CLASS A AMPLIFIERS

Chuck, I was under the impression that some particular examples of the Aleph amps with minimal gain stages were unable to double down, but, all the other Pass amps were able to double down. I would guess that those which could/can doube down would halve their class A out-put as they did so.

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