Deconstructing DJ Innovations: The Shure Whitelabel
How does a needle/cartridge translate grooves in a record
into a sound?
A cartridge is a transducer, just like a microphone. It is designed to convert energy from the mechanical domain (the record) into the electrical domain (signal out of cartridge). In the case of a microphone your voice pushes air, which moves a diaphragm and coil around a magnet, creating an electrical signal. A record needle traces ridges in the record groove. The resulting vibrations are converted into an electrical signal inside the cartridge.
The stylus is made up of a diamond, which is attached to the end of the cantilever, which is in turn suspended by the bearing inside the brass housing. Opposite the diamond at the end of the cantilever is the magnet and a spring wire. The bearing and spring wire together make up the suspension of the stylus. The stylus is inserted in the cartridge body, which is made up of the coils and pole pieces. Everything in the stylus, except the magnet, are directly related to the mechanical domain. The magnet is the beginning of the electrical domain, working directly with
the guts of the cartridge body.
Simply put, the record groove contains peaks and valleys. The depth and height of the peaks determines the amplitude and frequency of the sound. A bass kick or note would have a longer, deeper valley while a high-hat would have a small, shorter valley. The combinations of these valleys on two walls, left and right, give us stereo. The diamond on the cantilever traces the groove, causing the cantilever to vibrate, which moves the magnet proportionally to the diamond (the more accurate the vibration, the more accurate the sound). The magnet moves between the pole pieces of the cartridge creating a magnetic flux cycle. Flux moves through the coils, which are wrapped around the pole pieces. This creates an electrical signal. The electrical signal connects to the turntable via the leadwires on a headshell and the contacts.
Why a diamond tip?
A diamond is used because it is one of, if not the hardest, materials known on earth. The temperature at the point where the diamond touches the record reaches hundreds of degrees Fahrenheit. Any other material would more quickly melt or deform.
What's the difference with the shape of the diamond?
The four (4) types of diamond shapes used in Shure cartridges are: spherical, biradial, elliptical, and Micro-Ridge. The contact-area of spherical diamonds are shaped like a ball. As you get towards the Micro-Ridge, the front-to-back radii of the diamond decreases, decreasing the diamond area that physically touches the groove wall. The diamond shapes directly effect how accurate the diamond will trace the groove and wear the record.
The stylus footprint is the surface area that physically comes in contact with the groove. The smaller the footprint, the more the diamond will get into and out of the valleys of the groove and create a more accurate reproduction of the information. Modulations in the groove can be as small as a millionth of an inch. A diamond with a large footprint (spherical) will not properly trace the small modulations, instead skipping over them and therefore not transmitting the information to the magnet…you won't hear the information. A diamond with a very small footprint (micro-ridge) will have more accurate high frequencies because it can trace the smallest modulations.
Spherical styli, like those used on the Whitelabel, are recommended for Dj applications and as a result, Dj cartridges use heavier tracking forces than hi-fi cartridge.
How many needles would you have to collect for the diamonds to be worth something?
It would be impossible to make the diamonds used in phono styli worth anything of real value. They are industrial diamonds, which have the same strength as diamonds used for jewelry, but they are uncut and very ugly. Plus, you would not be able to combine the diamonds back together into a single rock.
What were Whitelabel design goals?
The goal: to design an integrated cartridge for club DJs that was truly new and unique. This cartridge needed to deliver great sound with solid drop bass, flat mids, and accented highs, all tailored for the club environment. We also worked hard on the physical design. It needed to look sleek, but still offer the advantages of a headshell, with an adjustable stylus overhang, reliable electrical contact, and good stylus visibility. Other converns were trackability, tone-arm resonance, and skip resistance.
How did the team go about making them?
We worked backwards from what we know Djs want. We looked at the physics and forces that a Dj applies to the tonearm and cartridge, their sonic expectations and features we want included.
What's forward mass design?
It's a term we coined after researching the trackability, tone arm resonance, and cartridge performance of each product in the market in relation to the particular product's center of gravity. We found that headshell-mounted cartridges resulted in a better tone arm resonance and those products had a center of gravity closest to the diamond. Taking into consideration the nature of headshell-mounted cartridges and the physics that naturally surround them, we included these characteristics into the Whitelabel design.
Why is the Type 1 cantilever used?
Cantilever theory goes something like this: the thinner the cantilever, the more accurate the sound. There are always trade offs between sonic accuracy, strength, skip resistance, and record wear. You can have 2-3 features, but not all at the same time. The Type 1 is straight and slightly thinner, yielding a more accurate sonic response and designed for Dj applications.
What makes the Whitelabel unique?
It incorporates the benefits of using a headshell-mounted cartridge. This includes the ability to adjust the overhang of the diamond for different turntables and Dj touches, as well as centering the mass over the diamond, increasing the visibility of the stylus, and having a proper tone-arm connector.
from the magazine: BPM