How bad is the JRC 4556 opamp ?

[]|[ GorE]

Guys,
I was thinking of changing the JRC4556a opamp in my sound card to the AD8620.But another head-fier,"amol2003" did the same and was pretty sure that there was hardly any difference in the sound.He said it was placebo.
Now he has a cmoy and the HD-580 .......

So is it really worth changing the opamp ? since i will be running it via my cmoy.Maybe i could attach some bypass caps. to the opamp be done with it.

My current issues with my setup :
Slightly slow bass decays.
Slightly lacking texture.

Oh and is it true that when i use my cmoy via my sound card,the sound cards opamp isnt loaded as much as it would have ,had i connected my headphones directly into it ?

 

[morsel]

It is a decent opamp. I would leave it alone, but then again, I'm not big on rolling opamps.

 

[]|[ GorE]

I cant hear the difference the cmoy is making ! It sounds the same via the cmoy.Isnt the cmoy take the load off the sound card and its opamp ?

 

[fewtch]

Quote:

Originally Posted by ]|[ GorE I cant hear the difference the cmoy is making ! It sounds the same via the cmoy.Isnt the cmoy take the load off the sound card and its opamp ?

Listen to it amped for a few days, then switch back to unamped and see if you hear a difference... it's usually much easier to hear degradations than improvements.

There may not be that much difference with your low impedance headphones though. Unbuffered amps are not optimal with low impedance cans... consider buying or building a MINT instead.

 

[]|[ GorE]

I connected a 0.1uF and a 20nF capacitor parallel between V+ and V- of the opamp.Is that okay? Or does it have to be in between the rails and ground only ?

 

[mono]

Quote:

Originally Posted by ]|[ GorE I cant hear the difference the cmoy is making ! It sounds the same via the cmoy.Isnt the cmoy take the load off the sound card and its opamp ?

Think about what a CMOY is doing... taking the load off the soundcard opamp, but then placing the load on another opamp again.

My impression of 4556 is that it's very raw sounding. Ultimately you might want it replaced, or to replace the whole sound card but not yet- the more immediate (and larger) improvement is to not have a typical low-current opamp directly driving headphones. Essentially, part of the whole reason many move up past a CMOy to some other buffered amp design.

 

[]|[ GorE]

Update:

Cap. impressions:
The bypass caps seem to be revealing a bit more mp3 enconding artifacts.This always leaves the impression of added texture.RMAA tests indicate almost no change in any parameters.
But the peaks in the noise graph have reduced a bit.

I also change the 100uF 16V cap near the cards voltage regulator to a 470uF 35V Samwha SD Electrolytic cap.

Next step.Change electrolytics near the dac to polypropylenes.

Any suggestions ?

 

[ericj]

Quote:

Originally Posted by mono the more immediate (and larger) improvement is to not have a typical low-current opamp directly driving headphones. Essentially, part of the whole reason many move up past a CMOy to some other buffered amp design.

OK, but the 4556 is not a low-current opamp, at 70ma per channel.

There are better opamps for sure - even the njm2068 imho, which can sink roughly as much current and is faster, higher bandwidth, and lower noise.

On one hand, it's probably better to move amplification to something with a cleaner power supply than a computer.

On the other hand, if you wanted something to warm-up the sound, the 8610 is not the opamp for the job.

The differences from opamp to opamp are pretty tiny in any case.

 

[jbloudg20]

I am a big fan of the 4556. It is cheap, has a high output current, and sounds good. I don't think it will be worth the change for you to go to another. I would definately look at investing in a better amplifier, as that will probably yield better results.

 

[mono]

Quote:

Originally Posted by ericj The differences from opamp to opamp are pretty tiny in any case.

Have you not built an unbuffered headamp, a la CMOY and swapped chips? The differences might not be night and day on an absolute scale but in the context of hi-fi, IMO they're different enough driving loads.

 

[]|[ GorE]

Okay........i guess this is the end of the headphone road for me for 3-4 years anyway.
Thanks for all the help i have received from your guys.Bye !

 

[Xakepa]

Don't want to hijack the tread, but one thing engineers allways seem to appreciate is modular design. I mean...isn't it superior to have seperate componnts for every step of sound reproduction?...like

-bit-perfect digital output source (soundcard, deck, DVD-A...whatever)->
-DAC->
-amp->
-speakers/cans->

For instance, when I'm looking for a soundcard, I care most about the quality of the DAC (as I can't afford dedicated one) and ability to bypass any amplification - which AV710 does. I'll build my amp the way I like it...for the cans I have.

This way, modding a SC for better amplification seems like a half-hearted affair...

Just MHO

 

[ericj]

Quote:

Originally Posted by mono Have you not built an unbuffered headamp, a la CMOY and swapped chips? The differences might not be night and day on an absolute scale but in the context of hi-fi, IMO they're different enough driving loads.

Yes, but some days i hear it more than other days. The differences are subtle.

Maybe my point was that i wouldn't bother much with modifying a sound card. It'll only sound as good as the power supply, and that can only be filtered and isolated so much.

 

[mono]

Motherboard integrated sound I usually find to be quite horrendous, even having to fiddle with the mixer muting (or oddly enough, UNmuting channels to get rid of buzzing, even moving sliders on the MIC unmuted till a value results in less buzz than muted does (with no mic plugged in).

Sound cards, some aren't all that bad. It's common to find a linear regulator and they can be fairly quiet. Not perfect by any stretch but if that's what you want for a source then... might as well make the most out of it. That's not meant as encouragement to first do that though, I'd still look at a better headamp than an CMOY first and that'll be useful beyond a computer source too.