Strange noise when LSC running in 100 watt mode

[user 1198]

I am getting a really faint, strange noise from my Lone Star Classic when I play certain notes in 100 watt mode. When I switch to the 50 watt mode, the strange noise goes away. I suspect that a power tube is the problem.

Does anybody here know which set of power tubes are not being used when the amp is in 50 watt mode? I want to swap those tubes out to see if the problem goes away.

Thanks in advance

 

[Bren10]

I don't know which ones aren't being used in 50 watt mode but it sounds to me like you might have a microphonic tube. Put it in 100 watt mode and tap on each tube with a pencil eraser. I bet you'll find one that makes noise when you tap on it. If it's still under warranty, make sure you use a Mesa Tube to replace it.

I hope this helps.

 

[user 1198]

For anyone else that wants to know this information: I called Mesa/Boogie and they told me that in 50 watt mode the center power tubes are off.

Since my tubes are only 5 months old, they are still under warranty and they are sending me a new set. What a great tube warranty!