The rectifier tube is used to create a direct current from the alternating current of the incoming A/C power. The rectifier tube is a diode. That is it transmits the current only in one direction. The plate and cathode charges are responsible for the allowing of current in one direction only. The resultant sine wave of the A/C source is just chopped off on the negative side of the cycling waveform. So the power becomes direct current, but it still is going from zero to full back to zero just as the peak of the alternating current did, with a gap of staying zero when the negative AC part of the current is being blocked.
The negative portion can also be 'rectified' AND inverted to turn the negative side of the power pulse into the positive side. This is called a "full wave" rectifier. The resultant waveform still has the sine wave shape of pulses, just all positve, from zero to full and back to zero, (with no gaps) all in the same polarity, thus Direct current.(cycling from zero to full to zero constantly, but always positive)
For power supply that deliver a positive DC voltage from ground, AND an equal negative DC voltage (usually for balanced operation) the power supply is doubled up and one full wave rectifier does the positive, another the negative rail.
(the reason for DC smoothing capacitors is to smooth out these pulses and offer a steady direct current.)
So those giant caps in your amp serve more than just one purpose. They store energy yes, but they also smooth out the pulsing of the power supply.
The rectifier tube is not the direct cause of the quality of the sound in the power supply. The whole design of the power supply is what affects the sound quality. i personally would say as long as the rectifier tube is working properly, that is all it can do. A 'quality' tube may be better because it actually does the job better.
The difference between a power supply tube and a signal tube is that the power supply tube is a 'rectifier',(a diode) it does NOT have a direct connection to the signal. The Driver tube DOES carry and amplify the audio signal. And the quality of the driver tube is very important to the quality of the final audio signal.
Different designs use tubes in different ways. Some use both sides of the tube as the stereo, some use only one side. all sorts of possibilites. But no matter how it is designed, the tubes that carry the signal are the important ones.
In many tube circuits a second tube is used called a 'cathode follower' This tube (or tubes) are not as important as the driver tubes. They can be of a lower quality and have less impact on the sound.
(For example my VAC has 2 driver tubes 12Ax7 and two cathode follower tubes 12au7.
So for my preamp the 12ax7 should be the best i can buy for best sound. but the cathod follower the 12au7 only need to be decent.
So find out which tubes in YOUR preamp are driver tubes and replace those with better quality tubes. You can leave all the others as is.
OK?
