SET amp w/Neg feedback?

Jtgofish, that is not entirely true, although there is a class of loudspeakers for which it probably is. see:

http://www.atma-sphere.com/papers/paradigm_paper2.html

for more information.

Negative feedback violates one of the more important rules of human hearing by enhancing the odd-ordered harmonics used by the human ear as loudness cues. Hundredths of a percent is quite audible- bright, hard, harsh, clinical, chalky... -these are all words to describe extremely slight amounts of odd-ordered harmonic distortion.

Jtgofish, if you have a speaker designed using Voltage Paradigm rules, then what you experienced is absolutely right. We have had similar experiences.

A speaker using Power Paradigm rules will often work better, including the bass, using an amplifier without any feedback at all. Obviously such a speaker is designed expecting a different set of rules from the amplifier.

Rockadanny, it all has to do with the intention of the designer. In general, if the designer uses tubes its probably a Power Paradigm speaker he created. Voltage Paradigm designers usually use transistors. That will answer the question about 95% of the time. Beyond that, its a good idea to talk to the designer and/or read any white papers he may have written, or simply ask what sort of amplifier he recommends.

The equipment matching conversation that is all over high end audio is a direct result of the conflict of these two paradigms.

Rleff, the key to that is a flat impedance curve. The Avalon Eidelon does that well, as well as most magnetic planars, whose impedance curve has nothing to do with box resonance :)

There is another issue- the difference in performance between low impedance speakers and high impedance. Actually, the difference in impedance has little to do with the speakers and everything to do with the amps: **all amplifiers** regardless of the technology, will sound better driving higher impedances. IOW if sound quality is your goal, it will be better served by an 8 or 16 ohm speaker as opposed to 4 ohms, all other things being equal.

Another way to put this is if you had a speaker with 2 woofers, 2 midrange units and 2 tweeters, and all the drivers were 8 ohms, it would sound better wired as a 16 ohm load than it would wired as a 4 ohm load, regardless of the type of amplifier involved.

OTOH if sound **pressure** is your goal, and you have a transistor amplifier, a 4-ohm speaker might be preferred.