Each channel sports several 4700♟ blue capacitors and large, yellow polypropylene capacitors. The main circuit board, which consists of a high-quality epoxy pcb with solder mask and designator, has no point-to-point wiring. The case is standard sheet metal, but the screw holes are pre-drilled, with nuts fixed to the metal on the opposite side to allow firm tightening. Low-level devices are also matched carefully at build time.Ĭhassis construction and system-board assembly are first-rate. When they're matched at build time, all drift has been theoretically eliminated, so the sound of the amplifier will change minimally over time. Before a Fifteen is assembled, its output transistors are mounted on a large grid and burned-in for months. The Model Fifteen's build techniques help ensure its reliability-it comes with a lifetime warranty (available to the original owner only). Both signal circuitry and power supply are bypassed, with special attention paid to emitter resistors and output devices. The Fifteen employs the same ultrasonic bypassing techniques used in the company's Model Six Mk.II preamp. The amplifier's power supply employs a large, high-current toroidal transformer, 80,000♟ of filter capacitance, extra capacitor filtering of both the main output or current gain stage, and a local supply to the input differential amplifier. The Fifteen uses 1% custom metal-film resistors, polystyrene and polypropylene capacitors, printed circuit boards with special transfer characteristics, and switches and controls that feature silver and gold contacts. The result, according to Glen Grue, was an "improved squarewave response and a more natural, more dynamic, more savage sound from the amplifier." First, the current delivery to the front end was improved with better impedance matching between supply and signal-bearing circuitry second, the amount of input-stage regulation was reduced and third, the output-stage emitter resistor values were changed. How does the design of the current Fifteen differ from that of the model I first heard? Using listening and bench tests, the Classé design team made circuit adjustments to the earlier design. As with other bridged amplifiers, the Fifteen in Mono mode cannot be used with crossovers or servo modules that feature a common ground. The Mono positive speaker input is the left positive, the Mono negative the right positive. When the rear-panel Stereo/Mono switch is set to mono, the left input serves as the Mono input. Each Fifteen is protected by a 120V, 8A fast-blow fuse, as well as the electronic protection circuits. Other nice features are a detachable line cord and a supplied Allen key for the top-plate bolts. The company-supplied nut driver allows the owner to tighten these bolts down onto speaker-wire spade lugs, making for an extremely tight electrical connection. Speaker connections are made via the heavy, silver-plated bolts that have been a feature of Classé Audio amplifiers since their first model, the DR-3. Its thick, curved faceplate has sculpted, one-piece handles, and is finished in either satin black or soft-shadow silver. The Classé Fifteen is a conventional, single-chassis, 60-lb solid-state stereo amplifier with rounded heatsinks, rear external switching for regular or balanced inputs, and a toggle switch for stereo or bridged-mono operation. Shortly after I received the DR-15s, Glen replaced them with a single silver Classé Fifteen. I found the amplifier to be highly accurate sonically, but overly polite-sounding. The DR-15 had been produced when David Reich was a member of the design team. I first heard the Fifteen in an earlier version, the DR-15, when Classé's president Glen Grue shipped me an all-black pair of them while I was reviewing the Classé Six Mk.II preamplifier (Vol.17 No.2, p.107). The Classé Fifteen solid-state stereo amplifier is just such a surprise. It makes the listening exciting and the writing easier. The review then becomes an exciting discovery, reaffirming the pleasure one takes in good audio, and in listening to music being reproduced as it should be. I think every audio reviewer hopes for a surprise-when a good, but not outstanding, product is refined by the manufacturer into something special.
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