Working up a distortion pedal that calls for a JRC4560. I have everything but. What would be best? JRC4558, JRC4580, TL062, 72, 82, NE5532. Started to look at data sheets but I'm called blearyeyes for a reason.... :P
I am going to experiment but any technical reasoning to pick one over another would be appreciated.
The 4580 is fairly close in specs.
Quote from: Scruffie on April 03, 2018, 08:46:24 AM
The 4580 is fairly close in specs.
Thanks Scruffie.
Is the 4560 newer?
Not a clue, see if there's some dates on the datasheets.
I have learned it is annoyingly tricky to nail down release dates for a lot of the ubiquitous chips we use.
That said, I can find info on the 4560 going back to 1991, and the 4580 to 1994.
Were these when they were released? Not a clue! I'm not even sure where one would go to look and google is just confusing matters!
I'm usually overwhelmed with the onslaught of information. It's a freaking guitar pedal. I should just get a few fakes off of eBay and I'll enjoy the effect of thinking it is correct for the design.
Always sounds better that way.
I should really check the datasheets again before I say this but as i'm feeling lazy i'll go off memory and say I think the 4560 & 4580 are pretty much lower noise/higher bandwidth versions of the 4558 with slightly improved slew specs but the slew rate is still much lower than say a TL072, so they could potentially distort a bit nicer depending on the circuit and depending on what your definition of 'nice' distortion is.
But yes, I think you'll get most of the actually audible qualities of those specifications from a relabelled mystery dual opamp.
I looked at the datasheets for the 4558/4559, 4560, and 4580, and the equivalent circuit diagrams. They're all pretty similar, though as the ID number goes up you get significantly faster slew rate and the 4580 also has a better noise rejection spec. But even the 4558 has a slew rate of 1 volt/micro-sec, which ought to be plenty fast for audio applications. (Figure that a maximum slew would be 5 volts at 10,000 Hz, which is 0.05 volts/micro-sec.) I would be comfortable with swapping any of these around.
Sometimes, different types of op-amp designs behave differently when hitting the supply rails, which might make an audible difference (for distortion - clearly in an undistorted application you don't want to hit the rails). But the 45xx designs all seem pretty similar to each other.
I'll put the 4580 in to test and ordered 4560s from china. Case closed.