McIntosh MX 113 – High End Stereo Equipment We Buy

McIntosh is one of the most dependable brand names when it comes to high-end audio systems. For years the brand has been recognized by audiophiles throughout the world as equipment that delivers clear and consistent quality in music. McIntosh is probably best known for its amplifiers and preamps, but the company produces many other components and parts for stereo and home theatre.

What are the specs for the McIntosh MX 113?

Frequency response:
20Hz to 20kHz
Total harmonic distortion:
0.1%
Gain:
62dB (MM), 20dB (line)
Input sensitivity:
2mV (MM), 250mV (line)
Signal to noise ratio:
72dB (MM), 85dB (line)
Output:
250mV (line), 2.5V (Pre out), 10V (Pre out Max)
Semiconductors:
2 x JFET, 3 x MOSFET, 30 x transistors, 31 x diodes, 2 x IC
Dimensions:
16 x 5.4 x 15 inches
Weight:
26 lbs

What else to know about the McIntosh MX 113?

"The McIntosh Tuner-Preamplifier unit concept accommodates all regular inputs of tuner, phono, tape, etc., and allows the selection of the right power amplifier needed for your system. The MX 113 is the most advanced version of this remarkable AM-FM/FM Stereo Tuner preamplifier with switchable selectivity. It has performance beyond any other manufacturer's equipment available today.

Special Features

Multiple "selectivity" switchable from the front panel. An elegant solution to a tough problem.

Linear Phase (constant delay) IF amplifier for low distortion at even high selectivity and low distortion.

Steggered tuning condenser elements to improve RF front and behavior, less interstage coulping, lower spurious effect, higher Q circuits.

Tremendous accomodiation of strong RF input signals - up to 10 volts without overload - overcoming an aggravating limitation of conventional tuners.

Highest spurious rejection 90 dB (IHF) and highest image rejection 95 dB (88 to 108 MHz). This means you receive the stations at the right place on the dial only. You don't receive the same stations or some mixture as you tune across the dial.

Ultra Sonic "muting" provides smooth inter channel FM noise suppression. Has complete connection to McIntosh Maximum performance Indicator to maximize your listening pleasure.

McIntosh developed a special detecting circuit used in the multiplex section. An advantage of this circuit is the elimination of the critical adjustments necessary with commonly used matrixing circuits. The circuit detects the L - R side-bands, then automatically matrixes the recovered information with the L + R carrier signal. This yialds the left and right program output with maximum separation. TUNING MECHANISM AND DIAL DRIVE

In the MX 113, the unique design and careful manufacture of the mechanical assembly gives smooth flywheel tuning. By controlling the relationship of mass and mechanical resistance, and by dividing the workloads in the dial drive system, it becomes nearly impossible to detect any backlash. Yet, the entire dial drive is a model of mechanical stability. For added ease and increased tuning accuracy, a section of the dial pointer is illuminated.

FM SECTION

The Radio Frequency (RF) section houses the complete FM-RF front-end and part of the AM RF circuit. A seven-section variable capacitor is the heart of the RF section. Four sections of the variable capacitor are in the FM front end and the remaining three are in the AM section. By interleaving the sections (AM-FM-AM-FM-etc.) spurious responses are significantly reduced. The four FM sections of the variable tuning capacitor provides a high degree of RF selectivity and excellent spurious rejection. Using the latest "state of the art" field effect transistors with a welldesigned variable tuning capacitor has provided the MX 113 with an excellent RF front-end ….

FM-IF AND DISCRIMINATOR SECTION

The MX 113 uses linear-phase IF filters. Each filter was designed from a FORTRAN computer program for minimumphase and constant delay. The mathematical complexity of the filter design procedure is almost beyond belief. Using numerical integration in the S-Plane, an "IBM" 1130 high speed computer spent eighteen minutes on the mathematics for the design of the IF filter. It would have taken a human engineer, working twenty-four hours a day, seven days a week, and working error-free three-hundred years to perform the same mathematical calculations! ...

FM STEREO MULTIPLEX SECTION

Mclntosh has developed a special detecting circuit used in the multiplex section. A particular advantage of this circuit is the elimination of the critical adjustments necessary with commonly used matrixing circuits. The circuit detects the L - R sidebands, then automatically matrixes the recovered information with the L + R carrier signal. This yields the left and right program output with maximum separation. ... AM SECTION

The AM-RF amplifier circuit includes a three section variable tuning capacitor in the metal enclosed shielded RF module which also houses the FM-RF front end. A three section variable capacitor is used for greater spurious rejection. The RF amplifier is unique. The circuit has constant sensitivity, constant selectivity, high image rejection across the complete AM band. Ordinary AM-RF circuits cannot do all of these simultaneously. This circuit design achieves equal sensitivity even at the low end of the band. Spurious, image, and intermediate frequency rejection are all superior. The same circuit delivers equal selectivity across the entire band. The Mclntosh circuit is unique in a superheterodyne AM receiver ...

...The AVC (automatic volume control) system was designed to prevent bursting or thumps when the AM is tuned through a strong signal. Distortion at low audio frequencies is minimized by using two AVC filter sections instead of the conventional one.

PHONO PREAMPLIFIER

There are three transistors in each channel of the phono preamplifier. The output of the third transistor is connected by a negative feedback loop to the emitter of the input transistor. The feedback loop reduces noise and distortion. It also provides precision RIAA frequency compenation required for magnetic phonograph cartridges. Feedback remains in effect even at 20 Hz, where gain is highest. The negative feedback also provides a low output impedance for the tape output. ...

L + R AMPLIFIER

The L + R amplifier consists of a single transistor connected as a voltage amplifier. Negative feedback is used around the summing amplifier to maintain low distortion and provide a low impedance for the center channel output.

POWER SUPPLY

The power supply of the MX 113 has received very special attention.

Three separate rectifier circuits are used. First, a fullwave rectifier supplies DC to all audio circuits. The second full-wave rectifier supplied DC to all tuner and multiplexdecoder circuits. The third supply provides DC to the AM circuit. The power supplies are elaborate in design. They use electronic filtering to insure the lowest possible background hum level, maximum stability, and extremely good regulation." - From McIntosh Brochure

Brief History of McIntosh

Long mapped-to Binghamton New York – the current headquarters and manufacturing center for McIntosh Labs – not many people know the brand was originally launched outside of the Nation’s Capital in Silver Spring Maryland, in 1949. In 1956, the brand built their original facility in New York, according to the official brand website.

Other McIntosh Products We Often Buy

Typically, StereoBuyers purchases mostly used amplifiers, especially the vintage amps and high-end McIntosh models such as the MC202 or MC252, and the C220 preamp, for example. We have also purchased many pre-owned tuners from McIntosh over the recent years, including the MR67 and MR78 models, for example.

StereoBuyers has purchased tens of thousands worth McIntosh brand equipment since 2014, with individual buys ranging from $100 to well over $50,000. If you are moving, ready to upgrade, or have McIntosh equipment you do not or will not be using, why not contact us today to find out if it is worth good money?

If you are interested in selling your used McIntosh equipment to us in the greater NYC area or Colorado, please click here to fill out a Free Quote Form and we will get back to you. If we agree on terms, we come to meet you where you want, and pay cash.

The following images show actual McIntosh equipment purchased by StereoBuyers.