MK IV rev A problem with RHY 1, breaks up too early

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fantomaz

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Hi guys,

I own a super cool Rev A MK IV that I fear has a little problem...

RHY 2 and LEAD channel work absolutely fantastic, as usual, but I have trouble getting a clean sound out of RHY 1 with humbucker equipped guitars...

I should mention that my amp has been recently totally retubed with mesa approved tubes...

I get an "almost to the point of breakup" sound with single coils with the RHY 1 gain on 2, and, of course, it breaks up with humbuckers.

I should mention that I run the amp on tweed power, triode, class A and Harmonics, and into a hot plate, as I have always done, but I don't see how this should affect the preamp section... As mentioned earlier the other channels behave normally, except for the fact that I have to keep the masters quite low to match the very low signal I get out of RHY 1...

Is it possible that it is due to a faulty preamp tube? If yes, which one is responsible for the first stage of RHY 1?

Thanks in advance!
 
Hey,

I've managed to somewhat reduce the problem by switching to the old V1 tube I had (which is a ***** to do)
and by using the "bright switch" by pulling the gain pot, and reducing the RHY1 treble to maintain the same level of highs...

But I still can't get a totally clean sound with hubmuckers, and they are super low powered humbuckers from an old 335... no di marzio here...

The manual says it shouldn't break up until 6 but it does it from 3... Do you think there is something wrong with my amp?
 
Hey guys

I found out what the problem was: worn out power tubes...

The power tubes were changed only six months ago but I use the amp everyday, and I guess the fact that I run the amp in class A with the volume on 10 into a THD hot plate has taken quite a toll on the 6L6...

I switched the outside tubes with the inside ones and the problem is gone...

I guess I just have to get used to changing power tubes more often... :)
 

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