how does current work in an amplifier?

The are some misconceptions about current. Here's the big one:

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

Others have already touched on the serious aspect of this, the idea that for 200 watts you need 7.07 amps (if a 4 ohm load) which is not really all that much.

Another way of stating 'high current amplifier' is to say that it behaves as a nearly perfect voltage source. Confusing?? yeah. Here's how it works: if the amp makes 28 volts into 8 ohms, that is 98 watts. Now if it is a 'voltage source' it will make the same voltage into 4 ohms and that is double the power, since the current increases as the impedance decreases.

The *real* issue is, is this behavior correct for a panel speaker? For certain box speakers it certainly is, as there is a woofer in the box that has a resonant frequency and that is represented by an impedance peak. With a 'voltage source' amp, that would cause the amp to throttle back its overall power as it encounters the peak. This keeps the frequency response flat.

So is this the right response for a flat panel? The panel has an impedance curve that has nothing to do with a box, and it does have cancellation as you approach the low frequency cutoff. You might want more power, if anything, as you approach the cutoff, to maintain flat response.

Tricky.

This might be why there are so many advocates of tube amps on Magnaplanars; A tube amplifier will try to make something more like constant power into a load rather than constant voltage. This means the voltage and the current will vary with the load.

IME you don't need all that much current to make Magnaplanars sing, the amp just has to be comfortable with the load, which is not that hard. Otherwise they are fairly easy to drive.

Yeah, Tony, That's why I doubled the 8vac I saw flicker by, TO 16v for my calculations.
I am well aware of power factor and the math involved. cosine of the angle and all. I've been a 'fan' of that approach to evaluating speakers as 'good' or 'bad' load for quite a while. Tube amps, for example simply do not like certain reactive loads......I don't 'member if it is capacitive or inductive......

People are stuck in the impedance / sensitivity paradigm for 'goodness' of load and usually fail to consider reactance.... / power factor.

And, from our FWIW department, a good cheap addition to your kit may be the purchase of a 'kill-a-watt' meter. Reads out KWH, voltage, PF, Watts / VA and current. Not bad for 25$

Anyway, I may have simplified the math, but in principle I think I'm right. People do not need these wacky current ratings which are 1. meaningless 2. not measured to a standard.
People also use far less power than they think they need. I doubt I've ever been more than about 15% of my amps RMS rating. Most people also really love their 'd' amps and the artificially hi power rating. The ASP1000 module, for example has only a 30 second rating while my ASP500 module has a 60 second rating. Even counting a 10x crest factor, I doubt I've even approach 200 watts total output....and that is LOUD.

AHHHHH! Atmo:
Good answer! Also, tube amps are considered a 'current source', right?
So the right speaker for a tube amp differs from the right speaker for a SS amp.

That's why the 'comparison' threads between tube and SS are not quite......meaningful.

I'd LOVE to hear a 100x2 tube amp with my panels. I'll bet it'd work just fine, thank you very much!

That is a perfect conclusion Magfan and Atma. Speakers and amps work as a pair. And I agree with Atma that speaker impedances dropped when SS became more common. High impedance, high efficiency speakers with a tube amp is probably the most cost effective quality sound/dollar. And here I am sitting at the opposite end of the spectrum with a massive amp, low impedance speakers. It sounds great, but I have to alert the power company whenever I plan to crank it up:)

Tony, except that tube amps tend to be more expensive and high effiency speakers tend to need help extending the bass, which doesn't come cheap either.