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From: fish@ihu1g.UUCP (Bob Fishell)
Newsgroups: net.audio
Subject: Re: Tubes and solid state
Message-ID: <447@ihu1g.UUCP>
Date: Fri, 22-Jun-84 14:51:30 EDT
Article-I.D.: ihu1g.447
Posted: Fri Jun 22 14:51:30 1984
Date-Received: Wed, 27-Jun-84 08:25:56 EDT
References: <494@drutx.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 35


>Without question, quality solid state gear sounds superior in the lowest
>octaves, say under 200 Hz, and the highest octave, say over 14KHz.  But
>why does quality tube gear have that unique ability to resolve low-level
>detail near the noise floor and ambience that solid state gear cannot?

Solid state amps sound better in the lowest and highest ranges because
it is directly coupled to the loudspeakers.  Tube amps, of the high-
fidelity variety, are coupled with enormous toroid transformers, whose
characteristics at low and high frequencies tend to be nonlinear, attenuating
the sound at both ends.

Tube amps do yield certain advantages over solid-state ones, particularly
when the amp is driven into clipping.   Tubes clip softly, which 
doesn't create all those tweeter-destroying harmonics.  However, the 
pleasing audible characteristics of tube amps is more of an illusion
created by nonlinearities in the circuit than by an ability to recover
information from the source.  Tube circuits tend to have even harmonics
as most of the THD, and it has been demonstrated that the even harmonics
are not such an unpleasant form of distortion.  This is part of 
the "ambience" you seem to be hearing.  

As for an ability to resolve detail, that's an illusion, too.  In
reality, tubes yield less recovery of detail than transistors do,
but they have an uncanny ability to get rid of things that you might
not *want* to hear.  Ask anybody who plays an electric guitar or Fender/Rhodes
electric piano what sort of amp they prefer.  They'll pick tubes every
time, just because they *sound* better, specs notwithstanding.  Tubes
tend to give a characteristic "warmth" to music that transistors lack.
However pleasing this may be, though, it's still a form of distortion,
or more aptly, sound coloration.
-- 

                               Bob Fishell
                               ihnp4!ihu1g!fish