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What is a Half-Speed Master?

Every Record Starts With A Master 

The records sitting on your shelf are all made based on one original master pressing of a recording. When your favorite albums were recorded, either digitally or on tape, these recordings were then converted into a disc made from lacquer. This disc is called the master, and it serves as the reference point for all vinyl copies of an album.

In order for each vinyl record in your collection to be made, the process needed to begin with this lacquer master disc. This master is created based on the final, fully mixed recordings of the songs on an album, and is used to make copies of the record. When a master disc is created, it is cut from a sheet of lacquer using a machine called a mastering lathe. The mastering lathe creates a lacquer disk, etching the recorded songs into the lacquer to make a reference for sides A and B of a record. 

The lacquer master is then turned into a double-sided “stamper” using a process called electroplating. Electroplating allows for the lacquer master’s grooves to be mass reproduced on vinyl. This electroplated stamper becomes the basis for all of the copies of the record that are pressed.

How Your Turntable Generates Sound From A Record 

When the master is created, the precise lathe that cuts the grooves in the lacquer is what begins the process that, eventually, ends with a vinyl record that you can use with your turntable. The grooves etched into the lacquer master by the lathe produce specific vibrations when vinyl copies of the master are read by the stylus on your turntable. These vibrations are then translated into electrical signals and amplified by your preamp and speakers.

The stylus on your turntable is made out of unrefined diamond. This extremely hard material can ride in the grooves on a vinyl record, picking up vibrations at specific frequencies as the record spins. These frequencies are converted into amplifiable signals inside your turntable’s cartridge. The cartridge holds the stylus, but also contains a magnet and a coil. As the stylus picks up vibrations from a spinning record, the magnet in the cartridge generates a field that is then turned into an electrical signal.

The signal created by your cartridge is still inaudible at this point. Without amplification, your record player can read the grooves in a record, but it cannot reproduce them as sound. To listen to music using your turntable, you’ll need a preamp and speakers. A preamp takes the signal from the cartridge and amplifies it. High-quality preamps amplify the signal without negatively affecting sound quality. A great preamp is one of the most important components in your vinyl listening setup, and is well worth the investment.

Some turntables include built-in preamps, while others are made without onboard amplification. If your turntable has a built-in preamp, all you need to listen to records is a set of passive (unamplified) speakers. These speakers connect to your turntable and do not need any additional power or amplification to produce sound. 

If your turntable does not have a built-in preamp, you either will need to set up a standalone preamp box or get a set of active speakers. Active speakers include built-in preamps, amplifying the signal sent from your turntable and producing sound.

Understanding RPM

Your record player is designed to spin a specific amount of times per minute. The amount of revolutions per minute that your turntable spins is abbreviated as RPM. Modern records are mastered to be played at 33⅓ RPM or 45 RPM. These types of records are often simply called “33s” or “45s.”

In the early days of the turntable, smaller shellac discs that spun at 78 RPM were prevalent, but they could only play a few minutes of music per side. The limited play time from a 78 is due to the fact that the higher a record’s RPM is, the less recorded sound it can play back. 33s and 45s both spin at a rate that is sustainable for a full-length album. However, the higher the RPM of your record is, the better the sound quality will be. 

Many audiophiles and vinyl enthusiasts seek after the high quality of sound afforded by 78s. However, most modern record players are not configured to play anything other than 45s or 33s. Spinning at a higher RPM, 45s produce higher sound quality than 33s, but are less common than their lower-RPM counterparts in the modern vinyl record market.

Why Mastering Speed Matters 

The standard mastering process cuts grooves into the lacquer that play back at full speed, either 33⅓ RPM or 45 RPM. However, full-speed mastering can make it more difficult for the lathe to cut accurate grooves in the lacquer. Higher frequencies are often more difficult for the lathe to accurately render in the lacquer when a full-speed mastering process is used. For this reason, some masters are made at half-speed.

When a master is cut at half-speed, the original recording is slowed down before the mastering process begins. When a half-speed master is cut with a slowed-down recording as the reference point, it will play at normal speed when the final vinyl copy spins on your turntable.

Since full-speed mastering can often cause some frequencies to be lost, half-speed mastering offers a helpful solution. When a half-speed master is cut, higher frequencies are rendered at half their original hertz, making them much easier for the lathe to accurately render them. Then, when the RPM is doubled for the vinyl pressings, these higher frequencies will still be preserved.

Are Half-Speed Masters 100% Better? 

Based on what you’ve just learned, you might be wondering why half-speed mastering is not the industry standard for all vinyl records. Cutting a master a half of a record’s RPM preserves those hard-to-get frequencies, taking the sound quality of a record up a few noticeable notches. However, half-speed masters also take more time to produce. Cutting a half-speed master takes double the time that cutting a standard master takes, making it less convenient and affordable.

When audio engineers and producers are deciding on the best way to cut a master for a vinyl pressing of an album, the extra time that the process of half-speed mastering takes can definitely play a role in determining the route taken. It makes sense that lower-quality sound would be quicker and cheaper to produce, but investing in a half-speed master can dramatically improve the final sound quality in a record.

Half-speed masters are hard to beat in terms of sound quality. One of the major reasons why listening to music on vinyl is so rewarding is because it is a lossless audio format. Most digital forms of audio are compressed to make loud parts of the signal quieter and quieter parts louder. Although compression is a staple of modern audio production, it can also lead to a “lossy” sound. Lossy audio is often described as missing certain frequencies due to excess compression of subpar processing. When you listen to an MP3, for example, you are hearing a compressed version of a recording that is missing some of its highest and lowest frequencies.

In contrast to MP3s and many other digital audio formats, the analog audio that you get from a vinyl record is lossless – it retains those frequencies that are often over-compressed by digital audio. This means that, if your speakers, turntable and preamp are high-quality, you will be able to listen to a recording in as close to its original form as possible. 

Since half-speed masters can further reduce the loss of specific frequencies, they can dramatically improve the sound quality that you get out of a record. For engineers, producers, artists and, of course, fans, this exceptional sound quality is a big deal. Getting the best possible sound out of the vinyl format is part of what makes listening to records and building your audio setup so rewarding. You never want to settle for a mediocre listening experience when it comes to your favorite albums and artists.

So, are half-speed masters 100% better all the time, no matter what? The answer is complicated. A half-speed master can produce a more true-to-the-recording sound than a standard master thanks to the rendering of high frequencies at lower hertz. Since these frequencies are cut slower, they are easier for the mastering lathe to render accurately. When copies of a record are pressed based on a half-speed master, they can be played at normal speed and not sound slowed down or warped. Thanks to slowed-down audio being used in the mastering process, doubling the RPM restores the recording to its original speed.

However, half-speed mastering does not magically resolve sound issues and problems with low-quality recordings. If anything, a half-speed master will expose these flaws in a recording even more. Getting great sound requires a high-quality recording, a good master, and excellent sound equipment. Sadly, a half-speed master isn’t a magic means of making every recording sound great, but it can definitely be a big help.


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