Stereo Tuners

By Chuck Hawks

McIntosh MR85
McIntosh MR85 tuner. Illustration courtesy of D&M Holdings, Inc.

Some sort of tuner is a program source found in almost all high-fidelity audio systems. Old-fashioned broadcast radio may be, but practically everyone listens to it, at least some of the time. Receivers, the heart of most home music systems, incorporate a tuner on a common chassis with a power amplifier and a pre-amplifier. Audiophiles using separate amplification components, whether an integrated amplifier or pre-amp/power amp combo, need a separate tuner. The separate tuner is the subject of this article, although most of the information also applies to the tuner section of a receiver.

Most tuners can receive both AM and FM broadcasts and some of the more recent models can receive subscription satellite radio (Sirius, XM, etc.). The most popular is the FM band. FM stands for "frequency modulation" and this form of broadcast offers lower background noise (greater quieting) and a wider frequency response than AM (amplitude modulation) broadcasting. FM is the high-fidelity band and most FM stations are music-oriented. Almost all FM broadcasts are in stereo, while only some AM stations broadcast a stereo signal. Today, AM station formats tend toward news, sports and talk programs, although there are still some music-oriented AM radio stations.

Suffice to say that FM broadcasting is the more popular format and the one of most importance to most component tuner manufacturers and customers. It is the FM section of an AM/FM tuner to which the lion's share of the technology and expense is devoted. In most modern tuners, the AM section is an afterthought, included only because it is expected. Many of the better portable radios, especially the "AM and shortwave" receivers, have far more sensitive AM sections than many component tuners. If AM radio listening is important to you, you will have to look for a tuner with a good AM section. They are in the minority, but there are some. A good AM tuner should have an external AM antenna input (usually a screw terminal), in addition to the ubiquitous ferrite bar antenna attached to the back panel of the tuner.

Most people do not understand the importance of a good antenna to radio reception. It is vital! A low sensitivity tuner with a good outdoor antenna will outperform a "hot" (high sensitivity) tuner without an external antenna.

AM broadcasts are low frequency (long wave) and require a large antenna for efficient reception. A 50-foot "long wire" antenna works well. (Actually, the longer the better.) These are available at low cost at Radio Shack and other outlets specializing in radio supplies. You can easily make a long wire yourself using a random length of bare, stranded copper wire. The wire gauge is unimportant. String it between two posts or a convenient tree and the corner of your roof, insulating if from grounding by using a non-conductor to secure the ends. Crimp or solder an insulated wire down lead from one end of the antenna to the AM antenna input on your tuner. Your AM reception should be greatly improved.

There should also be FM antenna inputs on the back of your tuner. These will accept TV type flat lead or, perhaps, a 75-ohm coaxial lead-in (TV cable). The entire FM broadcast band is between TV-VHF channels 6 and 7, so what works for TV also works for FM radio. Radio Shack and other electronics stores usually sell outdoor FM antennas. Alternatively, roof top TV antennas usually work well. Just use a TV/FM splitter at the termination of your TV down lead and run from the FM taps to your tuner.

The most common type of indoor FM antenna is the dipole (a "T" shaped antenna) made from 300-ohm, two-conductor, TV flat wire. These can be pinned behind your drapes or tacked to the wall. They generally work satisfactorily in an urban environment where FM stations are reasonably near-by. Often included with tuners, they can also be purchased at Radio Shack. Alternatively, TV (or similar dedicated FM) "rabbit ears" will serve well as indoor FM antennas.

As common as broadcast radio, particularly FM, is as a program source, there are fewer discreet tuners on the market than in previous generations of audio components. This is due to the prevalence of receivers in home audio systems, since receivers incorporate a tuner, eliminating the need for a separate component tuner. A/V receivers, the most popular category, typically substitute an inexpensive chip for a real tuner section and let it go at that. Radio reception is an afterthought in most A/V receivers.

Serious radio listeners will need a separate tuner. Some of the best tuners are no longer made, but are still in high demand on the used component market. Marantz no longer offers a component tuner, which seems strange, since several of the all time best vintage tuners were made by Marantz. The circa 1964 Marantz 10B (vacuum tube) tuner is reputed to be the best sounding tuner of all time. The Model 20B, successor to the 10B, is also very highly regarded for its superb sound. Higher performance is available from the 1975 vintage, solid state Marantz 125 (dual meters) and Model 150 (built-in oscilloscope for tuning). Marantz's Model 2130 of 1978, also with an onboard oscilloscope, is extremely highly regarded. The Marantz Esotec series ST7 and ST-8, introduced a year later, are very similar to the 2130. These are all high-end tuners and extremely well built. Almost any vintage Marantz tuner, especially one of the upper level models, is worth having if in good operating condition. Naturally, these upscale Marantz tuners are among the more expensive tuners on the used market.

Marantz's main competitor in component tuners, at least in the USA, has always been McIntosh. McIntosh tuners are also highly regarded and equally well made. McIntosh's first tuner was the mono MR55, an AM/FM tuner with a particularly outstanding AM section. The FM sensitivity was three microvolts; the AM sensitivity was only 1.5 microvolts. When the MR55 was made, AM radio was still important as a music source. I owned an MR55 for many years and it was the best long range AM (Dx) tuner I have ever used. The first McIntosh stereo tuner was the MR65B, a vacuum tube, FM only unit sold from 1962-1964. MR65's are still good tuners, with a 2.5 microvolt sensitivity. The MR-73 was the first McIntosh tuner with the familiar black glass front panel. This AM/FM unit was also the first McIntosh solid-state tuner. It was sold 1972-1979. The top of the line McIntosh of that period was the MR77, an FM only tuner of exceptional performance. All McIntosh tuners are premium models, since they have never made popularly priced components. Any McIntosh tuner in good operating condition is worth owning.

The Sequerra tuners were designed by Richard Sequerra, designer of the famous Marantz 10B. The Sequerra Model 1 was a solid-state FM tuner introduced in 1974 and discontinued a couple of years later. It was top rated throughout its short life, but very expensive for the time, with a total production of only about 1400 units. (The majority of these were reportedly purchased by radio stations.) Day-Sequerra, Inc. is still in business and specializes in broadcast radio and TV equipment. Their website is www.daysequerra.com

Kenwood, long a major player in amateur ("ham") radio circles, also made excellent stereo tuners. They had the radio technology and applied it to their component AM/FM tuners. The top of the line Kenwood tuners are considerably less expensive than used Marantz and McIntosh tuners and perform at about the same level. Although not built to quite the "bullet proof" standard of the top Marantz and McIntosh tuners, these classic Kenwood tuners are very nice and may be the best bargains on the used market.

Another "hot" tuner was the Rotel RT-1220, which boasted an FM sensitivity of 1.5 microvolts and AM sensitivity of 15 microvolts. Sony, Yamaha and Sansui have also produced some fine tuners.

If I were buying a new tuner today, since at this writing Marantz does not offer a new component tuner, I would look no farther than the McIntosh line. Unlike most component manufacturers, McIntosh still offers tuners of uncompromising quality. The current McIntosh line includes the MR85 (AM/FM), MR87 (AM/FM designed for the European, Asian and Oceanic regions) and MR88 (AM/FM/XM/HD). Of these, the MR85, at about $2800 (2011 MSRP), is the least expensive. Other new component tuners available in 2011 include the Accuphase T-1100, Cambridge Audio 650T and Azur 550T, NAD M4 (also C445, C425, C426), Naim NAT05 XS, Onkyo T-4555, Parasound Ztuner V.2, Quad Elite FM, Rega Radio 3, Rotel RDG-1520, Teac T-R680RS (also T-R670) and Yamaha TX-497 (also T-S500). This list is not all-inclusive, but these are reasonably well known manufacturers.

All component tuners should come with specifications that allow comparison. Electrical specifications do not tell you exactly how a tuner will sound, but they are useful comparative tools. Here are the specifications for the McIntosh MR85 tuner:

    FM TUNER SPECIFICATIONS

    USEABLE SENSITIVITY

    14dBf (1.4uV across 75 ohms)

    50dB QUIETING SENSITIVITY

    Mono: 19dBf

    (2.4uV across 75 ohms)

    Stereo: 35dBf

    (15uV across 75 ohms)

    SIGNAL-TO-NOISE RATIO

    Mono: 75dB

    Stereo: 70dB

    FREQUENCY RESPONSE

    Mono: 20Hz to 15kHz, +0/-1dB

    Stereo: 20Hz to 15kHz, +0/-1dB

    HARMONIC DISTORTION

    Mono: 0.3% at 100Hz,

    1kHz and 10kHz

    Stereo: 0.45% at 100Hz and 1kHz;

    0.65% at 10kHz

    INTERMODULATION DISTORTION

    Mono: 0.25%

    Stereo: 0.45%

    CAPTURE RATIO

    1.2dB

    ALTERNATE CHANNEL SELECTIVITY

    75dB

    SPURIOUS RESPONSE

    100dB

    IMAGE RESPONSE

    75dB

    RF INTERMODULATION

    65dB

    STEREO SEPARATION

    45dB at 100Hz and 1kHz

    35dB at 10kHz

    SCA REJECTION

    65dB

    AM TUNER SPECIFICATIONS

    SENSITIVITY

    20uV (external antenna input)

    SIGNAL-TO-NOISE RATIO

    48dB at 30% modulation

    58dB at 100% modulation

    FREQUENCY RESPONSE

    Mono: 20Hz to 15kHz, +0/-1dB

    Stereo: 20Hz to 15kHz, +0/-1dB

    HARMONIC DISTORTION

    0.5% max at 50% modulation

    FREQUENCY RESPONSE

    50Hz to 6kHz NRSC

    ADJACENT CHANNEL SELECTIVITY

    45dB minimum IHF

    IMAGE REJECTION

    65dB min, 540 kHz to 1600kHz

    IF REJECTION

    80dB minimum

    GENERAL

    RATED OUTPUT

    1.2V Fixed

    0-1.2V Variable

    OUTPUT IMPEDANCE

    Less than 100 ohms

    POWER REQUIREMENTS

    120V 50/60Hz, 20W

    OVERALL DIMENSIONS (H X W X D)

    5 3/8" (13.8 cm) x 17 1/2"

    (44.5 cm) x 17 1/2" (44.5 cm)

    WEIGHT

    25.5 lbs. (11.6 kg) net

    43 lbs. (19.5 kg) in shipping carton

These can be taken as representative of a modern, high performance, stereo tuner. Take note of the FM specifications for sensitivity (particularly at 50db quieting), signal to noise ratio, frequency response, harmonic distortion, intermodulation distortion, alternate channel selectivity and stereo separation. On the AM side, sensitivity, signal to noise ratio, frequency response and adjacent channel selectivity are important factors.

If possible, audition the tuners you are considering side by side, connected to the same antenna system. (The antenna system is critical.) Even better, arrange to audition them in your home. The way a tuner sounds and works in the real world is more important than any specification. A tuner that boasts an FM sensitivity of 1.5 micro-volts may not work as well in your home as one with a 3.0 micro-volt sensitivity, depending on a variety of outside factors, such as your distance from the stations to which you want to listen, the proximity and operating frequencies of other area radio stations, ground clutter and so forth. "Try before you buy" is always good advice.

Like all audio components, electrical specifications and performance are not the whole story. Build quality is also an important feature. Since tuners are electronic devices with few moving parts, they should last a long time if built with good quality components, including durable, long lasting switches and knobs. Top quality components and workmanship are expensive, but worth it in the long run. Superior build quality is one of the reasons vintage Marantz and McIntosh components are so highly regarded and why they often cost more now (used) than they did when new. Good listening!




Back to the Audio Online Page

Copyright 2011 by Chuck Hawks. All rights reserved.


CHUCKHAWKS.COM HOME / GUNS & SHOOTING / NAVAL, AVIATION & MILITARY HISTORY / TRAVEL & FISHING / MOTORCYCLES & RIDING / AUDIO ONLINE