what opamps would you use here? JBL cs60.4

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Looking at playing with the front ends on a jbl cs60.4 (mobile audio) amp I have.


Thinking opa1642 for (1) and ne5532 for (2) based on impedance's, but not sure.. Chose those also because i have those parts already 🙂. I do not care about the other opamps, they will not be used for the most part. Ditto for half of (2), bass boost wont really be used.

Just hoping to play around with this one a bit since i have schematics.. I also have a dscope, so i can look closely at results.


Thinking decoupling will need a closer look if i use opa1642 on front end as well.
 

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That schematic omits the supply rails completely - yes fast opamps need fast decoupling between rails, close to the packages.


Also IC202A is directly driving an RCA jack - most opamps need an output resistor to be stable driving long cables, so that needs fixing. 100 ohms is usually enough for most opamps.
 
Sorry, I cut that section off. +/-15v, realistically 14.5v though. There is a 100u and a .1u on each rail, but plopped in the middle of all opamps.

Nice catch on ic202, that is odd there is no series resistance. I wont be using that circuitry, but i'll keep in mind.
 
Not sure improving Op Amps will significantly "improve sound".
4558's here are used conservatively, well within their capabilities, and signal level is high, so noise isn´t really a problem either.
But of course it´s your time and money 🙂
 
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