DFX9 Digital Delay

DFX9 Digital Delay from early 1992, with original box

Introduced at Winter NAMM 1989, the DFX9 Digital Delay was advertised with the DFX5 and DFX6 in early 1990, and also appeared in DOD's FX.CAT90A catalog (see below). As DOD's first compact digital delay pedal, the DFX9 was intended to compete with the Boss DD-2/DD-3 series of digital delays, which had first appeared six years earlier. The DFX9's basic circuit was likely derived from the DigiTech PDS 1000 Digital Delay and its descendants. With the subsequent addition of the DFX91 (analogous to the Boss DD-5), the DFX9 became DOD's "entry level" digital delay. The DFX9 was discontinued by 1998.

• Controls:
  • two LEDs (left LED indicates delay effect is on; when the Range/Mode switch is set to Infinite Repeat, the right LED indicates a sampled phrase is playing)
  • Level (no delay when counterclockwise, 50% wet/dry mix when fully clockwise)
  • Repeat (1-20 repeats)
  • Delay
  • 5-position Range/Mode rotary switch:
    1. 3.5-15.6 ms of delay
    2. 13.8-62.5 ms
    3. 55.5-250 ms
    4. 222-1000 ms
    5. Infinite repeat (222-1000 ms)
  
  
• From the manual (second version, shared with the DFX91): "The DFX9 ... delays sound to make effects. When mixed with the original signal, the effects include doubling, slapback, and echoes. Other useful effects are infinite repeat...."
  
  
• Catalog description: 1990
  
  
• Technical info:
  
  
  • Specifications: Delay Ranges as stated above; Signal to Noise Ratio = 92 dB typical; Input Impedance = 470 kOhms, Output Impedance = 4.7 kOhms; Maximum Gain = 1950 V/V; Maximum Output Level = 5 V peak-peak; Bandwidth (dry) = 40 Hz to 20 kHz, (wet) = 40 Hz to 10 kHz; Digital Resolution = 12 bit
    
    
  • Recommended battery type: The DFX series included a note in their instruction manual, and inside its battery cover, that only alkaline batteries should be used (specifically an Energizer no. 522 9-volt, though any brand will work), as other batteries may not even provide enough power to start up. The DFX9's exact current draw is unknown, but we recommend always using an AC adapter for any digital effects pedal.
    
    
  • Notable IC chips: SCX61/V4 micro CMOS gate array chip, socket-mounted TMS4256-10L dynamic RAM chip, NE570N compander, two 4558-type op amps
    
    
  • Internal trim pots: three; however, we do not recommend messing with trim pots
    
    
  • Component-side circuitboard image: December 1991
    
    
  • Related circuits: DFX91, DFX94
  
  
• External links:
  • @ discofreq's FX site
  • @ harmony-central.com (via archive.org)
  • @ noiseguide.com
  
  

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