what electrical characteristics we should care when upgrade op-amp ?

[huu_tri0101]

I want to upgrade better op-am in my audio amplifier ( old one is JRC 4558), what electrical characteristics in new op-amp I should care when upgrade ? What characteristics need better? What characteristics need the same ?
Thank you everyone.

[madshaman]

Noise specs and harmonic distortion for the sound.

To make sure it will work:

GBW (same is ideal, or a bit lower if can't match),  The output swing under the old opamp's supply needs to match or exceed the old one's, also the output driving ability needs to meet or exceed the old one's.

Efficiency should match or exceed the old one's.

Even with this I'm leaving a lot out and might have omitted something important.

Good luck!

[tszaboo]

Even with this I'm leaving a lot out and might have omitted something important.

Like power supply voltage limits 
Audio opamps, and opamps in general are magic. There are hundreds of parameters missing from the datasheet, which might be important.

[madshaman]

Even with this I'm leaving a lot out and might have omitted something important.

Like power supply voltage limits 

No, I covered that:

The output swing under the old opamp's supply needs to match or exceed the old one's

I am assuming the OP knows enough to check the old opamp's supply is tolerable for the new opamp; I figured it should be obvious from the above statement or there's not a good chance the OP will be able to succeed other than by accident.  In any case, they know now.

Audio opamps, and opamps in general are magic. There are hundreds of parameters missing from the datasheet, which might be important.

Could you please elaborate?  I think the values in most data sheets would be more than enough to pick a suitable replacement.  If not, I would also like to learn what I may be missing when choosing an opamp.

What parameters are missing that would lead to failure if not known?

[free_electron]

you missed an important one : same pinout and package !

[madshaman]

you missed an important one : same pinout and package !

:-)

[madshaman]

Even with this I'm leaving a lot out and might have omitted something important.

Like power supply voltage limits 
Audio opamps, and opamps in general are magic. There are hundreds of parameters missing from the datasheet, which might be important.

My sardonicism sensor is broken again isn't it :-)

[tszaboo]

My sardonicism sensor is broken again isn't it :-)

Ok, it is working again 
But in general, they tend to leave out capacitive loading, effects of EMI, power off characteristics (as strange as it sounds it is actually sometimes important), channel crosstalk vs frequency, latch up behavior,  THD vs load, and other significant characteristics.

[scratch_monkey]

My advice, for audio gear, unless the opamps are free, don't bother. Put the money towards better speakers. Or more music. The faults of modern audio amplification systems are insiginificant compared to to horrible response of any mechanical device, for example, your speakers.

If you want to go really exotic, build a plasma tweeter.

[madshaman]

My sardonicism sensor is broken again isn't it :-)

Ok, it is working again 
But in general, they tend to leave out capacitive loading, effects of EMI, power off characteristics (as strange as it sounds it is actually sometimes important), channel crosstalk vs frequency, latch up behavior,  THD vs load, and other significant characteristics.

Lol.  And thanks.  This situation is so hard to give advice for, it's almost a situation where if you need to ask, you really need someone else who doesn't need to ask to choose for you, but it's hard to indicate this without sounding like you're trying to put the OP off.

I suppose indicating that swapping an opamp isn't quite as simply as maybe switching to a new brand of windshield wipers or spark plugs or ink cartridges (and still, only certain replacements are viable) has value.

[madshaman]

My advice, for audio gear, unless the opamps are free, don't bother. Put the money towards better speakers. Or more music. The faults of modern audio amplification systems are insiginificant compared to to horrible response of any mechanical device, for example, your speakers.

If you want to go really exotic, build a plasma tweeter.

Don't forget the frequency response of the listening room, that will also nullify good speakers.  At least with a room you're pretty much assured a linear response (not to be confused with a flat response); that's not the case with the speakers or the amplifier.

[Monkeh]

I want to upgrade better op-am in my audio amplifier ( old one is JRC 4558), what electrical characteristics in new op-amp I should care when upgrade ? What characteristics need better? What characteristics need the same ?
Thank you everyone.

You will not achieve any audible difference. Leave it alone.

[madshaman]

I want to upgrade better op-am in my audio amplifier ( old one is JRC 4558), what electrical characteristics in new op-amp I should care when upgrade ? What characteristics need better? What characteristics need the same ?
Thank you everyone.

You will not achieve any audible difference. Leave it alone.

On the contrary, I believe the OP could achieve an audible, visual, olfactory *and* financial difference unless they follow your advice *or* do lots of reading and build some simple opamp-based circuits before attempting the operation; then there's a chance for no audible difference ^^'

To the OP, none of this is meant as derogation, it's more a suggestion and opportunity to do some studying and learning and not have to take this advice of others as authority; particularly *bad* advice that can come from random audio forums.

I can recommend some good books on sound reinforcement, amplifier design and basic electronics if you're interested.  The only difference between some forum members and yourself is that they've studied these things already.