SOUNDSTAGE! ON HIFIHot Product Archives

Published December 15, 2002


Linn Klimax Twin Stereo Amplifier

As an audiophile I firmly believe that good looks aren't all that important (and a good thing too -- have you ever seen a group of us?). Sure, beauty is nice, but having a good work ethic and enough guts to dig in and get the job done right will take you a lot further. Beauty, as the saying goes, is only skin deep.

But what if it wasn't? What if you could be drop-dead gorgeous on the outside and do your job better than anybody else in the world? Why then, my child, the world would be your oyster.

All it takes is good genes to produce a hottie -- to approach perfection requires that you start out good and then work really hard to remove everything that separates you from your ideal.

Sleek good looks, a deeply ingrained work ethic, and a genetic heritage of edge-of-the-possible engineering -- gosh, that do sound like a Scot, don't it?

Sounds like a Linn. The Linn Klimax Twin stereo switch-mode power amp, in fact.

Welcome to the world, baby girl!

Art strives for form and hopes for beauty. (George Bellows)

The Linn Klimax Twin is unquestionably beautiful. Its sleek, compact chassis is milled from two solid aluminum-alloy billets to within a micron -- a process upon which Linn's sister company, Castle Precision Engineering, lavishes about eight hours of computer-controlled multi-axis machine work per chassis. The top "clamshell" then has 14 slits bored by a SIP vertical jig borer -- about the most accurate and stable production cutter on the planet -- and both halves are then hard-anodized. This might seem like overkill, but the resulting solidity and mass provide concrete sonic benefits: resistance to acoustic vibration, inherent protection from errant electrical noise and RFI, and extremely rapid heat exchange (which the anodization only enhances).

Looking inside the Klimax Twin's chassis, it's obvious that the amp's beauty extends deeper than the aluminum skin: two small high-quality circuit boards are separated from each other by the case's central heat exchanger. One of these constitutes the Klimax Twin's futuristic power supply; the other is devoted solely to the unit's audio circuit. The small size of the boards and the density of circuitry dictate that all signal paths are extremely short.

What you won't see in the Linn amp are several components that have been included in almost every amplifier since the dawn of the electronic age: a honking huge transformer, massive rectifier, and big ol' power supply capacitors. In fact, the immense size of many high-end amplifiers is almost the direct result of their necessarily large transformers and reserve capacitors -- and the bulk not necessitated by those is due to the amount of heat dissipation that the voltage regulators require to keep the circuit's power supply consistent. It's not too big an exaggeration to call an audio amplifier a tiny bit of circuitry attached to a large power supply and heat sink. On the plus side, conventional "big iron" amplifiers are relatively simple and inexpensive to make.

There are compact, efficient amplifiers called "switch-mode devices" -- you've probably got some around your house. They tend to be used in applications such as computing, where sound quality isn't crucial to the device's performance, because they do generate high-frequency noise. They also require a great deal of manufacturing precision and costly parts.

Linn's been using switch-mode designs for years, primarily in their low-power products. But a few years ago, the company committed itself to perfecting the technology for amplifiers and produced the 290W Klimax Solo (500W into 4 ohms), a monoblock amp that had critics turning cartwheels. The Klimax Twin is a direct descendent of the Klimax, configured as a stereo amplifier offering approximately 100Wpc (230Wpc into 4 ohms).

Beauty draws more than oxen. (George Herbert)

The Klimax Twin's switch-mode power supply takes the AC out of the wall, filters it, and then rectifies it in order to convert 120V of alternating current to between 300V and 350V of direct current. (Danger, Will Robinson! Do not open the case with such lethal voltages lurking inside. Just don't.)

Extremely fast (20 nanoseconds!) semiconductor switches (hence the name) take extremely small "bites" of the DC and feed them to an extremely small transformer, which isolates and transforms the high voltage to the operational value that the audio circuit requires. Fast rectifiers convert that to freshly minted DC, which a coil and thimble-sized capacitors then filter. There are 16 stages of power-supply regulation in the Klimax Twin's power supply.

This sounds straightforward, but actually preventing all the ultra-high-frequency noise generated by switching, from invading the audio part of the device is not far removed from a miracle. Linn somehow manages to do it in the Klimax and Klimax Twin -- of course, if it were simple, everybody would be using switch-mode power supplies.

The KT's audio circuit utilizes surface-mount technology, which Linn has been refining for many years. Surface-mount technology appeals to the huge electronics manufacturers because it offers substantial manufacturing cost benefits, but Linn uses it because SMT circuits are physically smaller while offering the same electrical function. In high-performance electrical circuits, territory itself is a disadvantage -- the smaller the surface area, the fewer the parasitic effects, such as RFI and other noise.

The Klimax Twin employs monolithic output devices -- single chips, which contain all the component parts of a complete power amplifier in a scant few square millimeters of silicon real estate.

Of course, since conventional SMT devices are designed to maximize economies of scale rather than audio performance, Linn had to discover a chip design manufacturer whose amplifier chip designer happened to be an audiophile -- and they did! That designer cooked up a MOSFET-based design that satisfied the high-volume requirements of his employer and, with careful tweaking and the right topology in the Klimax, met Linn's performance criteria.

While the KT is extremely efficient compared to a conventional transformer-type amplifier, it isn't 100% efficient. Nothing is. A certain amount of the Linn amp's power is converted to heat, which it dissipates in two ways: natural air convection and an internal fan. The vents cut into the Klimax Twin's clamshell case keep air flowing through the amp's centrally located heat-exchange "chimney," and its heavy aluminum casework transfers internal heat to the surrounding air. However, the amp has a heat-sensing switch that will turn on an internal fan to keep the circuit from getting too warm. In cases of extreme heat build-up, the amp will turn itself off rather than burn up. Keep the Klimax Twin's airways clear for best results (and the quietest operation).

The amp has a blue power-indicating LED on its face. On its rear, underneath the overhanging top-plate (which makes for a handsome package, but an awkward connection scheme), the KT hides pairs of both single-ended WBT RCA and balanced XLR inputs, an input selection switch, an input-mode -- indicating LED, RCA line-out sockets, two pairs of high-quality binding posts (the KT is available in Europe with Neutrik Speakon 4 sockets instead), and a modular IEC power socket. That's a lot of stuff, and the KT's case is svelte, so there's not much space -- hawser-type cables are not going to work. Thin is in.

I'm skipping over a few sexy features, such as Linn's trick automatic mains-sensing voltage switching and input-signal-sensing activation circuit. I reckon a beauty's gotta keep a few secrets if she's going to preserve her aura of mystery, and we have already peeked under the hood, after all. But if you're determined to know all, go to or and you'll find everything in the .pdf file of the unit's owner's manual.

Oh yeah, one more small detail. The Linn Klimax Twin retails for $8995.

Well, nobody's perfect.

Beautiful enough, if good enough. (Latin proverb)

The Klimax Twin's true beauty isn't even remotely visible -- transparency, by its very nature, can't be seen. Actually, it can't be heard either. That's kind of its point.

And this might conceivably be a sticking point for some listeners, since you have to be extremely attentive to hear when something is doing nothing. (As a past master of the art, I can attest to the fact that you will hardly ever get much credit for doing nothing -- even if you do it extremely well.) Be that as it may, the most salient characteristic of the Linn Klimax Twin is the complete absence of all those qualities that signify that you are listening to reproduced music.

First is the complete absence of any noise embedded in the signal. No tizz, no harshness, no burr on a transient's sharp leading edge -- no nuthin'. And no matter what speaker load I threw at it, neither was there any sense of strain or rhythmic heaviness or dynamic limitation.

Bass, when present and reproduced by speakers up to it, was deep and effortlessly fast. In fact, I suspect many listeners will miss precisely how real the Linn's bass sounds -- at first, anyway. I sure did. Eventually, however, one notices that an acoustic jazz bass's walking beat or a funk bass's plucked rapidity possess greater measured regularity than you have probably ever heard on record.

A walking bass line sounds simple, but a good one is deceptively complex -- it actually has quite a few functions. On its most obvious level, it anchors the beat to an organic, very human meter, like, ummm, walking. So it must be regular. But if it's too regular, it doesn't sound organic and it's boring. So, the standard approach is to arpeggiate chords with slight emphasis on alternating beats.

However, merely changing the one beat to correspond to the chord also sounds boring if kept up for long, so the really good bass players start substituting variations, such as slipping in passing notes, which sort of "lead" the ear to a note actually in the chord being played. Really, really good bassists also mix it up harmonically by substituting notes from the scale's mode form or changing the arpeggiated sequence (slipping in a measure of 1-3-7-6 to break up a pattern of 1-3-5-6, for instance) or playing a chromatic rather than arpeggio sequence (sometimes called the make a jazz noise here maneuver) or shaking up the quarter-note pace with a flurry of eighth notes or triplets. Actually, really, really great jazz bassist have tricks I can't even begin to articulate.

My point, however, is that walking bass seems simple, but is made up of countless subtle shifts in meter, touch, and harmonic structure which, paradoxically, have to sound regular above all. Otherwise, there's no forward momentum.

Most hi-fis blunt that sense of momentum because they don't begin to capture the subtle shifts in touch or even the immense differences between an open and a muted tone -- they miss the first and reduce the range of the latter and, as a result, recorded music loses much of the swing inherent in the real thing.

The very best high-end components preserve more of those shifts and differences -- and the Klimax Twin does it better than anything else I've ever heard. And yet I say it’s a difference you might not even notice upon first hearing -- how does that work?

Partially, it's because we humans are extremely good at hearing what we expect and when we don't hear that, we think something's wrong. Our hi-fis have trained us to expect them to sound different from live musical performances. And we audiophiles react to the most infinitesimal improvements as if they were momentous. Change the rubber feet under a preamp for spiked ceramic cones and we say, Wow -- listen to that! But actually make a significant change in the realism of a system and we say, Wait -- that doesn't sound "right."

But that's not all. The Klimax Twin doesn't have many of the colorations we audiophiles tend to value. It doesn't sound sweet -- and it doesn't sound hard or cold or clinical, either. It has no character at all. This is emphatically different from lacking character -- self-effacement is a character trait, isn't it? However, on first hearing, many audiophiles will feel the Klimax Twin sounds "flat" or "lifeless."

That may be because its not what they expected -- it might not even be what they prefer (preference, of course, is a different concept from quality). But while the KT doesn't add its own characteristics to the music, it does a superb job at getting out of the way of -- and presenting -- the character of the recording itself. And that may or may not be what you want to hear.

What is beautiful is good, and who is good will soon be beautiful. (Sappho)

As it so happened, the Klimax Twin's stay in my system almost perfectly coincided with my other favorite amp of 2002, the Ayre K-5x. Both accept single-ended and balanced inputs, so I teamed them with the Ayre K-1x preamplifier, which can output either SE or balanced signals. Interestingly, I could hear no audible difference between SE and balanced input with the Linn. Both sounded superb, both were quiet as the tomb. For what it's worth, the V-5x sounded better when connected to the K-1x through its balanced input, especially in its portrayal of dynamic swings.

For the purposes of head-to-head comparisons, I also employed Shunyata Research Aries balanced interconnects and Lyra speaker cables, the Audio Research CD3 (balanced output mode), and Roman Audio's Centurion loudspeakers.

The Linn outputs 100Wpc while the Ayre produces 150Wpc, but I was never able to faze either of them. If you know you have a brutal loudspeaker load -- something akin to a dead short, perhaps -- power delivery might conceivably be a problem, but I doubt it. (Linn suggests, "If it really bothers you that you may not simultaneously be able to melt every drive unit in your loudspeaker system, not to mention your ears, then lay in a 230V mains supply … [to provide] maximum theoretical power.")

Playing Charles Mingus's epic masterpiece, the 28-minute "Cumbia and Jazz Fusion" (13 Pictures [Rhino/Atlantic R2-71402]), the two amps were pretty evenly matched. Mingus's incisive walking bass dominates the song (in ill health, he played it seated, bolstered by amplification) -- it seems to lead us from one musical vignette to another, ranging from classic Mingusian big band shouts to Colombian-influenced melodic fragments to tunes that have a folkish middle-European inflection. At one point, Mingus shouts, "Who said mama's little baby loves short'nin' bread? That's just some lie some white man up and said! Mama's little baby loves caviar!" The band responds with alternating chants and hot solos, and the piece lumbers back on its peregrinations.

The Linn captured that lurching shamble of the bass pushing things along -- the headlong stagger-step sequence of musical neighborhood following musical neighborhood. So did the Ayre. The Linn gave Mingus's bass mass and solidity, perfectly capturing the deep tones and loose string slap of each note. So did the Ayre.

Damn! It's my job to hear these differences.

"It's Not Over Until the Fat Lady Sings" from Terje Rypdal's Skywards [ECM 533768] provided an extremely subtle difference. The disc is one of ECM's finest examples of "chamber jazz," melding Rypdal's piercing, soaring electric guitar, which seems to float on its own cloud of sustain, to the slowly shifting backdrop of cellist David Darling, bassist Palle Mikkelborg, drummer Jon Christensen, and violinist Terje Tønnesen. The song relies upon the contrast between the icy bite of Rypdal's sound and the lugubrious, plaintive murmur of the other four, most predominately the sustained descending melody played by Tønnesen. It's another seemingly simple but emotionally complex piece that essentially evaporates as one tries to dissect it -- but emotionally evocative it decidedly is.

After a great deal of back and forth and forth and back, I'm almost positive the Ayre ever so slightly sweetens Rypdal's bite. Not much, but a little. How much does that mean, really?

Ah, that's a hard one. With either amp, the song is beeyouteeful and melancholy. With both amps, the emotional impact is essentially the same. And, we must never forget, when it comes to preference many people might even prefer the Ayre's slight warming up of those high frequencies -- maybe I'm even one of them. But I think the Linn is simply reporting all of what's there and the Ayre is missing (or slightly altering) some of it.

Once heard, however, I began to notice this on other performances -- it wasn't just a one-time event, it's a definite trend. One that's so subtle I couldn't even hear it at first. One some people won't hear at all -- or, if they do, might not even find worth mentioning.

What a coincidence -- at almost precisely the same time, I get two amplifiers that are all but indistinguishable in performance. All in all, they stack up extremely well against each other.

However, the Ayre is almost precisely half the Linn's price.

Beautiful! Good! Perfect! (Horace)

Of course, that's a question of value -- and there, it's each to his own. The Ayre is a brilliant performer and is, possibly, an example of how a mature technology that pushes so hard against the constraints of its own limitations that it actually transcends them. We've seen something similar happen in turntable design since the introduction of CD -- LP playback has seen more progress in the 20 years since the technology was "obsoleted" by digital playback than it had in the 20 before that.

And that isn't meant as a put-down to either the Ayre or LP playback -- both do a bang up job of delivering musical sublimnity and that's the only true justification for any hi-fi component. But the Linn Klimax Twin looks toward the future. I suspect that the next real sonic step forward will come in the realm of Class D amplification and the switch-mode power supply will be an essential component in perfecting that technology. Linn spent over £1 million in research developing SMPS and SMT, both crucial components for moving forward into the future. That expenditure is reflected in the Klimax Twin's price, but it will inevitably trickle down into more affordable implementations as well (I note the new $2995 250Wpc Linn 2250 power amp employs an SMPS).

And if we carry that "perfection is approached only as a technology reaches maturity" argument to its logical conclusion, what fantastic news that the Klimax sounds like the fullest flowering of the technology it replaces right out of the gate! If this is where we start, where can we possibly eventually wind up? All I can say definitively is that the Linn Klimax Twin switch-mode stereo amplifier is, like the Linn Sondek CD12 before it, the finest example of its category I've ever heard. It's the result of a fanatical approach to every detail, not to mention a concerted push of the performance envelope -- that level of obsessive engineering doesn't come cheap.

And then there's the whole question of beauty. The Linn's handsome façade requires no justification -- beauty needs no excuse. But the Linn's trim size and discreet charm mean it can be used in situations where traditional hi-fi aesthetics would be sorely out of place. You don't need to tuck the Klimax Twin in an armoire or audio closet. Not only is it unnecessary to closet it away, I can think of few folks who would even consider it. A pedestal, maybe -- but a hiding place? Never! (Linn makes, and I can certainly imagine using, a wall bracket that mounts the KT on the wall -- I almost said "unobtrusively," but why? I'd shine a spotlight on it.)

I certainly can't afford the Klimax Twin, but that doesn't change the fact that I'd own it in a heartbeat if I could. If you're not bound by such trifling considerations, put it on the short list for your next amplifier purchase -- and even if, like me, you could never aspire to such lofty heights, you should still audition it, if only to truly understand what is possible in audio amplification today.

Besides, beauty, once heard, is never lost.

 ...Wes Phillips

Linn Klimax Twin Stereo Amplifier
Price: $8995 USD.
Warranty: Two
-year parts and labor (parts portion extended by three years when the user returns the warranty card).

Linn Products Limited
Floors Road
G76 0EP
Scotland, UK
Phone: +44 (0) 141 307 7777 or 0500 888909
Fax: +44 (0) 141 644 4262


US distributor:
Linn Products Inc.
8787 Perimeter Par Boulevard
Jacksonville, FL 32216
Phone: (904) 645 5242 or (888) 671-LINN
Fax: (904) 645 7275


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