6L6 to EL34 conversion

bereanbill · 8th February 2009, 03:27 PM

Here goes...let me start by qualifying the simplicity of my question : I am a novice, hobby-type tinker with most of my interest in musical instrument amplification.
Ok...that said : I want to convert a 6L6 powered amp to EL34 due to space constraints. The filament tap is rated at 3 amps, so that is not a problem.. what changes must I make . It is cathode biased, class AB1. Any help is appreciated...God bless !!!

jjman · 10th February 2009, 05:22 PM

One consideration is that the 6L6 is internally connected between it's cathode and suppressor grids. The EL34 is generally not. So you may need to rewire some of the socket to ensure an appropriate connection for the EL34's suppressor grid.

Check the pin diagrams for each and compare to what you already have there. Keep in mind that there may currently be a resistor mounted on the currently "unused" suppressor pin for convenience. You may need to re-locate it.

EL34s can also call for a higher value screen resistor in comparison.

bereanbill · 11th February 2009, 04:56 AM

Thanks for the info...so I need to jump a wire from the cathode pin to the supressor grid pin ? I have seen amps use the extra pin as an open solder lug...that wont be a problem to relocate.
Do you think going to a KT-77 would be easier?

jjman · 11th February 2009, 04:55 PM

I’m not familiar with KT-77. I’m only familiar with the 6L6 vs EL34 thing since I made that change on a guitar amp I once owned. There was no audible change in tone but that amp had much going on inside that prevented the true tube sound from coming thru. I sold it and bought a ’71 Fender instead.

8th February 2009, 03:27 PM	#1
bereanbill diyAudio Member Join Date: Jan 2009	6L6 to EL34 conversion Here goes...let me start by qualifying the simplicity of my question : I am a novice, hobby-type tinker with most of my interest in musical instrument amplification. Ok...that said : I want to convert a 6L6 powered amp to EL34 due to space constraints. The filament tap is rated at 3 amps, so that is not a problem.. what changes must I make . It is cathode biased, class AB1. Any help is appreciated...God bless !!!

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10th February 2009, 05:22 PM	#2
jjman diyAudio Member Join Date: Jan 2009	One consideration is that the 6L6 is internally connected between it's cathode and suppressor grids. The EL34 is generally not. So you may need to rewire some of the socket to ensure an appropriate connection for the EL34's suppressor grid. Check the pin diagrams for each and compare to what you already have there. Keep in mind that there may currently be a resistor mounted on the currently "unused" suppressor pin for convenience. You may need to re-locate it. EL34s can also call for a higher value screen resistor in comparison.

11th February 2009, 04:56 AM	#3
bereanbill diyAudio Member Join Date: Jan 2009	Thanks for the info...so I need to jump a wire from the cathode pin to the supressor grid pin ? I have seen amps use the extra pin as an open solder lug...that wont be a problem to relocate. Do you think going to a KT-77 would be easier?

11th February 2009, 04:55 PM	#4
jjman diyAudio Member Join Date: Jan 2009	I’m not familiar with KT-77. I’m only familiar with the 6L6 vs EL34 thing since I made that change on a guitar amp I once owned. There was no audible change in tone but that amp had much going on inside that prevented the true tube sound from coming thru. I sold it and bought a ’71 Fender instead.

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