Accuphase P 7100 Brochure
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Impressive power amplifi er capable of delivering 1000 watts 2 into 1 ohm – Amplification stages feature fully balanced signal paths as found in high- quality instrumentation amplifi ers. Further refi ned MCS+ topology and cur- rent feedback design result in even better S/N ratio, distortion, and other performance parameters. Massive, high-efficiency 1.5 kVA toroidal trans- former and 11-parallel push-pull arrangement of high-power transistors de- liver enormous amounts of linear power into ultra-low loads down to one ohm. The P-7100 is a successor to the highly regarded P-7000, inheriting its general design policy and major features while realizing further improvements in vari- ous aspects. A major new highlight is the overall in- strumentation ampli er con guration, which allows fully balanced signal transmission in all stages of the ampli er. In addition, the power ampli er section employs MCS+, an improved version of the innova- tive Multiple Circuit Summing principle developed by Accuphase. In conjunction with the famous current feedback topology, this provides further improved performance characteristics. Only strictly selected high-quality parts and materials are used throughout, and the output of the ampli er is designed to achieve very low impedance and constant drive voltage. In the output stage, 11 pairs of high-power transistors with a rated collector dissipation of 150 watts are ar- ranged in a parallel push-pull con guration for each channel. The devices are mounted to large heat sinks on both sides of the main chassis for ef cient dissipa- tion of thermal energy generated during operation. As a result, the ampli er is capable of delivering power in a linear progression down to an ultra-low load impedance of one ohm. Even speakers with very low impedances as well as speakers whose imped- ance uctuates drastically can be driven with ease. By using the P-7100 in bridged mode, it is possible to create a monophonic ampli er with even higher power. This performance is sustained by a mas- sive Super Ring toroidal transformer housed in an aluminum enclosure with excellent heat dissipation characteristics. The transformer is rated for 1.5 kVA, and is coupled with two large ltering capacitors rated for 56,000 µF each. This allows the ampli er to meet even the most demanding and rapidly uctuating power requirements with ease. The input stage features another Accuphase in- novation called MCS+ (Multiple Circuit Summing) which helps to minimize noise. The material used for printed circuit boards has a decisive in uence not only on electrical characteristics but also on the sonic end result. The P-7100 employs Te on boards with extremely low dielectric constant and low loss. The copper foil side of PCBs and all input and output ter- minals as well as all major signal carrying points are gold plated. Balanced inputs help to shut out external noise. The combination of outstanding circuit design with top-quality materials and parts produces music of unsurpassed purity that immediately captures and enchants the listener. Hearing is believing. n 11-parallel push-pull power unit delivers guaranteed linear power output of 1000 watts into 1 ohm (music signals only), 500 watts into 2 ohms, 250 watts into 4 ohms and 125 watts into 8 ohms The output stage uses high-power transistors with a rated collector dissipation of 150 watts and collector current of 15 amperes. These devices boast excellent frequency response, current ampli cation linearity, and switching characteristics. n Printed circuit boards made from Tefl on with low dielectric constant and low loss * Te on is a registered trademark of DuPont USA. n Robust power supply with Super Ring toroidal transformer and high fi ltering capacity The P-7100 features a massive toroidal power transformer with a maximum rating of 1.5 kVA, and two large electrolytic capacitors rated for 56,000 µF each, specially selected for optimum sound quality. n Bridged connection allows upgrading to a true monophonic ampli- fi er with 2000 watts into 2 ohms (music signals only), 1000 watts into 4 ohms, and 500 watts into 8 ohms Bridged connection results in a monophonic ampli er with four times the power output than during stereo operation. This gives effortless dynamic power. n Balanced inputs prevent externally induced noise n 4-step gain selector minimizes residual noise (MAX, –3 dB, –6 dB, –12 dB) n PCB copper foil and all major signal path components are gold-plated n Mode selector makes it easy to switch between dual mono, stereo, or bridged operation n Large direct-reading analog power meters with meter on/off button n Input selector button (balanced/unbalanced) on front panel n Oversize speaker terminals accept also Y lugs Toroidal transformerHigh-power transistors Filtering capacitors Gain selector Unbalanced/balanced input connectors Meter and input selector buttons * 1-ohm operation possible with music signals only Output voltage (V) Figure 2 Load impedance vs. output pow e (output voltage/output current) Figure 1 Circuit diagram of amplifi er section (one channel) Gold-plated parts Output current (A) Bias stabilizer circuit Bias stabilizer circuit Bias stabilizer circuit Bias stabilizer circuit Bias stabilizer circuit Large speaker terminalsHighly reliable parts selected for sound qualityAssembly with meter and protection circuitry MCS+(Multiple Circuit ) Summing + INPUT – INPUT NFB NETWORK NFB NETWORK GAIN CONTROL CIRCUIT REGULATOR NFB NETWORK REGULATOR OUTPUT
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Instrumentation amplier conguration Signal input stage Power amplier stage + INPUT – INPUT GAIN CONTROL CIRCUIT NFB NETWORK NFB NETWORK OUTPUT Instrumentation amp confi guration allows fully balanced signal paths The amplifiation sections of the P-7100 feature the newly adopted instrumentation amplifier principle whereby all signal paths from the inputs to the power amp stage are fully balanced. This results in excellent CMRR (Common Mode n Power ampli er assembly with 11 parallel push-pull transistor pairs per channel mounted directly to large aluminum diecast heat sinks, instrumentation ampli er and MCS+ circuitry, and current feedback ampli er Instrumentation Amplifi er Principle and Further Refi ned MCS+ Topology Current feedback circuit topology assures excellent phase characteristics in high range In the P-7100, the signal current rather than the more conventionally used voltage is used for feed- back. Since the impedance at the current feedback point is very low, there is almost no phase shift. Phase compensation can therefore be kept at a minimum. A slight amount of NFB results in maxi- mum improvement of circuit parameters. I/V converter Ampli er Current NFB network Trans-impedance ampli er Current adder (–) input buffer (+) input buffer Principle of current feedback amplifi er Output 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 power amplifier operation stability and reliability. Further refi ned MCS+ topology for even lower noise Accuphases original MCS (Multiple Circuit Sum- ming) principle uses a number of identical circuits connected in parallel to achieve superior perfor- mance characteristics. MCS+ is a further refined version of this approach. Improvements in the bias circuitry of the input-stage buffer amplifier result in greater stability. This in turn makes it possible to extend the parallel operation approach to the class-A drive stage of the current/voltage convert- er, thereby further lowering the noise floor. r