FX35 Octoplus

FX35 Octoplus, from 1986

The DOD FX35 Octoplus debuted in mid-1986. Its original circuit appears to be at least loosely based on the original Boss OC-2 Octaver schematic, with a flip-flop IC as an octave divider and four op amps in addition to the components used for the clickless FET footswitch. Unlike the Boss OC-2, the FX35 features a Tone control (boosts bass or treble of the octave signal only), and only one suboctave note is created. Like all octave dividers, the FX35 cannot track chords very well (although root-fifth power chords can sound okay, at least until one note starts to warble out), but tracking can be enhanced by using your neck pickup and/or adding a boost or compression pedal before the FX35. The FX35 was discontinued by late 1994.

• Controls: Octave Level, Tone, Direct Level
  
  
• From the manual: "The FX 35 Octoplus generates a signal one octave below the input signal, allowing guitarists to play bass lines or to "fill out" or add "body" to the sound. (NOTE: The FX 35 is for playing single notes only.)"
  
  
• Ad copy: Ever wish you could play two guitars at the same time?
  
  
• Technical info:
  
  
  • Specifications (1986): Input impedance = 500 k Ohms, Output impedance = 1 k Ohms; Maximum Input level = 4 V peak to peak; Gain = 0 dB; Direct frequency range = 40 Hz - 20 kHz; Lower Octave range = 40 Hz to 750 Hz; Signal to noise ratio > 90 dB
    
    
  • Official schematic provided with pedal by DOD (Rev. C, 8/11/86)
    
    
  • Notable IC chips: CD4013BCN dual D-type flip-flop CMOS; LM324N, LM1458N, and TL022CP op amps
    
    
  • Component-side circuitboard image: Sept. 1986
  
  
• External links:
  • @ ftp.dod.com - instruction manual (1986), .pdf format
  • @ discofreq's FX site
  • @ harmony-central.com
  • @ noiseguide.com
  
  

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