Accuphase P 4100 Brochure

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Accuphase P 4100 Brochure

Extracted text from Accuphase P 4100 Brochure (Ocr-read)


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Stereo power amplifier capable of delivering 500 watts into 1 ohm (music signal) -“ Instrumentation ampli er principle allows fully balanced signal paths. Further refined MCS+ and current feedback topology assure outstanding S/N ratio, minimum distortion, and excellent performance in all other aspects, resulting in superb sound quality. 3-parallel push-pull arrangement of high- power transistors in each channel, sustained by power supply with massive 950 VA toroidal transformer. 4-step gain control minimizes residual noise. The P-4100 is a stereo power ampliļ¬ er that takes sophisticated sound to the next level. While inheriting design technology from highly renowned Accuphase models such as the P-7100 and M-6000, the new model features instrumentation ampliļ¬ er topology and a reļ¬ ned MCS+ circuit to lower the noise ļ¬‚ oor even further. Only specially selected top-grade materials and parts are used throughout with impressive results. In order to bring out the full potential of the loudspeakers, an ampliļ¬ er must be able to cope with drastically fluctuating speaker impedance conditions. This can only be achieved by ensuring constant drive voltage at all times. In other words, the output impedance of the ampliļ¬ er must be kept very low. This also makes it possible to absorb the counterelectromotive force generated by the voice coil, thereby eliminating a major source of intermodulation distortion. The P-4100 achieves these design goals with ease. The output stage for each channel uses three pairs of high-power transistors with a Pc rating of 220 watts, arranged in a parallel push-pull conļ¬ guration. This ensures low output impedance. Stable operation is achieved by mounting the devices to massive heat sinks on both sides of the chassis, for efļ¬ cient dissipation of thermal energy. As demonstrated by the power rating of 500 watts into 1 ohm (with music signals), the P-4100 can easily drive speakers with very low impedance, and speakers with uneven impedance curves are handled with complete authority. Using the P-4100 in bridged mode creates a mono ampliļ¬ er with even more impressive power capability. The power supply section which acts as energy source for the ampliļ¬ er employs a massive 950 VA toroidal transformer in combination with large ļ¬ ltering capacitors, providing ample reserves even with drastically ļ¬‚ uctuating loads. The overall conļ¬ guration of the P-4100 employs the latest instrumentation ampliļ¬ er principle, allowing fully balanced signal paths throughout. In addition, the power ampliļ¬ er section features reļ¬ ned MCS+ topology in combination with current feedback, for further enhanced electrical performance characteristics. n Power modules with high-power transistors in 3-parallel push-pull arrangement deliver 500 watts per channel into 1 ohm (music signals only), 360 watts into 2 ohms, 180 watts into 4 ohms, or 90 watts into 8 ohms. n Amply dimensioned power supply with high-efļ¬ ciency toroidal transformer and large ļ¬ ltering capacity. The high-efļ¬ ciency toroidal transformer is rated for approx. 950 VA, and the two extra-large 47,000Ī¼F aluminum electrolytic capacitors were selected for best sonic performance. n Bridged mode allows upgrading to monophonic ampliļ¬ er with 1,000 watts into 2 ohms (music signals only), 720 watts into 4 ohms, or 360 watts into 8 ohms. Bridged connection increases the output by a factor of 4, creating dramatic power reserves in a monophonic conļ¬ guration. n Four gain control settings minimize residual noise.The gain control alters gain in the ļ¬ rst stage of the instrumentation ampliļ¬ er. Four settings are available (MAX, -“3 dB, -“ 6 dB, -“12 dB). n Large analog power meters with on/off switch. n Mode selector for easy switching between dual mono/stereo/bridged operation. n Fully balanced input stage shuts out external noise interference. n Two pairs of oversize speaker terminals accept also Y lugs plugs. Toroidal power transformer Filtering capacitors Gain selector Parts selected for sound quality and reliability * 1-ohm operation possible with music signals only Output voltage (V) Figure 2 Load impedance vs. output power (output voltage/output current) Figure 1 Circuit diagram of ampliļ¬ er section (one channel) Output current (A) MCS+ (Multiple Circuit Summing) Instrumentation ampliļ¬ er High-power transistors in 3-parallel push-pull conļ¬ guration Gain controlMeter on/off button Input selector High-power transistors used in output stage Assembly with unbalanced and balanced input connectors Assembly with meter and protection circuitry Large speaker terminals NFB NETWORK GAIN CONTROL CIRCUIT NFB NETWORK + INPUT -“ INPUT Bias stabilizer circuit Bias stabilizer circuit NFB NETWORK REGULATOR REGULATOROUTPUT Bias stabilizer circuit Bias stabilizer circuitBias stabilizer circuit

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Instrumentation amp conļ¬ guration allows fully balanced signal paths The newly adopted -œinstrumentation amplifier- principle ensures that all signal paths from the inputs to the power amp stage are fully balanced. This results in excellent CMRR (common mode rejection ratio) and minimal distortion. Another significant advantage is that external noise and other external influences are virtually shut out. The result is a drastic improvement in operation stability and reliability. Current feedback principle assures excel- lent phase characteristics in high range As shown in the illustration, the P-4100 uses the output signal current rather than voltage for feedback. Since the impedance at the current feedback point is very low, there is almost no phase shift. A minimal amount of NFB therefore results in maximum improvement of circuit parameters. Further reļ¬ ned MCS+ topology for even lower noise Accuphase-™s original MCS (Multiple Circuit Summing) principle uses a number of identical circuits connected in parallel to achieve superior performance characteristics. MCS+ is a further refined version of this approach. By extending parallel operation to the class-A drive stage of the current/voltage converter, the noise floor has been lowered further. n Power ampliļ¬ er assembly with three parallel push-pull high-power transistor pairs per channel mounted directly to large heat sink, MCS+ circuitry, and current feedback ampliļ¬ er. Instrumentation ampliļ¬ er conļ¬ guration Signal input stage Power ampliļ¬ er stage + INPUT -“ INPUT Instrumentation ampliļ¬ er and further reļ¬ ned MCS+ topology Principle of current feedback ampliļ¬ er NFB NETWORK NFB NETWORK GAIN CONTROL CIRCUIT OUTPUT -“ INPUT Buffer + INPUT Buffer I/V converter Current NFB network Trans-impedance ampliļ¬ er Current adder Ampliļ¬ er Output