Vinyl Records on YouTube.
Hi, welcome to an episode of “Thinking Inside the Box” on Noah’s Ark. In the video, we’re gonna talk about vinyl records and how they store and reproduce music. At the end of the video, I’ll also talk a little bit about how to master for vinyl.
So vinyl records weren’t the first medium ever created to store music. In fact they were preceded by wax cylinders and shellac records. However we can now safely say that they were one of the most successful medium in a commercial sense and to this day, they are considered to be the best way to listen to music.
There are a couple of reasons why vinyl records were so successful including the actual packaging and artwork that contribute to the beauty of the actual physical product. However, many consider the sound quality to be pristine due to the fact that the reproduction is analog unlike digital media such as CDs or mp3s.
Let’s take a look at different record formats and their corresponding properties.
Typically a vinyl record comes in 3 different sizes namely 7, 10 and 12 inches with a combination of 3 different rotation speeds namely 33.3, 45 and 78 rotations per minute. These parameters will affect the length of music that can be stored on the record.
However, the amount of storage on a phonograph record is not a fixed standard. It’s highly up to the mastering engineer or cutting engineer to decide how close or how far away to carve the grooves against each other. The engineer has to make a compromise between length and loudness of the music.
The more the grooves are close to each other the more music can fit on the medium as the total number of grooves on one side of the record increases. The more the space between the grooves, the wider the grooves can be thus allowing deeper actual cuts that transmit signal to the turntable needle.
As a rule of thumb, a standard 12” 33.3 rpm record (also known as an LP) will hold up to roughly 25 minutes of music on a side, as opposed to a 7” 45 rpm record (EP) with roughly up to 12 minutes of music. The older SP record at 10” 78 rpm could only hold up to 3 minutes and this is the reason why many earlier songs were very short to be able to fit on this format.
Over the course of recording history, a fundamental change occurred when records were switched from a monophonic medium to a stereophonic one. This technological advancement was primarily attributed to Alan Blumlein for inventing stereo recording techniques at Abbey Road Studios.
To understand the differences between a mono and stereo vinyl record let’s take a look at how the grooves look like on a microscopic scale and how the stylus picks up the mechanical signals in order to eventually convert them to an electronic signal.
A mono stylus is essentially constrained into one direction of movement: left and right. The grooves that dictate the movement of the stylus are therefore symmetrical and the frequencies of the curves mirror the actual waveform to be reproduced.
On the other hand, the stereo record is slightly different in the sense that the stereo stylus now has two dimensions of movement: left/right and up/down. The lateral movement dictates the frequency and signal level as before and the vertical movement represents the two channels. The grooves now become asymmetrical when the signal is not completely monophonic. A perfectly in phase signal will produce a lateral movement and a completely out of phase signal produces a vertical movement.
This is where bass frequency content and out of phase signals come into the pictures and cause problems. You may have heard to make sure the bass frequencies stay in the centre of the mix and to prevent any out of phase signal.
This is due to the fact that since bass frequencies produce longer wavelengths and therefore longer lefts and rights in the grooves, the chances of the needle projecting out of the groove are much higher than high frequencies that produce only small curves. The same applies to out of phase signal where vertical movement can easily make the needle slip and skip the record.
To combat these requirements, elongate the running time and to further protect this storage medium, a special EQ curve is applied when music is carved onto the medium and played back from the medium. This phono EQ curve is called the RIAA curve where the bass frequencies are drastically cutoff and the high frequencies are drastically boosted. During playback the phono preamp will apply the exact inverse curve to restore the original signal.
Most amplifiers and turntables incorporate a phono input or preamp where this EQ curve is applied and the signal boosted. This is why some people experience very thin playback of vinyl records when a regular turntable output is directly connected to a regular input on an amplifier because the inverse curve is not applied.
To prevent these problems, the mastering engineer has to pay attention to these factors when carving the record. Measures that can be taken include summing the bass frequencies into mono up to a certain cutoff frequency and monitoring the signal with a phase meter.
To find out more about vinyl records, you can watch the video above or on YouTube here.