So I ran unmatched pairs for a very long time without knowin

[badguitarist]

Until yesterday when I replaced my tube I didn't know I ran unmatched pairs of tubes for nearly a year now. Does that do any harmful to my amp?

 

[Don]

Unmatched pairs, as long as they're within Mesa'a spec, can be a good thing depending on the sound you're after.

Some players of classic amps prefer mismatched power tubes for a raunchier sound.

They have to both be in the range of safe bias though.

 

[eldi]

I think the worst that could happen to your amp by running mismatched tubes is that you could blow your fuse. If I'm wrong, someone please correct me...

 

[badguitarist]

Thanks mates for the info. I was just afraid if this did anything harmful to the amp hardware. I hardly noticed any differences in tone after replacing them with a matched pair.

 

[ANIMATED SUSPENSION]

How do you know they were unmatched ?

 

[badguitarist]

How do you know they were unmatched ?

I read the code on the bottom edge of the 2 outer tubes. 1 reads 05 AC BLU and 1 reads 03 AC RED. My amp is a Mark IV

 

[ANIMATED SUSPENSION]

Oh right !! Didn't realise they were M/B tubes !!
That is actually quite a bad mis match even within Boogie specs :

Mesa scale Groove Tubes scale

Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6

The 05 and 03 are just batch codes and AC is the tester's initials (They all say AC don't they ?!?!) The colour is the important bit. If it sounds and works ok, then it hasn't done any damage.

 

[mr_fender]

Using any Boogie tubes should be fine as long as they are the same type (6L6, EL34, etc) and the amp is set to match those tubes (for those with a bias switch). They are all within the proper bias range. Boogie doesn't specify a particular color for any single amp. It should not harm the amp, however tone and efficiency may suffer. Tubes are sold in matched pairs because most modern amp configs are setup in a push-pull configuration (Class AB?). One tube amplifies the positive side of the waveform and the other amplifies the negative side (for the most part :wink: ). For a pure linear response, you wan't both sides of the waveform to be amplified equally... hence the matched pair. If they are a little different, the result will be an asymetrical reproduction of the waveform and possibly crossover distortion as well. These extra harmonics (distortion) may or may not sound good to you, depending on what you are shooting for. It's more complicated than that, but that's the general idea.