Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Arry on October 12, 2022, 02:00:42 pm
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Hi everybody, on my Fender Bassman reissue I recently installed a Hoffman 5F6A board. I noticed that the bias range offered by the pot is a bit limited, and would like to have the option to set the bias to about 70% of the maximum plate dissipation (something I cannot reach now, even with the pot turned all the way up).
Which resistor should I change to allow for a hotter bias? Thanks!
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It's the one with the "Bias Range" flag and arrow. Make it larger for hotter bias.
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Thanks Sluckey. What value would you recommend I try?
Arrigo
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1.2K, 1.5K, 1.6K, 1.8K, 2.2K, whatever it takes. I would set the bias pot to midrange and then experiment to find which resistor gets closest to your desired 70% point. This will allow you to be able to adjust hotter or colder than 70%.
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Hi everybody, on my Fender Bassman reissue I recently installed a Hoffman 5F6A board. I noticed that the bias range offered by the pot is a bit limited, and would like to have the option to set the bias to about 70% of the maximum plate dissipation (something I cannot reach now, even with the pot turned all the way up).
Which resistor should I change to allow for a hotter bias? Thanks!
The install instructions tell you exactly what to do
https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_
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Hi everybody, on my Fender Bassman reissue I recently installed a Hoffman 5F6A board. I noticed that the bias range offered by the pot is a bit limited, and would like to have the option to set the bias to about 70% of the maximum plate dissipation (something I cannot reach now, even with the pot turned all the way up).
Which resistor should I change to allow for a hotter bias? Thanks!
The install instructions tell you exactly what to do
https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_ (https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_)
Doug you really have some nice instructions. Hoffman Board Install Instructions (https://el34world.com/Hoffman/instructions.htm) link from above posted link:
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Hi everybody, on my Fender Bassman reissue I recently installed a Hoffman 5F6A board. I noticed that the bias range offered by the pot is a bit limited, and would like to have the option to set the bias to about 70% of the maximum plate dissipation (something I cannot reach now, even with the pot turned all the way up).
Which resistor should I change to allow for a hotter bias? Thanks!
The install instructions tell you exactly what to do
https://el34world.com/schematics.htm#Hoffman_5F6A_Bassman_
Excellent, I hadn't even thought of checking the instructions booklet : )
1.2K, 1.5K, 1.6K, 1.8K, 2.2K, whatever it takes. I would set the bias pot to midrange and then experiment to find which resistor gets closest to your desired 70% point. This will allow you to be able to adjust hotter or colder than 70%.
Thanks!