Why Tube Pre-SS amp over SS Pre- Tube amp?

I'm a purist. Tubes (SET) all the way. Pre to amp. It works for my ears. SET, particulary, very magical, holographic, you've heard the whole nine of adjectives: and they are true. I wouldn't let an SS pre amp touch my SET amp. Kind of like putting slip covers over a beautiful new sofa. Of course, there are probably SS pre amps that can do the job that my pre does, but I gots to draw the line somewhere in my sonic journey.

Warren,

I do agree with you that all tube, is the way to go. I currently use a SET amp as well.

I have, however, heard a number of non-SET amps that are really good alternatives. One is a near one-of-a-kind OTL that is about 20 years old that the owner was will to part with for something like $70k. Another astonishing amp I heard was a Western Electric pushpull amp in a massive vertical rack arrangement. The owner had only one amp (i.e., mono) and cannot find another to make a stereo pair. I heard it in a side-by-side comparison with an Audionote (uk) Kageki (the SET I own). It was a better amp, but, then again, it costs almost four times what the Kageki costs.

I have heard a number of fine systems with solid state linestages in them, but, these systems are so different from mine and I cannot say what contribution to the overall sound was made by the solid state linestage. Still, some of these linestages, like the Connoisseur and the Naim 552 I heard, must be pretty good if the systems sounded pretty good.

Tz7, I am an engineer but not an electrical engineer, so maybe an EE type can weigh in here. My understanding of MOSFET's is that their transfer function is more like that of tubes than that of bipolar, HEXFRED, or other transistor types. They probably are also used in circuits with a lot less global negative feedback than those of bipolars, whose distortion tends to be odd- and higher-order, thereby requiring more feedback to minimize distortion.

SET amps are not in and of themselves the last word in SOTA amplification.

It's not that simple.

>> 12-27-06: Rlawry
>> Tz7, I am an engineer but not an electrical engineer,
>> so maybe an EE type can weigh in here. My understanding
>> of MOSFET's is that their transfer function is more
>> like that of tubes than that of bipolar, HEXFRED, or
>> other transistor types.

the reason that MOSFETs can be made to sound more like tubes (compared to BJTs) is that the MOSFET current-voltage transfer function follows a square law. Thus, MOSFETs end up creating more even-order distortion (just like many tubes) than odd-order distortion (just like many tubes).
The BJT's current-voltage xfer function follows an exponential curve. Thus, BJTs end up creating more odd-order harmonic distortion that can sound strident.

>> They probably are also used in circuits with a lot less
>> global negative feedback than those of bipolars....

this is not a true statement at all! The type of device (MOS or BJT) has nothing to do w/ the amount of negative feedback used in a circuit. It has more to do with the amount of gain in the circuit & what parameter the designer is trying to control (output impedance, distortion, noise, etc).
Just FYI: vacuum tube circuits also use (global)negative feedback - some use a lot & some use very little & others something in between.
There are several tube amps that use zero global NFB & guess what........................
there are several s.s. amps that use zero global NFB. So, it is all design-based & not device-based.