One of the power tubes in my new Express 5:25 is going out. Must have been on for quite a while on the music shop floor. The store has offered a set of matched replacements but they were out of stock of the Mesa EL84s. They offered a set pf Groove Tubes Premium Gold matched set (GT Power range rating: Low: 3), but said that a shipment is due from Mesa this week.
The Mesa EL84s that were in the amp originally are RED code.
I have read online that it is best to stick with Mesa tubes for their fixed bias amps like the Express 5:25 for tone, durability and of course warranty.
My questions:
1. is there any harm in using other tubes, or is tone the only thing that would suffer?
2. I read a post from an amp tech stating that he has had a few fixed bias Mesas that he had to "fix" after users put non-mesa tubes in them.
3. If I were to use other brands of tubes, what is the bias rating I should be seeking? I have seen the chart below online but not sure how accurate or credible the source is:
Mesa scale Groove Tubes scale
Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6
The Mesa EL84s that were in the amp originally are RED code.
I have read online that it is best to stick with Mesa tubes for their fixed bias amps like the Express 5:25 for tone, durability and of course warranty.
My questions:
1. is there any harm in using other tubes, or is tone the only thing that would suffer?
2. I read a post from an amp tech stating that he has had a few fixed bias Mesas that he had to "fix" after users put non-mesa tubes in them.
3. If I were to use other brands of tubes, what is the bias rating I should be seeking? I have seen the chart below online but not sure how accurate or credible the source is:
Mesa scale Groove Tubes scale
Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6
