Page 2 of C200 Audio Control Center by McIntosh Laboratory, Inc.

mcintosh c200 preamplifier/controller sources control processing power a speakers new digitally controlled attenuator system and menu-based input selection are the featured refinements in the c200 preamplifier/controller successor to the c100 representing mcintosh engineering at its finest the c200 is a fully balanced design with separate chassis for total isolation of the audio signal it uses the finest one-percent resistors and capacitors and internal gold-plated contacts with solid-soldered joints no details are overlooked in the design of a preamplifier virtually devoid of any measurable noise featured technologies displays see systems engineering in main brochure for more on mcintosh system architectures sealed glass tube coil fully balanced dual-chassis design the extraordinary c200 is fully balanced from input to output ­ a configuration that essentially cancels all distortion the precision volume control has four matched sections and the main gain stage uses four matched amplifiers operating in push-pull even unbalanced signals are converted to and processed as balanced signals the preamplifier chassis which contains only audio circuits and inputs/outputs is completely isolated from the power supply and the microprocessors ensuring total noise rejection the controller chassis contains the selector switches digital display all control microprocessors and the power supply after any switching operation the control circuits are automatically turned off to eliminate any possibility of microprocessor noise reaching the audio circuits the only connection between the preamplifier and controller is a 25-pin shielded cable silent electromagnetic switching in a conventional preamp an input signal travels to a switch and then travels to the input circuitry unfortunately the farther a signal must travel the more distorted it becomes and this says nothing of what detritus a dirty switch can add to the signal mcintosh silent electromagnetic switching literally brings the switch to the input the distortion-free switch consists of a glass tube containing oxygen-free gas and two signal leads separated by mere thousandths of an inch the tube sits in a multilayer copper coil and the entire assembly is encased in shock-absorbent plastic when dc voltage is applied to the coil in response to a switching command current flow creates a magnetic field that causes the leads to bend and contact one another completing the circuit the inert gas eliminates corrosion of the contacts ensuring a low-resistance distortion-free switch that never needs cleaning another benefit is that non-selected inputs are truly off eliminating potential sources of interference lead circuit completes when leads touch switching command causes dc voltage at coil lead the input selectors on mcintosh control centers actually control state-of-the-art silent electromagnetic switches more about the c200 s volume stage a fully balanced design requires stringent attenuator specifications mistracking not only effects left and right channel balance it also influences common mode noise and distortion rejection the four sections required must track better than a stereo attenuator by a factor of at least 10 to 1 therefore mcintosh has chosen a digitally controlled attenuator that provides 213 steps of 0.5db each the step match between the sections is typically less than +0.05db mechanical potentiometers cannot provide such tracking accuracy a post attenuator stage is interlaced with the main attenuator it rapidly reduces the output amplifier gain to unity the result is an immediate drop in the noise floor to better than -110db this is much lower than possible with a mechanical potentiometer noise and distortion are virtually eliminated attenuation changes occur at the zero crossings of the audio signal so that there are no audible artifacts during volume adjustment one of three different volume rotation curves vs can be selected from the c200 s setup menu slow two turns of the knob traverses the entire dynamic range

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