Well, I have another 40 opamps coming of various specs. Most for my amp though.
post #1171 of 2194
9/5/07 at 1:03am
Cheapo SOIC Socket-Hack done.
- no more slobbering on X-FI SMT pads and feeling guilty about cutting legs off "good" op amps. - (weeeeee!)
- SMT pads on board seem to be robust enough to handle insertion forces. (very light with this mod, compared to DIP8)
- will most likely add some epoxy for added safety.
AD8599 is a very nice sounding op amp, compared to LME49860/720
- first impression is, ummm, "more classical" than LME's, with same low and high clearity.
RMAA results show no obvious anomalies and slightly better distortion figures.
- will leave it to Germanium to critique
SOIC socket hack - parts:
Finished op amp "module:"
SOIC socket hack - AD 8599 installed in Line-Out position:
SB0460 with AD8599 op amp, Line-Out - sample rate: 96k - tantalum bypass - op amp SOIC "socket hack"
RMAA Results: http://www.esnips.com/doc/202603be-5.../X-FI-MOD-035b
RMAA Detailed: http://www.esnips.com/doc/d13bdb7a-3.../X-FI-MOD-036b
Yes I was going to try that & see if it helps here . It has gernerally worked before. This is bypassing the 2 -220uf caps by the opamps I tried it before but never looked closely at the IM distortion which improved in good portion. Even though the bass is very solid now, better than stock , I feel there is still room for improvement. Looking to put about 10uf here. You see my tests Ter1?
I guess I have been very busy on here lately haven't I??
"...The LME49680 appears to have the classic lower negative feedback distortion characteristics. Higher low order distortion & cleaner high order which acording to the accepted thought on feedback & distortion the LME49680 would have the upper hand & sound less clinical. Is that what you mean by discribing the AD8599 as more "classical" as in more clinical like older opamp designs Bichi??..."
The fact that the distortion characteristics are plainly visable & different, even with such a low grade ADC handicapping the design, it appears that the LME49680 is not the low distortion part it is claimed to be.
I would try to get the NJM2114 to compare as that is what comes stock on my card. It seems to actually have better distortion characteristics than either of these in this circuit.
Hi Germanium, can you have a summary of all your mod of x-fi elite pro in one post? Of course you can modify it based on your new founds.
Some other questions,
1. I remember you said after you bypassed the 2 220uf caps by the opamps, the highs are too bright, so you don't suggest doing that? You have changed you mind on this? You suggest 1 10uf metalized caps now for the 2?
2. The 2 220uf by the opamps are for power supply? If so, BG will be good choice, right? The original is 25v 220uf, can I replace them with 16v 1000uf BG ones? The voltage is okay?
3. What are the functions of the 2 columns of 25v 100uf and 16v 47uf caps? For power supply use or other use? What caps do you suggest besides BG caps that I can replace them with the same voltage and capacitance?
4. For question 3, do you still suggest "100" be bypassed with 2 3.3uf and "47" be bypassed with 1 3.3uf ?
5. Do you still suggest bypass the 220uf power supply cap near DSP with1-3.3uf metalized film cap?
Thanks! You are so welcome here!~
Thanks for the detailed analysis!
- guess I'll have to send you two sockets and a few op-amp "carriers" so you can enjoy easy op-amp swaps, eh?
- PM with mailing data, if interested.
Yes, "classical" as in clinical. Refrained with accuracy and "blending," as opposed to, ummm, "excited."
- would be interesting to see how a LME49840/760 would spec on your SB0550 and its digital section...
- could mount a LME and NJM2114 on two carriers, provided you manage to get a socket soldered on.
Completed an analysis of various single freq, whitenoise digital playbacks and RMAA.
- see no ill effects of digital section power (tant) and socket modifications.
- beginning to wonder if "technical" improvement limit is the DAC/ADC, and not so much the op-amps.
Have ordered a handfull of NJM2114's and should be here in a week or so.
Also pondering "pinning" coupling cap terminals, for easy shorting or cap coupling with various types.
Sounds like my analysis was correct for the sound of the AD8599 from the graphs you provided.
I also noticed an wild variation of open loop phase distortion in the audio band in the graphs provided by Analog Devices which may be contributing to thier less favorable high order distortion plot but on the other hand this may be a case of AD being more honest than many others in the open loop plots. AD provided substantially more detail about a lot of things including what percentage of thier yields tested to within certain tolereances.
Let me know how thing go in your tests, ok.
Yes the DAC is our limit. Our opamp mods or cap mods won't better the RMAA numbers. BUT, changing the opamp can change qualities RMAA doesn't measure, like detail. Look for an opamp with higher slew rate. 50-150 V/us, and lower settling time (500 to 50ns). This will help bring out detail. I have to change this damn OPA2132 though, the sound is nice and detailed, but lacks the impact and brightness I need. Way to mellow for me.
- will do....
- interesting you mention "phase distortion" on AD8599
- could have sworn a bassoon "moved" on a fade out, during a listening test (wrote it off as my imagination...)