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Tips to Improve your Vintage Radio:

IMPROVED SOUND QUALITY:  The audio quality of your vintage radio can be improved by a simple modification. Add a 100 Ohm resister between the bottom leg of the volume control and ground.  Then connect the junction of the volume control and the 100 Ohm resister to one of the speaker terminals.  Connect to the speaker terminal that improves the sound.  This will add degeneration to the audio circuit.

VOLUME CONTROL AT ZERO AND THERE IS STILL SOUND:  In some older radios the volume control will completely turn off the sound.  A 0.001 MF capacitor across the volume control to ground will solve the problem.

 

IMPROVE THE BASS OF YOUR RADIO:  Generally you can improve the bass from your radio by increasing the capacitor that couples the 1st audio tube's plate to the Audio Output tube's grid.  Try doubling the capacitance of this coupling cap. 

 

IMPROVE THE TREBLE OF YOUR RADIO:    To reduce the treble for a more mellow sound or with less adjacent channel interference, add capacitance to the plates of the audio output tube and the 1st audio amp. At first just add an extra capacitor, after you decide the optimum value you can go back with just one cap.   Increase the capacitance by 50% and try.  If that is more reduction then you wanted then remove one of the added caps.  If you want more treble, then just replace the existing capacitor on the output audio tube’s plate with a cap of about 30% less capacitance.  Always remember to use capacitors with a voltage rating equal to or greater then the original.  Never install capacitors with a lower voltage rating!!

 

SK7  SG7 AND SA7  SB7 SWAPS:  The 6 or 12 volt SK7 tube can be replaced with the corresponding 6 or 12 SG7 in most radios.  The SG7 has twice the transconductance and should improve the gain of the radio. A 6SA7 mixer can also be replaced with a 6SB7.  The 6SB7 has twice the gain and should give a noticeable improvement.   Alignments will probably neeed a touch-up after these changes to deliver the full potential.

 

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