Power Amp Trouble

JLL

A couple of days ago a fuse blew on my mesa 50:50 power amp...after replacing the fuse, i noticed that the 4th power tube did not light up anymore,after checking it it looks like it blew..the silver film on the top of the tube looks like it burned out.....Can the amp run on 3 tubes??? what could happen in this situation? also, would it be better to just buy the replacement tube or is replacing all 4 tubes better??

LuredMaul

You definately don't want to run the amp with 3 tubes,best idea is to take it to a repairman and have all the tubes replaced

guitar3456

You should change the tubes in Quads. Two reasons, it's usually cheaper to get a Quad than two Pairs..usually. I repair and do custom mods on amps and I own the 50/50. It's one of the only amps that will create a hige offset if a tube goes out..that can and will damage the other. The 50/50 uses 4 tubes, 2 for each individual channel if stereo.

If a vaccum is lost on a tube the silver dot you see will be white. If it's blowing fuses you have either a bad tube or a power supply problem in the unit. What you can do, pull the tubes out and turn it on. If it blows the fuse you have additional power supply probs. If not, order yourself a Quad of tubes. Some models used 6L6, some used EL34's.

I suggest JJ's or Svetlena brands. EH are not bad, but can become microphonic with physical shock and vibrations. Don't buy Groove Tubes..just a suggestion. The luck on those are pardon the pun..50/50.

These are in pairs which is fine since you have 2 pairs for each channel.

http://thetubestore.com/teslael34l.html

http://thetubestore.com/ne-6l6gc.html