kee--(at)--ustin.ibm.com () writes:
>Sounds great. You use the neato solid state amps, I'll just scrape
>by and make do with these old, silly, weak, tired tube amps...
This post is not intended as a reply to Mr. Keen. I agree with
his preference for tubes, but some day they'll...some day they'll...
oh..sorry..momentary flashback.
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The overall effect is very dependent on design. No reason why a
solid-state amp should have inherently more bass, for instance.
And *lots* of nasty unreliable solid-state amps have come thru
my shop.
Tubes will probably continue to be less consistent, but that may
mean that solid-state amps have 'consistently' bad tone. I will
not argue that, since everyone has their own preference. The
fact is, though that when cost is no object, most guitarists
go with tubes.
Tubes will probably continue to be more expensive, true.
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And on the technical side (you were waiting?):
Tube amp power supplies can get by with much less regulation,
and frequently have to, due to the cost of high-voltage regulators.
This means that the amp will tend to starve its own preamp slightly
when it is pushed hard. This is one of the reasons that tube
rectifiers are popular: The additional impedance in the supply
causes even more 'sag'. The overall effect is a sort of compression,
and enhanced perception of sustain.
Tubes do not top- or bottom- out sharply. This attributes what
could be called 'headroom'. Also causes a compression/sustain
effect at high drive levels.
Tube amps have big transformers. Properties such as phase shift
and damping factor are affected. Lower damping factors in tube
amps mean that speakers become more of the equation. And the sound
becomes looser, less controlled. This is usually regarding in
hifi amps as a drawback, by the way.
Tube amps usually have low overall feedback levels. Not Hendrix-
style feedback. Internal electronic feedback in extremes was one of
the real problems with early solid state designs. It caused some
types of (bad-sounding) distortions that hadn't even been named
yet...slew-induced distortion, and transient-intermodulation.
Some new amps try to minimize 'global feedback', but it is generally
tougher to accomplish in a solid-state amp.
Here's the tough one: Why hasn't anyone done a perfectly convincing
piano sample? Because hitting one note on the piano causes the whole
instrument to vibrate. Sets all the other strings in motion.
Well, to some extent, tubes end up being mechanical devices. Tap on
them and you can generally hear a microphonic effect. Is it
coincidence that old combo amps like Vibro's and Super's are held
in high regard? Possibly, but some hold that the amp is acting
like a holistic organism (hey..) and feeding a part of energy back
into its own tubes.
This could be good or bad, but it's something a transistor amp
doesn't know how to do. Transistor amps, contrary to the above,
behave as small isolated sections. Very little interaction, good
or bad, thru their power supplies, etc.
So, it's a different thing. If you want a tight, controlled sound,
which maybe you *do* want for your stereo or bass guitar, then the
solid-state amp may be the thing.
If you want a looser, maybe less predictable, personal sound, with
inherent compression, that acts like a breathing organism, then
find the right tube amp and learn how to make it respond.
Mark Garvin
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