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The Opamp thread
Apr 12, 2010 at 9:27 PM Post #2,521 of 7,383
Quote:

Originally Posted by Spacehead /img/forum/go_quote.gif
All my AD8599 seem to hiss a little. Original op amp was NJM4556. I have cleaned it very well IMO, but maybe the denatured ethanol leaves some residue which is conductive.
Joints should be good.

Now I already changed the op amp to AD8620 but it had that hissing too, I wonder what is going on. I hope to get that fixed without failing the card.


I have not been able to fix that. That is maybe a failed card ... Can't believe it, just bought it!!!
 
Apr 12, 2010 at 9:35 PM Post #2,522 of 7,383
Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif
Then I would suggest you solder up something a bit more permanent.

You could clip off the bottom socket and solder the wires to the proper points. This way you would have DIP 8 sockets to use for your opamps tests. Of course you would have to come up with a method to keep the sockets/wires under control so they weren't just hanging. Between the top and the bottom ideas you should be able to come up with something.
Hope this helps.


I did my own adapter:
2lszl86.jpg


15g6ue9.jpg


w2gcn5.jpg


test results
http://i40.tinypic.com/121aeth.jpg
(Tested with Creative's testing methodology)


Card is terrible looking but works. But of course only for front channel.
 
Apr 12, 2010 at 10:33 PM Post #2,523 of 7,383
those tantalums sounded very harsh and hard. I had to remove them. I didn't have anything super good at hand so I used these mylar 0.1 uF capacitors. They sound softer and listenable now with AD8620. My ears are feeling odd now, maybe I am trying to find out imperfections or something.
k9wawy.jpg
 
Apr 13, 2010 at 12:05 AM Post #2,524 of 7,383
Interesting DIP -> SOIC adapter! BTW, something like a toothbrush can be used to remove remaining contaminants from the PCB.
 
Apr 13, 2010 at 12:06 AM Post #2,525 of 7,383
Interesting DIP -> SOIC adapter! BTW, something like a toothbrush can be used to remove remaining contaminants from the PCB.

Can see the low end roll-off on the LME49860 in the RMMA graphs.

Edit: this forum sucks for posting. Takes forever to respond. BLAH!
 
Apr 13, 2010 at 12:37 AM Post #2,526 of 7,383
Quote:

Originally Posted by 12Bass /img/forum/go_quote.gif
Interesting DIP -> SOIC adapter! BTW, something like a toothbrush can be used to remove remaining contaminants from the PCB.

Can see the low end roll-off on the LME49860 in the RMMA graphs.

Edit: this forum sucks for posting. Takes forever to respond. BLAH!


Yeah AD8066 gives best bass response.
I have used toothbrush too but I think that stuff is residue from the denatured ethanol... or does the toothbrush plastic dissolve in ethanol ?!

And about the dip to soic mod, this is huge for me! The changes in the source sound so clearly that I am pretty amazed.

And now I understand that ADA4627-1 is soooo transparent sounding in my PPAV2.

I could now try Intersil EL1516, that is one of my exocit and superfast op amps.
Luckily those 33 ohm output resistors on the X-FI layout slow op amps considerably and there is lot of compensation in the feedback loop too so EL1516 should work. I wish for extremely wide soundstage with precise detail and crisp mids, plus tight bass!
 
Apr 13, 2010 at 2:21 AM Post #2,527 of 7,383
These modern op amps are so good that their performance doesn't suffer so badly from bad conditions, long wires with lot of capacitance and inductance.
I made a single to dual converter carrier and installed it with OPA1611 x 2 to my so hard modded X-FI Fatality
smily_headphones1.gif

i2kcok.jpg


1607ya9.jpg


loopback Test results (LM4562 input op amp as always)
results gets a little worse as more wire gets added.
http://i42.tinypic.com/25zh0jn.jpg
RMAA
General performance Very good

BTW OPA1611 has pretty smooth sound or I am just tired?
 
Apr 14, 2010 at 5:44 PM Post #2,534 of 7,383
Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif
I know that page, i would like to know its sound and if is good to drive headphones
normal_smile .gif



My opinion is not so good but here is an objective article: Tangent
 
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