changing op-amps in a delay pedal

Discussion in 'Effects, Pedals, Strings & Things' started by ROKY, Jun 29, 2006.


  1. ROKY

    ROKY Member

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    Lots of talk of swapping chips in Tube screamer type pedals ..

    I have a couple of 80's Digitech delay pedals (PDS1002,PDS8000)
    and noted they use TL062 chips.
    2 to drive the input/output volume section of the circuit the 3rd I'm
    not certain about.

    Would I get a grittier/warmer sound if I used,say, JRC4558s or 59s ?

    I know they won't be analog in sound, but I'd like a fatter sound with
    more inherent dirt.

    Any thoughts ?
     
  2. basscracker

    basscracker Guest

    don't know :confused:,would seem so though.people do the exact opposite with the DMM,they take out JRC4558 and put in TLO72's for clear repeats.
     
  3. carltonh

    carltonh Member

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    I don't know, but as someone who also owns a PDS8000, I'm curious if anyone has used any power adapter other than the original one. I think mine says 11 volts on it. It gets quite hot whenever plugged in, so I worry that I may eventually have to use something else.
    My only other thought is, "How could it not be fat enough already?" The only additional thing I think someone might want out of the PDS8000 would be extremely short delay times.
     
  4. ROKY

    ROKY Member

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    Thanks for the input .. my own logic was leaning towards that .
    Also, thinking maybe the unit would be more U2-sounding w/ the hotter chips .
     
  5. ROKY

    ROKY Member

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    I power mine with a Pedal Power 2 using the 9-volt adapter cords
    Works like a charm .
    I use the PDS1002 when I need shorter delays.

    As far as not being fat enough, their not as thin/clean as say a modern
    Boss delay, but I'd like to add some more warmth dirt, and hoping swapping
    the chips might, in fact, do the trick .

    In the case of the PDS8000 it is grittier on the repeats at the longer settings,
    I'll admit it, but I don't use the really long delays, too much.
     
  6. Cusack Effects

    Cusack Effects Member

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    Since the Op-Amps are not used to clip the signal, you probably won't get any night and day differences between Op-Amps. If you change the Op-Amp, you may find a slight difference in distortion, but the distortion should be fairly low anyway, and you probably won't notice. Unless you put a really crappy op-amp in.

    If you want to make it sound bad, you are better off changing the resistors. Put in Carbon Comp resitors of a very high value. They will add a ton of noise. If you change all the resistors in a given stage with 10x or 100x their value, the gain will be the same, but the noise will go up. That may help obtain what you want?
     
  7. theelectic

    theelectic Guest

    LOL the opamps are already relatively noisy, being low power versions of the TL07x series :)
     
  8. GuitslingerTim

    GuitslingerTim Member

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    I substituted several different opamps for the JRC4558 in my Deluxe Electric Mistress with dramatic results. The TL072 was very bright and clear. The TL082 was fat and dirty--it may be just what the doctor ordered. The NE5532 had a thicker tone than the TL072, but offered more definition than the TL082. I also tried an OPA2134, and wanted to try an OPA2064, but Digikey was out of them. Both cost about $5 apiece compared to less than a dollar for the others. The problem with the OPA series is they are very fast opamps that can cause a flanger or other modulation effect to self-oscillate at extreme settings. I don't know if you would have the same problems with a distortion pedal. I've heard positive reviews of the OPA2064 when used in place of the JRC4558 in distortion or overdrive units.
     
  9. ROKY

    ROKY Member

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    Thanks a lot for the input/clarifications ..

    I don't necessarily want it to to sound "bad" as in garbled/distorted .

    Example:
    I get a certain harmonic goodness when I run the pedal thru a Guyatone Flip series trem
    a tube unit -- it makes for a thicker sounding delay; very natural.

    So I'd like a similiar tone w/ out being dependant on running it thru a tube box.

    So using different chips won't fatten the tone up, per se ?
     
  10. ROKY

    ROKY Member

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    Tim, thanks a lot for that !

    It looks like I need to just buy some chips and see what my ears like
    the TL082s sounds like one good possiblity .
     
  11. braughwd

    braughwd Member

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    I'd reccomend putting in a ic socket in, if it doesn't already have one. It'll make it way easier for you.
     
  12. ROKY

    ROKY Member

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    Oh,yeah, these particular pedals have sockets in them, already.

    I don't solder, so it's the only way for me..:eek:
     

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