Tag Archives: audio amplifier

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl

Loudspeakers designed and measured to sound flat in an anechoic chamber will sound terrible in a real life listening room environment. That’s just the way it is.

The price of flat

There’s really no such thing as a flat loudspeaker.

Loudspeakers are such inaccurate mechanical devices that if one were to attempt a flat frequency response, enormous levels of compensation would need to be applied. And, even then, those compensating changes in amplitude would only work in a very small area.

Unlike an audio amplifier whose input vs. output is fairly straightforward, speakers present an enormous challenge—one that depends on so many outside variables (box, baffle, room size) as to make it a non-starter.

The price of flat, as it pertains to loudspeakers, is equivalent to the price of peace.

Unaffordable.

Not to despair. Fortunately, our ear/brain mechanisms are powerful enough to adjust so that when we listen, it sounds “flat”.

And at the proverbial end of the day, if it sounds flat then it is flat.

Problem solved.

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

I mostly agree with this and certainly the amount of power an audio amplifier produces doesn’t alway correlate with sound quality, but parts used and poor build quality, can have an effect beyond the designer.

I once imported a high end audio line from Australia and the products were  very well designed and the parts quality was good, but the build quality and packaging were horrible and ended that experiment for me!

More power equalled worse sound

One of my readers, Daniel, was surprised to find that a smaller power amplifier sounded better than a bigger, more powerful version. He wondered how that could be given how many times I have waxed enthusiastically about the benefits of headroom and power.

Of course, the answer lies not in the power differences but the skills of the designer.

It is often tempting to focus on one area of performance as the key indicator of how a piece of equipment will sound in our systems. Unfortunately, it’s never quite that easy. The number of variables determining sound quality is so many as to make one’s head spin like Regan MacNeil.

Which is why we listen.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

OK, but not sure about this.

Watts watts?

A watt’s a watt, or is it? The technical definition of a watt is a unit of power, equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.

To get a watt out of our audio amplifier we need voltage and current. Once we have that unit of power the magnetic motor system in the drivers converts that energy into movement that compresses the air and we hear sound. A watt is a watt, yet not all stereo amplifiers at the same wattage sound the same. So what’s going on?

Amps with identical wattage ratings sound different because moving watts are different than steady-state watts.

If we were instead looking at wattage steadily powering a lightbulb we’d not really see any difference if that watt was produced by hydro or steam power. But in audio, we don’t listen to steady-state tones. Instead, we’re listening to rapidly moving air pressure. How that air moves defines what we hear.

Thus, we’d be more accurate to suggest that the motion of watts is what matters, not the watt itself.

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Measurements can explain certain things regarding how an audio component might sound, but to design just around measurements is usually a bad idea. Paul goes into this a bit more deeply.

Beware the measurements

For readers of this blog, it will come as no surprise my thoughts and attitudes on measurements of audio equipment. Yes, measurements are important, but only when in concert with listening—and then too only if you look deep into those measurements to find out how/why what you measure sounds the way it does.

If you’re interested in diving deeper into this subject there’s perhaps no better way than to sit down with an experienced designer and have them take the time to explain how and why measurements simply do not tell you the whole story.

Take for example global feedback in an audio amplifier circuit. If we have an amp circuit with relatively high levels of distortion, we can simply wrap the output back to the circuit’s input and voila! lower distortion. The feedback is a fix-it mechanism correcting for the failings of an amplifier’s design. But at what cost? Nothing in engineering is free. Loads of negative feedback offer low distortion figures but at the same time, harden and constrain the sound. Knowing this is invaluable to a designer who can then ask the question, “what if we don’t have distortion in the first place?”

If you’re interested in diving deep with a designer, here’s your chance. Our own Darren Myers, one of the brightest and best engineers in the industry, spent a good hour and a half with John Darko in a great podcast titled, Beware the Measurements.

Have a listen and enjoy.

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

The sound of class A

I am often asked what’s the difference in sound between audio amplifier bias schemes like Class A and Class AB?

I understand the motivation of placing labels on circuits when making a product choice. Like tubes vs. solid state, or analog vs. digital. We like to characterize the qualities of technologies so we might put them in neat little category boxes.

The problem is, of course, that Class A and Class AB are biasing schemes that alone haven’t as much to do about how circuits sound as you might imagine.

Certainly, we could say that many Class A topologies generally are sweeter and without the character-changes-with-level some AB circuits have—and we would not be too far off the mark—but consider that many of us have never actually heard a pure Class A power amplifier.

In fact, what we think of as Class A is generally found in a small signal device like a preamplifier or output stage of a DAC, and that most power amplifiers are Class AB.

So, for most of us, our experience with the various classes of biasing schemes aren’t apples to apples, they are more like peaches to plums.

Methinks, in this case, most of our opinions are formed on the basis of what the audiophile myth-making machine would like us to believe.

From where I stand, biasing is but a very small factor in a complex world where everything has an impact on sound quality.