FX90 Delay

Original series FX90s from 1984, later 1984, and 1987 (above);
second series FX90s from 1990 and 1992 (below)

The FX90 Delay was introduced in mid-1984 as the 12th DOD FX-series pedal. It was the last FX-series pedal to feature "bars" graphics and the first with three control knobs. Although its circuit was revised some 12 times (up to Revision L), the FX90 always used an analog MN3005 BBD chip, the same chip used in the first version of the Boss DM-2 Delay. We have found that the FX90 can be easily coaxed into self-oscillation, if the Mix and Repeat knobs are turned up high enough, without having to tweak any of its three internal trim pots. DOD produced the FX90 into the 1990s, well after their DFX9 Digital Delay was introduced, but it was discontinued by early 1993.

• Controls: Delay time (60-300 ms), Mix, Repeat
  
  
• Catalog descriptions:1984 1986 1987 1988 1991
  
  
• Early FX90-specific cosmetic changes: pedals with blue-capped control knobs were produced in 1984 only; pedals with white text instead of grey text were made from 1984 to early 1985.
  
  
• Historical context: Although DOD had made battery-powered delay pedals as part of their Performer series (introduced in 1982), they were relative latecomers to the compact delay effects pedal marketplace. Ibanez had introduced its first analog delay in 1979 and replaced it with the venerable AD-9 in 1981, the same year Boss released their highly-regarded DM-2. In 1983, Boss introduced the DD-2, which was probably the world's first compact digital delay pedal (and the beginning of the end of the popularity of analog delays).
  
  The DOD FX90 is closer in design to the first version of the Boss DM-2, but by the time it was introduced in 1984, Boss had released the DM-3, which also had a "dry" output jack. According to The Boss Book, the suggested retail price of the DM-3 would have been $40 higher than the FX90; this price difference probably gave the FX90 a competitive advantage over the DM-3 in the U.S. However, the discontinuation of the DM-3 in 1988 was more likely due to the overwhelming success of the Boss DD-2/DD-3 family of digital delays. We cannot comment on how the DOD FX90 compares to a Boss DM-2 or DM-3 (or to the Ibanez AD-9, for that matter), but unlike those pedals the FX90 is still a relative bargain in the used marketplace (usually selling for $50-$100).
  
  
• Instruction manuals: At least three different covers/versions of the instruction manual exist: (left-right) mid 1980s, late1980s/early 1990s, early/mid 1990s. None of them have a copyright date; aside from the size and front cover they are identical, with exactly the same content.
  
  
• Suggested list price (ad copy, October 1984): $139.95
  
  
• Technical info:
  
  
  • Specifications (from the manual): Input impedance = 500 k Ohms; Output impedance = 4.7 k Ohms; Gain = 0 dB; Band Width = 30 Hz to 25 kHz (dry), 30 Hz to 1.3 kHz (delay)
    
    
  • Notable IC chips: one MN3005 4096-stage BBD chip driven by a MN3101 clock generator/driver CMOS chip; one NE570N compander; and one misc op amp tied into the Mix control (early models always used a TL022CP, while later models used a LM1458N, a TL022CP, or a TL062CP)
    
    
  • Internal trim pots: three; however, we do not recommend messing with trim pots
    
    
  • Component-side circuitboard images: Oct. 1984, Oct. 1984 (although the circuitboard of the second one is probably a few months older than the rest of the pedal) Feb. 1987 Dec. 1989 Nov. 1990 (rev. K) Sept. 1992 (rev. L)
  
  
• FX heritage: FX90 FX96
  
  
• External links:
  • @ ftp.dod.com - instruction manual (circa 1984), .pdf format
  • @ discofreq's FX site
  • @ harmony-central.com
  • @ noiseguide.com
  
  

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