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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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The Technics SL-10 is a direct-drive, linear tracking automatic turntable, which was produced from 1979 to 1985.[1]
The SL-10 was the first linear-tracking turntable to feature direct drive, a Technics innovation dating back to 1969 with the SP-10 Mk I. The SL-10, along with its fully programmable stablemate the SL-15, was able to penetrate the consumer electronics market much more effectively than any preceding linear-tracking turntable, and it spawned a wave of imitators throughout the 1980s, along with many derivations by Technics itself.
Unlike many of the inexpensive designs that followed it, the SL-10 is cast from aluminum and weighs 6.5 kg (14 lb). Its chassis is the same size as a standard LP jacket, doing away with the large plinth, visible tonearm and general bulk associated with conventional radial-tracking turntables that the public was familiar with up to that point.
The SL-10 came equipped with the Technics EPS-310MC moving-coil cartridge. Due to the low output of the moving-coil cartridge, the SL-10 includes a built-in, bypassable step-up preamp to allow it to connect to standard phono inputs. The original Technics EPS-310MC moving-coil cartridge was designed to be replaced as a unit; the stylus was not removable. The cartridge has since been discontinued; the SL-10 will accept any P-mount/T4P cartridge. The SL-10 is capable of being powered by an external DC power adapter or a standard AC power supply. The motor is quartz-locked, providing accurate rotational speed.
Perhaps the SL-10's most unusual feature is its ability to play records in any position, even in a vertical position. In fact, records could be played upside down with the lid closed; the SL-10's internal disc clamp holds the record in place, and the tonearm, being dynamically balanced, maintains a consistent tracking force regardless of the turntable position.
An example of the SL-10 is in the collection of the Museum of Modern Art.[2]
Platter Type: 300 mm (11+3⁄4 in) diameter die-cast aluminium[3]
Speed Accuracy: +/- 0.002%
Wow and Flutter: 0.025%
Rumble: -78 dB
Tonearm Type: Dynamic balanced linear tracking gimbal suspension
Effective Tonearm Length: 105 mm (4+1⁄4 in)
Original Cartridge: EPC-310MC
Cartridge Frequency Response: 10 to 60,000 Hz
Dimensions: 315 mm × 88 mm × 315 mm (12+1⁄2 in × 3+1⁄2 in × 12+1⁄2 in)
Weight: 6.5 kg (14 lb)
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Technics SL-10 is a direct-drive, linear tracking automatic turntable, which was produced from 1979 to 1985.
Turntable anti-skating is a feature used in phonograph turntables to prevent skating of the tonearm. Due to the offset between the cartridge's axis (which is approximately tangential to the disc) and the tonearm's pivot, the force applied (through friction) by the rotating disc to the cartridge tends to draw the tonearm toward the center of the record and distort the balance of the sound and of the wear suffered by the stylus and the vinyl groove. To prevent this, an appropriately-sized opposing force (a rotational torque) is applied at the tonearm. This is accomplished in various ways by dedicated mechanisms, depending on the tonearm's manufacturer, and ranging from a small counterweight adjustable by a knob, to adjustable spring or magnetic mechanisms, usually calibrated in grams of force. Note that while the angular velocity is, ideally, constant, the peripheral velocity of the moving groove against the stylus is not, varying for instance from approximately 50 cm/s down to 15 cm/s from start to finish of a 33 rpm, 12" (30.48cm) record. The angle of skew of the stylus cartridge with respect to a chord of the circular record (and groove) while the tonearm rests on the record is also variable. Thus, any opposing force applied to the tonearm to counteract skating, if not variable during the playing of the record, is fixed, and at best an average value, only really perfectly in balance with the skating force at just one unique radius from the center of the disk. Yet, anti-skating schemes perform a useful function in minimizing asymmetric wear of styli and grooves, although not eliminating it entirely. Linear-tracking turntables were invented in part to eliminate the possibility of skating.
The Technics SL-J2 is a quartz-controlled direct-drive fully automatic turntable system produced by Technics between 1984 and 1988. It features a linear tracking tonearm with an optical sensor that allows for the kind of track-skipping more typical of CD players. The sensor also detects the size of the record sitting on the platter (7-inch or 12-inch), which allows the needle to drop precisely on the first track. 10-inch records must be played manually.
In a video tape recorder, tracking is a calibration adjustment which ensures that the spinning playback head is properly aligned with the helical scan signal written onto the tape. In the case of VHS, a linear control track at the tape's lower edge holds pulses that mark the beginning of every frame of video; these are used to fine-tune the tape speed during playback and to get the rotating heads exactly on their helical tracks rather than having them end up somewhere between two adjacent tracks. However, the exact distance between the rotating video head and the fixed head reading the linear track can vary by a couple of micrometers between machines due to manufacturing tolerances, so most machines offer a manual or automatic tracking control to correct such mismatches.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
