04-08-2026, 08:39 AM
If you want to modernize the tone control, put a 0.005 uF 600V cap between the 6F6 plate and chassis ground across the output, then install the tone circuit below in the 1st AF amp. Use one of the more modern schematics for the purpose.
Below is a section of a more modern Philco set (41-255) which will fit.
Use a 500K Pot (Linear taper would be best but Audio taper would work) with a power switch (The original "Tone Switch" was also the power switch). Add the yellow section to the circuit. Use a 0.003 uF cap between the triode plate of the 6Q7 1st Audio Amp and the "Full CW leg of the tone control. The center (wiper) terminal goes to Chassis Ground. Connect the Full "CCW" leg of the tone control to the junction of Cap #43 and Resistor #45.
Below is a section of a more modern Philco set (41-255) which will fit.
Use a 500K Pot (Linear taper would be best but Audio taper would work) with a power switch (The original "Tone Switch" was also the power switch). Add the yellow section to the circuit. Use a 0.003 uF cap between the triode plate of the 6Q7 1st Audio Amp and the "Full CW leg of the tone control. The center (wiper) terminal goes to Chassis Ground. Connect the Full "CCW" leg of the tone control to the junction of Cap #43 and Resistor #45.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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