How do tube Watts compare to SS Watts?

Bartok, the KT 88 (similar to 6550), etc aren't push-pull. They're pentodes. Push pull is an amp circuit config.Cheers

I thank all of your for sharing your opinions! The Theil 2.2s are presently driven by a Conrad-Johnson 80W ss amp with a C-J tube preamp. This is more than adequate for the music and volumes we enjoy. Using the ss W to tube W factor of 0.5, roughly, 40-50W tube might work; 60-75W very likely will work. I'm hoping to get something definitely warm not neutral. (I've always preferred the tone of Fritz Kreilser over that of Jascha Heifitz.) Ilooked into the Jolidas, and they are certainly impressive. But I've noticed that some folks think that they are not particularly warm or "tubey." I can't say and they are not available around here for roadtesting. Given constraints on tone, wattage, and cost, I think I'll nose around for early '60s American amps that have been, at least partly, refurbished. Or...maybe back to the Jolidas. Thanks again. Rascal

Greg, thats interesting. Not sure what a pentode is. Is the KT90 a pentode? If yes then all these 3 tubes are used in amp circuit designs that are different from SET designs using the 300 and 845 tube. Rascal, I also prefer Kreisler over Heiftz. Oistrakh was my prefered violinist, but I recently sold off his 6 cd set In Prague, oop. The set had too much romantic era stuff, which I don't care for. I love Gideon Kremer's recordings, except the Schnittke 4 vc's, which fault lies with Schnittke. Even though Schnittke is one of my top fav composers, his 4 vc's left me uninterested. Read my reviews on amazon.

Bartokfan. A pentode is a vacuum tube that has three grids, namely a control grid, a screen grid and a suppressor grid. The screen grid was added to isolated the control grid from the plate to reduce Miller effect.

A tetrode is a tube that has a control grid and screen grin (no suppressor grid). The suppressor grid is added to reduce secondary emissions from the anode.

A Triode has no screen or suppressor grid.

Triodes, Tetrodes and Pentodes can all be used in a push-pull or single ended configuration. When used in single ended configuration they all have to run class A, in push-pull they can be run in either class A or B (or combination thereof.)

Tetrodes and Pentodes have their screens grids biased to +. If you bias the screed grid from the anode, it is know as triode mode. If you bias the screen grid from a tap on the primary winding of the output transformer, it is called ultraliniar mode. If you bias the screen grid from the power supply, it is called tetrode/pentode mode.

The method of biasing the screen grid alters the character of the tube slightly. Many amps have a switch to toggle between two of these modes.

A KT90 is actually a kinkless tetrode (the KT stands for Kinkless Tetrode). I believe that is actually a pentode with the suppresser grid tied to the cathode. And EL34 is an example of a pure pentode.

Regards
Paul

Rascal52240, a Watt is a Watt is a Watt. It is a measurement. An inch on a ruler is the same as an inch on a tape measure. That said, Watts needs to be considered as part of an equation. Your Thiel's 22's have a nominal impedance of 4 Ohms and a minimum impedance of 3 Ohms. Better ss amps may double their power into that load. In your case as a matter of measurement ss Watts may be 2X more powerfull than tube amps with the same standard 8 Ohm rating. Thiel designs their cross-overs in such a manner so as to provide a steady impedance for the amp, which helps maintain steady amplitude. Some argue that, these steps drain the ultimate apparent power from the system. The point of all this is; Thiel's respond best to lots of quality power. Of course, your room and ultimate sound levels will determine just how much power you need. For many years I used the same ss c-j amp you are currently using on earlier Thiel's CS 2's. Those 2's had an easier 6 Ohm nominal, 5 Ohm minimum load. A move to a much better 250 watt amp demonstrated qualities I never new my CS 2's were capable of. Jim Thiel told me himslelf that his power recommendations were based on the standard 8 Ohm rating of quality ss amps that were capable of doubling down, and if one were to choose tube amps, one should double those power recommendations. Comparable tube power usually costs more than the same ss power. Doubling that tube power can get a bit expensive. With a budget of $1K, I'd suggest you use ss watts. Furthermore, very few integrateds have the guts to really make Thiels sing, it usually takes a dedicated power amp to get the most from Thiel's, especially when you get away from the smaller 2 ways. An old audiophile cliche' that some how seems to work more often than it should, suggests that one should double the manufactures' minimum recommendation. For your Thiel 22's that would mean 200 watts into 4 Ohms. A quality 200 watt per channel tube amp might be hard to find for under $1K. To drive your Thiels, that money may be better spent on better ss watts.