Which high power SET

Lots of good points above especially the posts by Larryi and Keithr. It is easy to fixate on the power rating and debate a 8w vs. 15w vs. 30w amp. The reality is that the numerical rating often does not correlate with how a particular SE amp sounds on a particular speaker. It is much more important to find an amp that is a synergistic match to the particular speaker. With a SE amp, it is important to use a speaker of high efficiency and easy-to-drive impedance characteristic. This is true regardless of the rated power output of the SE amp. In my case, I use a SE 46 amp which only has a little more than 1 watt output, yet it sounds much more powerful than the rating would suggest.....provided you use a compatible speaker. My speakers are around 98 db efficiency and a fairly flat 16 ohm load so they qualify as a nice match. Nevertheless, as good as the 46 amps sound, and they are the best sounding SE amps I have heard, for my tastes and on my speakers I eventually always return to my PP amps and usually find them to be a more satisfying sound overall. My PP amps happen to be more powerful (around 35 watts) and that probably contributes to the unstressed dynamic peaks but the PP amps also have more control, a tighter grip on the music. Interestingly, some people hearing both amps on my system prefer the SE 46 and some prefer the PP KT-77. There is room for both camps.

It can be difficult to predict one's preference just from reading forums like this one. You really have to live with each amp in your system for an an extended period and then decide for yourself.

I think this discussion leaves out an a couple of important factors. The first is the size of the listening room and the second is the listening level preference. The impedance curve is important as well, but to me speaker efficiency is a much lower priority. For a few years now we have been showing our 300B SET at 10 watts with Fritzspeaker Carbon 7s at 6 ohms and 87 dB. Room size was 13 x 18 or so. No problems whatsoever. Couldn't even get the amp to clip. Room overload was the only issue because we could play it loud.

Hi Clio09,
Not sure if you've read the entire thread. Earlier posts have mentioned room
size and listening levels as important variables that must be considered. As
I told you at CES this year, your amplifier was terrific sounding.
Charles,

I run 85dB (if that!) Infinity RSIIb speakers with a homebrew 200WPC, zero NFB, SET amp and it's the best sound I've ever heard. Crystal clear highs, full lush mids, rock solid thunderous bass. Sounds like a fleawatt SET, with twin superchargers!
Unlike some of the reports here, I do not have a problem with bandwidth at any volumes I care to enjoy, including LOUD.

So, anything is possible.

Action Shot

.

If it's topology, it means harbeths with its low sensitivity are generally incompatible with any SET amp, irregardless of it's power output. Given a hypothetical world where both push pull and SET generate the same power output, does push pull drive harbeths better simply because of topology?

Yes!! What is not getting the air time it should in this discussion is the fact that to take advantage of an SET, **you must not push it past about 20% of full power**!

You can go past that amount with a push pull amplifier and not have ill effects.

This is all about your amplifier investment dollar- with a speaker of efficiency that low, your investment dollar in an SET will not be served due to the fact above.

The impedance curve is another issue! It is pretty evident that the Harbeth is expecting that the amplifier used with has some negative feedback to linearize the output of the loudspeaker. Your EL34 amplifier has that feedback. If you put a zero feedback amp on that speaker its likely that the range of that high impedance in the midrange will take on some prominence.

To understand more about this phenomena, see this link:

http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php