• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Schematic help

I am going to build copy of the RCA rs-193 amp, but don´t understend their schematics. I don´t understend their loudness connection. There is 5 connections, but regular potenentiometers have just 3 connections. Can anyone solve the wiring mystery? I attached the schematic.
 
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Moderator
Joined 2011
Yes, eliminate everything between the coupling capacitor and the balance control.
Then add a dual log 500k volume control just before the balance control.
A 250k control can work, if you can't find a 500k control.

If the balance control doesn't work well enough now, then at the expense of lower gain,
you can add a 220k resistor in series with the coupling capacitor.
 
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