16ohm Earphones with a class A amplifier

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The simple answer is yes, but it will be a battery eater.
Which is why it is never done for portable equipment.

Single ended class A is the worst, push-pull is 1/2 as bad.
But both are very bad because the power supply drain
has to be set for maximum volume, (x2 for SE), even
if your not using it, so it can be done, but a bad idea.

It is done for many home hifi headphone amplifiers,
both valve mainly and some transistor ones, e.g :


rgds, sreten.
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Portability might not be a part of the question. In fact I'm not sure what is.

I mean any power amplifier, regardless of class, can drive headphones. The class A amplifier is no different and a 16ohm load will be easy for it to drive. The only issue you could potentially have is that most power amplifiersdesigned, for driving loudspeaker, have high gain. This is because loudspeakers, generally, require large voltage swings to drive them, headphone do not. Depending on the preamplifier or source you might have trouble setting the volume accurately.

Then again the gain of the power amplifier isn't mentioned. The question only asks if a class A amplifier can drive 16 ohm headphones. Yes is the answer, but it will only remain within the class A region of operation if it has enough bias current to drive the headphones properly. I mean we could be talking about tiny class A amp here designed to drive headphones only. 16 ohms is a very tough load as headphones go and if the headphone amplifier has been designed around driving 64-600 ohm headphones it could struggle to drive 16 ohm loads whilst remaining within class A.
In context I bet the question is more about class ab vs a. And how you need more bias and current to stay in class a with low r loads. The answer is yes, you can drive any load headphone with a class a amplifier but it's less feasible to drive a 16 ohm headphone with class a than it is to drive a 16 ohm headphone in class ab due to the bias involved (which increases power consumption, size and therefore heat).
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