CLASS A AMPLIFIERS

Unsound

As I understand it (from information gathered from the pass web site) the X series (class A/B) does double down but the XA (pure class A) does not. And as someone mentioned class A amps tend to be sweeter more detailed in the midrange.

Chuck

Chuck

Hi Chuck, thanks for the update. I went to the Pass site. I didn't see anything about power into lower impedances, but, you may very well be correct. There was mention of the XA series not having the current delivery of the X series and that the XA's using only two gain stages like the afore mentioned Alephs'.

Unsound, I remember having a conversation with Jon Soderberg, formerly with Threshold and now a top repairman for the older amps. He told me that on the SA-1 that I was actively pursuing that it would double in power into 4 ohms but that the Class A amount of it would be cut in half. Whatever the Class A power was into my Apogees, it was really sweet.

Unsound

Here is the exact information fronm the pas web site I quoted.

"The XA-200 will deliver 200 watts rms into 8
ohms of impedance. This is the amplifiers class
A limit, driving the XA-200 harder or reducing the
impedance of the load will not convey any additional
power. Driving into a short will not convey any
additional power. These are not design oversights or
flaws in the XA-200, but rather a condition of the
very highly biased Class A operation. However, as
an interesting point of reference, 200 watts driving
a 87dB/1W/1m speaker will deliver a 112 dB (very
loud) average acoustic signal in a 100 cubic meter
room. Transient peaks will be somewhat higher."

Chuck

Chuck, thanks. It's interesting that Pass suggests that "These are not design oversights or flaws in the XA-200, but rather a condition of the very highly biased Class A operation." I don't recall this "reasoning" from some other Class A amplifier manufacturers. It may even contradict what is commonly percieved as techincally available from Pass' previous designs.