Long-playing discs (24-Minute/40-Minute)

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Long-playing discs (24-Minute/40-Minute)

トーマス・エジソンらがダイヤモンドディスク式蓄音機を試聴する様子（1911年）

Image credit: US National Park Service, Public domain (Wikimedia Commons)

Long-playing discs (24-minute/40-minute) were an experimental format using ultra-fine grooves for long playback times, introduced by Edison toward the end of its disc business. According to an overview by the Library of Congress, by 1924, competition with radio had worsened the business environment, leading to the development of experiments and product presentations for long-playing discs. They were introduced in October 1926, at the same time as a new line of console-type models were presented.

However, the actual number of items released (issued) that can be confirmed from the documents is limited to eight 10-inch items and six 12-inch items. The number ranges (10001–10008, 30001–30006) are clearly indicated, so they can at least serve as a reference for understanding the range of items released.

Series Overview

The core of this series was its "longer playing time." Design values were set at 12 minutes per side for the 10-inch disc (24 minutes total for both sides), and 20 minutes per side for the 12-inch disc (40 minutes total for both sides), positioning the series as a product group that aimed to significantly expand the playback time limits assumed for standard commercial discs at the time.

On the other hand, the actual number of products released was only eight 10-inch models and six 12-inch models, which shows that this was a format that was released to the market in a limited range, rather than a ``big series'' that would be expanded over the long term.

Development and release history

In the 1920s, Edison's disc business faced changes in the market environment, and it is said that the business began to stagnate around 1924 due to competition with radio. In this environment, the company continued to experiment with records that could be played for long periods of time, and in October 1926, it introduced the Long-Playing Record and a compatible phonograph.

Long-Playing Records are not just a system that can be achieved by adding a disc; they require special conditions for the playback mechanism. Specifically, they are designed to extend playback time by using extremely fine grooves, and require new gearing to slow down the tone arm's feed speed, a lightweight dedicated reproducer, and a diamond stylus ground to an extremely small size.

The company prepared new models of Console 1-4 to support long-time boards, and presented a configuration that combined a standard reproducer with a reproducer for long-time boards, allowing the tracking speed to be reduced by switching gears. A gear reduction set for retrofitting existing machines was also introduced, and the long-time board was positioned as a product that "united the board and machine under one condition."

Standards and playback conditions (technical basis of 24-Minute/40-Minute)

エジソン社のディスク式蓄音機（外観例。写真はL-35）

Image credit: CC0 1.0 (Wikimedia Commons)

It is explained that the longer playing time was achieved not by reducing the rotation speed, but by increasing the groove density. UCSB's explanation points out that the core of the disc is the increase from the previous 150 grooves per inch to 450 grooves per inch, and that the design values are 12 minutes per side for 10-inch discs and 20 minutes per side for 12-inch discs, with the total groove length of the 12-inch discs being approximately 1.25 miles. Other sources describe this series as 80 rpm fine-groove discs.

The ultra-high-density grooves also placed requirements on the playback system. Specifically, new gearing was required to slow the stylus tip feed speed, a new, lighter reproducer, and a small, polished diamond stylus (0.002 inches wide, 0.0035 inches long) to fit the fine grooves. Furthermore, the document describes the development of new console models (Console 1–4), which would be able to slow the tracking speed by switching gears, and would be equipped with both a standard reproducer and a long-play reproducer. Additionally, a gear reduction set is suggested as a modification for existing consoles. Cabinet finishes (Trafalgar brown mahogany) and price ranges ($165–$300) are also described.

Please note that the image above is an example of the appearance of an Edison disc phonograph, and is not a document indicating that it is a machine specifically for long-play recording (within the scope of reference in this section, it cannot be determined with certainty that the device in the photo is a machine specifically for long-play recording).

Production and recording methods and catalog size

While the ideal of recording long discs directly is discussed, in practice, it is shown that long discs relied heavily on dubbing from existing recordings. In particular, it is described that the method of creating long disc masters using Diamond Disc masters was adopted, and that long tracks were prepared in 4-5 minute increments and then converted to long discs in post-production.

These production conditions also affected the content, as the catalog was compiled from existing Diamond Disc catalogs, with older recordings mixed in. The content was described as focusing on orchestral and small ensemble works, primarily concert music and some operatic selections. As a result, the release was limited to eight 10-inch and six 12-inch discs, each clearly labeled with a number range (10001–10008, 30001–30006).

Series Features

エジソン社ディスク盤のラベル例（EDIS-40494）

Image credit: US National Park Service, Public domain (Wikimedia Commons)

This feature is not only apparent in the technical "long duration" but also in the advertising usage. The advertisements emphasized the value of continuous playback with less need for replacement, using the metaphor of being able to run a dinner party from start to finish with "Soup to Nuts." They also showed the mathematical advantage of halving the cost per minute (cost per minute of music).

On the other hand, the evaluation noted that the volume was significantly reduced compared to a regular record, and the tone was leaning toward a thinner side. Furthermore, it was pointed out that precision in the shellac formulation and molding process was crucial to the creation of a long-playing record, and that the record itself was fragile, that the extremely thin grooves made it easy for minute scratches to recur in the same spot, and that humidity and other factors could render the record unplayable. These findings indicate that the long-playing time was not a new function of the "record" alone, but was achieved as a result of the overall process, including the manufacturing process and handling conditions.

The business environment at the time and audio strategies (to prolong the life of the disc business)

The document states that the spread of radio affected the company's business around 1924, and that while operations were scaled back, experiments with long-play records began, and that long-play records and a new console were introduced in October 1926. In addition, the document notes that, as a concession to the market, an attachment that could play competitors' lateral-cut records was also offered.

The historical significance of the series

Long-playing discs (24-minute/40-minute) are an example of an attempt to commercialize long-playing discs in the 1920s, with specific design values for longer recording times (12 minutes on a 10-inch disc per side, 20 minutes on a 12-inch disc per side), incorporating ultra-fine grooves and specialized playback conditions (feed mechanism, reproducer, and stylus dimensions). When considering the history of long-playing media in later years, this can be seen as an example that revealed early on that increasing recording time was not achieved solely through groove density, but also required simultaneously achieving the right conditions for machinery, production processes, and handling.

Furthermore, the limited number of copies released, the fact that production relied primarily on dubbing, and problems such as low volume and fragility of the discs are concrete examples that show that technological achievement alone does not guarantee market success.

End and evaluation (barriers to widespread adoption)

While the ultra-fine grooves of the Long-Playing Record significantly extended the recording time per disc, the actual content was mainly dubbed from existing recordings, and it deviated from the ideal of recording a long symphony in succession. It has been stated that the volume is lower than that of a standard record, and the tone tends to sound thin.
Additionally, because the grooves are extremely thin, handling and needle placement have a significant impact, meaning even the smallest scratches can easily cause repeats (repeated scratches in the same spot), and moisture or improper handling can lead to increased noise or even the inability to play.
Only a small number of copies were released, and as a result, it was not a commercial success.

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