Variations of Flying Faders motorized faders
Variations of Flying Faders motorized faders
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The information posted here is advisory in nature and is believed to be complete and correct. Anyone using this information does so at their own risk and assumes all liability for damage or loss that may result.
All Flying Faders motorized faders are derivatives of the Penny and Giles Series 3200 fader, but several different variants were used. The first section below details the changes in the fader as supplied by P & G. The second section describes Martinsound/Neve variations of the external hardware related to the motor and string.
- The original version, D460110, used on the first couple of dozen Flying Faders systems, used graphite-impregnated Teflon bushings on the slider. We found during the development of the fader that the silicone oil lubrication could dissipate, leaving a dry Teflon bushing that didn’t last very long or feel very good. The solution was to include the graphite in the bushing as a ‘fail safe’ lubricant that continued to work even if the oil was absent. The graphite bushings are black in color.
These faders had slider wipers consisting of 4 wires per wiper. All later faders had 5-wire wipers, with the wires of slightly smaller gauge.
The string attachment method was a #2-56 screw that screwed into a threaded hole in the cast slider. Unfortunately, a factory conversion from American drills sized in numbers to a slightly larger equivalent metric drill created a rather loose fit for the threads, and on rare occasions this led to stripped threads in the slider. (This problem can usually be corrected by punching small dents around the hole with a sharp center punch. Use a good support for the slider flange so that the flange is not bent in the process.)
The screw passed through a sandwich consisting of a flat metal washer, a nylon washer, and a metal barrel spacer with an anti-rotation boss against the slider flange. The string threads through two notches or holes in the barrel, with the knot protruding between the nylon washer and the barrel. This scheme provided convenient adjustment of the string by simply loosening the screw and pulling on the knot.
The brush wiper for Touch Sensing was connected to the slider frame, and hence the metal-plated knob, by either a small wire or one of the unused brush wires folded back to contact the slider frame. Early units used solder to attach the wire to the slider frame, but later units used a hole through the frame and conductive epoxy to replace the solder.
Somewhere along the line the extruded aluminum shells changed from unfinished aluminum to black anodizing.
- The second variant, D460214, replaced the graphite impregnated Teflon bushing with a Tercite bushing. Tercite is a hard turquoise-colored engineering plastic that operated without damage when the silicone oil dissipated.
The Tercite change was accompanied by the increase in number and reduction in diameter of the wires in the slider brushes noted above.
The string attachment scheme was changed to include a threaded #0-80 insert that was swaged into the slider frame, eliminating all problems with stripped threads. The barrel spacer was eliminated and the string was threaded through the nylon washer. The anti-rotation feature was lost with this change. (This change was alsoincorporated into some of the later D460110 product.)
- The third variant addressed the problem of the dissipation of the silicone oil. Silicone oil has a bad habit of migrating onto all of the adjacent parts of the fader, including the slider assembly and the end caps. This would leave the rod and bushings without adequate lubrication. The solution was to treat the end caps and slider assembly with a coating that resists the migration of the oil, thereby extending the time between relubrications. The coating provides a change of surface tension that prohibits the oil from wicking onto the coated parts. Unfortunately, there is no easy way to distinguish treated from untreated parts, other than applying some silicone oil and observing if it beads up.
Once the oil migration was minimized, the old-style Teflon bushings could once again be utilized. This yields lower friction than any of the other designs, but this can also lead to positioning overshoot in the servo system.
Stereo faders require adding a second audio attenuator to the fader assembly. The normal 3200 Series fader accomplishes this by using two precision tracks, each mounted on a separate substrate. The motorized version, however, already utilizes one of the precision tracks as the position-sensing linear potentiometer for the servo system. The solution for the Flying Faders stereo version was to convert one of the secondary touch/switch tracks to a full linear potentiometer. The final configuration in a stereo fader is:
- Log attenuator at the bottom of the left* substrate,
- Touch contact strip at the top of the left substrate,
- Log attenuator at the bottom of the right substrate, and
- Linear attenuator at the top of the right substrate.
(* As viewed from the recording engineer’s seat.)
The linear attenuator resistive track must be narrower than the normal tracks at the bottom of the substrate, and as a result, the nominal resistance of the stereo fader linear track is 30 Kohms rather than the normal 10 K ohms of the broad tracks. Theoretically, the narrower tracks could be slightly more prone to resistance change with wear.
The stereo slider must have an additional set of wiper brushes to contact the addition tracks in the fader, and this raises the sliding resistance of the fader slightly.
A few changes were required to fit two faders into the normal space of a single fader module. The fader shell was modified to stagger the motor mounting bracket off to one end so that the motors of the adjacent faders could nest together in a symmetric interlaced pattern. Right and left versions of the shells also have the pulley-mounting studs on opposite sides. The sliders have dual threaded inserts, allowing use of the same slider on either side.
The controls for the dual fader were mounted on a circuit board sandwiched between the fader faceplate and the fader. This required a longer tongue on the slider to reach though this extra thickness.
The mechanical features of the stereo and dual faders went through the same evolutionary steps outlined for mono faders above.
In addition to the normal log taper audio fader version, Flying Faders utilized several other tapers, including:
1. Linear taper for use with diode function generators that build a custom non-linear curve to drive VCA modules,
2. VCA taper that drive VCA modules directly, and
3. Various film taper modules that have a faster rate of attenuation at the top and a stretched out range near the bottom of the fader.
The wire lengths varied to accommodate the custom printed circuit boards and other installation requirements.
Other changes included a variety of designs for the protective ‘shed’, the curved sheetmetal cover that protects the rod from dirt and spilled fluids. Various widths and contours were tried to reduce rubbing of the string attachment screws and the slider.
P & G also made changes to the knobs and slider tongues that render some combinations of knobs and tongues incompatible. Trying to fit the wrong pair together may result in cracking the knob.
A black and red Maxon motor (MaxonMotorUSA.com) was utilized in the original design, but Maxon was unable to ramp up motor deliveries fast enough to meet the initial delivery schedule demanded by Neve. A substitute Micro Mho motor, slightly smaller and less powerful than the Maxon and easily identified by its gold color, was used in the interim.
Another variation was the washers used to space the ball-bearing pulleys away from the side of the fader. The original method was to use a bowed washer to raise the inner race of the pulley bearing. That particular washer was chosen for its thickness and diameters, and the bow of the washer was just incidental. Later units used a thicker flat washer.
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