Help me not blow up a Mark IV!

[ryjan]

Noob toob question. I just recieved a pair of =c= EL34's for the outer sockets of my Mark IV. The tube has "bias point 35" written on them. Are these safe for a Mesa? If so, what would the acceptable range be? Thanks for your patients. :lol:

 

[Paul Secondino]

Without actually checking them in the amp, no one can say for sure. But we all know that Mesa biases their amps extremely cold so it's likely that they will be fine.

The bias supply is such in the Mesa simulclass layout that the outer tubes are biased hotter than the two inner sockets.For this reason, the tubes in the center do not have to be exactly matched to the two outer tubes. But there are tolerances that need to be adhered to. So I suggest plugging in the El34's and checking them if you can . I use a weber bias rite and generally don't want to pull more then 35mA cathode current. Chances are the Mesa wont pull that much anyway unless the tubes are very hot ones

 

[ryjan]

Thanks but what about us unprepared folk who don't own a bias meter and have limited electronics understanding. :wink: I recieved these from tubedepot and I told them what amp they were going in and it even says so on their packing list. I just want to triple check so I don't fry a very expensive amp.

 

[JOEY B.]

Thanks but what about us unprepared folk who don't own a bias meter and have limited electronics understanding. :wink: I recieved these from tubedepot and I told them what amp they were going in and it even says so on their packing list. I just want to triple check so I don't fry a very expensive amp.

They will be fine. I had a set from tube depot that had a rating of 39 on them. I used them in a Mark IV and a IIC+ without any issues. In the Boogies they only pulled about 20 mA at idle. Let it rip. :twisted:

 

[THTH]

They should be fine if you told them what amp you are using them in. I have some EL34's from the tubestore with a 48 on them and they work fine. Try using them first on tweed power to make sure they don't red plate. If it appears ok - no excessive heat, smell, etc, try full power while you are watching them. My EL34's run really cold even at full power, but sound great in the IV. Good luck.

 

[MrMarkIII]

I recieved these from tubedepot and I told them what amp they were going in and it even says so on their packing list.

You might have mentioned that. :roll:
You have done exactly the right thing, and you should be fine.
Turn it up!

 

[miqueas92]

Tubedepot = dependable