Mesa F-Series... F-50 Problem, help please!

[leonwhite73]

Hi There,

Wondering if anybody can help me here. I'm not very tech minded tho so hope I don't sound too dim in this post...
Anyway, my F-50 amp seems to sound fine through the 'clean' channel, but is crackling/spluttering at high volume through the distortion/contour channel. The two large tubes visable from the back of the amp (6L6 in the manual) seem the normal colour they should be, a dim orange, and one of them seem to have a slight 'blue' glow (don't know if this is normal or not). If this does sound like a tube problem to any of you out there, which ones do I need to replace? The amp is used a lot as I'm in two bands, so it has been used heavily!

Hope you can help!
Thanks very much! Leon.

 

[155]

surely tube related

 

[plumptone]

+1. Any time you get that "sputtering" sound, you should suspect a tube problem. I have an F-50 as well. I comletely retubed the amp after playing fairly hard for one year with a set from Doug's Tubes and the results were stunning.

 

[nemesys]

Sounds like it's probably a preamp tube -- I had the same problem with mine. Swap them out with a known good tube, one at a time, until the problem goes away.

 

[leonwhite73]

Hi chaps,

Thanks very much for you advice!
I've ordered 4 new pre-amp valves so hopefully that will solve the problem... I keep ya posted if it doesn't!

Thanks again,
Leon.

 

[decosimo]

Hi chaps,

Thanks very much for you advice!
I've ordered 4 new pre-amp valves so hopefully that will solve the problem... I keep ya posted if it doesn't!

Thanks again,
Leon.

what kind did you get?

 

[leonwhite73]

Hi Decosimo,

I got 4 Mesa 12AX7's, haven't get 'em yet - hopefully will solve the problem!

Leon.

 

[155]

I thinl it may be your power tubes though

 

[leonwhite73]

Well Mr 155, a gold star for you... It was the 2 6L6 power tubes, so I've ended up replacing all the valves in the amp! Oh well, al least it works now. I found this out when I replaced with the new 4 x 12AX7's and the problem was still there - borrowed 2 x 6L6's from my mates amp, stuck them it and it sounded great.... Should have done this in the first place!

Never mind, its sorted, and thanks for all your help on this forum,

Leon.

 

[nemesys]

Glad to hear you got it sorted!