I tried to recover an old transistor amplifier. I replaced several components, mainly transistors, with types that they told are equivalent. However, the amplifier has distortion. What happens.
If capacitors and other passive components have been replaced by modern equivalents, the distortion problem is probably not due to them. What happens is that in many old equipment germanium transistors were used and the modern silicon equivalents are not equivalent. As they have a different polarization point, they can cause distortions. A correct procedure would be to recalculate the stage polarization resistors, but this requires good knowledge. Another possibility is to try to experimentally change the base polarization resistors of the transistors.
