is mixing STR454 6L6 AND STR440 6L6 power tubes safe?

[R_ADKINS80]

Both tubes have qualities I like the the other doesn't have......can they be mixed in the same amp?

 

[R_ADKINS80]

Any other thoughts? I left a message at Mesa and no one has called me back yet from yesterday.

 

[Sustain]

I was on the phone with Mesa yesterday about something else and asked them about mixing tube types as long as they were rated at the same bias, and they advised against it without supplying any good reason. I told them there are plenty of people out there that run el34 bias setting with 2 el34s and 2 "hot" 6v6 tubes at same time, he sounded interested, but advised against it for no good reason, basically suggested I only use mesa tubes. I think he was just trying to supply me with a "safe" answer, because I really cant see what the difference would be as long as the tubes were rated to be at the fixed bias setting you are using....shouldnt make any difference at all!

Please correct me if im mistaken!

There are alot of people I have seen on here who mix it up as long as they are 2 matched sets, at the same relative rating between the 2 sets, and are paired outside to outisde, inside to inside.

 

[ko112]

I could use some help with this too...

I had 4 x 6L6 str 454 mesa tubes in my mark 4, all rated blu.

When I brought the amp to my tech, he replaced the 2 inner sockets with 2 x 6L6 str 440 rated grn, also mesa brand.

Is this ok for the amp? Any advice is appreciated!

 

[trem]

Green rated tubes draws more current then the blue ones ie. "hotter". The outer sockets on the Mark IV are hotter than the inner ones, so using hotter pair of tubes on the inner sockets is correct. Most probably your tech checked the bias to come up with the green rating. Does it sound better after the change?

 

[ko112]

hey trem,

Thanks or the response.

Ya it definitely sounds better, and he told me the 454's he took out are still ok, but not great power wise.

I also noticed the 2 440's in the inner sockets visibly light up alot more than the 454's, and you can see they are giving off more heat.

I just want to make sure I'm not screwing up my amp.