Correct MA Range for Dual Recto 6L6 to EL34 conversion

[JMPMAN]

Just purchased a used Mesa 3 channel Dual Rectifier head and was wanting to convert from stock 6L6's to EL34's, but I don't know the correct MA range. Anyone know? Thx

 

[disassembled]

All tubes draw different amounts so that's a really open question. Mesa sets their bias low so that it can work with just about any current production tube. You should get a bias probe from weber if you are really curious how much EL's will draw. I will tell you this though..... bob at eurotubes runs some of his 6L6's with the EL34 selected to bring them up to about 40 mA's.

If you need it set to draw a certain amount of current then you probably will have to mod the bias circuit for be an adjustable fixed circuit instead of just a fixed circuit.


Greg

 

[JMPMAN]

Thanks, but I want to run the 34's and not the 6l6's. So, as long as they are in the ballpark of 35-40ma's, is that ok along with the correct bias being selected on the switch?

 

[disassembled]

Mesa amps don't give you a choice. You just pop in EL34's and set the bias switch to EL34 so there's no need to worry. It will work fine with any current production EL34.

Like I said all tubes draw different amounts of natural plate current (even the same brand). If you buy from the tubestore, eurotubes, Dougstubes, etc you should specify what amp you are using the tubes in and they should recommend some for you that will draw close to 35-40.

Or you can just go with Mesa tubes or Groove tubes and call it a day.


Greg

 

[disassembled]

Oh and the current draw is only part of the equation. You must also factor in the tubes max dissipation and the plate voltage.



Greg

 

[JMPMAN]

Thanks for the quick reply. I have some quads of JJ's and SED Winged C's that I wanted to see how much difference it would make from the stock 6L6's, and I'd like to save some money and not have to buy Mesa's. And luckily that happen to be within the range specified.

 

[disassembled]

You have nothing to worry about it. Mesa's aren't like Marshalls with an adjustable fixed bias so you can plug and play pretty much any modern tube in there. If you are anal about where your output tubes are set you can always get it modded for adjustable bias and get a bias probe (about $50 in parts plus the install of the bias pot).


Good luck!

Greg