Can tube amps give true high end bass?

Jmaldonado says...

Besides, the higher output impedance of tube amps create the conditions for slightly undamped resonance that adds to the "joy" factor. The end result is a warm, rich bass around the 40-200 Hz region to which you have become accustomed by now.

Jmaldonado, where do these "undamped resonances" come from and how do they manifest themselves? I am perfectly willing to believe the "joy factor" you mention comes from colorations, but how does "high output impedance create conditions for undamped resonances? Are they speaker cabinet resonances?

Even worst, you probably are missing the very lowest bass frequencies that only a solid-state amp can produce, and which contribute greatly to the realism of your bass playback.

Jmaldonado, please elucidate. Why would this be the case? What frequencies are we talking about? Those below 40Hz?

Regards,

what is high end bass and what is it's opposite, low end bass ? the phrase "high end" is less meaningful and more ambiguous, since there is no definition of the term other than one's personal opinion, than the simple straightforward concept of articulation of bass notes and a natural timbre of an instrument which reproduces frequencies below 80hz.

this is just an example of a continual use of audio adjectives which does not further communication.

why not be more specific and say what you really mean ?

T bone, I think that Jmaldonado is talking about the damping factor. The damping factor refers to the amp's ability to control the motion of the driver. The DF is a ratio of the impedance of the speaker and the output impedance of the amplifier. Most SET amps have DF's around 10-20, whereas good SS amps have a DF of >100. A system with a poor DF will be unable to start and stop the woofer with any great degree of precision, so the woofer cone will continue to oscillate for a period of time. This gives "bloom" to the bass. You can get used to it ... in fact it's one of my guilty pleasures :)

The other thing to note is that speaker impedance curves are not linear and tend to drop around the bass region.

Most tube amps have output transformers which will help to lower the output impedance but output transformers can introduce their own sonic colourations as well.

Amfibius, Thank you very much for the explanation. I had ignored damping factor as a possible reason for this "resonance" because Jmaldonado talked about the amplifier rather than the amplifier/speaker interface. I realize that speaker impedance curves are (generally) not linear and for most speakers, will drop around the bass (except for my former ESLs) leading to the lowest DF at the lowest bass. I guess I automatically assume that people, especially those with low-power SETs, would seek appropriately matched speakers so they would get speakers with low DF requirements. My tube amps do quite well with my efficient and high impedance woofers, though my amps are "cursed" with very large OPTs and a surfeit of power and my speakers are designed to use low-power amps.

I wonder if that is the reason why we tube amp owners "miss" the lowest frequencies in the bass... I had thought that the main reason I was missing 12Hz was that my speakers reportedly only go down to 18Hz :^).

In any case, I would have thought that once one gets down to below 40Hz, it becomes much more an issue of the speaker's frequency curve than the amp's (if properly matched) and in the real world, anything below 60Hz and I expect that room loading/acoustics will make a mockery of the "flat frequency response curve" that an amp, tube or SS, produces.

NO they cannot on anything under 8 ohms