[sdiy] tube preamp and fx chain

[René Schmitz]

Hi Spencer and all,

Spencer Johnson wrote:
> if i follow a tube preamp with a chain of different effects, will it
> kill the elusive "tube sound" that everyone desires? suggesting that
> it won't kill that elusive sound, will following it with a solid state
> power amp kill the sound?

I've already commented on the input stage below.

Now the output is similar. A speaker is a resonant system, albeit this 
is mainly a mechanical resonance. (The inductance doesn't play the major 
role here, but the mass-spring system.) This resonance is damped by the 
electrical impedance that is presented to it. Coarsely generalizing, a 
tube power amp has a higher output impedance than a solid state one 
(lower damping factor), hence the mechanical resonances of the speaker 
are more pronounced.

Besides this there are all those things that come from different 
nonlinear actions in a tube amp, like power stage distortion and core 
saturation effects, which you don't have in a solid state amp. But which 
only are present when the power stage is nearing its rated output. With 
lower volume, most of the sound does come from the preamp.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159