Non Mesa brand tube rating help (Voltage ratings)

Southernhell · Feb 12, 2008

I need some info here guys.

I am buying some tubes from a great guy I know whose occupation is selling tubes like Euro and Dougs.

What I would like to do is get a rating window for 6L6's as well as EL34's that can easily be used in a Dual Rectifier as direct plug in replacement. I am talking the test rating number that sellers put on the boxes. I think this would help others as well seeing that we are all on the look out for reasonably priced tubes.

For example, I have a quad of JJ E34L's from Euro that are rated at 34. I called Bob and spoke with him and he said that he likes to sell those tubes rated in the upper 20's for Dual Rec use to be safe in case I wanted to use the diode rectifier, but if I were to use tube rectification a 34 should be ok if I don't push the amp hard.

I do not know what a safe window for 6L6's are. The set bias on these amps somewhat confuses me as I am used to being able to adjust the bias voltage. Can anyone help out on this?

I ask because this guy can get me a matched quad of Shuguangs for $46 with $5 within continental US. I just need to let him know the safe range for the amp. This guy sells other brands and pretty much can get what you want to include NOS at really reasonable rates. He suggested the Shuguangs as they are nothing more than non rebranded Ruby's

fishyfishfish · Feb 12, 2008

I wouldn't use the "34" as an absolute in gauging what the bias is set on your amp. I think Eurotubes uses it for something else. Mine were labeled 37. The 6l6's I got from them were 78. Get a Bias Rite, or like device and measure the plate voltage. http://www.webervst.com/tubes/calcbias.htm

stokes · Feb 12, 2008

"I do not know what a safe window for 6L6's are. The set bias on these amps somewhat confuses me as I am used to being able to adjust the bias voltage. Can anyone help out on this?"
Just install a bias adjust pot in your amp and adjust your bias.Tubes you buy that are pre-graded for your amp are usually cold anyway,they have to be so as to be "safe" for both rectifier modes.

Southernhell · Feb 13, 2008

fishyfishfish said:
I wouldn't use the "34" as an absolute in gauging what the bias is set on your amp. I think Eurotubes uses it for something else. Mine were labeled 37. The 6l6's I got from them were 78. Get a Bias Rite, or like device and measure the plate voltage. http://www.webervst.com/tubes/calcbias.htm

I was just using that "34" as an example. I usually run my bias at about 70% of the Max plate dissipation in my Marshall amps.

I was asking what grading range should be used on a non adjustable bias amplifier. I understand the Mesa/Groove tubes charts, but do not have a clue when discussing what a safe range would be for tubes from neither of those companies. I only ask because the guy I buy my tubes from usually deals with buyers who have adjustable bias amplifiers. I just do not want reliability issues. I guess I could just check the B+ of my Rectifier and tell him to go from there.