the tubes are not hot to the touch is that you are not driving the amp. Rail the sucker for about 30 minutes and they can get hot enough to burn blisters, so no touching your tubes! The purple glow is normal, and in 60 watt mode the two outside tubes are fired up, the inside is on standby. Rock On!

 

[wilson]

cool, thanks for the info!