Who makes

The Nelson Pass amps I referred to earlier that act essentially as current sources and therefore have very high output impedance are listed at his "First Watt" site here. (His amps that are marketed under the Pass Labs name are of course voltage paradigm amps, as Bruce indicated). The ones I was referring to, which I suppose could be called "current paradigm" amps, are the F1, F1J, F2, and F2J, which are indicated as no longer being produced. The literature provided at the site indicates that they are of course only suitable for use with a limited number of speakers, primarily those using just one driver and providing high efficiency.

What may be more interesting, though, are the currently produced SIT-1 and SIT-2 models, which I hadn't been aware of previously. Based on a quick look at their descriptions, specs, and manuals, those would appear to be true solid state power paradigm designs, although their power ratings are limited to SET territory at 10 watts.

Best regards,
-- Al

12-02-13: Bifwynne
Al or Ralph, if you can simplify or clarify what I just said, I'm sure I and the other readers would appreciate your edits.

You said it all clearly and well as far as I am concerned, Bruce, aside from a minor miswording that I suspect was inadvertent: As you probably realize, damping factor is not measured in ohms. Since it is the ratio of two impedances, it has no units.

Best regards,
-- Al

Hi Bifwynne,
It doesn't seem that Shakeydeal was making a proclamation but rather just
stating an opinion about his preferences. I know this is of course pure
subjectivity but I understand his rationale for feeling that way.
Charles,

12-02-13: Bifwynne
Suffice to say that a speaker with highly negative (i.e., capacitive) phase angle and low impedance characteristics in the power spectrum (say 30 to 400 Hz ??) can really give a tube amp, even a SS amp, a bad day. That in part makes for a tough to drive speaker that calls for a "current" beast like a Bryston or Krell SS amp.

That is another good point. Is the current output more important than the voltage as that is what gives the speaker its dynamic range? What is voltage good for? It seems like a cheap way make the amp appear to be powerful when reading the specs.
Thanks all. I will have to give this some thought. Previously, I had the simplified idea that if a speaker is over 8 ohm, and especially 16 ohm like those back in the 60's, you need tubes because you just won't get any power out of a reasonable sized ss amp.

"What is voltage good for? It seems like a cheap way make the amp appear to be powerful when reading the specs."

Obviously, there can be no power without voltage, but with home hifi, not all watts are created equally. True powerhouse amps are either large and heavy and use beefy power transformers and in most cases with typical less efficient Class A or even Class A/B amps will also require extensive heat sinks to dissipate the heat created by wasted power.

The exceptions are amps designed to be more efficient, like Class G amps that have been around for many years or more significantly these days, Class D amps, that achieve new frontiers in power amp efficiency and sound quality not possible prior/otherwise.

One of the most unique advantages of a tube amp in regards to how far teh watts go is soft clipping. Tube amps soft clip by nature, which means sonic artifacts of amp clipping is more acceptable to our ears than is the case with most hard clipping SS amps.

Best to avoid clipping altogether IMHO, which in the past was quite hard to avoid in many cases using traditional Class A/B technology. No longer the case with new higher efficiency and more practical (for many compared to a traditional Class A/B monster sized power amp) high power Class D amps.