[ROBSCIX]

Quote:

Originally Posted by foureight84 /img/forum/go_quote.gif Yea it's a good idea. I thought it's kinda cheap since the OPA627SM goes for $70 each... This is $50 for two, so it does sound really too good. I noticed that he has sold a bunch and with 100% + feedback, he seems legit. I emailed the seller for more information as you guys suggested. Going to confirm with TI after.

It is better to be safe the sorry. I have heard both the OPA627 and 637SM and they are quite nice. As to if they are worth the asking price, that is up to you. I see by the other post you went with a different model over the TO-99 SM modules.

 

[buz]

Too late to go mess around with opamps tonight but I think I'll give this shot on Saturday...

I'm wondering, it is says
LT812
1028
(two lines) on the SMD chips - is that normal or are these clearly fake? If so, any place where I could get legit LT1028A, preferably already on dual adapters or possibly as DIPs?

 

[leeperry]

not fake

 

[buz]

So mine look very similar, except that it says 812 on them... Have not yet ordered any AD797. Ah well, will give the LT1028 a try on Saturday for sure.

 

[leeperry]

Quote:

Originally Posted by buz /img/forum/go_quote.gif it says 812

batch/plant number of some sort

 

[buz]

Ah well, if I don't feel it sounds good, I will go hunt for a real LT1028A

. And maybe that M-Stage while I am at it

 

[Spacehead]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif Then I would suggest you solder up something a bit more permanent. Brown dog has some adapters that may help...These->Link You could use the above to make somethign up. However, considering how you describe your card with all the points here and there You might want to go with some DIP8 extension cables int eh picture at the bottom from AudioGD-> Link 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 am trying very hard

that is a differential-to-single-ended converter

my SNR is very poor now, there is pretty loud hiss in the background. OPA1642 has good voltage swing there and output is quite distortion free.

I have not yet fully understood what I should do.

The CS4382 datasheet recommends Sallen-Key 2-pole filter to the dac outputs. It is implemented on the card but I am trying to learn things so I built my own.

I have gain of -6 there, so first I could try to reduce it. My PPA v2 has a lot of quiet gain available.

ps. bought another X-FI for better RMAA results (testing purposes).

 

[Spacehead]

There was still one good circuit on the X-FI PCB. I routed front channel to it from DAC and changed AD8066 to there. Nice clean solder joints and only 6 wires needed.

It didn't make the sound too bad:
http://i42.tinypic.com/25yx72h.jpg

SNR: 95 dB
THD: 0.0024%

I think that is hifi enough.

I have learned to solder soic8 op amps quite skillfully, it is very easy to change them now without breaking the pads.

 

[Mad Max]

Hmm, I thought through-hole soldering would be easier than SMD soldering, but i am finding the reverse to be the truth.

 

[Spacehead]

Quote:

Originally Posted by Mad Max /img/forum/go_quote.gif Hmm, I thought through-hole soldering would be easier than SMD soldering, but i am finding the reverse to be the truth.

And circuits done in SMD sound better due to lower noise.

 

[12Bass]

Depends... SOIC takes good eyesight and fine motor skills. Also, the lack of sockets is problematic for swapping chips.

 

[kuben]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif not fake

I can use those 797's in STX I/V?

 

[leeperry]

Quote:

Originally Posted by kuben /img/forum/go_quote.gif I can use those 797's in STX I/V?

they will fit, and will also most likely work...they work perfectly fine in my PCM1793 DAC, and AD797 is said to be a drop-in replacement for LM4562

the ebay seller is using better looking adapters now: http://i.ebayimg.com/22/!BqHZITw!Wk~...LwyoQ~~_12.JPG

 

[murrays]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif they will fit, and will also most likely work...they work perfectly fine in my PCM1793 DAC, and AD797 is said to be a drop-in replacement for LM4562

Not really a "drop in": the AD797 is a single and the LM4562 is a dual.

 

[leeperry]

indeed, I meant using adapters of course