Sorry, just the opposite is true. Tube amplifiers show a relevant distortion already at low output signals. 0.3% distortion at 0.1W into 4Ohm load is typical.

When increasing the output level the distortion increases, but only very smoothly. 1% at 1W/4Ohm and 10% at 10W/4Ohm are typical values.

When further attempting to increase the output signal, also the output transformer begins to clip and a heavy increase of distortion can be seen.

A typical distortion versus output power plot of a tube amplifier looks like this:




This plot is from this link http://www.stereophile.com/integratedamps/398/index6.html

A transistor amplifier, on the other hand, standardly shows very low distortion of about 0.01% to 0.3% over the whole output signal range. Further attempting to increase the output signal results in a sudden, heavy increase of distortion.

Typical distortion versus output power plots look like this:




This plot is from this link http://www.st.com/stonline/products/literature/ds/1451.pdf

Or like this:



This plot is from this link http://www.st.com/stonline/products/literature/ds/8326.pdf


By the way, there are tube amplifiers on the market which show much lower distortion than in the example above. These ones really sound nice.



Have you ever analyzed the distortion that is produced by a standard loudspeaker when two tones are radiated, caused by the moving membran??


Kai