Members thegamestop Posted May 13, 2010 Members Share Posted May 13, 2010 I bought an old DOD fx50 overdrive preamp at a pawn shop today cheap to mess around with. It has a chip marked tl022cp that has four prongs on either side. I have switched the chip in a rat pedal to put in a lm308n in that pedal. Can I do this kind of mod with this pedal? Any guides to what chips can be replaced with? The lm308n added a more grittier sound to the rat, and I would like to do that with this pedal or give it some more low end. Link to comment Share on other sites More sharing options...
Members cmog Posted May 14, 2010 Members Share Posted May 14, 2010 The TL022 is a dual low-power op-amp. It is common in mass-manufactured pedals, known to be used for controlling rate/depth of clock drivers in modulation pedals. It draws little current, which is a good thing in LFO circuits. But it is probably used in the DOD overdrive due to its low power consumption. You can use any dual op-amp - JRC4558, TL072 etc. Changing the TL022 will probably provide higher amplification and less noise as well - bonus Link to comment Share on other sites More sharing options...
Members ALoserNamedAron Posted May 14, 2010 Members Share Posted May 14, 2010 Socket it with one of these and swap em in and out. http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets You can get better ones from smallbear with a few IC chips as well. ~Aaron Link to comment Share on other sites More sharing options...
Members thegamestop Posted May 14, 2010 Author Members Share Posted May 14, 2010 Thanks guys, I found a small article about changing the capacitor. I changed the only capacitor in the pedal from a 47 uf to a 470 uf, because I read the higher the value the more bass response. I haven't got to mess with it much more. Link to comment Share on other sites More sharing options...
Members devonteran Posted May 14, 2010 Members Share Posted May 14, 2010 Socket it with one of these and swap em in and out.http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets You can get better ones from smallbear with a few IC chips as well.~Aaron This. Have fun, go to radio shack and buy a few chips. Swap them in and out to see what you like the most. I did this with my GGG tube screamer and can't remember what I settled on, but they were all different. I'll have to go double check now because I'm curious. Link to comment Share on other sites More sharing options...
Members spentron Posted May 15, 2010 Members Share Posted May 15, 2010 I changed the only capacitor in the pedal from a 47 uf to a 470 uf, because I read the higher the value the more bass response. There's a few caps in that pedal, and I don't think that's an interesting one. Looking at the FX50B, that one has almost flat response except for a tone control network, but no one seems to have an FX50 schematic. Its probable basis in the 250 and the MXR Dist+ would indicate a .047 or .05 cap connected to pin 2 or 6 of the IC, leading towards the gain control, as a primary bass roll-off, but only as gain is increased. You can try randomly swapping around tone parts but knowing how it works is a lot better. Link to comment Share on other sites More sharing options...
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