can you please help me around how to use my first tube amp?

hi, congrats on an excellent sounding amp!  i had a rogue cronus magnum ii and loved it.  

dont be intidated about bias adjust, it is easy.  just let the amp warm up for 20 min or so, remove the screws on the small window plate.  

then flip the switch for bias check of each tube, read the meter and use the small screwdriver to adjust the blue potentiometer screw until the meter reads the correct current per the manual.  

for the speaker taps you need to remove the tubes and chassis cover.  you can see the wires going to the terminals, just loosen the nuts with an open end wrench and put the wire on the other terminal.  8 ohms will sound best with most speakers but it is worth a try to see how the other tap sounds.  good luck!

this is awesome feedback

thanks so much

what happens if the tubes are not biased?

it may sound unhalanced left to right or not as strong and powerful as it could.  if they are over biased the tubes could burn out prematurely.  

also it is a good way to spot a bad tube.  a bad tube cannot be biased to the correct current.  

definitely warm up the amp and at least check the bias of each tube by flipping the individual switches on and off and read the meter.  the manual says that they do not have to be perfect so you might not need to adjust the bias but i recommend it

An imbalance in bias within a push/pull pair (the two KT120 on the left form one such pair; the 2 on the right are the other), or far too low of a bias, will cause audible distortion. It can vary, but expect either a scratchy or choppy kind of incoherence to the sound from the affected channel(s). It’s the opposite of sounding "clean"! Like I mentioned earlier, any biasing issue in the Atlas should be immediately audible - unlike in the Apollo (and to a lesser degree M180), which mas multiple redundant push/pull pairs! 

Careless biasing could also possibly cause a level imbalance between Left and Right pairs, but in my experience that’s far less likely to be severe enough to be very audible, versus an imbalance within one or both pairs causing obvious distortion.

It is a very NICE feature that the Rogue tubes amps allow individual biasing of each tube. Other amps require matched pairs or quads of tubes in order for the push/pull "balance" to be correct. Of course I still buy matched pairs/quads anyways haha.

As @avanti1960 mentioned, stability in the bias point, once set, is a good indication the tube is solid. You’ll want to check the bias periodically over the next few sessions to look for tubes which may not be holding bias (I mean a swing of more than 5mA, not the usual normal variance of 1 - 2mA) - they should be replaced immediately!

Make sure the speakers are connected . Just in case you didn't know that!