Category Archives: Phonograph History

1950 Zenith Cobra-Matic Record Changer

Seventy-five years ago today, the August 28, 1950, issue of Life magazine carried this ad from Zenith announcing the “Cobra-Matic” record changer. A couple of the consoles including it are shown below. “Cobra” is the shape of the tone arm, and “Matic” means that it’s fully automatic.

And it was planned for the future. Who knew what other speeds and sizes of records might show up, so this one was continuously variable for 10 to 80 RPM, to be compatible with all known records, and any that might show up. Record size was also adjustable, so this changer was set for anything.



1925 Children’s Phonograph

A hundred years ago, many, or maybe even most, families had a phonograph in the parlor. So the entrepreneurial dealer had to consider other markets, and one natural would be getting a phonograph in Junior’s room.

Therefore, this ad in the June 1925 issue of Talking Machine World shows the Genola, from the General Phonograph Manufacturing Company of Elyria, Ohio.  It would play all flat records up to ten inches, and was a hit with both children and parents.

It retailed for $5, which works out to about $82 in 2025 dollars.



1955 Sleep Learning

Screenshot 2025-05-23 12.19.34 PMShown here, in the June 1955 issue of Popular Electronics, is French actress Jeanne Demery hard at work learning Swedish for an upcoming play, all while she sleeps. We’ve reported previously (here, here, and here) about the concept of sleep learning. According to Wikipedia, it doesn’t work, but as a kid, it sounded reasonable to me, and sounded like a good way of bypassing the drudgery of studying.  I had to sleep anyway, so it seemed reasonable to take advantage of that time to learn.

The problem I ran into was the lack of suitable equipment.  The tape had to play while I was deep asleep, and ideally keep repeating.  I had a tape recorder, but once the tape ran out after a few minutes, I would be left without anything to learn.

With one of the devices shown in this article, I would have been all set up.  It looked like a phonograph with a timer, but it could also be used as a magnetic recorder.  The normal cartridge was replaced with a magnetic head, and speech could be recorded onto a magnetic disc.  The device was the Dormiphone, and was manufactured by Modernophone, Inc., 30 Rockefeller Plaza, New York.  It retailed for $229.50, which works out to $2747 in 2025 dollars.  That would have been out of my price range as a kid, so I guess that was another reason why I had to do my learning the traditional way.

(We searched in vain for more information about actress Jeanne Demery, but about the only thing we were able to find was this newspaper article also detailing her sleep learning achievements.)



1925 Carryola Master Portable Phonograph

1925MayTalkingMachineWorldOne hundred years ago this month, the May 1925 issue of Talking Machine World reminded dealers that there was money to be made in the Big Outdoors, namely by selling portable phonographs to those at camps and summer cottages, those on motor tours of fishing and canoeing, or anywhere that a phonograph would add enjoyment.

Specifically, they were selling the Carryola Master, from the Carryola Company of America, 647 Clinton Street, Milwaukee. It was said to give beautiful tone, and its motor was silent in winding and operation.



Radio Facsimile, 1925

One hundred years ago this month, the May 1925 issue of QST contained this feature discussing methods that hams could use to send and receive facsimile images. Synchronization was the big issue, but the magazine pointed out that every home contained a device capable of rotating at a fairly precise speed of 78 RPM. The article showed how the family phonograph could be geared to the fax machine, and the exact speed could be adjusted to match the sending station.

A number of sample images are included, showing that the technology was within the grasp of most hams of the time. You can view the cover and full article at the PDF above.



1940 Phonograph Stroboscope

1940MayRadioService DealerEighty-five years ago this month, the May 1940 issue of Radio Service Dealer provided this handy stroboscope for testing the speed of record players.

The included instructions explained how to place it on a piece of cardboard, or an old record. If a record was used, it was critical to make sure the hole was exactly in the center. Then, it was placed on the platter, and illuminated with a neon bulb powered by 60 Hz. At exactly 33-1/3 RPM, the outer segments would remain stationary, and at 78.26 RPM, the inner ones would do the same. If the speed were too fast or too slow, the segments would appear to move forward or backward.



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Converting Your Old Phono to Play 33’s and 45’s: 1955

1944AprPMSeventy years ago, it was starting to look like those newfangled 33 RPM LP records, as well as 45 RPM records, were going to catch on after all. But that handsome radio-phono console in the parlor only played 78’s. Fortunately, a kit was available to add those new speeds. You purchased a new record changer, which came with a mounting board with precut holes to accommodate the new changer. You measured the old board, and cut the new one to fit the cabinet. Connecting the power and phono input were then simple. Depending on which cartridge the new player had, you might also need to add a preamp.

This guide appeared 70 years ago this month in the April 1955 issue of Popular Mechanics.



1955 British Radio-Phono

Screenshot 2025-02-14 10.13.11 AMThe excitement is palpable in this image from the cover of the March 1955 issue of Practical Wireless. It looks like they’re simply listening to a record on their radiogram (what we would call a radio-phono on this side of the Pond). But one of them actually built the set according to plans in the magazine.

The set was said to be a selective and sensitive station getter, and had a tolerably high standard of reproduction for both the wireless and the gramophone. The March issue started the construction plans for the eight-tube set, to be continued in the April issue.



Hi-Fi Hobbyists, 1955

1955JanPE1955JanPE2Seventy years ago this month, this couple made the cover of Popular Electronics, January 1955, by putting the finishing touches on their Hi-Fi system.

The issue of the magazine carried a number of articles that would be helpful to them, and noted that the Hi-Fi fan was at heart a hobbyist. That could mean a music lover, someone who simply enjoys good reproduction, or building the equipment.

The painting was by  Leo R. Summers.