Operating Theater: DOD DFX94 Digital Delay / Sampler

This was another non-functioning pedal handed to me by my friend Mauz, the DOD DFX94 Digital Delay / Sampler. I’d gotten pretty cocky after I’d fixed his DOD FX9, so I took this one on with confidence.

When working, the DFX94 was purported to have a spacious maximum of 4 seconds delay along with an “infinite repeat” and a sample function. I had no idea how to get any of these special functions to work as finding a DOD manual online is kind of like trying to find a funny Owen Wilson movie. What I did know was that the normal delay functions wouldn’t power up.

DOD pedals seem to be notorious for switching problems. The way the footswitch works is to momentarily connect a transistor pair to ground, shorting a flip-flop circuit, and then all this other stuff happens that makes the pedal switch on and off (an excellent article on the subject is contained here: http://www.geofex.com/Article_Folders/bosstech.pdf). I test the switching on a pedal that uses this system by shorting it past the switch.

I shorted where the wires connected to the switch; nothing. The switch was fine, so maybe it was a broken wire. I shorted where the wires connected to a plug; nothing. Maybe it was the plug. I shorted the jack of the plug to the PCB; nothing. Finally, I shorted the PCB solder pads themselves and the pedal switched like normal. The culprit was a loose connection with a group of solid leads going to the double-sided PCB.

The same problem occurred in a different spot on the DFX9 I had fixed for Mauz before. I heated up the leads real good and gave them a generous amount of solder to soak through both sides of the PCB. The switching problem was solved. The pedal was working again, just like Owen Wilson (unfortunately).

The DFX94 does contain 4 seconds of delay. In my opinion, it sounds fairly warm compared to the popular BOSS digital delays. The repeats died off too quick, though, so I opted to fix that.

I adjusted the 50k trim pot at location P2, clearly labeled “repeat” underneath. When the repeat knob is at maximum the pedal now just keeps going for awhile and eventually starts distorting into some luscious noise. It’s handy if you wanna clear a room. Or you could put on Wedding Crashers.

The “infinite repeat” function on the mode knob works just like the DFX9. The delay is automatically engaged. Hit the footswitch and that repeat keeps going while the instrument signal plays through, bypassing the effect. This is indicated once the LED on the right lights up. You can now play over the looped phrase.

An addition to the DFX94 is the sample function. Turn the mode knob all the way to the right and you can record a phrase. Both LEDs will be on, but you won’t hear any delay. When you hit the footswitch, the right LED will dim and the pedal will be recording. When the right LED lights back up, it’s done. The sampling time is controlled by the delay knob for up to 4 seconds. Now switch the mode knob to “trigger” mode. When you hit the footswitch it will play the phrase you recorded while the instrument signal goes through unaffected. Go back to “sample” mode, and you can keep recording on top of the original phrase as many times as you want. Switch back to “infinite repeat” mode and the mess will go on forever. Kinda like The Royal Tenenbaums.

After taking care of the insides, I did a bit of work on the outside of the pedal. First I replaced the missing knobs with some I’d salvaged. I wanted to make sure they didn’t go missing again.

VERY carefully I expanded the slots of the knurled pots. This “pig iron” is an extremely cheap metal. It will break, so this should be done with the utmost care. Do not overdo it or you’ll have a broken pot. Do it just right and your knobs will be as snug as You, Me and Dupree.

The battery cover for this little guy was missing. As if you’d want to run a digital delay on batteries. It’s sucking 32mA on average and will suck life out of batteries quicker than The Darjeeling Limited can suck the life out of a theater. Curiously, it uses less power than its little brother, the DFX9. I still opted to close off the battery compartment rather than have a loose 9V battery snap flying about. I cut a small piece of plexi-glass and fit it into the battery compartment.

I like the DFX94, but some of the options are way more than any guitarist needs in a live situation. Noise “artists” should take note of it, however, because it can be a lot of fun screwing with this thing… unlike Drillbit Taylor.

more info on the DFX94: http://www.americaspedal.net/dfx94/