McIntosh MR73 (1969–1971)

McIntosh's first solid-state tuner kept one tube on the payroll - a 6HU6 "magic eye" that glowed green every time you found a station.

Overview

The MR73 is a stereo solid-state AM/FM tuner, built by McIntosh from 1969 to 1971 and sold new for $549.00. It was McIntosh's first solid-state tuner. The Binghamton shop stopped leaning on glass bottles for the signal path and committed to transistors. The front end, IF strip, detector, and multiplex decoding are all solid-state. Exactly one tube survives - a 6HU6 "magic eye" used as a signal strength indicator, a glowing green fan that widens and narrows as you creep up on a station. It's the most modern tuner McIntosh had built, and it still winks at you in vacuum-tube green.

Owners report the MR73 as a tuner for people who want analog tuning without a wall of controls. There are no digital presets, no scanning, no memories, just a big tuning knob and a meter you learn to read. The anodized gold and black front panel is late-period McIntosh, and it's the part of the tuner that has aged best.

On paper the FM section is competitive for the era. Useable sensitivity is rated better than 2.5µV (IHF), signal-to-noise better than 70dB, and harmonic distortion under 0.3% in mono and under 0.7% in stereo. Stereo separation is specified at better than 35dB at 1kHz. The AM section is rated at better than 12µV at 1000kHz, which is decent for the period but not what anyone bought an MR73 for. FM was the point.

Every MR73 left the factory aligned and tested against published specifications using high-precision bench gear, and the service documentation assumes you'll do the same if you ever realign it. A 1976 classified ad in Audio (February 1976, p.109) lists the MR73 on the used market alongside the McIntosh C-28 preamp and Tandberg 9000X deck.

The alignment instructions are explicit that the accuracy of any realignment is only as good as the calibration of the test equipment used. If you don't have the right gear, don't attempt it. That's a fair warning, not marketing bluster. This is not a tuner to learn alignment on.

Key Features

A Solid-State Signal Path With One 6HU6 "Magic Eye"

The MR73 splits its design between fully solid-state audio and RF stages and the single 6HU6 tuning indicator tube. The 6HU6 does no work in the signal path. It's purely a display, the classic "magic eye" whose green wedge closes as you approach center frequency. It dates the tuner to the transition moment it represents, and it makes MR73s fun to tune by hand today. A meter tells you where you are. A magic eye tells you when you've arrived.

Anodized Gold and Black Front Panel

The faceplate is anodized gold with black detailing, the palette McIntosh used across this generation of components. Forty-plus years of UV exposure and cigarette smoke have wrecked plenty of period faceplates, and the anodized finish on this one tends to survive better than paint or silk-screened lettering.

Analog Tuning With Minimal Controls

Owners consistently note the MR73's appeal for listeners who want analog tuning and a short control list. There are no menus, no presets, no scanning logic. You turn the knob, you watch the eye, you listen.

Factory Alignment and Documented Service Procedure

McIntosh aligned and tested every MR73 at the factory against published specs, and the service documentation lays out a full realignment sequence in AM-FM-MPX order. The manual also documents a factory modification for early units: on serial numbers 10T01 through 27T84, a kit (No. 044-175) swapped transistor Q2 for an FET and reworked a pair of 220Ω resistors around the RF front end's feed-thru capacitors, addressing decreased FM sensitivity or a noisy tuner. If you're looking at an early MR73, check that serial range.

Historical Context

The MR73 arrived in 1969 as McIntosh's first solid-state tuner, for a company whose reputation had been built on tube designs. It stayed in the catalog through 1971 at $549.00. The single 6HU6 indicator tube is the tell. McIntosh had moved the signal path to transistors but hadn't yet given up the visual language of the tube era.

Collectibility & Value

Recent resale prices for the MR73 have ranged from $490 to $899, which puts it at the affordable end of vintage McIntosh tuners - well below the tube-era models that preceded it, and roughly in line with later solid-state tuners that don't carry the "first" distinction. The ceiling of that range is driven by condition and whether the unit has been serviced. The floor tends to be as-is examples.

One known issue technicians report: the MR73 has no stereo beacon lamp bulb socket, and no provision for one. That's a factory omission, not a failure, but it means there's no simple drop-in fix if you want a stereo indicator light. Anyone wanting one is looking at a modification, not a lamp swap.

Support is otherwise reasonable. Owner and service manuals are available through vintage audio resources, and the aftermarket has stepped in where it matters: LED lamp kits covering the MR73 alongside the MR74 and MR77 sell for around $20.95, replacement AM antennas turn up around $20.00, and original MR73 service info with bulletins has sold for as little as $9.00. If you're buying one, budget for a proper alignment by someone with the bench gear the manual specifies.