[]|[ GorE]

Changed the JRC4556A on my Audigy Value card to the AD8620AR.

Result : on my 40 ohm PHilips HP805 , theres no WOWing "improvement" as such to me.Sure,theres a bit more of ambience and atmosphere and a slight recession of mids compared to the JRC4556A but these cons of the JRC are certainly not enough to put all the blame of the Audigys output stage on the opamp itseld.The JRC4556 is a nice and fine "warm" sounding opamp which will satisfy most people including me.

Conclusion: A last 10% improvement of the sound card.Not worth voiding the cards warranty.

 

[]|[ GorE]

V+ and V- bypassed with 10uF , 0.1uF tantalum and 30 nF ceramic caps.

 

[fewtch]

The rest of the Audigy is probably not very good, so maybe that's why you don't notice much improvement. If the DAC isn't good, just improving the analog stage won't gain you much.

 

[]|[ GorE]

Could it be oscillating ?

 

[]|[ GorE]

IS + and - 5V supply being provided by the sound cards voltage regulators good enough for the opamp ? I guess not. Maybe i should put in the AD8397 which is supposed to work from + and - 3V upwards.

 

[guzzler]

Why guess? Look at the datasheet:

Quote:

Dual Supply Operation: +/- 5V to +/- 13V

 

[sgrossklass]

This seems to confirm that within certain limits, power supply buffering/decoupling is of yet higher importance than the opamp itself, and this had already be improved beforehand with good effect.

 

[jiiteepee]

On CS4382 evaluation board data sheet (8 ch DAC) has been used a Fairchild's NE5532 op-amp. How this op-amp compares to JRC4556A, or to ST4558C (which one has been used on Audigy 2, 2 Zs and 4)?

jiitee

 

[guzzler]

The 5532 is the generic "audio" opamp and is used in a lot of products. It's not bad, and for the price they're unbeatable. There are, however, better chips out there. The 455x are in a similar bracket, but personally I don't really like them

 

[thedoctor]

Quote:

Originally Posted by ]|[ GorE Could it be oscillating ?

you do have proper power bypass for the Opamp. so i doubt it's oscillating. and AD8620 isn't as picky as AD8066. try touching the Opamp after maybe 20 minutes of music. if it's hot, then you have a reason to worry.

 

[]|[ GorE]

The opamp doesnt even get warm.

 

[Clutz]

Quote:

Originally Posted by ]|[ GorE The opamp doesnt even get warm.

It's not clear to me why you suddenly think it might be oscillating. Is it because of a lack of improvement in sound quality, or something else?

 

[]|[ GorE]

I guess its because people prasie the ad8620 like well.....you know .

 

[guzzler]

Quote:

Originally Posted by ]|[ GorE I guess its because people prasie the ad8620 like well.....you know .

Just putting a good opamp after a bad DAC stage isn't going to make the DAC sound good. Changing opamps will (for some people) subtly change the overall sound, but the major part is dominated by the input.

 

[]|[ GorE]

Quote:

Originally Posted by guzzler Just putting a good opamp after a bad DAC stage isn't going to make the DAC sound good. Changing opamps will (for some people) subtly change the overall sound, but the major part is dominated by the input.

True.The card does have an inferior dac.