Damping Factor - Interesting article

@david_ten asked: " Reaching out to those that know this stuff: does damping factor play a role with (influencing) perceived scale (image size)? If so, how? Thanks. " 

Not directly, to the best of my knowledge, but imo it can indirectly. 

My understanding is that low damping factor generally calls for high amounts of global negative feedback, which in turn can obscure low-level detail.  And soundstage size and depth, along with a sense of immersion or envelopment, benefit from preserving low-level detail. 

That being said I'm not an amplifier guy, but as a dealer for both types and as a speaker manufacturer and dealer, I've had a fair amount of experience in driving the same speakers with both high and low damping factor amplifiers. 

Here's another paper which examines the two paradigms of amplifier design, the constant-voltage paradigm (most solid state, generally high damping factor) and constant-power paradigm (mostly tubes, generally low damping factor).  This paper was particularly useful to me as a speaker designer: 

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

Duke

@david_ten wrote:

"1. Regarding:

My understanding is that low damping factor generally calls for high amounts of global negative feedback, which in turn can obscure low-level detail.

"Is this more of a solid state amp issue?"

In practice probably so.

David_ten: "How does it apply to tube amps with zero to very low negative feedback AND corresponding low damping factors?"

I would expect it to have all the low-level detail benefits of any other successful low-damping-factor amplifier.

David_ten: " Regarding:

I’ve had a fair amount of experience in driving the same speakers with both high and low damping factor amplifiers.

"Your generalized findings / results?"

First a bit of background: I design speakers with fairly high and unusually smooth impedance curves so that they have very similar response with both amplifier types across most of the spectrum, and then include user-adjustable bass tuning to adapt to the effects of amplifier damping factor into the bass region impedance peaks. So frequency response differences are minimal, and generally relegated to the region south of 100 Hz, where there can be a "free lunch" to the tune of an extra 1/4 to 1/3 octave extension with a low-damping-factor amp.

The following is my opinion; I can’t "prove" any of this.  Consider these to be generalizations; I’m not a writer of audio prose; and [disclaimer] I'm an Atma-Sphere dealer:

With low-damping-factor tube amps, I hear more of a sense of ease and liveliness and immersion. I’m hearing more stuff going on, it’s like the voices and instruments have more texture. Music is more engaging at lower sound pressure levels, which I think is related to the low-level details not needing as much SPL in order to be audible. At high sound pressure levels the difference is arguably even more noticeable, as there is an absence of the edginess which often starts to set in as the SPL goes up. I’m hearing more of a difference in soundscape and ambience from one recording to the next, with more of a sense of being "transported into" the recording, especially when it’s a really good one. There is a powerful emotional experience (some might call it spiritual) which some music can convey, but it calls for intensity and density and freedom from distractions. The least expensive amplification I have found which can do this is low-damping-factor tubes... specifically, the Atma-Sphere S-30 and M-60 [dealer disclaimer reminder].

Roberttdid wrote: " The example of the constant power amplifier as a tube-amplifier with transformer taps, is in my mind no different from the voltage amplifier paradigm presented... "

As a speaker designer I can tell you that the difference between the two amplifier paradigms is significant, whether or not output transformers are involved. The relationship between the impedance curve and the speaker’s output level differs depending on the amplifier type, such that if the speaker’s impedance curve has significant peaks and dips, it will measure and sound different with the two amplifier types.

Duke