PS AUDIO does not make Digital Amps

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Well-known member
Jan 4, 2005
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Interesting reading..........or correction. From their Newsletter.

We never were digital
Sometimes I think we try so hard to make a point that we lose sight of reality. Such is the case with SDAT, our acronym for the output stage of first the HCA-2 power amplifier and now the GC series of amplifiers. SDAT stands for Super Digital Amplifier Technology. The problem with this acronym is it is not correct: there's nothing digital about the HCA-2 or the GC amplifiers. Nothing at all.

I must admit that in spite of our engineering department's cautions and warnings, I went ahead and used the erroneous acronym when we introduced the HCA-2 because I thought it might be easier for people to understand that this was something new; something revolutionary.

Well, it's time to set the record straight. We're dropping the acronym SDAT because of its inaccuracies. Truth is, there's nothing digital about anything in any of our power amps.

Since the introduction of the HCA-2, which won the coveted Stereophile Class A recommended component award for power amps and graced the cover of Stereophile, people have labored under the misguided impression that the amp had a digital output stage when, in reality, it had a 100% analog output stage. My apologies for this misguided attempt at making the technology "easy" to understand.

Our amps, from the HCA-2 to the new GC series are PWM amplifier output stages fed by a pure class A input stage. In the case of the GC Series the class A analog input stage is called a Gain Cell. A PWM (Pulse Width Modulated) stage, built the way we do, is 100% analog. There's no conversion from analog to digital. Briefly, if we were using a digital output stage, we'd be converting the music into a series of numeric representations.

In a PWM amplifier, the music is converted to a series of analog pulses of varying lengths in an analog comparison stage that measures the difference between the music and a linear triwave ramp, thus making the output stage extremely linear and efficient. In fact, a PWM analog output stage is far more linear than a standard class A or class AB output stage and certainly more efficient.

In any case, we got so many questions at CES about our "digital" amplifiers that I thought it might be important to set the record straight. We don't make digital amplifiers. Never have.

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