Tuesday January 16, 2018

Bob Carver's Amazing Line Source™

Forget everything you know about conventional loudspeakers; Bob’s Amazing Line Source breaks the mold of any previous design. Most frequently thought of as an amplifier designer, Bob has designed several noteworthy and critically reviewed loudspeakers as well, e.g., Phase Linear® Andromeda (later Phase) III, Carver® Amazing Loudspeaker, Carver AL-III, and Sunfire® Cinema Ribbon CRM-2, to name a few.

Let’s let Bob describe this interesting technology in his own, inimitable way:

What is a line source anyway? As Frank Capra used to say, "What is the deal here?"

How a line source operates has been understood by scientists for a long time, harking back to the days of Bell Telephone Labs. A brilliant researcher who worked there taught the world how they worked; his name was Dr. Harry Olson, a physicist, an experimenter, a theoretician, and he developed the complete theory of the line source. He showed how an infinite line source would behave when generating a sound wave, and how a practical line source could become a close approximation to an ideal (infinitely long) one. So what happened? Why are line sources just now becoming popular with audiophile listeners, Hi-Fi dealers, and the press? Well, the answer is because it has been difficult to understand the detailed operating principle of a line source. Lots of advanced math, complicated room interactions not easily understood, and the extreme difficulty of developing a practical method of actually building one. The scientists at JBL®, Bose® and others have tackled the problem, have written papers that ARE easy to understand, and the world now knows how to do it.

I actually learned my craft from the early work of Dr. Harry Olson, and from my colleague Leslie Williams, a physicist for whom the math was a walk in the park.

In the esteemed Leslie Williams’s Own Words…
What counts in a loudspeaker designed for stereo reproduction is the resulting High-Fidelity, be it ‘you-are-there’ or ‘they-are-here.’ High-Fidelity must include accurate frequency and transient response, life-like levels without audible distortion, and realistic portrayal of ambience and imaging. Having personally made many forays to push the state-of-the-art, both by, 1) creating psychoacoustic models that mathematically depict most of Hi-Fi, and 2) designing and building speakers for music playback for friends, I’ve found that integrating all of the elements from source to brain into a coherent system design is crucial – not just a single component or room or technology. The speaker is the nexus, since it touches more of the system than anything else. Bob’s Amazing Line Source gives the best Hi-Fi, not because of any single aspect (e.g., line source, tube amps, or driver technology), but because he has done the best system design. Some of my tech notes from measuring and listening to them for a few days in 2012:
  1. The midrange double line has a uniform polar pattern over its bandpass
  2. Neither the midrange nor the tweeter line exhibits any chaotic frequency response due to array factors (for reference, read Don Keele, Jr.’s – former editor of Audio Magazine – work)
  3. There are no measurable (let alone, audible) specular reflections
  4. The form factor of the sub acoustically integrates with the room on the floor or wall, in the corner, or under your seat
  5. In consumer speakers, the tweeter is a noticeable bottleneck – but not with The Amazing Line Source
  6. ALL speakers should be either far from, or directly on, the wall. The Amazing Line Source works – even with imaging – for both
  7. The Amazing Line Source is unique in being acoustically transparent to the source with life-like levels and a small horizontal footprint, and
  8. Seamlessness both vertically and horizontally in a room.
No other speaker does both to the necessary extreme in a room. Though…
Big professional line arrays may play louder, but they are line arrays, not true line sources. Big difference!
…as a designer, listener to live music, and lover of Hi-Fi: I’m jealous.

The best and most fun way to understand how it works is to do a thought experiment; let's join Albert Einstein, Stu Hegeman, Max Planck, and me in a loudspeaker thought experiment. But first, we’ll take a shortcut and segue all the way to the finished design (and what I heard). I will use words, even though I can’t come close to Harry Pearson or Robert Harley. Here goes….

My Amazing Line Source Speakers present a huge and majestic soundstage that captures the complete sense of acoustic space that helps make music come to life in our listening rooms.

I heard sound images inside a larger acoustic that seemed so real it was downright spooky. The soundstage extended far behind the speakers, wider than the speakers, higher than the speakers, possessing a majesty that I found difficult to believe. But not so difficult I did NOT believe it; every time I listened, I found myself asking over and over… "How do they do that?"

A solo female singer will appear center stage, up and back slightly, perfectly focused, singing her heart out as if she were in our room, all the while being inside that larger acoustic bubble. It is very, very spooky. And I promise that Beethoven's Ninth symphony will bring tears to your eyes.

“Let’s indulge ourselves for a minute and imagine that we could conjure up the ideal loudspeaker without regard to physics or the limitations of today’s technology. Our fantasy allows us to specify the transient speed of a full-range ribbon, but with the weight behind those transients provided bymoving-coil drivers. We’ll take the transparency of an electrostatic with the dynamic contrasts and “jump factor” of a horn design. Since this is all wishful thinking, we can specify no horn colorations to go with the horn-like sense of immediacy and dynamic verve. We’re free to order up the visceral bass weight and body of a large ported enclosure accompanied by the dynamic agility, textural resolution, and pitch definition provided by a small sealed enclosure. And while we’re at it, our dream speaker will exhibit no box coloration, have high sensitivity, and be an easy load for a power amplifier.”

Robert Harley, The Absolute Sound®, Issue 229

It’s been often said, ‘You can’t change the laws of physics.’ But we can come close, and often we can come so close that we cannot tell the difference between advanced physics and magic. Someone important once said that, I don’t remember who. Well, my new loudspeaker does seem to defy the laws of physics (It doesn’t really of course, but it sure seems to). I have pushed the limits as far as I know how; transient speed, transparency, dynamic agility and sheer acoustic output power. There is no other that can match it as a large signal transducer! Certainly not in terms of pushing the limits of science and wave-launch technology. First off, the column of (thirteen) ribbon drivers deliver pristine vocals as well as high-speed musical transients from floor to ceiling, with an attack and authority that is difficult to believe. The twenty-two conical drivers (eleven on each side) bathe the listening area with room-filling sonics, providing a soundstage whose breadth, depth, and height are even more difficult to believe. The drivers (ribbon and conical) combine to provide both a sense of majesty and low-level detail retrieval and resolution previously all but unheard of in a typical, high performance loudspeaker. Moreover, the ultra slim, isosceles-like enclosure (a bonus in the world of “monolithic, monster, monkey coffins,” as Milt McNally used to say!) is utterly free from any box coloration, and is virtually reflection-free in the listening room.

A true line source speaker is simply a speaker so tall and acoustically long that we, the listener, hear a speaker that goes all the way to infinity. Up to infinity and down to infinity, resulting in what a scientist would call a "perfect wave launch."

The wave from such a speaker behaves as if it emanates from a gossamer thin filament running from below the center of the earth to beyond the moon. A pure, beautiful, cylindrical sound wave.

When we listen to such a wave, we find that we can hear musical nuances that we often cannot hear at all using normal speakers.

Think of it this way: Consider a thin pole that is eight feet tall, extending from floor to ceiling. On the pole are mounted 22 lit birthday candles, each a light source. Additionally, imagine the floor and ceiling to be perfectly polished mirrors. When we look down at the bottom of our speaker, we will see lit candles reflected in the mirror continuing all the way down to minus infinity. If we look up towards the top of our speaker, we will see reflections of candles that go up to plus infinity beyond the farthest star in our galaxy. The top and bottom of the room and its physical limitations seem to vanish, leaving only the splendor of the concert hall in the listening room.

All these reflections are real light sources to our eyes, as real as any real candle; we can read a book by their light. The candles in the mirrors make as much light as the actual candles on that pole. Absolutely non-intuitive! Now instead of candles, imagine that we replace them with lots of small loudspeaker drivers. Or better yet, a long ribbon that makes sound. The result is an infinitely long ribbon of sound because the same holds true for speakers, candles and ribbons alike; the virtual drivers in the mirror make just as much sound as the “real” drivers in the room, and behave for sound the same way as the candles behaved for light.

For sound waves, we can remove the polished mirrors and simply use the floor and ceiling to make the line source work perfectly! (Normal floors work for sound the same way polished mirrors work for light.)

This may just be the best loudspeaker there is!

Perhaps even more unbelievably, The Amazing Line Source will bring all of the imaging, soundstage, spatial characteristics AND excitement noted by Bob, above, with as little as 15 watts of tube power (30 watts, solid-state)! Match The Amazing Loudspeakers with a pair of Bob’s Raven or Crimson 350 amplifiers in your listening room today. Or for the ultimate, ‘live performance’ experience, a set of Bob’s Silver Seven 700 amplifiers – You will be blown away!

The Bob Carver Amazing Line Source is unlike any other loudspeaker ever produced! Audition them today at your nearest Bob Carver dealer!

Specifications (each speaker)

Height: 90”
Cabinet: Extruded Aluminum
Extrusion Profile: 4.625” x 6.875”
Weight: 135 lbs.
Color: Anthracite
Footprint: 4.625” x 6.875” less base
Forward firing ribbon drivers: 13
Lateral firing, high excursion drivers: 22
Spatial ribbon drivers: 1
Impedance: 6 ohms
Rated Power: 1,000 watts
Minimum Power: 15 watts, tube (30 watts, solid-state)
SPL: 120 dB @ 700 watts
Sensitivity: 92 dB @ 2.83 Vrms
Country of Origin: United States of America
Warranty: 10 years
The Amazing Line Source is supplied with one Sunfire® SubRosa Flat Panel Subwoofer (SRS-210R SYS), including its matching Amplifier (SRA-2700EQ).

Though Bob thinks one is plenty, for those who want even more bass, a second SubRosa Subwoofer/Amplifier may be added at extra cost.
Specifications subject to change without notice.

  • 0 Units in Stock
  • Manufactured by: Carver

This product was added to our catalog on Monday August 11, 2014.

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