Published On: February 13, 1990

Carver Silver Seven Mono Vacuum Tube Power Amplifier Reviewed

Published On: February 13, 1990

Carver Silver Seven Mono Vacuum Tube Power Amplifier Reviewed

Bob Carver knows a thing or two about amp design, and the huge Silver Seven is actually two separate chassis, and 38 tubes, for each channel. It's also a good $30,000+. This is a far departure from a power amp in a coffee can and remains a historically important power amp even today.

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History lessons may bore most of you, but some background is needed to understand the brain-rattling Silver Seven. A lesson in psychology wouldn't hurt either, because what we're looking at here is a response to hurt pride, or ego, or whatever it takes to drive a mass-market manufacturer to produce a four-chassis power amplifier clocking in at seventeen big ones.

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Bob Carver, a wizard designer who can't decide whether he wants to be Albert Einstein or Cecil B. De Mille, has the high end in his blood. Founder of Phase Linear, Carver can take credit for being one of the first to manufacturer gigantic overkill transistor amplifiers. The seeds of cost-no-object high end took root in the late 1960s and early 1970s, and Phase Linear was a key player. But Bob's tenure with the company which bears his name has seen only the production of affordable products with no aspirations toward the high end, signified by a mix of genuine innovation and marketing excess. Indeed, some of the Carver notions are so bizarre as to border on the comical, but this hasn't stopped the company from selling many millions of dollars worth of hardware.

Carver has always enjoyed winding up the press with what are known as 'the Carver Challenges'. Three years ago, Bob took on the American high end community – mainly in the pages of ¬Stereophile¬ – by suggesting that he could make one of his more affordable amplifiers sound just like whatever cherished high-ender his critics cared to name. The technique he employed was what he calls 'Transfer Function Matching', in which the differences between an input signal and an amplifier's output are used to identify its 'sonic fingerprint'. By inverting an amplifier's output and summing it with the output of a second amplifier, the amplifier can be tweaked to sound like the first. If the two are absolutely identical, then a null will be created by complete cancellation. Any differences will be the distortions or by-products to be removed for tweaking the second amp to sound like the first amp.

Subjective tests followed, apparently supporting Carver's contention, but his victims were less than satisfied with what reached the shops. Stung by this, Carver decided to produce his
own cost-no-object 'statement', returning to what he has described in print as his true love: tubes.

Carver knows his target victims well enough to realize that what he needed to produce was an absolute mother of a tube amplifier which would offer the sound of the classics, the true greats, while being able to emulate the virtues of modern amplifiers in every respect. If it seems like Carver tailored the amplifiers to perform in such a way as to appease certain reviewers, well, that's probably the most pragmatic (if somewhat cynical) approach I've ever heard of as far as hi-fi design is concerned. On the other hand, if you, the reader, believe that Reviewer A is a knowledgeable and honest individual whose opinions are to be valued, then it also stands to reason that the designer who builds an amplifier to that reviewer's exact tastes has made what that reviewer genuinely considers to be a superlative product. In other words, forget the motive, which will always be to sell amplifiers and garner rave reviews (or vice versa). The proof is in the performance.

Carver's Silver Seven Mono Vacuum Tube Power Amplifier is described as a classic circuit benefitting from modern developments. Taking no chances, Carver has incorporated every
known tweak short of Beltism, so the end user need do nothing except install the amplifiers in the system.

The Silver Seven takes the form of two chassis per channel, including a massive power supply connected by a multi-core umbilical cord to an equally massive power amplifier. Starting from the ground up, each hand-rubbed, black lacquered chassis rests on four rubbery Simms Vibration Dampers, which in turn rest on polished granite anti-vibration bases; Carver is taking no chances here on mechanical interference causing microphony and you do save on Isoplats. The power supply chassis, measuring 252x452x245mm (wdh) including the feet and baseplate, sports a large needle-type meter on its front sloped panel, the meter monitoring tube condition.

The slope continues back toward the massive mains transformers, behind which lurk the fuses, the mains and umbilical leads and the on/off and stand-by switches. This is Ergonomic Failing No 1, because – I don't care how purist you are – these amps will not be left on at all times once you've experienced either the heat they generate or the way they set your electricity meter into overdrive. Having the switches on the front would make one's life a bit easier. The meter itself does diddly until something goes wrong, so I didn't get to see it dance. It does, however, look cute enough in its retro glory to have inspired Sony to put a similar meter on the front of their top-end amplifiers.

Switch-on from cold takes a good three or four minutes until the 'soft start' relays click and music emerges. At times when you wish to interrupt your listening sessions, you can switch the unit into stand-by; switching back on takes about one minute as the amp has been left 'idling'.

You'll know when the amps are on, believe me. Each 330x485x275mm (wdh) main chassis sports no less than ¬fourteen¬ 6550 output tubes, plus a 6550 as a voltage regulator; KT88s are an added-cost optional extra. A 12BY7 high-gain voltage amplifier pentode serves as the input valve and three paralleled 12BH7A power triodes drive the 6550s, completing the line-up. While the 1930s-mad-scientist styling may be aimed at securing a following in Japan, where such glorious kitsch has real cachet, seeing four chassis and 38 exposed valves is guaranteed to seduce ¬anyone¬ who ever looked at an out-of-date ¬Hi-Fi Yearbook¬ in a lustful manner.

Protecting the four input valves at the very front is a tiny barrier, to the right of which rests a gain control; the mains transformers reside at the back. Beneath these at the rear are two gold-plated input sockets, one for real-world pre-amps and one for pre-amps guaranteed not to leak DC. Playing it safe, I opted for the normal rather than the 'turbo' during the reviewing period, as I don't trust any hi-fi equipment, whatever the pedigree. The hot-rod input is labelled 'Lab Direct' and is DC coupled to the amplifier, while the 'Normal' input is AC coupled through a WonderCap. In a fit of bravery (or stupidity), I gave 'Lab Direct' a bash and will admit to experiencing a shade more transparency, but my cowardice soon had me reconnecting via
'Normal'.

Although the 'Seven features automatic biasing, a bias switch on the back comes into play when the valves have aged to a point where the meter shows an idling current creeping above 0.6 amps. Switch to 'high bias' and you extend the life of the tubes, as the plate current will fall back to between 0.2 and 0.6 amps.

Ergonomic Failing No 2 is also found on the back, another touch of 'retro' in the form of gold-plated screw tags for the speaker connections. The Silver Seven allows you to choose from taps of 1, 2-4 or 8 ohms, but screw heads are not that wonderful for grasping two bare cables or even two spade lugs if you're bi-wiring. For #17,000, though, I'd be surprised if Carver said
'No!' to a customer who insisted on five-way binding posts.

The Silver Seven derives its name from the use of silver wiring and silver solder throughout, and seven pairs of output tubes. Carver, eager to have this behemoth dubbed a modern classic, used traditional fully-balanced circuit topology, massive wide bandwidth ultralinear output transformers and the calibre of valves which I didn't think you could find in any quantity. The 14 tubes per side are driven to produce a conservative 375W into 8 ohms, with peak current on the 1 ohm tap of 35 amps; energy storage is 390 joules. Reading the owner's manual and the promotional literature reveals that the unit is tailored to sound vintage, but with such modern touches as ghostly silence, the ability to drive hungry and awkward loads and to offer bandwidth, slam and dynamic capabilities not realised by tube designs of the
Golden Age.

HW International left the Carvers with me long enough to allow me to try them with speakers including Apogee Divas (2-3 ohms), Stages (3 ohms), Celestion SL700s (6 ohms-ish) and a host of 8 ohm-plus speakers. As the Silver Sevens are unlikely to be driven by budget components, I restricted the sources to the Basis/SME/Koetsu Urushi analogue front-end and the Marantz CD-12 and CAL Tempest II Signature CD players. Pre-amps included the Audio Research SP-14 and Carver's own C-19 valve pre-amp, which I'll discuss in detail next month.

Read more about the Carver Silver Seven on Page 2.

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The Sound Of $1650-Worth Of 6550s Price shouldn't influence a reviewer or a civilian listener when assessing any product; it should only determine the final value-for-money rating and whether or not it fits a budget. Although the Silver Seven may not be the dearest amplifier on the planet, it's the costliest I've ever used in my review system and it took a bit of effort to force myself into dismissing the influence of the price tag. Then again, I wasn't presupposing

that the 'Seven would be all that marvellous, because I wasn't expecting the performance to match the overwhelming appearance or price tag. After all, Bob Carver's main achievements have been in the middle market, and I had no reason to believe that a slap in the face from the US press was enough to drive him to levels of sheer brilliance.

Boy, was I wrong. Even before the 'Seven had driven the mercury up a degree or three, I was finding my face locked in a grin/rictus. All of those 'chill factor' criteria were met, the amplifier delivering a flood of 'you are there' touches of the type that would have J Gordon Holt hopping with glee. Aside from imagining Bob Carver with a balloon over his head reading 'I told you so', the Silver Seven – regardless of the speaker to which it was attached – proved itself to be audibly superior to any amplifier in my arsenal or in recent memory. But before I get to the inevitable caveats , let me try to describe what this amplifier does for the music.

However 'classic' the sound is meant to be, it has lower registers unlike any vintage valve amplifier I can recall. Modern designs I've heard (regardless of their chosen technology) which
approach or match the Carver include the larger Audio Research amplifiers, most of the Krells, the big Rowlands, the Mark Levinson monoblocks and the Goldmund; note that none of these are 'inexpensive', so such low-end control and extension does not come cheap. If the bass does betray either its tube origins or Carver's avowed intentions, then it's only through a slight richness which absent from the solid-state designs mentioned above.

The vice-like control and the richness continue with absolute consistency up into the midband, where the latter starts to fade out in exchange for greater neutrality. I don't know how deliberate is Carver's sonic 'tailoring', but he managed to make the richness dissolve by the point where it's already stamped the sound with valve status, at the same time not allowing it to intrude into the all-important midband. The inaccurate (though undeniably pleasing) extra warmth heard on acoustic instruments and vocals played through vintage tube products is absent in the 'Seven's performance – a good thing as more and more time passes
from the days when most audiophiles lived with vintage gear and would be prepared to forgive such euphonic distortions.

As for the treble, it's the same recipe: transient attack to rival the fastest, most authoritative solid state devices you can name, with the sweetness (but not the tubby lushness) of the tube legends. However much it strikes me as dealing with mutually exclusive virtues, Carver has managed to juggle the old and the new with greater skill than I've yet experienced. Just as impressive as the tonal neutrality, though, is the manner of presentation, for the Carver has holographic capabilities (dictionary rather than 'Sonic Holography' definition) on a par
with the very best.

'Tall', 'wide' and 'deep' are only part of the story. The spatial characteristics also include uncanny precision and a seamlessness that avoids overetched, 'Viewmaster'-style landscapes. In this arena, the 'Seven has a few rivals bearing Audio Research, Krell and (when they're working) Jadis badges, so the Carver hasn't really pushed the boundaries in 3D terms. But rest assured that it's world class. But if it is compromise or weakness that you need to read about, then I should mention the way the Apogee Divas (not the Stages) rendered the 'Seven a bit breathless.

Whatever the power rating, this amplifier is not the gutsiest beast I've ever used. While the Diva was the only speaker in my possession to expose some limitations in the Carver's dynamic capabilities, I have knowledge of a few dozen other speakers which are just as demanding. True, they, too, could be avoided, but all are natural candidates for the 'Seven. Indeed, the majority of high end speaker builders assume that their products will be mated to powerful amplifiers. Normal levels were no problem, but playing hardball is not this amplifier's forte. The Aragon 4004 at 1/10th the price offered greater levels and no compression or clipping with demanding material like large orchestral works and sonic showstoppers.

But that doesn't stop me from regarding the Silver Seven as one of the very finest amplifiers money can buy. The big chuckle, though, is the price, which means that the Silver Seven is as much a marketing tool as it is a hi-fi statement, however undeniable and real its standard-setting virtues. Which leads us to...

'T' Is For Tiny
Earlier in this review, I mentioned Carver's 'Transfer Function Matching'. Quite obviously, the #1900 per pair, solid-state Silver Seven T monoblock is conceived to be the poor man's Silver
Seven, right down to the 'steam punk' styling. Somewhere, I read or heard that this amplifier was supposed to deliver '90% of the Silver Seven's performance for 10% of the cost'. Hmmm...

Rated at a 550W per side, the Silver Seven T is said to duplicate the 'transfer function of the Silver Seven'. Using Carver's Magnetic Field design circuitry, it actually pumps out more watts, can drive 2 ohm loads, weighs only 7.2kg per side (as opposed to the Silver Seven's 68kg), takes up floor space of only 370x292mm and looks just as wonderful. The controls are limited to an on/off switch at the front, while the rear sports the five-way posts I wish were on the Silver Seven.

This amplifier is notorious for having received one of the worst reviews ever published. I think I understand why, though the amp is by no means ready for display at Crufts. Basically, Carver was silly for hyping this as a poor man's 'Seven because even those who haven't heard the 'Sevens would therefore expect something so far beyond the 'norm' that the wee Carver would have had to perform miracles. Inevitably, the 'T lacks the absolute transparency, the delicate treble, the coherence and the authority in the lower registers of the 'Seven, but none would have minded so much had Carver not declared it to be a near-clone. Indeed, it has exceptional stage width, better-than-average depth, reasonable bass extension and – with certain cone-type loudspeakers at least – enough slam to suggest that its power rating is indicative of its performance.

However poorly it fared with the Diva, the 'T worked nicely enough with the Stages to make me wish that I hadn't (1) reviewed it side-by-side with the 'Seven and (2) heard Carver's claims. And I could only register dismay when the 'T failed to prove adequate when asked to drive the ATC SCM20 'mini' monitors. I'd rather not dredge up the hoary old debate which started with Carver's Cube of some 10 years back, with its astronomical power ratings and about as much guts as Charles Hawtrey. The 'T, also endowed with 'Magnetic Field' technology, also seems to perform less like a 500-watter than one would expect. It simply lacked the slam I associate with amplifiers from the Aragon 4004 on up.

But I can't trash the amp because I did manage to find speakers with which it mated beautifully, the Monitor Audio Studio 10 for example never causing the 'T to turn harsh or to sound 'over-driven'. But just as the Silver Seven sounded like a thoroughbred whatever the speaker, so did the 'T seem less than authoritative through all but the smaller monitors. It suggests that the 'T does not want to do too much work below 60-80Hz (the effective lower limits of most small boxes), in which case the 'T should be auditioned with this in mind.

Let's face it: The betubed Silver Seven is simply a 'dream' amplifier. At its frightening price, it's amazing that over 50 sets have been sold. Even Carver will admit that it's a flagship, like Infinity's IRS, designed to call attention to the rest of the range. That both the Carver Silver Seven and Infinity IRSes do sell is simply a bonus. But the 'T is the first off-shoot, and it does not succeed in bringing the 'Seven Experience' to the masses. It's simply a good, if undistinguished amplifier.

Because the 'T is so aesthetically adorable – 'retro-tech' like the Olympus 'O Product' camera or Mazda's Miata roadster – it will probably sell to the same people (and that includes me) who buy 1930s styled pens or watches or cameras. But that doesn't help those of you who want a taste of the Silver Seven's glory at a lower tariff. For that, you'll have to wait for the forthcoming Silver Six, or investigate the first of the company's tubed pre-amps. Amusingly, Carver's first valve control centre is not a high-end piece but a #950 unit within reach of the same people who'd consider Naim or Exposure or Musical Fidelity; its high-end counterpart will follow later.

As for that showpiece Silver Seven, well, whatever the sins or graces of its progeny, it is simply a milestone in high-end design. I can't flat-out say that it's the world's best amplifier
because I haven't heard every amp available (nor has anyone else). Indeed, if anyone ever tells you that any single product is the best of its type, be highly suspicious and change to
another shop or magazine. But I'll tell you this: The Silver Seven, like most Ferraris, actually performs on a par with its aesthetic presence. When you first see the four chassis, you
can't help but grin. You realise that here is a product made truly without any constraints. It's audiophilia gone berserk. Then you listen. After you recover, you realise that rampant
audiophilia isn't so crazy after all.

Additional Resources
• Read more stereo amplifier reviews on HomeTheaterReview.com.
• Find an AV receiver to pair with this amplifier.

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