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.
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
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
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.