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For tube sound, which is more important: preamp or power amp?

I have always loved the “tube sound” - warmth, midrange, soundstage. Through the years (since about 1975), I have owned many tube and solid state amps and preamps, in various combinations. Presently, I have a tube amp and a solid state preamp. But like most of you, I am thinking of making changes, again.  Not to cloud the discussion, the specific brands are not important.  I also listen to acoustic music, females vocals, love mini monitors, EL34s, NOS tubes, and don’t care that much about bass.  So you can see that my taste fits the tube sound very well. But I have had systems that are too warm, not enough dynamics or details, and fat in the low end, too.

okay, now to the discussion.  To produce the tube sound, which is more important: the preamp or the power amp?  Let’s talk in general, and (if possible? May not be) not tied to one specific piece/brand/model of equipment.  I know there are exceptions to any general rule.  Not sure if it makes a difference to your comments, but I have no phono and am running line stage only.

As an attempt to prevent the conversation as going in a big tangent, let’s assume equality of price/quality. i.e. not comparing a $10k power amps contribution to a system to that of a $1k preamp.  Let’s also assume that the amp (tube or solid state) can drive the speakers just fine, such that compatibility does not limit the decision. And ignore mono blocks versus stereo amp differences.  

two follow ons: I have  the perception that preamps give you more bang for the buck - meaning that it takes less money to get a great tube preamp compared to a great tube amp.  Agree/disagree? And second, I have never owned a tube dac or CD player, and will assume that tubes in either of these is less critical than in a preamp or power amp. Agree/disagree?

i am interested in your thoughts.

Bill
meiatflask
charles1dad's avatar
charles1dad
10,250 posts
 
Danoroo,
Those specification numbers will reveal very little in regard to component sound quality. You must listen and judge by what you hear. Again I find myself agreeing with the wisdom of Jond.

I once owned a Symphonic Line which is a highly regarded German SS amplifier. It had excellent specifications and very good sound. Well my 8 watt SET amplifier took my sound quality and listening enjoyment to a higher tier. The SET's measurements/specifications on paper would be reconsidered clearly inferior to the Symphonic Line.

Numbers said one thing and the ears said another, the ears won decisively. Now its definitely possible you could prefer the SS amp over the SET . My point is that listening is required to make that judgement not test bench results.
Charles
cerrot's avatar
cerrot
1,700 posts
 
The most important is the synergy between they two.  Power amps just need to be powerful - clean, no or very low distortion, hopefully slam, etc.  Preamps need emotion.  
wolf_garcia
6,719 posts
 
The Had amp I bought has no specs…it's specless, except for the 12 watt per side and Single Ended Pentode claims in the Ebay description. Specless.

fusian
129 posts
 
My solution is to bi-amp, using a SET for the tweeter/mids, and a Push Pull for the woofers.

And I use a PS Audio SS pre-amp, but in passive mode most of the time, which keeps me all tube. Only when I really want to blast the Stravinsky, do I add some preamp transistor.

This set up pleases me a great deal.
atmasphere's avatar
atmasphere
11,874 posts
 
Also, looking the specs of most tube power amps it seems the S/N ratio isn't nearly as good as SS amps. The THD numbers aren't as good either with 1% at full power not uncommon. SS amps' specs look considerably better. Is this typical?
The problem here is that the ear puts a different weighting on what harmonic distortion is present. IOW, it almost does not care about the 2nd harmonic, but cares quite a lot about the 7th and other higher ordered harmonics. So a tube amp tends to have lower orders to which the ear is less sensitive; solid state amps have more of the higher ordered harmonics than tube amps.

The ear translates all distortions into tonality. So the 2nd contributes to 'warmth'; the higher orders contribute to brightness and hardness. Both are colorations!

The bottom line here is that although solid state amps appear to have less distortion, the distortion that they do have is far more audible and objectionable to the human ear. This is why tubes are still around decades on after they were supposedly 'obsolete'.
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