Chord SPM 4000 MKII
SPM 4000MkII stereo power amplifier
Much of what Chord has achieved is the result of using innovative, leading edge technology. For example, we believe that we are unique in using the technique of "dynamic coupling" of the power supply rails. Whatever transient demand is presented to the amplifier stages, the positive and negative rails remain in perfect equilibrium, with each compensating for the demands made on the other. This means that power delivery is always balanced and free from ground loop modulation distortion.
This, combined with enormous reserves of instantly delivered, precisely controlled power is what makes the SPM 4000MkII sound so effortless. The power supply rails operate nominally at Â± 110 volts, well above that which most amplifiers can accommodate. This and other advanced techniques enables the ultra high frequency low ESR power supply to store a great deal more energy far more efficiently. Clipping is virtually impossible. Furthermore, compared to other amplifiers of asimilar power rating the SPM 4000MkII weighs in at a mere 50Kg. Another new technique is used to protect the amplifier against overload, internal and external short circuits. The output signal path is totally free of any fuses or sound-degrading resistive components often employed for overload sensing. The SPM 4000MkII is designed to surpass the highest European safety and electromagnetic interference standards.
The amplifier sections are also highly sophisticated designs that make the most of the best high voltage, lateral structure MOSFETs available, 32 x 150 watt devices per channel. Combining the subtlety and musicality of a good valve design with the punch and accuracy of "state of the art" solid state products. The result is a "sliding bias" class A/B design with all drive circuitry operating in class A. At usual listening levels, most of the music will be reproduced in class A. Chord"s no-compromise design philosophy means there is no better built amplifier. Individually hand-crafted, it is constructed to aerospace standards from the circuit boards up.
Now in MkII form, numerous engineering refinements have been made to the SPM 4000 to increase its sonic performance, flexibility and lifespan. These include:
â€¢ A new front panel design.
â€¢ A new power-control and sequencing board.
â€¢ A new rear connector plate that allows for third-party power connectors and the use of new beautifully made, British-designed, heavy-duty, gold-plated, insulated speaker terminals.
â€¢ Refinements to the filter components of the subsequent amplifier stages, to insure greater high-speed performance whilst maintaining good overall stability.
â€¢ Internal upgrades including numerous circuit board and earthing changes. These were implemented to improve high-current power flow across the units and help extend the product''s lifecycle.
â€¢ A reduction of the value of the emitter balancing resistors in the first long tail pair in the second intermediate stage of the amplifier. This allows for a faster overall response and improves the square signal performance of the very high frequencies of the amplifiers.
2 x 750 W RMS into 4 Ohms
2 x 950 W RMS into 2 Ohms
2 x RCA-Phono single ended inputs