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Simplex X-L

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The Simplex X-L is a 35mm projector in the Simplex line of projectors. First released in 1949, it became one of the most popular projectors in North America and remained an industry standard until the end of the first-run era. X-Ls and their later variants are known as reliable machines that require very little maintenance besides regular lubrication.

Due to the number of X-Ls in existence and the relatively maintenance-free design, they are expected to be one of the 35mm projectors with the longest service life in the digital era.

History

A Simplex X-L modified for hemispheric projection inside a portable dome. From the International Projectionist, Vol. 39, No. 5, May, 1964.

The Simplex X-L was first introduced in 1949 by the International Projector Corporation, and was later manufactured by General Precision, Inc., National Screen Service, and Strong International. It was rebranded as the Simplex 35 in the 1960s, and the last model for general cinema use following the traditional single lens design was the Simplex PR-1014. The X-L also served as the basis for a number of other models, including those with lens turrets, studio models capable of reverse operation, and a dual-format 35/70 projector.

The Simplex X-L replaced the Simplex E-7 and other earlier models. Some of the main improvements in the X-L include a conical shutter for improved light output, an enclosed oil bath to maintain constant lubrication of the drive system, larger 24-tooth continuous sprockets, and the option of a water-cooled gate. It was also the first Simplex to offer the option of a curved gate to improve focus stability in 1957.

The X-L was compatible with the existing Simplex SH-1000 soundhead (also called the 4 Star soundhead) and new units branded as X-L soundheads were also released. The primary distinction between X-L soundheads and the SH-1000 was an additional compartment below the exciter lamp to house a preamp. In the 1960s the X-L models were replaced by the Simplex 5 Star soundhead, which replaced the gearbox of the earlier models with a belt drive. The X-L was also designed to be compatible with soundheads manufactured by RCA and others.

The design of the X-L remained largely unchanged for decades, with few differences that would impact daily use. One notable exception is the oil gauge and filler, which was originally located on the front of the mechanism. The gauge was replaced with a sight glass inside the film compartment, and the oil filler was moved to the top of the mechanism.

Modifications

35/70 Lens Barrel

A lens barrel with adjustable lateral alignment designed for 35/70 use installed on a Simplex PR-1014.

The original X-L lens barrel was fixed in place. When the dual-format 35/70 model was released, they improved the design of the lens barrel by providing a lateral adjustment to re-center the lens to the correct the centerline when alternating between 35mm and 70mm. The 35mm models can be retrofitted with this 35/70 version of the lens barrel to allow for the lateral adjustment of the lens. This is useful when switching between formats using the standard lateral alignment for optical sound and formats with an atypical lateral alignment (ex., full-frame 1.33, CinemaScope with 4-track magnetic sound, Superscope).

Drive-in Operation

Because the Simplex runs in an oil bath, the oil must pool at a low point in order to be pumped back to the top of the mechanism. On the standard indoor projector in which the mechanism was installed at a downward tilt, the oil system is designed to pump from the front of the mechanism. For drive-in installations where the projector is tilted up, a conversion kit is required to collect and pump the oil from the back of the mechanism.

Known Issues

Leaking Oil

The X-L is notorious for leaking oil. This is especially true for early models, which have a more porous casting. Later models have an improved casting and better seals, which helps mitigate the oil seepage.

Extra care must be taken when cleaning the projector to ensure that oil isn’t seeping into the operator side and pooling in the film compartment, pooling beneath the soundhead, dripping down the reel arm, or dripping onto the floor. One common solution for badly leaking X-Ls is to place a baking sheet lined with shop towels beneath the projector to collect the dripping oil.

Soundhead Pinch Roller

While it is possible to pair a Simplex picture head with a soundhead produced by another manufacturer, it is far more common for X-Ls to be paired with a Simplex soundhead that uses a rubber pinch roller to press the film against the sound drum. The rubber makes contact with the picture area and can leave marks on the film, especially when dirty.

In the platter era, some projectionists would remove the rubber so that only the film edge would make contact with the pinch roller, but that workaround cannot be used for reel-to-reel projection because it dramatically increases the time it takes to get the sound drum up to speed.

Threading

Threading diagram for the Simplex PR-1014.

For general information about threading projectors, see threading

  • Rotate the framing knob (Item 7) to its center position (FRAME reading level, as shown). Using the motor knob (SH-1000 soundhead) or the soundhead flywheel (5-Star soundhead), turn the mechanism by hand to place the intermittent sprocket (Item 9) in its rest position. In the rest position, the index mark (Item 10) will align with one of the painted white index markers on the intermittent shaft collar when stopping after sprocket rotation.
  • Open the pad roller assemblies (Items 2, 5). Open the film gate (Item 3) by moving the gate opening lever (Item 4) forward. The gate will lock in position (as shown).
  • Dismount the film gate by removing the (2) chrome knurled nuts. Use a clean, dry cloth to wipe down all film bearing surfaces of the gate and trap (Item 13). Replace the film gate and nuts. This should be performed at each threading operation.
  • Thread the film as illustrated. Engage the film on the intermittent sprocket (Item 9), and check for correct framing at the framing aperture (Item 12). When correct, close the gate by firmly holding the gate opening lever and tripping the gate release (Item 8). Walk the lever back by hand to prevent the gate from slamming into the trap with excessive force. Form loops above and below the gate as illustrated, and close the pad roller assemblies (Item 2, 5).
  • Turn the mechanism by hand to advance a few frames of film. Run fingers over each sprocket (Items 1, 6, 9) to ensure that the sprocket teeth are centered in the film perforations, and the film is centered on the sprockets. Double check the position of the film in the framing aperture (Item 12). A correct frame image in the framing aperture ensures correct frame positioning in the picture aperture (Item 11). The framing knob (Item 7) can be used to correct misframes, but doing so reduces the framing range during playback. It is advisable to open the gate and rethread with the framing knob in its center position.
Intermittent sprocket on a Simplex X-L projector. Observe its range of motion and set to the center of its travel before threading. See Framing for more details.
  • Thread the soundhead as instructed in the soundhead manual. A slight degree of film tension is required above the feed sprocket (Item 1) and below the soundhead. This prevents the film from snapping on motor start.

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