Well, that should be enough information, mis-information, and half truths to thoroughly confuse you.
What GS5556 said is right. The job of the output device is to control the amount of current through the speaker just like a water valve controls the amount water through a hose. That's why tubes are called valves by the Brits.
I'm not sure how Hack's comments pertain to the question so I'll leave that alone. Gs5556's comments may not have been a thorough description of transistor action but I didn't see them as descriptive of a diode.
What SdCampbell said is rather unconventional as it really makes no sense to call something a voltage device or a current device.
What Cford says is correct, the key word being control.
In audio these devices are set up to control the amount of current that is flowing through their loads. They are in turn controlled by an input signal.
All types of FETs are controlled by an input voltage on the gate and this voltage draws little if any current.
All tubes with the input signal on the grid are controlled by a voltage but may draw significant current on positive peaks in some situations.
All bipolar transistors are controlled by an input current.
FETs and tubes are often said to be similar because they are both controlled by an input voltage and they produce the same types of distortion.
I don't know what amps you were looking at but the low output curent is not a charecteristic of all FETs. Some can handle in excess of 100 amps (that's a lot.)
What GS5556 said is right. The job of the output device is to control the amount of current through the speaker just like a water valve controls the amount water through a hose. That's why tubes are called valves by the Brits.
I'm not sure how Hack's comments pertain to the question so I'll leave that alone. Gs5556's comments may not have been a thorough description of transistor action but I didn't see them as descriptive of a diode.
What SdCampbell said is rather unconventional as it really makes no sense to call something a voltage device or a current device.
What Cford says is correct, the key word being control.
In audio these devices are set up to control the amount of current that is flowing through their loads. They are in turn controlled by an input signal.
All types of FETs are controlled by an input voltage on the gate and this voltage draws little if any current.
All tubes with the input signal on the grid are controlled by a voltage but may draw significant current on positive peaks in some situations.
All bipolar transistors are controlled by an input current.
FETs and tubes are often said to be similar because they are both controlled by an input voltage and they produce the same types of distortion.
I don't know what amps you were looking at but the low output curent is not a charecteristic of all FETs. Some can handle in excess of 100 amps (that's a lot.)