What is transistor noise?
http://www.vias.org/transistor_basics/transistor_basics_04_05_03.html
The minimum signal that can be applied to a transistor is
limited by the internal noise generated by the transistor. Since
the transistor does not require cathode heating (one of the major
noise sources in the vacuum tubes), it is inherently capable of
operating at lower noise levels than its vacuum tube brother. At
present, the junction transistor is equal to the vacuum tube,
insofar as its noise characteristics are concerned. The noise level
of the point-contact types is between 15 and 30 db higher.
see the website, there is a lot more. do more research for
certainty.