[Filburt]

Just wondering. This is the op-amp I'm going to replace in my CD player, so I'm wondering if anyone is familiar with this chip and it's sound etc.

 

[Nerull]

Chances are good that, like the other JRC opamps (jelly beans) used in commercial CD player / DVD player outputs, they suck, pretty bad too. The good part is, you'll get better sound upon replacing them

. Make sure though to get dual or single respectively. It's definately a worthwhile upgrade, as I've done it twice and both times I've gotten really good results. Just make sure to try out a bunch to see which sounds best.

Also look into biasing to class A; and replace the nasty coupling cap that's probably after the opamp with something decent (my suggestion is Auricap, which are cheap and sound pretty darn good for the money.)

As always, happy listening!

~Tom

 

[Filburt]

Well I know it's a jellybean. Just wondering if anyone knows how it is soundwise. It's a popular line buffer to throw after the DACs on a lot of cd players and such, even being used in a Playstation apparently.

I'm replacing with either the AD8652 or AD8656. Class A biasing would require hacking in some sort of current source which would be pretty brutal to try to do in a portable device ;D

 

[Filburt]

Alright, well I ordered a few from Mouser and also will be getting an SOIC-to-DIP adaptor. So I should hopefully be able to test the NJM2100 versus the AD8656 head-to-head and decide if I'm going to replace the op-amp. Right now the cd player sounds great to me, but there's always that thought that I can improve it more than I already have (got 2 DACs on it already and some minor signal path stuff).

 

[Filburt]

Okay, I found a more common op-amp that sounds similar to the NJM2100. It's the AD823. Can anyone give me some suggestions on op-amps now?

I need the following: unity gain stable, runs on single-supply 5V, Rail-to-Rail Input and Output, <200nA input bias current, dual amplifier, and low noise and THD+N of course.

 

[quicksilver96]

What about the AD8517/8527? Specs are here.

Edit - Mmmm bias current a tad higher but you might be able to get it to work

 

[Filburt]

Well, I could get the bias current to work, but the rest of the specs don't look especially audio friendly, unfortunately. I currently am trying the AD8656 which is a bit smoother than the AD823 with more soundstage and depth, and maybe slightly less bright. Seems like it might be more detailed too, not exactly sure yet.

 

[quicksilver96]

Just an idea. This spec: single-supply 5V, seems to be the toughest to meet in something suited to audio

 

[Filburt]

Quote:

Originally Posted by quicksilver96 Just an idea. This spec: single-supply 5V, seems to be the toughest to meet in something suited to audio

Well, that's the one spec I have absolutely no control over. It _must_ run at 5v single supply.

After further testing, I think I may just go with the AD8656.