2 Channel Dual Rectifier regular bias current

[nwoforlif]

Hi Guys.

I am about to get a mA bias probe in the mail and was wondering what these values are for the 6L6 tubes and the EL34 tubes in a 2 Channel dual rectifier. Are they 70% of the full plate current capability?

35mA=6L6
38mA=EL34

Also what is the voltage when measuring across the grid resistors?

I bought my amp used and have a feeling that I have the wrong color (grade) of tubes in it. This probe is gonna help the because I'm probably close to the normal bias but I'm the type of person that wants to know for sure.

NWOFORLIF

 

[mikey383]

If you are using Mesa branded tubes, there is no way you have the wrong color in the amp.

I think the plate voltage in a Recto is around 475 volts. So at 34mA on a 6L6, you're running fairly cool (70% dissipation should be around 44mA @ 475V) To measure plate voltage, use pins 3 and 8.

http://www.webervst.com/tubes/calcbias.htm

That is a bias calculator that you can use to find the safe limits for tubes.

 

[nwoforlif]

Thanks for the reply on 6L6's! Do you by any chance know what the plate voltage and current is for the EL34 power tubes in a dual recto 2 channel at 70% dissipation? I have both types of tubes and change them according to my playing mood.

NWOFORLIF

If you are using Mesa branded tubes, there is no way you have the wrong color in the amp.

I think the plate voltage in a Recto is around 475 volts. So at 34mA on a 6L6, you're running fairly cool (70% dissipation should be around 44mA @ 475V) To measure plate voltage, use pins 3 and 8.

http://www.webervst.com/tubes/calcbias.htm

That is a bias calculator that you can use to find the safe limits for tubes.

 

[trem]

Unless I misunderstood your question, you can use the Weber bias calculator to calculate that too. Simply change the tube type. Plate voltage is set from the factory.

Thanks for the reply on 6L6's! Do you by any chance know what the plate voltage and current is for the EL34 power tubes in a dual recto 2 channel at 70% dissipation? I have both types of tubes and change them according to my playing mood.

NWOFORLIF