Is my amp "High Current"?


Hi, I own a McCormack DNA 0.5 amp that has been upgraded to rev. A at SmC Audio. I read about speakers benefiting from using a high current amp, and was wondering if mine was considered to be one.

Thank you.
koestner

Showing 7 responses by inpepinnovations

Mechans, confusing volts with amps and also throwing lbs for good measure renders your answer less than helpful.
Respectfully, Bob p.
Here is what is wrong, Nsgarch. Electrostatics do not demand high current, but are voltage driven. In fact, all speakers respond to the voltage applied at the terminals, depending on their sensitivities. that is why sensitivity is stated as sound output (db)/2.83V into 8 ohms (which is 1 watt).
Thus, if a speaker outputs 90db at 2.83V input and it is an 8 ohms speaker (at that frequency) and we expect 90db at the same 2.83V input, but at a different frequency which is at 4 ohms, then the power requirement will be double, therefore the amps double.
Electroststics are essentially voltage driven devices, i.e. the membrane responds to the varying voltage of the stator panels. generally 'statics' don't demand a lot of current. Dynamic speakers also respond to voltage, but due to their drive systems, they also need power, thus the need for more current at lower impedences, therefore more amps. Note, if the amplifier is incapable of supplying the necessary current for the power demand, it is the voltage that sags, thus the output from the speaker 'sags'.
Tube amps are generally not great current producing devices beyond their power limits into specified loads, but their stability with voltage makes them a good marriage with electrostatics. High current capability SS amps do much better with varying impedence dynamic speakers than tubes, usually. That is the part that you had reversed, I think.
Respectfully, Bob P.
Nsgarch, I am aware that the impedence goes down with rising frequency, but that does not necessarily mean that the power requirement and hence the current demand goes up. usually, the amount of high frequencies is very low and therefore the voltage necessary to move the membrane is less also, therefore not much power necessary to do the job. since, as you stated, there really isn't really much work done by these 'capacitors' not many amps are necessary.
Again, as you say, it is the varying voltage on the membrane between the stators that cause the membrane to move, thus making sound. Tht is what i mean by 'stats are voltage driven'. Not much energy is used through that action. Most of the energy is used in maintaining the constant voltage in the stators through their circuits.
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.
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.
Nsgarch, this discussion is getting nowhere precisely for the reason that you think that my understanding of power etc. is faulty, when in fact I can say the same for your understanding.
I guess my fault is in trying to explain in layman's terms what the relationship is among power, potential and current.
let's leave it at that.
One lat note, though. I am not the only person who pointed out that your understanding was reversed.
respectfully, Bob p.
That the discussion was about about amp efficiencies, no you hadn't made that clear.
Tube amplifiers are always less efficient in producing power, it is inherent to their nature and independent of the speaker load or type (ESL or dynamic). I.e., for the same power output, tube amps consume more power (from the electric company) than a SS, even a Class A SS.