I used to own the original UltraVerve. I wonder how the mk III compares to the original one. How about the Mercury mk III ? I auditioned the first one but didn't like the bass (bloated). The midrange was to die for though. I wonder how the Mercury mk III sounds now.
Not sure how you are defining "SET preamp," but as I would define it most and perhaps nearly all tube preamps are SETs.
Meaning that their output tubes (and other tubes that are in the signal path) are triodes, and the output stages do NOT consist of two triodes, or two triode sections, operated as push-pull pairs. Push-pull, btw, is NOT the same thing as differentially balanced, in case that is not clear.
The phrase "SET" is normally used to distinguish power amplifier output stages that consist of triodes that are not operated push-pull (and which usually provide very low power capability), from other output stage topologies that are operated push-pull and/or are based on tetrodes or pentodes.
We make some of the very few tube preamps that are **not** SET... ye olde Dynaco PAS-3 is SET, as is the Citation 1, many of the earlier ARC preamps, the CAT, the Joule Electra; Al is correct- most tube preamps are 'SET'. The term really is for *amplifiers*, where it creates a distinction, not preamps.
Hi Audiogabby. I have been using a Dehavilland Mecury II for the last three years. I agree with your assessment of it. However, I found that with the proper vibration control applied the bass can be deeper and taught. First, I put a 3mm Marigo Audio VTS dot under all of the tubes. Then I use a set of Marigo Mystery feet under it, which sits on an Adona rack. I also replaced the stock Russian output caps with Mundorf Silver/Oil ones (I consulted Kara before doing this). Finally, I replaced the 5 AW4 rectifier tube with a Tungsol 5U4GB. I'm no longer looking to change 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.
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.
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).