No, can't say I've made up my mind at all. Just the way I asked the question I guess
Hi Don. I just wanted to make sure that you were still truly open to either :yes:
Many people will mix/match tube/ss amps/preamps, hoping they'll hit the "sonic jackpot". However, knowledge is power (most of the time anyway) so I think it's helpful to first have a clear understanding of the difference(s) in how tubes and transistors affect an audio signal; and why using one or the other, in an amp
and/or a preamp may appeal more to a person's sonic preferences.
Everyone will agree that we don't want to unintentionally modify the signal after it leaves the source. So how can an audio signal be modified? Two ways: strength and frequency. The trick in audio reproduction, is to
intentionally modify the first (provide signal amplification) without
unintentionally distorting/corrupting the second (i.e. maintaining FIDELITY to what came out of the source.)
So lets talk about what amps and preamps do and
don't do with/to the signal:
Preamplifiers are way-stations between the source and the amplifier. Some single source users (generally the digital-only people) see no need for a preamp at all, as long as the source unit (the CD player) has a volume control built into it. For the rest of us, a
basic preamp offers source selection, source level matching, source impedance matching (so all sources look the same to the amplifier impedance-wise) balance adjustment, and output
attenuation (volume cointrol.) I use the word "attenuation" to call attention to the fact that a preamp's volume control is a
reducer, not an
increaser 
As you turn up the volume, you're
allowing more signal to get through to the amp; you are
not amplifying the signal. So what you should take away from this paragraph is that
Preamplifiers don't Amplify (phono preamplifiers, separate or built-in
do amplify but that's another conversation :yes
Amplifiers do amplify - and that's all they do! But first, I want to dispel a common myth: the myth is the idea that the power output tubes-or-transistors (the ones that get hot? :thmbsp
are doing the "amplifying". They are not! They are simply flow valves (like a faucet) that are able to provide a more "electrically forceful" duplicate version of the source's signal - I'll come back to this in a second; stay with me :yes: In both solid state and thermionic audio amplifiers, the
amplification function more commonly known as "gain" is the responsibility of the 'gain-multiplier' and 'driver' sections of the amp (sometimes known as an amp's 'front end', or input/driver section.) This is where the signal is
most vulnerable to corruption, than any other place in the audio playback chain. It's a bit like trying to blow up a photo (digital OR analog) without revealing the pixels or the silver grains. This is why in a tube amp like an MC275 for instance, the tubes that have the most influence on sonics are
not the big KT88 power tubes, but the little gain multiplier 12AX7's!
The
hard/warm/cold/soft issue
Why, oh why, oh why, are tubes WARM, and transistors COLD?? First, please remember that these adjectives all strive to describe something that happens to the signal, as it passes through various kind of devices and circuits. To boost a signal's strength, valves are used. The weak signal directly from the source itself, or when it comes out of the preamp, is used ONLY to operate the 'handle' of the 'valve'. The power that drives your speaker is NOT a boosted-up signal!! It's just raw power sitting there behind the valve, in the power supply, waiting for the signal to wiggle the valve's handle in accordance with the musical modulations. The modulated stream of power is what drives the speaker :thmbsp:
It is in the nature of elecrical valves (as opposed to water valves
) that they can only accept a positive or negative side of a signal's polarity, but not both at once (this is a generality for the purpose of this little essay.) They have to work in teams/pairs, better known as a 'push-pull' circuit. So one power tube/transistor 'opens its faucet' for the plus side of the signal's sine wave, and then hollers "your turn" to its buddy who then opens its faucet to make the minus side of the sine wave. The driver section of the amp (where the signal can get screwed up) is for the purpose of making the little signal strong enough to operate the valve handle :thmbsp
AND HERE'S WHERE THINGS GET WARM OR COLD: it's when one of the pair of valves hollers, "your turn"! This is because there's about to be a "hand-off" (of the music signal) like a baton in a relay race. One runner stops running and the other has to start running as fast as they can! Transistors can do this (turn on/turn off ) almost instantaneously; tubes turn on and off more slowly, as they energize/de-energize. If a pair of transistors aren't PERFECTLY syncronized as they turn on/off, there will be either overlap (producing hardness/glare/distortion) or a little gap, or discontinuity (producing loss of microdynamics and low level detail). With tubes, you never have the "gap" problem, but you have a larger or smaller degree of the "overlap" problem; and it can never be entirely eliminated.
So if you want to hear
every bit of the music, especially the important mid-range detail, use a tube amp. If you want it lean, get an Audio Research. If you want it warm a lush, get a Conrad-Johnson. If you want a perfect balance (in my opinion) get a McIntosh. If you want powerful bass and (the appearance of) High Definition, buy a great SS amp. McIntosh SS would be a good choice, were it NOT for their auto-transformers, which introduce a bit of a magnetic lag; producing a sound not unlike "slower tube hand-off".
Back to preamps. Preamps, since they don't (or unless they do) apply 'gain' to the signal, cannot affect the signal quality (warming/cooling) the way an amplifier can. A poorly designed or poorly functioning preamp can ADD stuff to the signal, usually noise, and as opposed to Myth #2, both tube AND SS preamps can be noisy or quiet depending . . . . . but toobies are more likely to be noisy because no tube is absolutely quiet, and most transistors are absolutely quiet :yes: Since a good amplifier will faithfully multiply EVERYTHING that comes out of the preamp, it will also boost tube hiss to (what for me is) an annoying level. (And that's how Mr. Dolby got so rich :yes
Bottom line: if you want "tube sound" (whatever you concieve that to be) get a tube amp - a tube preamp (except for the built-in tube phonostage part) will NOT give you "tube sound"; only tube noise (which many mistake for "tube sound" :yes
I have over the years enjoyed all the combos, but for the cleanest source and/or preamp signal and the most faithful power amp signal, I always wind up with SS pre, and tube power; and a ss amp for the woofers (or a sub.) With ONE exception (there's always
one isn't there?) and that's FM tuners (as if anyone cares anymore
) but tube tuners simply sound more musical to me, and FM is just a bit noisy anyway, so no problem
?
