FX-17 Wah/Volume

FX-17 Wah/Volume pedals:
early version with pinstripes (1988, left) and final cosmetic version (1993)

Introduced in 1987, DOD's FX-17 Wah/Volume pedal was fairly unique compared to other wah pedals available at the time. Its wah sound had a decidedly modern flavor, as opposed to a vintage Crybaby-esque timbre, and the FX-17 could also be used as a volume pedal or as a voltage controller. Because its circuit was designed to employ variable capacitance (see DIYguitarist's description of how it works, linked below) instead of an inductor (common in wah pedals) or potentiometer (common in volume pedals), the FX-17 boasted a more rugged design with fewer moving parts to wear out. However, its circuit is not entirely maintenance-free (see below). With its unique design, versatility as a wah, volume pedal, or voltage controller, and (relatively) small footprint compared to other wah pedals (although the FX-17 is larger than other DOD FX-series pedals), the FX-17 sold well enough to appear in catalogs until 2000. However, manufacturing may have ceased in 1998, based on serial number data.

• Controls: Rocker treadle; side-mounted wah/volume pedal switch; two trim pots (accessible through holes in the front panel)
  
  
• From the manual: "The new FX-17 offers three different functions, a "WAH-WAH" effect, a volume control pedal, and a 0 to +5 volt control pedal. The WAH or the volume control is selected by a push switch located on the side of the pedal. The FX-17 is an "industrial strength" pedal. Using proprietary techniques, this new wah/volume pedal does away with the strings and mechanisms that wear out, internal lights that burnout, or pots that become scratchy. When the foot pedal is rocked all the way back to the "wah" mode, a switch is depressed bypassing the WAH effect. The 0 to +5 volt output is for use as a synth controller pedal or other devices that require a voltage control. The FX-17 is battery or A.C. adapter powered, and built of heavy gauge steel to last a lifetime."
  
  
• Operation:
  
  
  • As a wah pedal: side switch must be in the "out" position, then turn the pedal on/off by bringing the rocker treadle to its full up position.
    
    
  • As a volume pedal: side switch must be in the "in" position. Note that the on-off switch activated when rocker treadle is in full up position has no effect in this mode.
    
    
  • As a 0 to +5 Volt controller: side switch can be in either position; connect the device to be controlled using a 1/8" cable. Note that if you are operating the FX-17 from a battery in this mode, you will need to insert a 1/4" plug into the INPUT jack to turn on the pedal.
  
  
• Cosmetic variants:
  
  
  • Rocker "tread" -- initially, the rocker treadle featured a rubber "tread" consisting of square-shaped "nodes". By early 1989, the pattern was rotated 45 degrees, so that the nodes were diamond-shaped from the perspective of the user, perhaps to minimize wear. Finally, by Fall 1991, the tread on top was the same as on the bottom of the pedal, with a horizontal pattern.
    
    
  • Pinstripes -- the original pedal featured horizontal pinstripes in the cutout at the center of the rocker tread, and on the front panel; these pinstripes disappeared circa 1989.
    
    
  • Pedal color: -- the original pedal was painted a dark grey color, but this gave way to a lighter silver color at about the same time the pinstripes disappeared, circa 1989.
    
    
• Instruction manuals: At least two different covers/versions of the instruction manual exist: FX17.MAN 3/87 (left) and 18-0005B (right), from the two pedals shown above. Both have a copyright date of 1986 and otherwise contain the same information.
  
  
• Technical info:
  
  
  • Specifications (1986): Input impedance = 500 k Ohms, Output impedance = 1 k Ohms; Band Width = 40 Hz to 16 kHz, Bandpass range = 200 Hz to 1.6 kHz; Gain = variable, -60 dB to unity; Maximum output level = 6 V peak to peak; Control voltage range = 0 to 5 V, +/- .05 V; Control voltage output impedance = 1 kOhms; Signal to noise ratio > 90 dB
    
    
  • Notable IC chips include a LM13600N dual OTA and a LM3080 OTA
    
    
  • Internal trim pots: at least two, accessible by using a small jeweler's flat-head screwdriver through holes in the front panel. Ordinarily, we do not recommend messing with trim pots, but these two were apparently designed to be tweaked by guitarists, although the instruction manual makes no mention of them. Viewed from the front panel, the left trim pot adjusts the wah sweep, while the right one controls output level; twelve o'clock appears to have been the default factory setting.
    
    
  • Maintenance: While the FX-17 does not have a pot that can become scratchy, it has a plastic film that can become worn or torn. Because this film provides a physical barrier and thus the variable capacitance of its circuit, if the film is damaged your signal might momentarily "drop out".
  
  
• External links:
  • @ ftp.dod.com - instruction manual (1986), .pdf format
  • @ DIYguitarist.com
  • @ discofreq's FX site
  • @ harmony-central.com
  • @ noiseguide.com
  
  

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