Double down, good or bad?


I came across this article on Atma Sphere's website:

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

In short, Atma Sphere believes having a power amp that is capable of doubling its power when impedance is half is not necessarily a good thing because speakers in general do not have a flat impedance across all freq range.

On paper, it does make sense. Though I am sure speaker designers take that into consideration and reduce/increase output where necessary to achieve the flatest freq response, that explains why most of the speakers measured by Stereophile or other magazines have near flat responses.

But what if designer use tube amps to design his speakers, mating them with solid state should yield higher bass output in general? Vice versa, tube amps yield less bass output at home?

I have always been a tube guy and learned to live with less bass weight/impact in exchange of better midrange/top end. Will one be better off buying the same exact amp the speakers were "voiced" with, not that it will guarantee good sound, at least not to everyone's ear.
semi
Ralph, As much as I respect your opinions, I don't agree with the suggestion that amps that measure well don't sound good, and amps that sound good don't measure well. While I'm not suggesting that we have all the neccesary measurements to guarantee terrific sounding amps yet, I do suggest that we currently have the neccesary measurements measurements to guarantee that we don't make terrible sounding amps. Obviously the same token that keeps tube amps a marketable comodity, does the same thing for solid state amps.
We are not here to argue, we are here to learn from each other's knowledge.

Magfan, glad to see another fab guy. I am a yield guy because of my EE/device physic background, but know process well enough to do my job. As we shrank from 0.5um, we added LDD, halo, and now HKMG to deal with leakage. On top, both N & P stress are going wild and we have far exceeded Moore's law prediction in transistor drive current from linear scaling! All thanks to brilliant minds that work endlessly to produce faster and smaller chips :)

I think amplifier & speaker interaction is still an area that's not well understood when coupled with psycho-acoustic, human do not hear like machine for sure. If there is a perfect amp, Nelson Pass would not have changed and optimized his design constantly. Didn't he think X series amp was perfect when it was introduced several years back, why the X.5 update?
I have a Pass XA.5. Its output doubles as impedance is halved. It replaced a Pass XA amp. Its output was constant. In my system, there is no comparison between the two. The XA.5 sounds much better. There is now much better control of the lower frequencies. Bass is more articulate, fuller and deeper. I'm sure results will be different for different amps and different speakers.

I wasn't aware that Nelson Pass thought his X series amp was perfect. That is a very interesting statement, er, question you pose.
As Atmasphere says.....it's not really a tube vs transistor thing.
The Halcro amps do not double power as the the impedance halves and Bruce Candy is a 'disbeliever' in very low impedance speakers thus his amps do not perform well into 'difficult' loads.
Does he lose a heap of sales because of that?......probably.
Unsound, I agree with you. I should point out that what you said in your last post is not anything I was suggesting. I think its nice if an amp measures well, if it also sounds good to the human ear.

What I have found is that the physics of making an amp sound good has to do first with understanding the rules of human hearing, then applying the physics to get the amp to follow those rules.

Negative feedback is a primary violator of one of the fundamental rules of human hearing (its use enhances the harmonics that the ear uses to determine volume of a sound) and a lot of amps use feedback to reduce distortion i.e. look good on the bench. Amplifiers that have good bench specs and no feedback are rare but they exist. Interestingly enough, most of those amps also have a reputation for good sound too.