Lafayette LA-550
A dual-fifty amplifier that asked its output tubes to loaf, sold by a catalog house with "laboratory standard" ambitions.
Overview
Lafayette sold the LA-550 as the factory-wired version of its KT-550 kit. The price gap tells you about the customer base: the kit went for $134.50, the wired amplifier for $184.50. Fifty dollars was real money in that era, and Lafayette was betting enough buyers would rather solder than pay it. The amplifier is a stereo power amp rated at 50 watts per channel. Lafayette's advertising leaned hard on the conservative rating. The 7027-A output tubes were only asked to deliver 50 watts even though the chassis was billed as a 100-watt basic stereo amplifier, a margin the company claimed was there to ensure long tube life. Whether that was engineering humility or marketing spin, the arithmetic is the same: the tubes run well inside their limits.
The frequency response claim is the one that raises eyebrows. Lafayette specified response from 2 to 100,000 cps, 0, -1 dB at 1 watt. That is a very wide window for a tube amplifier of the period. High Fidelity (March 1962, p.59) took it seriously enough to call it out in its equipment report, describing the LA-550 as rated conservatively at 50 watts per channel and featuring unusually wide frequency response. That's a period reviewer repeating the manufacturer's own framing, so treat the 2-to-100,000 figure as Lafayette's claim rather than an independently measured curve. Still, a mainstream hi-fi magazine bothered to flag the bandwidth, which suggests it wasn't pure catalog puffery.
Inside, the design is a multiple-feedback-loop topology. Lafayette's literature for the KT-550 describes the approach as achieving extremely low distortion without evidence of ringing or instability. The advertised distortion figure was less than 0.5 percent total harmonic distortion at 50 watts from 20 to 20,000 cps, with hum and noise better than 90 dB below 50 watts. Those are respectable numbers for the topology and the era. The "no ringing or instability" language suggests Lafayette knew feedback-loop amplifiers had a reputation problem, since get the loop wrong and a wideband design turns into an oscillator. The company's catalog copy for the KT-550 also promised the amp was "absolutely stable under any conditions of load," which is the kind of blanket guarantee that should make a careful buyer squint.
The parts list reads like a company trying to prove it wasn't just a discount house. Lafayette's own description of the KT-550 cites telephone-grade electrolytics, very high quality capacitors, deposited metal-film glass-core resistors, two printed-circuit boards, and grain-oriented silicon steel transformers. The transformer matters most in a tube amp, because output transformer quality sets the ceiling on everything downstream. Lafayette named the core material in its advertising, which is the sort of detail a builder mentions when the transformer is the expensive part. The wired LA-550 came complete with a metal enclosure measuring roughly 9⅛ by 12½ inches deep, shipping at 60 pounds. That's a lot of iron and chassis for a 50-watt-per-channel tube amplifier.
The rear panel is spartan by later standards: two input jacks, an off/on switch, and a switched AC outlet, per the High Fidelity report. No level controls, no mode switching, no tone circuitry. That's the point of a "basic" power amplifier. The control center does the thinking, and the LA-550 just amplifies. Buyers paired it with Lafayette's own KT-600A / LA-600A stereo control center, which the catalog positioned directly alongside it. The LA-600A wired preamp ran $134.50 and spec'd 5 to 40,000 cps ±1 dB, a considerably narrower window than the amplifier it fed. The power amp's bandwidth claim outruns the preamp's by a wide margin, so either the amplifier was overbuilt for its stablemate or the catalog specs across the line don't tell a coherent story.
Lafayette's advertising called the LA-550 a "Laboratory Standard" dual 50-watt amplifier "guaranteed to outperform any basic stereo amplifier on the market." That's marketing copy, and collectors should read it as such. The independent press was more measured. High Fidelity (March 1962, p.59) filed a full equipment report on the LA-550 and led with the conservative power rating and the wide response rather than echoing the superlatives. That's about the most favorable treatment a catalog-brand amplifier could expect from a magazine whose pages were shared with the establishment brands. The amplifier's reputation rests less on any single review than on the fact that Lafayette moved enough of them, in kit and wired form, to keep the model in the catalog and the KT-550 kit on the shelf alongside it.
For a modern buyer, the LA-550 is a wideband, feedback-heavy, transformer-rich tube design from a major catalog house, sold at a price that undercut the boutique brands and backed by a 15-day home trial. The 7027-A output tubes are the practical concern. They're the part most likely to need attention on a sixty-year-old unit, and the conservative operating point Lafayette chose is the best argument that a survivor's tubes might still have life in them. The metal enclosure and 60-pound shipping weight mean it's not a casual shelf piece. It wants a real stand and a real load. The two-input rear panel means the amplifier expects a period preamp, and it won't flatter a modern source plugged straight in.
What the LA-550 represents, more than any single spec, is the moment a discount catalog house decided to sell a "laboratory standard" amplifier on its own terms and price it so that the kit version was the real product and the wired version was the convenience tax. High Fidelity (March 1962, p.59) gave it a proper equipment report, which is more than most catalog-brand amplifiers ever got. Whether it outperformed "any basic stereo amplifier on the market" is unverifiable and probably wasn't true — but it was a serious, heavy, wideband tube amplifier sold at a price that made the establishment brands nervous, and that's a more interesting legacy than the ad copy.
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