EFICIENCY

Efficiency, Part One

As you will hear, Avantgarde Acoustic is not the first to recognize the benefits of high efficiency. Some famous horn loaded speakers have been highly efficient. But their sound was colored (instruments didn't sound like themselves). This was primarily due to the horn enclosure and also to the geometry of the horn itself.

The fact that musically inaccurate speakers enjoyed success in the marketplace is a testament to the benefits of efficiency in spite of other failings. But what is efficiency?

For our purposes, think of it as a measurement of energy transfer. A loudspeaker must transfer electrical energy into acoustic output. How "efficiently" it performs that task is usually expressed as a specification (sometimes interchanged with the term 'sensitivity' or sound pressure level):

1 watt (sometimes expressed as 2.83 volts) = 87dB @ 1 meter.

This is a typical loudspeaker sensitivity rating.

There are some eye-opening revelations in store for you, all related to the simple equation stated above. Stay tuned. You don't want to miss it.

Efficiency, Part Two

Somewhere it all went wrong. It was probably related to the introduction of higher-powered transistor amplifiers. With more power available, speaker designers could introduce smaller sealed boxes. The good news this provided music in places where a large horn wouldn't fit. Plus, these new sealed box speakers could be designed to have a flatter response, making them more sonically neutral.

The bad news although they were more space efficient, these new speakers were acoustically inefficient. But who cared with all the power available? There was the first mistake, as you'll hear in the next installment..

Efficiency, Part Three

Once speaker designers decided they didn't really have to worry about high efficiency, the door was open. Two common areas they concentrated upon were:

(1) flattening the frequency response by equalizing or "pulling down" any peaks in the response curves

(2) compensating for phase problems, roll-off slopes, and frequency response deviations with increasingly complex crossovers.

These efforts were honestly made in the search for higher fidelity. And the speakers did measure better. Unfortunately, they didn't serve the music.

For example, (1) and (2) produced a lot less efficiency. Amplifiers had to get even bigger. It became a vicious circle. Bigger amps meant less efficient designs. Speaker drivers had to move even further just to make any sound. The trick was to make this huge excursion linear, with no overshoot (unfortunately not possible).

As voice coils heated up from working hard, the speakers' dynamics suffered. A speaker that measured 'flat' when tested at a given test level became anything but flat when its drivers were pushed hard. 'High accuracy' became a euphemism for hard and fatiguing sound.

Complex crossovers presented us another set of devastating problems in addition to reducing efficiency. Music's fine details, its dynamic subtle ties got trapped somewhere in the crossover. The music lacked life. And these crossovers presented difficult loads to amplifiers. Even today, there are brilliant, well-meaning speaker designers who proudly point to the large, highly complex crossover boards in their loudspeakers. Pure technical achievements that wonderfully reproduce the most sought after audiophile sound effects. Unfortunately, the emotional impact of live music is missing

Our final segment on efficiency will introduce the concept of our emotional response to music reproduction. Without a natural response to music, what's the point?

Efficiency, Part Four

As far as nightlife goes, there's nothing quite like the experience of live music. There's an electricity in the air. Excitement. Expectation. Fulfillment. Coming home from a great concert you could almost float -- who needs a car?

Then you get home and listen to some more music. Yecch! What went wrong? Is the stereo broken?

Here's the problem. Your high-end stereo cannot hope to capture the subtleties, let alone the big moments of live music. Why not, you ask?

The composer and/or the performers have a message to deliver to you. At a live concert, you usually get it. The music speaks to you. How about at home? Probably not at least not in the way the musicians expected.

So what's the form of the message? Well, certainly it's in the way harmonies and instrumental colors play on your emotions. But that's just the e-mail.

The real package comes special-delivery with the music's dynamics. Dynamics are the punctuation marks in music. Think about it...

How about what happens when a classical piece ends? It's either trailing off to nothingness or it ends with a big crescendo. And what does that do to us?

If the performance merited it (and sometimes the music's message gets through anyway), we jump to our feet with a shout  and exuberant applause. Well, guess what, the composer set you up to do that with the dynamics of the music! It's how music gets our attention and keeps it. Now the bad news. Most every high-end speaker can't deliver the full package. The dynamic shifts require a freedom and an effortlessness that comes from efficiency, linear dynamics, and minimum driver excursion.

The good news? Get those right and you'll be laughing, crying, dancing (or at least tapping your feet) with the music right at home.

Finally, here's a simple equation for you to think about:

Your Music + Avantgarde Hornspeakers = Emotion.