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Need HELP on Randall RGT100ES 6L6 to EL34
Need HELP on Randall RGT100ES 6L6 to EL34
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Old 4th May 2010, 05:19 AM   #1
valdio is offline valdio
diyAudio Member
Join Date: Oct 2009
Default Need HELP on Randall RGT100ES 6L6 to EL34

Hello there, I need some help, I have an old Randall head RGT100ES that currently have 6L6 power tubes, I would like to turn this into EL34's (I love the 34 tone), I have an idea of how to do it BUT would like an expert advice, my gues is to ground the sup grid on each socket and change screen grid resistor value from 470 ohm to 1K ohm (as on marshalls), I have seen many true experienced experts to post answers on questions like this and now is my turn to ask for help, so please, I would appreciate help on this

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Old 4th May 2010, 06:45 PM   #2
livingdeliberately is offline livingdeliberately  United States
diyAudio Member
Join Date: Feb 2010
Default 6L6 to EL34 conversion

Just a note, I had repaired a 5150EVH recently where the owner thought it would sound great if he would replace the 4 6L6's with EL34's. He said it sounded great for about 30 minutes, then it died. I found that he had burned all of the circuit traces from the board that supply the heaters to the power tubes.
It is not a good idea to make this mod unless you are willing to upgrade the power tranfo to supply the additional 2.8 amps at 6.3v required to switch power tubes. (6L6 is .9a and EL34 1.6a each) the current draw will create havoc with the heater circuit. Also if the original tranfo isn't rated that high it will overheat. If you do get it to work with the original tranfo, there is a good chance of cathode stripping due to the possibility of an undercurrent-state, thus reducing the life of all the tubes. EL34 bias points are a bit different also.
I hope some of this information will be of help.
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