Stromberg-Carlson Model 440M Console Radio (1939)

My Stromberg-Carlson 440M console radio has a classic, stately look. Built in 1939, it has 10 tubes, motorized tuning, and the famous "Acoustical Labyrinth" speaker system.

This radio not only performs well, but is easy to service and shows outstanding build quality. These are hallmarks of Stromberg-Carlson, which began in 1894 as a telephone company and quickly established a reputation for fine engineering and durability.

I bought this set at a second-hand shop for a little over $100. It was in very nice original condition. Here's the radio before any restoration was done. Notice the front panels of matched walnut veneer.

The next photo gives a closer view of the dial and controls, as well as the veneer.

A magic tuning eye is seen in the middle of the dial, which covers three bands: standard broadcast from 550-1650 kilohertz, and shortwave from 2.5-22.5 megahertz.

Below the dial are ten pushbuttons, labeled Off, Phono, KVI, KIRO, KXA, KJR, KOMO, KRSC, KOL, KMO, Remote, and Manual. The eight call numbers are for Seattle area stations of the time. (Some, such as KOMO, are still on the air.) The Remote button selects the wired remote control. The station buttons both turn on the set and make the motorized tuner select the desired station.

If you are listening to shortwave, you push the Manual button and turn the tuner knob. The shortwave bands would potentially include hundreds of stations, so for shortwave listening you press the Manual button and turn the tuner knob.

From left to right, the knobs are labeled Volume, Bass (with Decrease, middle, and Increase settings), Tone, Range (to select one of the three bands), and Stations (the tuner).

The rear view shows several technical features. The round mechanism at upper left is the motorized tuner, controlled via the preset pushbuttons. The large round jack at the chassis's lower left is for a wired remote control. This remote was optional and I have never seen one in the flesh; if you have a photo of one, send me an email.

The beefy power transformer at the chassis's right is appropriate for a high-tubecount set like this, and emblematic of Stromberg-Carlson designs, which tend to err on the side of durability.

The bottom third of the cabinet is occupied by the Acoustical Labyrinth, a baffled enclosure that improves the audio quality. The rear of the speaker frame protrudes from the top of the enclosure, and the label in back gives a simplified view of how it works.

Stromberg-Carlson patented this system in 1939. Here are two of the patent drawings.

If you're interested in audio technology, you may find the complete description interesting: US Patent 2,014,777.

Here is a list of the 440M's ten tubes and their functions.

The 6AF6G magic eye is my favorite tuning indicator tube. Most magic eyes are a circle with a single pie shape that opens or closes according to a station's signal strength. The 6AF6G has two opposing segments, which can wired so that they respond differently to various signals, resulting in an eye with a sort of coarse-fine function. You can read more about such indicators in my magic eye article.

Electronics

Restoring the electronics was straightforward. Nothing was required beyond routine capacitor replacement and cleaning and lubricating the tuner and controls.

A welcome feature is the sturdy "roll cage" built onto the top of the chassis. This lets you turn the chassis on its side or even upside down on the workbench, without damaging delicate components. If only every radio had a service frame like that!

Cosmetics

The cabinet has various scuffs and scrapes, typical of any 70-year old piece of furniture. Stripping it would be overkill. Instead, I'll touch up the boo-boos and leave most of the finish intact.

I have used various touch-up techniques in the past. This time, I tried something new: oil paints. I have heard from people who claim success with oils, but it's an experiment for me. The next photo shows how I began.

Mixing various browns to match the area, I have begun retouching the top edge with a fine artist brush. Starting at the left, I've gotten as far as the center.

After the retouching is done, I'll give the entire cabinet a coat of clear lacquer to protect it and present a smooth surface. I'll post another photo when that's finished.