A simple, yet elegant 35Wpc Ultra-Linear design which turned out to be the perfect confluence of performance and value for the dollar. Wildly popular; sales are estimated in excess of 300,00 units.
Introduced in 1962, this Sid Smith design represented the pinnacle of Class A Ultra-Linear design, delivering a sweet 30Wpc from a pair of EL-34 power pentodes operating in fixed bias.
Harman Kardon Citation II
Leave it to Stewart Hegeman to bring speed to tube power amplification; claimed by H-K to be the world's first ultra-wide bandwidth tube power amplifier. Still competitive today, this chocolate-colored beauty is seriously collectible.
A 75Wpc stereo amplifier, designed primarily by Sidney Corderman in 1961. It comprises a perfect setting for the McIntosh Unity-Coupled output stage. Vintage tube sound at its best.
Audio Research 76A
Featuring a complex, regulated power supply, and a pentode output stage, it coaxed 75Wpc from a pair of 6550 beam power tubes. The start of modern tube sound and its emphasis on detail resolution.
GAS Ampzilla II
Jim Bongiorno’s masterpiece and one of the first genuinely great solid-state amplifiers possessing not only killer bass, but also huge dynamics and a major boogie factor. Said to be the world’s first servo-controlled power amplifier.
A seminal design that nudged high-end forward and almost perfectly highlighted the virtues of Class A operation. It essentially started Nelson Pass’s phenomenal power amp creative spree.
Cary Audio Design 805
This amp more than any other is responsible for the commercial success and revolution, if you will, wrought by single-ended triode designs in the early 90s.
EAR Yoshino 509
The major innovation is Tim de Paravicini’s balanced bridge mode output stage, in which the plate, screen grid, and cathode are assigned their own separate windings on a bifilar wound output transformer.
It matters not which David Hafler amplifier is chosen so long one Hafler is here. His best, IMO, was the Hafler DH‑200, but his most significant was the 70, which enabled of thousands of audiophiles to enjoy superb reproduction at budget prices in the early days of stereo and for a good while thereafter.
Tim de Paravicini has said that the only audio circuit apart from his own he wished he’d designed is McIntosh’s “Unity Coupled Circuit.” Of several obvious contenders, my choice is the MC275—introduced in 1961, designed by McIntosh co-founder Sidney Corderman—one of the first tube amps to sound truly neutral and offer high power (75 watts/channel, very high those days). Still in production today in its Mk IV version, this is an authentic classic.
As there must be a Marantz manufactured by Saul on this list, the Model 8 or 9 are the logical choices.
Nice as Quad’s tube designs were, Peter Walker’s real breakthrough was the 303. Introduced in 1967, it is nearly the only early solid‑state amplifier that gave and still gives the lie to sweeping assertions about early transistor amps’ grain and harshness (thanks to Walker’s innovative use of “output triples,” which made the 303 unconditionally stable). Natural, nonfatiguing yet lifelike, it and it only is allowed to drive my 57s (and it’s also splendid on any number of other speakers, especially LS3/5as and their progeny).