Is my amp "High Current"?

Inpep, voltage is defined as the POTENTIAL to do WORK by MOVING electrons from one point to another. In an electrostatic speaker, electrons do not move across the gap between the membrane and the stator(s) unless of course the two happen to touch, or the current builds up to the point where there is and electrostatic discharge -- arcing -- in which case the speaker is damaged by a hole being burned in the membrane. The membrane's movement is generated solely by the (alternating) attraction/repulsion of the charged surfaces, nothing else.

A constant high voltage (potential) is maintained on the stators, generally on the order of 20,000 volts. You don't get a shock because there's virtually no current associated with it, no capability of those volts to push any electrons through you ;-) The membrane has a constant potential as well, but it changes from + to - at whatever frequency the signal dictates. The faster the polarity alternates, the more current is required. That's how AC works, only in reverse. It produces current by CHANGING polarity, and NOT by pushing electrons through miles of wire (which BTW is what we'd have if Westinghouse hadn't prevailed over Edison ;-) ANYWAY, Ohms Law says I = V/R. Current = Volts divided by Resistance. Higher frequencies require more current to produce them (just the opposite of an AC generator) and from Ohms formula, if I gets bigger, and V stays constant, then R must get SMALLER. And there you have it. Yes, the amp must provide more power (watts) at higher frequencies, but only as much as necessary to increase the CURRENT to the membrane. The membrane doesn't need volts, because very little WORK is being done to move it. P (watts) = I (Current) x V (Volts) So if an amp can deliver watts which consist mostly of current instead of volts, that'll be just fine for a stat. In most (high or low wattage) SS amps, the current they deliver is rather a smaller proportion of each watt. Whereas, a tube amp's watts consist of a rather higher proportion of current in each watt. So if all you're after mainly is current, why not choose a lower wattage tube amp? And you get the bonus (IMO) of tube sonics to boot ;-)
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To me the "high-current" label is just marketing hype.

Chris

Nsgarch, itm is the speaker that 'decides' what it needs to produce sound, not the amplifier.
The electroststic speaker's membrane moves in concert with the alternating Voltage with which it is charged, just as you said. And, as you said, not much energy (watts) is used during that action. Not much more energy is necessary to produce the high frequencies (in fact less is usually necessary due to the low volume of those frequencies)in spite of the lowered impedence, thus no real need for 'high current' capability. The biggest problem for the amp on electrostatics is ringing or oscillation due to the highly capacitive nature of the load, not current draw.

Inpep, it's OK to think of it this way I suppose:

it is the speaker that 'decides' what it needs to produce sound, not the amplifier.

so long as it's understood that what is meant by "decides" is whether the speaker presents an electromagnetic load to the amp, or an electostatic load to the amp. If the load is electomagnetic, the amp will be required to supply voltage, but at a more or less constant current. If it's electrostatic, the amp will be required to provide current but at a more or less constant voltage.

So lets say you have a 40W tube amp, and that at 40 watts output, you're getting the product of 10A x 4V (= 40W) Now lets say you have 100W ss amp and that at 100 watts output you're getting the product of 10A x 10V (= 100W).

So both amps can deliver 10A. But the tube amp can deliver 10A at 40W output, while the ss amp delivers 10A at 100W output. If you need big voltage to provide power to drive an electomagnetic load like a big woofer, the high output ss amp makes more sense because it delivers 10V at it's max. 100W output. The toobie only delivers 4V at its max. 40W output. But if you're driving an electrostatic load, then the tube amp makes more sense because you can get the same current at less than half the power output of the ss amp. And you're gonna say, "So what, you're still driving the stat with 40W instead of 100W, so it won't be as loud as with the SS amp." However, that's not true if you're delivering the same high current (not voltage) the stat needs to generate strong electrostatic attraction/repulsion. In fact it is this property of tube amps which leads to the (erroneous) statement, which you may have heard, that "Tube watts are more powerful than SS watts." This is of course bullpuckey. I just depends what kind of watts your speaker "decides" it needs ;-)

Nsgarch, if a speaker needs big voltage (say 40 v) to drive it to a certain level then that is what it needs, and the subsequent power that it needs will follow if the amp can supply the current. The tube amp will give it that voltage (40V) and what ever current is necessary up to its power limits. If the speaker needs 40V and 100watts to produce that certain level, then the amp will supply the 2.5 amps x 40 Volts quite easily. The 40V requirement and 100watts requirement are fixed by the speaker. The amp can't decide that, because it can't produce 40V but can supply 25V at 4 amps thus 100watts, it will do that. As long as the voltage demand and power demand are within the tube amp's specifications, the voltage will not be be dragged down by the load. This not the case with SS, unless it is capable of increasing its amps into lower loads in order to make up for the increased power demand. That is why dynamic speakers are considered more 'current' driven.
At any rate, as you have said there is not much current involved in electrostatics, therefore it is varying Voltage that drives them. Electrodynamics, due to the varying current demands along with the varying voltage driving them, are more current driven. This the opposite to what you have contended.