User manual MCINTOSH MC7300

[. . . ] The power transistor characteristics, the power s u p p l y voltage used, and the output autoformer ratio have been matched for high efficiency, m a x i m u m power o u t p u t w i t h low distortion, and reliable long life operation. Versatile Mclntosh Power Amplifiers Deliver Full Power -- Always The M c l n t o s h o u t p u t circuit, superior in its performance, d e m a n d s a superior method of c o u p l i n g the a m p l i f i e r o u t p u t to the loudspeaker load. A Mclntosh designed and manufactured a u t o t r a n s f o r m e r ensures peak p e r f o r m a n c e and protection, as well as outstanding compatibility between a m p l i f i e r and speaker. The Mclntosh a u t o t r a n s f o r m e r offers these benefits: · Transistors, used in a m p l i f i e r o u t p u t circuits, are designed to work into an o p t i m u m low i m pedance load. Variations in frequency, or the use of m u l t i p l e speakers (which m o d i f y the i m pedance as seen by the o u t p u t of the a m p l i f i e r ) , often compromise an a m p l i f i e r ' s performance. [. . . ] · In the event of an o u t p u t c i r c u i t f a i l u r e , the M c l n t o s h a u t o t r a n s f o r m e r conducts the speakerdamaging DC (direct current) directly to g r o u n d , thus protecting expensive loudspeakers from potential damage. · The Mclntosh autotransformer contributes a flexi b i l i t y in loudspeaker connecting c a p a b i l i t y not otherwise possible. Here's how: Ordinary a m p l i f i e r o u t p u t circuits are u s u a l l y restricted to operating in 4 or 8 ohms. In stereo, the M c l n t o s h a u t o t r a n s f o r m e r perfectly matches the o u t p u t c i r c u i t to 2. In mono the MC7300 autotransformers provide matching into 1, 2, 4, 8 or 16 ohms. In addition, the autotransformer can provide either a 25 volt or a 70. 7 volt output that can feed m u l t i p l e loudspeakers for background music a p p l i c a t i o n s . Rear view Mclntosh Quality Begins With Careful Design For Cool Operation An amplifier's life can be cut short without the proper ventilation for cool operation. In fact, as little as one degree centigrade rise in temperature can reduce the life of an amplifier by 10%. Mclntosh has designed its a m p l i f i e r s to m a x i m i z e troublefree cool operation. Output stages are mounted on super-sized heat sinks that have m a x i m u m surface areas of cooling capability. The sinks are placed in an air t u n n e l chassis that occupies the a m p l i f i e r space from top to bottom. M c l n t o s h precision engineering has developed the Power Guard c i r c u i t * to prevent a m p l i f i e r s from being overdriven into hard c l i p p i n g ; ensure that the a m p l i f i e r produces its m a x i m u m o u t p u t w i t h o u t i n creased distortion; and protect the speaker from excessive heating. (*Power Guard is a patented Mclntosh design, U. S. patent #4048573) Compact discs have a higher 'dynamic range' over records and audio cassettes. Most compact discs claim a dynamic range in excess of 90 decibels. In n u m e r i c a l ratio this is greater t h a n 1000 times the ratio of p o p u l a r commercial analog records. For e q u i p m e n t to be digital ready it must h a n d l e overdrive without breaking up or grossly distorting the sound. V i r t u a l l y a l l power a m p l i f i e r s today are incapable of accepting 10 decibels of overdrive w i t h o u t gross distortion. Some a m p l i f i e r s totally collapse u n d e r t h i s p u n i s h m e n t . Mclntosh has devised a test w h i c h shows an amplifier's spectral f i d e l i t y under stress -- one of the most i m p o r t a n t characteristics of an a m p l i f i e r . If good enough w i l l do, there are dozens of brands to choose from. But if the best is what you need there is only one to consider: The Mclntosh MC73OO. Performance Guarantee Performance L i m i t s are the m a x i m u m deviation from perfection permitted for a Mclntosh i n s t r u ment. We promise you that when you purchase a new MC 7300 from a Mclntosh franchised dealer, it will be capable of or can be made capable of performance at or exceeding these limits or you can return the u n i t and get your money back. [. . . ] We promise you that when you purchase a new MC 7300 from a Mclntosh franchised dealer, it will be capable of or can be made capable of performance at or exceeding these limits or you can return the u n i t and get your money back. Mclntosh is the only m a n u f a c t u r e r that makes this statement. Performance Mclntosh a u d i o power ratings are in accordance w i t h the Federal Trade Commission Regulation of November 4, 1974 concerning power output claims for a m p l i f i e r s used in home e n t e r t a i n m e n t products. Intermodulation Distortion 0. 005% m a x i m u m if instantaneous peak power output does not exceed twice the output r a t i n g for any combination of frequencies from 20Hz to 20, 000Hz. Frequency Response (at one watt output) 20Hz to 2 0 , 0 0 0 H z +0 -0. 25dB l0Hz to 100, 000Hz +0 -3dB [Noise and Hum (A-Weighted) 105dB below rated o u t p u t . Ratings I H F Dynamic Headroom 1. 9dB Power Output Stereo Damping Factor Greater than 40 300 watts m i n i m u m sine wave continuous average power o u t p u t , per c h a n n e l , both channels operating into 2 ohms, 4 ohms, or 8 ohms load impedance, which is: 24. 5 volts RMS across 2 ohms 34. 6 volts RMS across 4 ohms 49. 0 v o l t s RMS across 8 ohms Mono Input Impedance 20, 000 ohms U n b a l a n c e d 40, 000 ohms Balanced Input Sensitivity Switchable for either 1. 4 or 2. 5 volts 6OO watts m i n i m u m sine wave continuous average power output into 4 ohms, 8 ohms, or 16 ohms load impedance, which is: 24. 5 34. 6 49. 0 69. 3 98. 0 volts volts volts volts volts RMS across RMS across RMS across RMS across RMS across 1 ohm 2 ohms 4 ohms 8 ohms 16 ohms Power Guard C l i p p i n g is prevented and THD does not exceed 2% with up to 14dB overdrive at 1kHz General Information Power Requirements 120 volts, 5 0 / 6 0 H z , 0. 6 to 13 amperes Output Load Impedance Stereo 2 ohms, 4 ohms, and 8 ohms; separate terminals are provided for each output. 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