[trooper05]

"Whatever you end up using, be sure to add a WIMA cap across the power pins (pins 4 & 8 on duals, pins 4 & 7 on mono/singles)"
 
Will this provide any benefit on a Asus STX? 
 
I currently run LME49990 super analytical OPAMP, I am after some OPA627's (Apprently sound more relaxed, laid back) but they are way too expensive and too many fakes around. Can anyone recommend something similar? Would OPA827 be a good choice?
 
Any advice would be appreciated! 

 

[pelopidas]

Just as there is a wild difference in electrolytic capacitor quality for audio so too do "oscon" type capacitors have variations in quality.
From what you were talking about, I am unsure if the capacitor is being used as an output capacitor or if it is being used as a psu cap. If you are talking about an output capacitor then I might agree with you that it should be avoided at all costs, but I would also avoid electrolytics at all costs too. If in a psu position it is hard to imagine that a polymer capacitor cannot supply electrons to a circuit.
From my empirical observations the Panasonic SEPF is a step down from Elna Silmic in any psu application. But it is much much better than a Panasonic FM for instance. It is a very correct sounding capacitor. Every little detail comes through cleanly and without harshness. All the bass comes out tightly without any muddy flabbiness. It's all there as it should be. It is incredibly fast. If you like fast electronic and want to hear every millisecond, every shiver of a cymbal, then try a SEPF. I actually use silmics bypassed with a lower value SEPF in my headphone amp. But don't take my word for it. Spend 2 dollars and try it your self.

 

[pelopidas]

To trooper
Try a wima so you know the sound, but then try a 10 uf Silmic on your 49990. I use the 49990 in my xonar bypassed with a Silmic and it might be what you are looking for. You keep the detail of the 49990 but add warmth and space.

The way capacitors are used close to the opamps is for stability. If you look at the product sheet you will generally see 10uf or 4.7uf and 0.1uf going from + to ground and from - to ground. This stabilizes the rails by removing any jitters and sending them to ground. However, the operation of the opamp is powered by the + and - and not by ground. While a 0.1 across the + and - is oftentimes used to calm an unstable opamp down (compensation would be much more effective) it is way to small to improve the sound. You will notice it if the capacitor you choose is sibilant. You will hear it in the treble, but 0.1 is not enough for the entire audible spectrum. When adding a capacitor to + and - you are in essence adding a power reserve to the opamp directly. In this position you will "hear" the capacitor. So it needs to be big enough to supply the whole dynamic range (think bass drum kicks which move the speakers in your headphones more than any treble sounds).

The immediate reaction to this might be "you don't want to hear a capacitor!" Well, there is no way around it. In your STX, your power comes from the computers PSU. Lots of "sufficient" capacitors there for powering your computer but all of them awful for audio. From there it goes to the STX which will have some filtering using more capacitors to clean up the noisy power of the computers PSU. From there it goes to your opamps that are bypassed to ground for stability using ceramic (yuk) and film and you also have some electrolytics there (nichicon fine gold?) for power reserve. All of these capacitors have an effect on your sound. This is why you need to choose the very best sounding capacitor to be the very last one in the chain.
For me it is ELNA Silmic on my xonar. it goes to my headphone amp which is a mixture of Silmic and SEPF and then finally on the opamps in my headphone amp I have ELNA Cerafine because they have a beautiful clarity that complements the full and rich Silmics.

So the fact is, you will be listening to capacitors so you have to choose which ones sound best to you.

 

[trooper05]

Thanks for the info @pelopidas How do you bypass on them small LME49990, you put in between pins 4 & 7 on both OPAMPS? Or is there a better way to do it?

 

[pelopidas]

I am assuming you have your 49990's on a dual adapter. In this case just go from + to - so pin 4 to 8. That will take care of both. If they are single soic then 4 to 7.
But you have a STX don't you? So you have sockets for dual opamps. Try it like the pic I attached. That's what I use in my xonar

 

[trooper05]

@pelopidas
Thanks for the info, I understand what you mean now, the capacitor is there to store a small amount of energy to ensure stability of the OPAMP. I am going to  try it on my LME49990 

, I didn't see the picture yesterday on your post seems simple to install. I guess my only concern is fitting the EMI shield back on

. 

 

[pelopidas]

I look forward to your impressions. Leave the emi shield of for a while so you can play around with different capacitors.
You can read about my experience a few pages ago.
www.head-fi.org/t/432749/the-opamp-thread/4905#post_11796572
 
As a side note, I started this by being dissatisfied with the bass on the AD797. 10uf Silmic totally changed that opamp, put some meat on the bone so to say.
As a side note, ( i guess the other side) is once you do this to the AD797 and LME49990 other opamps such as the 49720, 49710, 2107, 5534, 827 and even the LT1028 prove to be really inferior. My no.1 is 49990 with silmic and next is 797 with silmic. The 49990 is more spacious, noticeably better noise rejection and has an ease about it while being super detailed.
 
Can anyone recommend anything that tops those? Are the muses really worth all that extra money?

 

[trooper05]

@pepopidas
 
I just read your experience from a few pages ago, it seems you have experimented with various OPAMPS and capacitors 

. I have 10uF 25V ELNA on the way, I will post impressions once I have installed them (cant wait). 
 
I have only experience with 49720, 49710 and 49990, and stock OPAMP on STX. If you do find anything better than the LME49990 let me know! The only OPAMPS I hear that are better are discrete and are super expensive. 

 

[pelopidas]

I look forward to your impressions too. Don't just do the silmics, if you have any film, silver mica or anyother capacitors sitting around right now you can try it out. This way you can get a feel for what they sound like. Then of course, let us all know what you found out!

 

[trooper05]

I bypassed the LME49990 with 10uF 25V ELNA today. I am actually speechless on how much the sound has improved, there is more separation, detail and control in the lower frequency's. The background is black, the sound has become dark. Everything you stated in your earlier posts (www.head-fi.org/t/432749/the-opamp-thread/4905#post_11796572) was accurate. The sound is more relaxed exactly what I wanted.  I honestly did not expect so much improvement from this cheap mod

  
 
I even de soldered  and re soldered them to double check it was not my imagination
 
Next thing to try is a wima cap, I think I will stick with this for a few hundred hours first let them caps burn in, not even past the four hour mark yet 

.
 
The LME49990 also runs way cooler, anyone who is having trouble with hot OPAMPS should do this mod!
 
Thank you @pelopidas for the information!  

 

[pelopidas]

It really is interesting how much the 49990 benefits from this. The 797 also really is transformed but other chips not so much. I tried the 49720ha with the Silmic and a whole bunch of other capacitors but all that happened is that it removes a certain haze that only illustrates that opamps short comings. I think it is, like you said, the very black background that really exposes the true capability and sound of the opamps. The silmics, more than other capacitors, really lock the sounds solidly in the sound stage. That clarity is what I miss most when rolling non-Silmic-bypassed opamps now.

 

[SpudHarris]

Got a few caps on route for testing but have some Muse 33uF here. Which lead goes to pin 4, the long or short?

Sorry if I sound like a bimbo

 

[trooper05]

Here is the pinout for both a dual or single OPAMP:
                           DUAL                                                  SINGLE

              
 
The longer leg is normally the positive, so the shorter leg will go to pin 4. Unless of course you have a bipolar capacitor then it wont matter. 

 

[ScottFW]

Nichicon Muse caps are bipolar if memory serves. Newer ones have "BP" marked on them. For the electrolytics where polarity matters, I find it easier to rely on the stripe that identifies the negative lead.

 

[SpudHarris]

Thanks both for the replies

These are what I am hoping to use. I've had them for ages as I used to make LODs for my imod.