User manual MCINTOSH MAC 4100

[. . . ] Mclntosh has for some years kept a very low profile vis-a-vis the press. This hiatus in communications has fostered a polarization of opinion about Mclntosh: Is the company still de serving of its reputation for superb engineering, or is it trading on past glories?One review can't provide a definitive answer, of course, but the Mac 4100 receiver can be taken as a positive sign of health in Binghamton. [. . . ] This LED acts as a tuning aid; when the muting is on, the LED announces arrival at a receivable station before the unmuting action (which is gentle and slightly delayed) allows any audio to pass. If you use the AUTO setting and a turntable plugged into one of the green sockets is turned on, the receiver and any outboarded equipment run off the switched outlets will come on automatically, even when the receiver's power switch is off, and all will turn off again when the turntable shuts down. Thus an automatic model can be made to turn off the whole system unattended. Since the feature works by sensing current drain through the turntable outlets, the switch serves to override it should the turntable be one of those that draw some current even when they are off. The receiver's switching is handled by DC control voltages, actuated by the front-panel controls and fed to FETs that actually do the signal switching. There are two fundamental advantages to this approach: Switching transients are eliminated, and the short, direct signal paths made possible minimize noise pickup, RFI, and crosstalk. In all of these re- Mclntosh Mac 4100 Receiver Tuner Section Capture ratio 2 dB Alternate channel selectivity 76 dB THD + N 80 Hz 1 kHz 10 kHz IM distortion 19-kHz pilot 38-kHz subcarrier S/N ratio (at 65 dBf) stereo mono L ch 0. 25% 0. 17% 1. 8% R ch 0. 25% 0. 22% 1. 7% 0 06% -63½ dB -66½ dB 67 dB 71 dB mono 0. 16% 0. 15% 0. 21% Amplifier Section Manufacturers rated power 17¾ dBW (75 watts)/ch. Power output at clipping (channels driven simultaneously) Lch 20 dBW (98 watts) R ch 20 dBW (98 watts) Dynamic headroom (at 1 kHz) Frequency response RIAA equalization 1 ½i dB + V, , -V, dB, 20 Hz to 20 kHz + V», - 3 dB, 13 Hz to 35 kHz ±1 dB, 20 Hz to 20 kHz Input characteristics (re 0 dBW (1 watt); noise A-weighted) Sensitivity S/N ratio phono 1, 2 0. 27 mV 76½ dB aux 1, 2 30. 0 mV 80 dB tape 1, 2 30. 0 mV 80 dB Phono overload (clipping point) Damping factor at 50 Hz 88 mV at 1 kHz 100 34 HIGH FIDELITY MAGAZINE range of the signal-strength meter is well chosen as an aid in antenna orientation for best reception of problem stations. The amplifier section, too, exemplifies the extra care that sets the receiver apart. Whether the option that enables switching in three speaker pairs simultaneously requires them or not, it has three distinct protection systems. The most conventional is triggered by a heat sensor and shuts down the output until the heat sink has cooled to within safe operating limits. The Sentry Monitor circuit reacts to abnormal current conditions by restricting the drive to the output transistors. And the Power Guard circuit responds to overdrive that normally would create hard clipping by shaving off the potentially dangerous harmonics--"softening" the clip ping, so to speak. None impinges on normal operation; all minimize the effects--aural, thermal, or electrical--of abnormal operation. The Power Guard, for example, limits peaks so smoothly that you are unlikely ever to hear this receiver overload, as such. The top LEDs in the front-panel power display--the one possible concession to fashion in the design--are Power Guard pilots; below that, the display is calibrated from 100 watts down to 0. 1 watt in 5 dB steps. [. . . ] Tuner data are likewise very good--even superb--with no offsetting cause for complaint of any kind. It is obvious, too, that Mclntosh has a clearly formed idea of the sort of user it is designing for: someone who, while he is uninterested in playing the " p r o , " cares very much about quality and craftsmanship. The cosmetics, the " f e e l , " and the sound quality of the Mac 4100 are all superb; the controls are minimal for the degree of useful flexibility they provide, with little if any concession to users who simply like to putter. [. . . ]