mixing tubes

[REDDOG45]

I have a D&A phantom with a bad 6mj6 final tube. The amp setup is 4 - 6LQ6's driving 6 - 6MJ6's. I have a 6LQ6 tube that I would like to replace it with, but want to make sure that it will agree with the 6MJ6's.

[TheCBDoctor]

I have a D&A phantom with a bad 6mj6 final tube. The amp setup is 4 - 6LQ6's driving 6 - 6MJ6's. I have a 6LQ6 tube that I would like to replace it with, but want to make sure that it will agree with the 6MJ6's.

Hi REDDOG45,

I would like to pass on some info on a personal experience I had with a tube amp. Even if the Tubes are compatible you should always replace all of the tubes even if the others read good on a Tube Tester. A Tube tester does not put tubes under a load. The Tubes may read good, but in fact, may be bad.

Save yourself the time and expense of replacing just one tube. A good tube can be ruined by leaving in a bad tube that tested good on a Tube tester. It would be the same as replacing a bad tire on a car. The other tires may "look" good, but they have just as much wear as the one that is bad. It is no different with tubes.

Respectfully,

[REDDOG45]

That makes sense Doc, but can I still mix these two types if they are all good? (6lq6 and 6mj6?)

[Night Crawler]

Yes you can use a 6MJ6 as a replacement for a 6LQ6 [Please login or register to view this link]

Take advice given above tubes in parallel in an amplifier should always be replaced in sets if that is not done the weakest tube will cause the other tubes to draw more current and will cause them to fail prematurely
What you will notice when that happens is one or more of the good tubes will start to glow a nice shade of red.

[crazy_cooter]

The 6MJ6's are a lot better tube anyhow...just my personal opinion. They have heavier plates in them so i was told