high power tube amps vs ss

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

Atmasphere, are you comfortable telling us which in your opinion are the 5 ss amps that come close? Just curious.

I'm a big fan of Nelson Pass, Ayre and Ridley Audio. That's my short list... I think there are a few other candidates out there but I've not been able to hear them.

Me too regarding Nelson Pass designs. One of the few SS designs that to my ears really get closer to making music sound real other than , to my ears, a tube solution (preferably of the OTL variety) ideally matched with the speaker. It always comes down to synergy when making choices and this is not so easy. There are many speakers with difficult load characteristics that are superb that will not electrically match with tube amplification. There is no simple answer to this complex paradigm. Melding components together in a manner that makes recorded music sound real is not easily achieved by Tube vs. SS discussion, too many factors involved in the equation that is evidenced by the same questions continually being asked, IMHO.

I really appreciate the contributions of Almarg and Atmasphere (Ralph) to my better understanding of these issues.