Valve amplifiers be it single ended or push-pull, have long been thought of by many as superior beasts to solid state…whether their use be musical instrument related, or purely for audio replay, but what is it that still makes them more desirable to a growing number of musicians and audiophiles world wide than often the best of what solid state has to offer?
Well, here are some positive reasons. First off, valve designs produce predominantly low order harmonics (which is musically related); while solid state designs generally produce a full range of harmonic distortion, including the objectionable high order harmonics. This is due to a number of factors, including the transformer output of valve designs, and the large amounts of negative (electronic) feedback required in solid state designs, in comparison, valve designs need very little negative feedback, and some good sounding amps don't use any at all!
Circuit design undoubtedly plays an important role, valve circuits are often less complex and laid out differently, therefore It can be argued that simplicity is usually best, as the length and complexity can change the inductance and capacitance of a circuit. A more complex circuit will have a more complex sonic distortion characteristic. Minimalist single ended valve amps for example typically have a dominant very simple harmonic distortion spectrum. Complex modern transistor designs often have low level but extremely complex harmonic distortion spectra.
Another advantage of most valve amplifier designs is the high input impedance typically 100k in modern designs and as much as 1 Meg ohm in classic designs. By contrast, solid state amplifiers may have much lower input impedances, some as low as 20k This implies that it requires more energy to excite the input of a typical transistor amplifier to any given voltage than it does a typical valve amplifier. If sensitivity to small signals is a significant goal, then valve designs will typically outperform transistor designs.
Valve amplifiers in general do not need to use as much negative feedback as transistor amplifiers, and while some will argue [and rightly so in some cases] that the absence of negative feedback slightly increases harmonic distortion, by limiting the amount of negative feedback, it avoids instability, as well as slew rate and bandwidth limitations imposed by dominant-pole compensation in transistor amplifiers.
Valves versus transistors when driven hard distort quite differently, and it is well known and documented that valves clip more softly than transistors therefore allowing higher levels of distortion to be tolerated whilst still being able to portray the complex harmonic structure of for example a musical instrument..
I could not add anything to the above ^^^^^
=NATURAL MUSIC..... and results in
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Originally Posted by Ali Tait
