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Hoffman Amps Forum image Author Topic: 5E3 phase inverter resistor substitution  (Read 1598 times)

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Offline ALBATROS1234

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5E3 phase inverter resistor substitution
« on: November 25, 2023, 06:03:00 pm »
I am building a head that has the back end of a 5E3 with a 6SL7 instead of a 12AX7. Reading the schematic the plate resistor and the kathide resistor are 56K. I do not have any 56k resistors on hand and I'm right in the middle of building I have 68k though. I realize if I use 68k it would limit voltage to the plate a little bit as well as effect the cathodes output a little bit. This will cause an imbalance on the drive of the 6v6's. In my mind I'm thinking that's only 10K it probably won't be that big of a deal but I was looking for opinions is 56k set in stone ? What's the worst that could happen blocking distortion? Has anyone ever used a different value for these resistors in doing something similar with a cathodyne phase inverter? I welcome any input or criticism.

Offline sluckey

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Re: 5E3 phase inverter resistor substitution
« Reply #1 on: November 25, 2023, 06:37:31 pm »
56K is not set in stone. I have an amp that uses 47K. 68K will also work. But here's the important thing... The cathode resistor and plate resistor should be the same value.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline ALBATROS1234

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Re: 5E3 phase inverter resistor substitution
« Reply #2 on: November 25, 2023, 07:25:26 pm »
That's what I thought and I was going to do it anyway just to see what happened because I figured worst case scenario they'll be a little too much distortion cuz it may unbalance the circuit but I'm using a 6SL7 so it may need to be balanced. Thanks!

 


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