high power tube amps vs ss


I have always had low efficiancy speakers and had powerfull ss amps to power them. Now I see there are a number of tube amps in the 150 - 200 WPC range. My questions is: is there anything to be gained by switching to these higher power tube amps over ss amps?
winggo
Jallen I just put in a pair of MAZDA CIFTIES-12AU7's and I really like the top end end on these. Awesome sounding tube made in 1962 for the French Military.
Thanks very much, Matt. Yes, the Daedalus Ulysses, in the configuration I have that was introduced about 3 years ago which includes "all poly" crossover capacitors, is 98 db/1W/1m. It also has a very flat impedance curve, as well as high power handling capability, all of which makes it unusually versatile with respect to amplifier selection.

Regarding your question, what I said was "the power capability of a solid state amp into 4 ohms MAY [emphasis added] be as much as twice its capability into 8 ohms."

As you probably realize, the power capability of MOST solid state amps will be substantially greater into 4 ohms than into 8 ohms, in many cases approaching twice as much, and in some cases equaling twice as much. Two ohms may be a different story, of course, as a lot of amplifiers will not do well dealing with such a heavy load.

As you indicated, though, your McIntosh MC-352 amplifier has the same output rating into 8, 4 and 2 ohm loads. That is essentially a consequence of the unusual autoformer-based design of its output circuits. I am not aware of any non-McIntosh amplifiers that use a similar approach.

As opposed to a tube amplifier utilizing an output transformer, however, the solid state + autoformer approach provides considerably lower output impedance/higher damping factor (damping factor being spec'd at 40). As a consequence of that it WILL, like most solid state amplifiers, to a very close approximation double actual power DELIVERY (as opposed to CAPABILITY) as load impedance is halved, AS LONG AS it is operated within its 350W or so capability, and as long as the impedance of the speaker is a reasonable match for the output tap on the amplifier that the speaker is connected to.

In contrast to most tube amps, that essentially places the MC-352 in what Atmasphere refers to as the voltage paradigm camp, i.e., its output voltage for a given input will be essentially constant regardless of load impedance, as long as the amplifier is operated within its capabilities.

Regards,
-- Al
I will add this to what Al said: It is generally thought to be a good sign when a typical solid-state amp doubles in power as the impedance of the speaker is halved. A sign of a good power supply, IIRC.

And yes, generalizing about amps based solely on the amp being solid-state or tube is certainly problematic. But this doubling-down into lower impedance is something that applies for the majority of solid-state amps. Your amps happen to be an exception to that rule of thumb.
Al, does the autoformer lower the output impedance of the amp, or increase the perceived impedance load of the speakers. I appreciate the DF math works the same way, but just wasn't sure what changes.

In other the DF of amp is 20:1 if speaker impedance at the test frequency is 20 ohms and the amp's output impedance is 1 ohm. DF is still 20:1 if speaker impedance is 10 ohms at the test frequency and the amp's output impedance is .5 ohms.

Cheers,

Bruce
Hi Bruce,

I suspect that the specified damping factor of 40 for the MC-352 (actually, it is specified as "greater than 40," but I'll assume 40 for present purposes) represents the output impedance of the amp for a given output tap divided into the speaker impedance that tap is nominally intended to be used with.

If so:

The output impedance of the 8 ohm tap would be 8/40 = 0.2 ohms.

The output impedance of the 4 ohm tap would be 4/40 = 0.1 ohms.

The output impedance of the 2 ohm tap would be 2/40 = 0.05 ohms.

The output transistors would presumably see the same load when an 8 ohm speaker (that is truly 8 ohms) is connected to the 8 ohm tap, compared to when a 4 ohm speaker (that is truly 4 ohms) is connected to the 4 ohm tap, compared to when a 2 ohm speaker (that is truly 2 ohms) is connected to the 2 ohm tap.

BTW, thanks for your kind comment earlier in the thread.

Best,

-- Al