Carver Research Lightstar 2.0 Review by Robert E. Green

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Carver Research Lightstar 2.0 Review by Robert E. Green

Post by TNRabbit » Wed Feb 24, 2010 7:30 am

The Carver Lightstar Reference 2.0


Here is one of the world's great amplifiers, a device that almost transcends the boundary between real and reproduced music, does everything right, and costs only $249,500. But hey, it's the music that counts, and who cares about money anyway?

Oh, excuse me - that price was dollars and cents. Damn, missed that decimal point: the actual price is $2495.00. So I was kidding but not about how good this amplifier is. That part is for real.

All right, so I'm being catty about the high-priced units. But HP made the point in Issue 110 better than I, even in a catty mood, can make it for myself. With a straight face, and no comments, he compared the Lightstar's sibling, Carver's Sunfire, which shares the power supply innovation of the Lightstar 2.0 and costs about the same, with amplifiers costing 10 or 20 times as much. And the Sunfire was a real contender, losing out only via the unbelievable idea (to me) that it was short on dynamics. The same good showing would have been made with the Lightstar 2.0, maybe even more so for reasons I shall explore in a moment. (And I shall get to dynamics too.)

The big thing to understand here is that we are talking about revolution, the end of the ancien régime, the end of the reign of high-priced amplifiers. People who want to buy amplifiers to demonstrate how rich they are can go right on and buy the over-priced amps that in the trade are regarded as "Hong Kong products" (because so many people in Hong Kong have pots of money they spend on audio). But people who just want practically perfect amplifiers, amplifiers that are realistically as good as amplifiers can be, can get them at plausible prices. The Sunfire was one. The Lightstar 2.0 is another.l

To turn from generalities to the specific performance of the Lightstar 2.0, the word that comes to mind is "awesome." The idea of an amplifier that can generate 3,500 watts on transients into a I-ohm load and 600 watts into 8 ohms for up to two seconds - yet is normal in size and runs quite cool- seems almost to defy standards held just a little while ago. Clearly, the Lightstar 2.0 is never going to run out of punch in any real-world situation in a domestic environment.

Why this is important is not difficult to understand. An amplifier that is working well within its operating range is an amplifier that is working well altogether. It is the sudden fluctuations in demand on the power supply, the extraordinary demands on current capability and the like, that move amplifiers into a realm where they do not work as they should. This simply does not happen with the Lightstar 2.0. And, when operating within its range - that is, all the time - the Lightstar 2.0 creates the impression of essentially complete neutrality. It is hard to be sure what complete neutrality really is. But the Lightstar 2.0 does something very like vanishing, like giving the impression of direct transmission of the source material into the speaker. One hears the virtues and defects of the source and of the speakers. One hears next to nothing of the amplifier. And this remains true independent of speaker load.

This is true in tonal terms. And it is also true in terms of clarity and resolution and transparency of complex textures. Orchestral music remains firmly and completely resolved, no matter how complicated or loud it gets. (That is, as far as the amplifier goes. Finding recordings and speakers that live up to that is difficult indeed.)

There is always a certain danger in describing a component as neutral, clear and transparent. Those adjectives, positive at first glance, are likely to be read as "hard, edgy and treble-exaggerated". So let me note explicitly that none of these negative attributes even remotely applies to the Lightstar 2.0. While it is not "voiced" to sweeten material deliberately, it reproduces the real sweetness and beauty of music when it is there in the source to be reproduced.

I am inclined to offer some speculative explanations of the transparency and detail of the Lightstar 2.0, since excessive high frequencies are clearly not it. First, the Lightstar 2.0 is extremely quiet. With intrinsic noise 110 dB below full output, the dynamic range of the Lightstar 2.0 exceeds that of a CD by a considerable margin, and of course, leaves the LP in the dust. (Actual CD recordings seldom have noise levels anywhere near as low as they could. There is lots of room for improvement in the recording industry.)

A second consideration, 1 would guess, is the nature of the power supply. With conventional power supplies, where the signal interacts with the power supply voltage, the possibility at least exists that large signals can create what amounted to a modulation of the power supply voltage that would interfere with fine detail. This cannot happen with the Lightstar 2.0. (This may not be a big effect, and indeed I am not certain it is audible at all. But the amplifiers that have "fast" power supplies - Sunfire, Lightstar, Chord, the Credo from Switzerland - sound more detailed in general than conventional amplifiers.2) The Lightstar 2.0's power supply also provides great isolation from the vagaries of the household power line. It will operate perfectly even if line voltage drops to around 95!

There has been a good deal of writing about dynamics of amplifiers in recent years. So this might be a good moment to point out that an amplifier like the Lightstar 2.0 is essentially incapable of misbehaving about dynamics in any true sense. Indeed, this is true of any solid state amplifier that is not operating close to overload of some kind. Think of it this way: the error signal- that is, the difference between perfection and actuality--should be and is about 40 dB or more down in level from the signal itself in a broad-band, low-distortion amplifier. This error is simply not large enough to count in terms of literal loud/soft perception.

Perceived dynamic behavior must be some kind of function of small frequency response deviations and/or distortion. For example, tube amps can sound dynamic at clipping from the distortion products giving the sound extra bite. Ironically, a better amplifier can sound less dynamic in this sense.3

In any case, the Lightstar 2.0 is, in real terms, as dynamic as all-get -out. You will not run out of power here under any circumstances that one can plausibly imagine.

Bass behavior is another favorite issue of reviewers. The Lightstar 2.0, with its virtually unlimited peak current and high damping factor, has superb bass performance. While the fact that it is not flat to DC might have in principle some small effect compared to amplifiers that are, this is only in principle. The tiny amount of phase shift attached to the Lightstar 2.0's low 3 dB-down point (1 Hz) will be utterly lost in the shuffle of room effects and those phase effects induced by speaker roll-off. (It is really extraordinary to read bass critiques of amplifiers of this sort made via systems that are lucky to be within 5 dB of flat in the bass - which is almost any system at all that has not been digitally equalized in-room.)

It is important to point out, too, that no tube amplifier of any known and practical sort could equal the performance of the Lightstar 2.0 in many important areas. First of all, only a few special tube designs have an output impedance low enough to be anything like neutral. Amplifiers in the 1-ohm-or-more (or even 0.5 ohm) range just won't be flat into real-world speakers. The sound may be nice, but it cannot be truthful, unless one uses a speaker that has been explicitly designed for use with the particular amplifier. (The behavior of tube amps can also change with level so that the non-neutrality itself is level-dependent.)

Second, no tube amplifier can offer this kind of power and current capability - or at least none that is a practical domestic device. Real-world tube amps aren't even close, and even those monsters with nominal high power (and enormous price) cannot match the Lightstar 2.0's current capabilities.

Third, no tube amplifier that I am aware of is this quiet, although some are fairly close at the noise-at -1-watt level. (None that I am aware of has a competitive figure for noise below full output.)

Certainly many people have found some special midrange magic in tube circuits, and, for small-signal purposes - recording equipment, preamps - tubes have remarkable properties (e.g., distortion going to zero as signal goes to zero). But, for amplifiers playing into contemporary speakers, it is hard to see how tube amplifiers can compete, especially if economic considerations are allowed, or, indeed, even if price is no object.

So spectacularly good is the performance of both the Lightstar 2.0 and the Sunfire that a comparison between them seems almost unfair. One ought to be concentrating on how they equal or better the performance of much higher-priced amplifiers. But of course, comparison is inevitable.

My reaction is somewhat left hand/right hand. The reviewer, the analyst, the thinker, the right hand hears the Lightstar 2.0 as neutrally voiced and thus as the more accurate representation of what is actually on the recording. The Lightstar 2.0 is also technically of the next generation, especially in its amazingly low level of noise - although, given how noisy recordings are, this may be only a theoretical advantage at this time. And, perhaps because the Lightstar 2.0 is voiced to have flat treble, it presents even more detail than the already extremely detailed Sunfire.

On the other hand, the left, musician, would be drowner in sonic beauty, resenter of the world of almost unrelievedly aggressive recordings. .. that part of me appreciates the voiced character of the Sunfire, combined as it is with all the remarkable performance I discussed in Issue 108. And, in the real world, the even greater ability of the Lightstar 2.0 to produce enormous bursts of current played little role for me. I never got close to current limiting the Sunfire.

Here is a modest proposal. Why could we not have switchable "voicing" on one or both of these amplifiers - e.g., alternative output taps? (It would certainly be a lot more useful than the Sunfire's "current source" I-ohm output impedance taps.)

Meanwhile, choices like this depend a lot on which speakers one is using. An aggressive speaker might improve with the Sunfire, while a laid-back or neutral speaker would combine with the Lightstar to reproduce true neutrality. And you know what? You can buy one of each for the price of a few pairs of Vaic tubes, or less than three percent of the price of a pair of Gaku-ons.

The Lightstar 2.0 is truly something remarkable. It is innovative engineering thought like this and its implementation at affordable prices that makes one feel that High End audio is worthwhile in a meaningful social context. The Lightstar 2.0 plays music in every sense of the word. Its designer, Jim Croft, belongs among the masters, and a masterpiece this is.



I would like to thank Robert Greene and The Absolute Sound for the rewarding review of our power amp. It is very gratifying for our Lightstar development group to have our five-year quest toward a truly neutral power amp be so well acknowledged.

With the imperfect medium of stereo recordings the framework in which all of us have to do our design work, it is very hard to resist building into a component some form of sound enhancement to get the output to sound more musical than the input signal. As tempting as this is, it also keeps us from making progress. Multiple compensating components in a system make the task of advancing the art and science of fidelity very cumbersome, to say the least. It also makes it very difficult for the audiophile to advance the capability of his audio system if each piece of equipment contributes its own sonic flavor.

Hence, we took a leap of faith that the best systems of today would not only tolerate but thrive on a neutral, accurate power amp even though it might expose sonic colorations in the rest of the system. Robert Greene and our Lightstar users have confirmed that we are on the right track.

With Lightstar, we attempted to go beyond the best possible signal path purity to a level of performance that can maintain full capability under real-world, unpredictable variables, such as AC power spikes and voltage fluctuations; nonlinear, reactive loudspeaker loads; radiation from other components; and ultra-wide dynamic range.

As impressed as Robert is, the attribute that we feel is even more important is that with Lightstar, this level of performance is now transportable to any environment, with any system. This is achieved with our novel "Active Digital Transformer" power system, which creates the ideal relationship to the signal path circuitry by optimizing over 250,000 times a second for the environment in which the amplifier is being used. Besides protecting small signals from outside disturbances, this system also provides unusual large-signal performance advantages compared to conventional amplifiers.

While the amplifier operates as a true high-current voltage source by doubling power perfectly as you lower impedance remaining stable down to less than 0.5 ohms - it also provides sustained dynamic power such that it can more than double its output (i.e., more than 600 watts into 8 ohms) for over 2,000 milliseconds - two seconds - at a time, substantially greater duration than any program peak in our experience. With previous power amplifiers, you can either have high dynamic headroom or high-current power doubling w/ halving of the impedance - but Lightstar is the only amp that provides both.

Other significant features include both balanced and single-ended inputs, dual binding posts for convenient bi-wiring, remote control turn-on and a high-gain mode that obviates the need for active preamp gain circuitry so that Lightstar can be used with a passive straight wire preamp (such as our Lightstar Direct) and still have full gain and dynamic capability while creating an even more neutral presentation.

Last of all, I want to thank Robert Greene for the kind words regarding my involvement with the "masterpiece:' The Lightstar project is the result of contributions from many engineers at Carver Corporation, including the skillful and tireless works of Vic Richardson, a chief engineer at Carver for over 15 years.

-Jim Croft, Vice President, Research and Development ,Carver Corporation

Manufacturer: Carver Corporation, P.O. Box 1237, Lynnwood, Washington 98046
Designer: Jim Croft
Source: Manufacturer loan
Price: $2,495 Warranty: 3 years

1 About the new Marantz tube amps, one of the contenders in HP's comparison, price $50,000. The Marantz Model9's price would be about $3,500 in today's dollars, adjusted for inflation. Has it not occurred to people to ask themselves why it is that contemporary tube amplifiers, with essentially the same circuits, cost ten times as much? Something like "All the traffic will bear" comes to mind.

2 The power-supply principles of the Chord and the Credo are different from those of the Lightstar and Sunfire (and from each other). The Lightstar and Sun fire share a type of power supply unique to them.

3 The impression that the Sunfire lacks dynamics might be caused by its "voicing down" of the lower treble, not its literally lacking dynamics, which is essentially not a possibility.

Analog: Townshend Audio Mk III, Nakamichi TX-l000' turntables; Graham 1.5st, Mørch DP-6, SME III pickup arms; Audio Technica AML-170, Stanton C8-100 cartridges
Digital: BTA Research, Phillips CD-80 as transport; Audio Alchemy DACs
Electronics: Plinius 12 preamplifier; Sunfire and Credo amplifiers
Speakers: Quad ESL-63; Soundwave Pointsource 3.0, Spendor SP-1j2; Hales Concept Rve. Gradient 1.3, Carver Amazing Loudspeakers (original version)
Cables: Goertz. Promethean
Accessories: Townshend Audio Seismic Sinks

Taken from: TAS issue 111 September/October 1997

From FrankieD's lips to your ears: Sunfire - a quiet box of endless power.

Sunfire TG-IV/400~7 Amp
Carver SD/A-360 CDP
Benchmark DAC-1
Active bi-amp: Ashly XR-1001 & 2 Rane PEQ-15s
Main: HotRodded AL-IIIs
Sub: Klipsch RT-12d
Center: Sunfire CRS-3c
Surround: Sunfire CRS-3 (x 2)

OconeeOrange wrote:"Gary likes to play it 'loud' as do I. His system begs you turn it up until you die"

RIP WIlliam B. Dibble, 1948-2012. I'll miss you my friend.

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