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>Is it likely that 1/2It's certainly -possible- for this to happen as it's a dual opamp. Check the
>of a TL082 would fail like this? Is a TL082 a common part easily replaced?
>I'm little bit less certain about the source of this problem, but afterMy limited understanding is that in general, the 4558 is not a good part
>studying the schematics for a while I think this is most likely caused by a
>4558 opamp that all voltage sources to the VCF go through. Do my findings
>make sense? Is it likely that a failed opamp would behave like this? Is a
>4558 a common part easily replaced?
>3. I recently read online about a simple modification for JP-8. Someonevolume
>suggests changing the opamps at the final output amplifying stage of a JP-8
>to a better, low-noise opamp (they suggest NE5532) to reduce background
>noise. This person never tried it on a JP-8 but did it on several other
>Roland products of the same period that suffer from the same type of
>background noise that I notice in the JP-8. Careful setting of output
>and adjustments on my mixer can reduce the noise acceptably, but it wouldbe
>good to improve it more if possible.Screw that 5532 crap and get an Analog Devices OP275.
>The JP-8 output stages have 4558 and 4556 opamps. Each voice uses severalto
>4558 and some TL-082. These particular TL-082 were individually tested for
>slew rate before installation at the factory. Do you think it is worth
>replacing the few opamps in the final output stages? Is worth the trouble
>then replace opamps in each of the 8 voices? Can I do these kinds of partsThe 4558 has a terrible slew rate and doesn't belong in the audio path in my
>changes without damaging the overall warmth and sound of the JP-8?