Tag Archives: Power 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.

I’d be willing to bet that for every audio designer that thinks high end audio amplification design like Paul, there are an equal amount that think otherwise. As far as an amp breaking a sweat, my experience with certain types of solid state amps is that they sound their best when breaking a sweat.

Careful on the input

One of the ways we designers make good sounding audio amplifiers is to lightly limit the input frequency while at the same time extending its high-frequency response.

That’s something that might seem counterintuitive but it works.

For example, at the input of a power amplifier, I like to form a light low pass filter of around 30kHz but within the amplifier’s circuitry, extend its bandwidth to as high as is practical—hopefully somewhere close to 100kHz.

This combination of limiting what the amp has to deal with while making sure what does come in is easily handled makes for a wonderfully open and easy presentation of music.

I like to think of it as a car with more power than it needs, and then a light foot on the accelerator pedal.

Easy in so the amp never breaks a sweat.

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 problem with evaluations

What do you call the lowest-performing student graduating medical school?

A doctor.

In any field, the range from good to great is all over the map. Graduation degrees, specifications, and even reviews only tell us so much.

A power amplifier meeting all the basic requirements of distortion, frequency response, and power output does not—can not—sound the same as a different design with identical specifications.

It’s why we interview our medical providers.

It’s why we read the first chapter of a best seller before committing to the whole.

It’s why we listen to our amplifiers.

Specs, degrees, and reviews are fine for clearing away the cruft of the unworthy.

The rest is up to you.

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.

Our first integrated

I just received my second CoViD shot last night and so find myself on shaky ground at the moment but wanted to make sure I didn’t miss a day of a post.

I was just ruminating on the steps leading up to our first integrated amplifier, the Elite.

When Stan and I had built our fledgling company to the point where we hired our first two employees, Lowell and Jeff, we were building two products: our phono stage and its companion Linear Control Center. The LCC was not a whole lot more than a volume and balance control, an input, and a gain selector.

From a circuit perspective, there was a 10X stereo preamp inside that offered 20dB of gain the user could choose to run the signal through or not. Passive or active preamplifier.

As Jeff and Lowell did their best to keep up with customer orders, Stan and I worked on our new power amplifier to be called the Model One. The power amp’s circuitry was not a whole lot more than the LCC’s gain stage with a pre-driver, driver, and output transistors. The Model One was capable of 70 watts per channel into 8Ω.

Because we didn’t want to “color” the sound of our new amplifier while it was in development, we chose not to use the LCC as a volume control. We wanted the signal path as free of circuitry as possible so that we would be tuning only the amplifier and not the combination of LCC and amplifier.

But we still had to control the volume of the turntable/phono stage.

Stan grabbed a power drill off the shelf and without saying a word proceeded to punch a hole in the amp’s front panel, then from inside the amplifier popped in a potentiometer, and added a knob.

Voila! The first PS Audio integrated 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.

Cross breeding

Purity is appreciated when it comes to purpose, water, and immorality. It’s not so great when it comes to a power amplifier’s architecture, where hybrids rule.

For many years, amplifier manufacturers were determined to keep their designs pure: 100% solid-state, all vacuum tubes, nothing but FETs, class D from input to output. Over time we’ve come to grips with why this commitment to design purity is not such a great idea.

Power amplifiers are misnamed and therein lies the problem.

On the surface, they seem simple enough: little signal in, big and powerful signal out.

What’s missing is the recognition that inside a power amplifier we have two completely distinct systems each with very different amplification duties: voltage and power.

The input voltage gain stage takes a small voltage and amplifies it into a big voltage. From beginning to end there is only voltage and no power. If you were to take the output of a power amplifier’s first stage and attempt to drive a loudspeaker you’d be met with silence.

To produce watts we need the second system, the actual power amplifier (where it got its name).

The fact that each of these two stereo systems has such very different functions should be clue enough to understand why a purebred power amplifier’s a bad idea.

The smart designer recognizes the difference between the two systems and applies the best technologies for the job: vacuum tubes and FETs are much better at delivering voltage while bipolars, power MOSFETS, and Class D stages are best at delivering power.

Purity benefits us most when we apply it to where it matters.

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.

Hard to imagine

When Stereophile reviewer Michael Fremer writes “on electric bass… the M1200 is a monster”, he’s not alone. More and more emails daily come across my screen extolling the virtues of the M1200’s bass.

How can it be that one flat measuring power amplifier can sound remarkably more powerful in one area than another?

Flat is flat, right?

Not so fast. Let’s have a closer look at the M1200’s measurements. 10Hz – 20KHz +/- 0.5dB

A measurement of 10Hz – 20KHz +/- 0.5dB says a lot if you look closely (and know what you’re looking for). What’s first apparent is its ruler flat performance within the range of human hearing.

But a deeper look shows something else: the amp is down at 10Hz by only 1/2dB. This is important because it means that an octave higher the amp is perfectly flat. Ruler flat response within the audible band is critical for removing phase shift. Turns out the ear is very sensitive to phase shift and the way to keep the phase from shifting is to start any measurable roll off well below the limits of human hearing.

You see, most power amplifiers will have specs that are more like -3dB at 10Hz (-3dB is important because it’s believed that’s where the ear perceives a level change). Fine that the point we first perceive a level change is below the ear’s frequency limits but what’s not mentioned is the phase shift. To be -3dB at 10Hz means you’re 1/2dB down point is well up into the audible range of bass—and we get phase shift.

When phase shift happens in the audible frequency range it will convince the ear the bass sounds wimpy.

And one more point.

A monster amp like the M1200 not only has no phase shift in the audible bass regions, it also has the power and reserves to effortlessly deliver that phase free note without any change in character.

Measurements aren’t always clear and simple.

The story behind the measurements matter.

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.

Some well deserved marketing from Paul today, heaping praise on PS Audio’s new power amplifier, their Stellar M1000 monoblock power amplifiers. I’ve not heard them, but a lot of power for their size and very efficient, using a Class D output stage.  One reason they probably sound good is due to their use it of B&O’s ICE power modules, which I think sound a lot better than the more typically used Class D Hypex modules.

And the hits just….

…keep on coming. In the January issue of the UK’s HiFi News, our killer M1200 monoblock combo received another stellar review (pun intended).

“The latter track positively erupted, the amplifiers creating a searing midband with Matt Heafy’s sinewy guitar tone brought to the fore, and drums again hitting with the speed and aggression of a champion boxer.”

Reviewer Mark Craven goes on to write:

“This slender monoblock amp is not solely devoted to room-shaking power. It has that capability, but appreciation of its punch comes with an appreciation of its grace. The sound is a confluence of steel and silk – fast, rhythmic and able to respond astutely to the shifting dynamics of music. A smooth treble lifts it high above the realms of the rough-and-ready, and there’s an energetic delivery of the midband. But the star attraction – the one that gets your blood pumping right away – is its exceptional bass handling.

To check my Bluesound Vault 2i was behaving itself, I fired up, at random, Chris Rea’s ‘Daytona’ [The Road To Hell; Tidal Master]. After no more than a second I had stopped worrying about my network connection and started focusing on the music. This gentle, mid-tempo homage to a Ferrari race car (complete with tires squealing over the outro…) arrived with a slippery, fluid and authentic bass sound that I wasn’t prepared for, the kind that has you wondering why you haven’t always done your listening through 600W monoblock amplifiers.”

If you’d like to read the entire article, you can download a copy by clicking here.

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.

Bi-Amping, which I cant even do with my Daedalus loudspeakers, never did anything to improve sound quality to me and actually could easily introduce more problems than it solved. Paul has reached the same conclusion!!

Does bi-amping still make sense?

Twenty something years ago, horizontal bi-amping made a great deal of sense. One type of power amplifier for the woofer sections, another for the top end.

It made sense because amplifiers of those days rarely did everything well. Perhaps the big amps kicked booty on bass while grating nerves on the top end. Little tube amps were wimps on the bottom end but sweet as honey on the top.

Leveraging an amplifier’s good points while steering clear of its failings was a reasonable proposition. Today, most speakers still come with dual sets of binding posts so as to allow for bi-amping.

But do we still need it?

I think not. Today’s amplifiers are great from top to bottom of the frequency range. A pair of M1200s, or a BHK, garner rave reviews from the lowest bass notes to the ringing of bells and beyond.

Bi-amping is a thing of the past.

And thank goodness for that.

 

 

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.

Mine is break in and warm up, once a piece of stereo equipment is sufficiently broken in.

Audio taboos and sacred rituals

There are certain audio taboos we’re loathed to violate. High atop my list would be plants atop speakers. (But it behooves us to be diplomats if we’d like not to sleep on the couch)

Diplomacy aside, we purists rarely tolerate violations of our taboos and sacred rituals.

Some taboos make sonic sense: plugging all your equipment into an AC extension strip, stacking a turntable atop a power amplifier.

Perhaps more prevalent than taboos would be the sacred rituals which cover everything from record handling, room light levels, seating positions, warm-up time, and source protocols.

I never start a listening session with vinyl. My ritual is to get the system warmed up and me adjusted to it with known digital references. Then, and only then, am I comfortable switching sources.

What are your audio taboos and sacred rituals?

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

Too many facts

The problem with facts is choosing which to follow. For example, it is a fact that regardless of which audio cable we use to connect the output of a power amplifier to our Audio Precision test equipment the results will be the same. Of course, that doesn’t mean the cables are the same.

As access to information increases so too do the available facts of any subject. Some facts are important to include while developing understanding while others detract or at best confuse us. If we’re designing an amplifier it’s best to stick to the facts pertaining to our specific design rather than chase factual rabbits down confusing holes.

How to choose which facts to follow?

Before the internet’s deluge of information, our limited research turned up end results that resonated with us: a product we liked, a person we admired, a book worth reading, a teacher worth learning from, a circuit worth emulating. Once a direction had been chosen, we could then dive deep into the facts that pertain specifically to that end result.

Today, we have a tsunami of facts and end results that may or may not be relevant, yet each can send us spinning off into the confusion of the weeds.

If we want to rely on the clarity of facts we need to make sure we are researching the relevant ones.

Pick a product, pick a guide, pick a direction, and then study the facts that helped shape it.