What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





McIntosh MX 117


 
The MX 117 AM-FM Stereo Tuner-Preamplifier concept is a total Mclntosh master control center that allows you to select the matching Mclntosh power amplifier for your individual requirements. All needed inputs such as two record players, two tape recorders and auxiliary can be accommodated, along with the built-in AM-FM stereo tuner. The advanced circuits and performance features of the Mclntosh MX 117 make it an ideal and especially convenient solution for the most discriminating stereo listener.
FM AFL AUTOMATIC FREQUENCY LOCK
The Automatic Frequency Lock is a patented Mclntosh circuit that activates when you tune to the center frequency of an FM station. A varacter diode fine tunes the tuner with a correction voltage from the AFL circuit. When the center ON -station vertical LED indicator lights, the AFL circuit is in operation and the tuner stays locked to the signal. There will be no drift from this accurate tuning, insuring minimum distortion and best overall FM performance.
2. ELECTRONIC FET ANALOG INPUT SWITCHING
All critical input switching is done electronically using field effect transistor analog switches. The front panel selector simply switches small amounts of control DC voltage which turn the FET analog switches on or off. Since the FET analog switches are located near the input jacks, the length of interconnecting leads is much shorter. This design eliminates switching noise as well as frequency loss caused by the longer signal leads necessary in conventional circuits.
3. HEADPHONE—OUTPUT AMPLIFIER
The built-in headphone amplifier is capable of driving a pair of dynamic headphones with less than 0.02% harmonic distortion. Because of its extremely low distortion and power capability, it is also the main preamplifier output.
4. TRI-FREQUENCY PROGRAM EQUALIZER
Three separate controls allow the balance and response of musical information to be adjusted with far more flexibility than with conventional tone controls. The center frequencies of the controls are 30 Hz, 750 Hz and 10 kHz. Plus and minus 12 dB of control is available. Use of the program equalizer controls does not affect in the slightest the low noise, low distortion performance of the tuner-preamplifier. When the equalizer controls are in their center detent or flat position, their action is neutral and response of the tuner-preamplifier is absolutely flat.
5. TRUE LOUDNESS COMPENSATION
The MX 117 active circuit loudness control is continuously variable with constant midrange gain and operates independently of the volume control. The loudness contour is accurately modeled after the Fletcher Munson family of "Equal Loudness" curves. Use of this control restores proper perceived frequency response at even the softest listening levels.
5. TRUE LOUDNESS COMPENSATION
The MX 117 active circuit loudness control is continuously variable with constant midrange gain and operates independently of the volume control. The loudness contour is accurately modeled after the Fletcher Munson family of "Equal Loudness" curves. Use of this control restores proper perceived frequency response at even the softest listening levels.
5. TRUE LOUDNESS COMPENSATION
The MX 117 active circuit loudness control is continuously variable with constant midrange gain and operates independently of the volume control. The loudness contour is accurately modeled after the Fletcher Munson family of "Equal Loudness" curves. Use of this control restores proper perceived frequency response at even the softest listening levels.
6. PRECISION TRACKING VOLUME CONTROL
The volume control manufactured for Mclntosh Laboratory is a step attenuator which has tracking accuracy within 1 dB throughout its entire range. Such extremely accurate matching is achieved through electronically controlled trimming of the resistance material deposited on pairs of miniature printed circuits. Tracking accuracy and quiet performance are permanently maintained.
Use does not affect performance as in ordinary volume controls.
7. ELECTRONIC FET RF SELECTIVITY SWITCHING
A back panel switch gives additional FM RF selectivity for best performance in areas with extremel strong station signal strengths. This switch feeds a control DC voltage to PIN semiconductor diodes which electronically perform the RF switching functions.
AUTOMATIC STEREO NOISE SUPPRESSION
A new third generation phase locked loop stereo decoder incorporates a unique variable stereo separation - noise reduction control circuit. This circuit operates from the IF amplifier signa strength detector. When listening to weak or distant FM stations, optimum stereo separation and signal to noise ratio is automatically provided. You get a smooth transition between stereo and mono depending on the prevailing signal conditions. This means that with the Mclntosh MX 117 you always get the most noise-free reception of weaker stereo signals. Since this circuit automaticallyadjusts in varying amounts, you never hearthe abrupt switching present in conventional circuits.
UNIQUE AM TUNER SECTION
The AM circuit in the MX 117 is unique in designfor a superheterodyne tuner. The AM RF amplifier circuit has constant selectivity, constant sensitivity and high image rejection across the complete AM band. In addition there is no loss of audio frequency response at the low end of the band. No conventional AM circuit can offer all these features simultaneously. These advanced AM performance characteristics of the MX 117 bring about a re-discovery of AM listening.
INTEGRATED CIRCUIT OPERATIONAL AMPLIFIERS
Both the magnetic phono and the equalizer amplifierstages utilize new high technology integrated circuit operational amplifiers. Noise factors are incredibly low and distortion levels are at or below the limits of the best present day test equipment.


PREAMP SECTION
FREQUENCY RESPONSE:  + 0 - 0.5 db from 20 Hz to 20 kHz
RATED OUT PUT LEVELS
Main Out : 2.5V
Line Out : 1.25V
Headphone : 750mV
Tape Out : 250mV
DISTORTION:  0.02% maximum at 2.5V output from 20 Hz to 20 kHz
INPUT SENSITIVITY AND GAIN
Input to Main Out
Phone 1 and 2:  2.2mV in for 2.5V out (61.1 dB gain at 1 kHz)
AUX, Tape 1 and 2: 250mV in for 2.5V out (20 dB gain at 1 kHz)
Input to Line Out
Phono 1 and 2 : 2.2mV in for 1.25V out (55 dB gain at 1 kHz)
AUX, Tape 1 and 2 : 250mV in for 1.25V out (14 dB gain at 1 kHz)
Input to Headphone Out
Phono 1 and 2:  2.2mV in for 750mV out (50.7 dB gain at 1 kHz)
AUX, Tape 1 and 2 250mV in for 750mV out (9.5 dB gain at 1 kHz)
Input to Tape Out
Phono 1 and 2:  2.2mV in for 250mV out (41.1 dB gain at 1 kHz)
AUX, Tape 1 and 2:  25pmV in for 250mV out (0 dB gain at 1 kHz)
SIGNAL TO NOISE
Phono 1 and 2:  -90 dB IHF A-weighted, below 10mV input -80 dB unweighted, below 10mV input
AUX, Tape 1 and 2:  - 100 dB IHF A-weighted, below 250mV input
-90 dB unweighted, below 250mV input
INPUT IMPEDANCE
Phono 1 and 2:  47kl2 and 50pF
AUX, Tape 1 and 2:  47kohm
OUTPUT IMPEDANCE
Main Out:  less than 100ohm (to operate into 5kohm or greater)
Line Out:  600ohm (to operate into a 600ohm line)
Headphone:   8ohm
Tape Out:  less than 200ohm (to operate into 5kohm or greater)
EQUALIZER CONTROL RESPONSE
Center Frequencies :  30, 750, and 10 kh
Boosr and Cut:  ± 12 dB

AM SECTION
SENSITIVITY.  75μV IHF with external antenna
SIGNAL TO NOISE RATIO:  45 dB minimum IHF or 55 dB at 100% modulation
FREQUENCY RESPONSE:  + 0 ~ 6 dB from 20 Hz to 3500 Hz
HARMONIC DISTORTION:  0.8% maximum at 30% modulation
ADJACENT CHANNEL SENSITIVITY:  30 dB minimum IHF
IMAGE REJECTION:  65 dB minimum from 540 kHz to 1600 kHz
FM SECTION
USABLE SENSITIVITY:  2μV (11.2dBf) IHF
QUIETING SENSITIVITY:  5μV(19.1dBf) IHF -50dB(Mono);  50μV (39.5dBf) IHF -50 dB (Stereo)
SIGNAL TO NOISE RATIO  :70 dB IHF minimum both Mono and Stereo
HARMONIC DISTORTION
0.18% (Mono) IHF maximum
0.38% (Stereo) IHF maximum
ALTERNATE CHANNEL SELECTIVITY:  75 dB IHF minimum
IMAGE REJECTION:  100 dB IHF minimum
STEREO SEPARATION:  45 dB minimum at 1 kHz

GENERAL INFORMATION
POWER REQUIREMENT:  120 Volts 50/60 Hz, 45 Watts
SEMI CONDUCTOR COMPLEMENT
24 Bipolar Transistors
18 Field Effect Transistors
62 Diodes
24 Integrated Circuits
MECHANICAL
MECHANICAL INFORMATION
SIZE
Front panel measures 16 inches wide (40.6 cm) by 5 7/16 inches high (13.8 cm). Chassis measures 14 3/4 inches wide (37.5 cm) by 4 13/16 inches high (12.2 cm) by 13 inches deep (33 cm), including connectors. Knob clearance required is 1 1/4 inches (3.2 cm) in front of mounting panel.
FINISH:
Front panel is anodized gold and black with special  gold/teal nomenclature illumination. Chassis is black.
MOUNTING::  Exclusive Mclntosh developed professional PANLOC.
WEIGHT::  24 pounds (10.9 kg) net, 36 pounds (16.3 kg) in shipping carton.


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