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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
peterayer
1,382 posts
 
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.
halcro's avatar
halcro
2,664 posts
 
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.
atmasphere's avatar
atmasphere
11,772 posts
 
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.
magfan
1,583 posts
 
Semi,
did you look up the Smith Chart?
That will help in your quest.
gregadd
574 posts
 
We can conclude then that a technically correct amp is good. Doulbe down if done right is good. See(hear?) Bryston amps. It depends on where you are going and how you want to get there.
If you pass on Ralphs' amps merely because they don't double down you are making a mistake. On the other hand there are speakrs that should not be mated with Atmasphere.
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