SET Preamps

I agree with everyone who said most or nearly all tube preamps are SET, but why?

In other words, why is a simple single-ended triode able to give 21st-century state-of-the-art performance in a preamp circuit, while similar performance in the power amp seems to require ultralinear push-pull circuits or something even fancier? Is it just the ability to drive the nasty load characteristics of the average loudspeaker? Just interested in case anyone knows the answer :)

Why is a simple single-ended triode able to give 21st-century state-of-the-art performance in a preamp circuit, while similar performance in the power amp seems to require ultralinear push-pull circuits or something even fancier?

Simply put, the power amp has to deliver vastly greater amounts of current and power to the speaker than the preamp has to deliver to the power amp. Which makes it a whole different ballgame.

Regards,
-- Al

If you want my opinion I really feel that if you do fully differential in the preamp, there is a huge benefit there also, IOW even though there are many very musical single-ended tube preamps, they *can* be improved upon.

Hi Atmasphere: Please specifically define improved. Thanks, Jeff

OK 'improved upon':
*lower noise,
*blacker backgrounds,
*far greater immunity to the length or quality of the interconnect cables,
*lower distortion/less need for negative feedback (since distortion components would be canceled with each stage of gain),
*potential for reduced number of gain stages (for example, to work with LOMC, you would need a total of three gain stages including the line section).