CLASS A AMPLIFIERS

It depends on the amp. In theory if it is a solid state amp we would hope to see 600 Watts @ 3 Ohms if the amp is rated as 200 watts @ 8 Ohms. This generally doesn't apply to tube amps. Not all (in fact few) amps are capable of this kind of power delivery. Don't assume an amp is capable of this.

Charlot

To keep it simple - the benefit of the Class A amplifier is in it's sonic product! This is one of those things that is ineffable and must simply be heard and compared.
I have been listening to Class A amplification since the late 1990's and have no complaints. In 2005, I built a 1 watt SET that currently supplies my sonic entertainment.

Keep in mind that transistors as well as tubes can run in Class A. In fact, transistors in Class A come pretty close to doing tube-like stuff sonically.

Hope this helps.

Studio1

Spear11,

It depends on the amplifier; the regulation of its voltage and its current output capacity.

We've been discussing amps that "double down" - those that will double their power
if the load impedance is halved. If we let V be the RMS voltage; then we can use
equations for power that look like the DC equations - but the use of the RMS values
make them applicable for AC power.

For a voltage source, the power P = V^2 / R; or P*R = V^2 = a constant if V is strictly
regulated. If the amp is rated at 200 watts at 8 ohms, then V^2 = 1600 volt^2. For
your 3 ohm speakers, P * (3 ohms) = 1600 volt^2.

Therefore, P = 533.3 watts.

Now this also presupposes that the amp has the current reserves to fulfill this. For
200 watts at 8 ohms; the current is given by P=(I^2)R; so that the current I = 5 amps.
For 533.3 watts at 3 ohms, the current will be 13.33 amps.

IF [ big IF ] the amp has the current reservers to output 13.3 amps, and the voltage is regulated to be the same irrespective of load impedance; then this hypothetical amp
can put 533.3 watts into the 3 ohm load.

Dr. Gregory Greenman
Physicist

The Pass XA.5 series is single-ended, class A, and doubles down going from 8 ohms to 4 ohms.

>> 01-19-06: Aball
>> No. The sonic benefit is that the entire signal is
>> swung by a transistor (or several in parallel) instead
>> of individual halves of the signal being split up by
>> two different transistors. Since there is no "handing
>> off" of the signal to another transistor, there is
>> potentially less distortion.

I hate to say this Aball - what you have explained above is single-ended operation & not class-A operation!
it just so happens that many/all single-ended tube & s.s. amps are class-A.
For class-A operation the transistor is biased along the load line in such a way that it always has max current flowing thru it whether a music signal is input into it or not. hence the heat dissipation.
s.s class-A amps can be single-ended (Aleph series) or can be push-pull (almost every other model).
In push-pull you will have P & N type transistors but it is not necessary. For example the Plinius SA-250 has N type push & N-type pull. Slightly higher output impedance i.e. lower damping factor but all N types can be matched better.
I'm sure that you know all of this as you are trained as a EE, I think? Probably wrote your post in a hurry or while cramming for an exam the next day?
FWIW.