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Hotrodding the X-Fi: A Layman's Guide (No 56k) - Page 73

post #1081 of 2194

(X-Fi Fatal1ty Sanyo Os-con SEPC 820uF 2,5V for main chip voltage filtering used)

This attempt not helped me to get rid of the pause bug - eg. pausing and unpausing movie with any player, using AC3 filter 24bit output cause switched channels or terrible noise after unpause.
Damn.
Bridging the polymer with 10uF SMD ceramic helped more, but it is still like 50/50 chance to get a pause bug there. Panny FM 470uF with 4,7uF ceramic helped me much more before, damn.
post #1082 of 2194
Quote:
Originally Posted by trodas View Post
(X-Fi Fatal1ty Sanyo Os-con SEPC 820uF 2,5V for main chip voltage filtering used)

This attempt not helped me to get rid of the pause bug - eg. pausing and unpausing movie with any player, using AC3 filter 24bit output cause switched channels or terrible noise after unpause.
Damn.
Bridging the polymer with 10uF SMD ceramic helped more, but it is still like 50/50 chance to get a pause bug there. Panny FM 470uF with 4,7uF ceramic helped me much more before, damn.
That's the dumbest thing I've seen, 2.5V is no where near what voltage rating is needed. Now 16v is above spec, but you need 6.3v minimum.

Especially since oscons are sensitive to overvolting.
post #1083 of 2194
Quote:
Originally Posted by germanium View Post
"...I would not use non polarized caps between the DACs & the opamps as there is a fair D.C. voltage on them & I understand they take a very long time to break in as well. D.C. coupling is a better route in most cases. The D.C. voltage could alter the caps characteristics over time. Non polarized caps are designed to be used situations with very little or no D.C. offset. Polazed caps should have at least a 50% voltage bias on the so they don't go negative on the positive terminal with A.C. signal applied. When D.C. coupling the DACs to the opamps on the X-Fi cards The D.C. cancels out in the opamps so it is not a problem in most cases.
Quote:
Originally Posted by LawnGnome View Post
This I agree with.
I have had measurable increases in SQ even when only changing the power caps on the digital side and for the DAC.
Test results in my thread.
I should have been more clear...
- not the polarized DAC facing caps, but the output facing coupling caps for line-out.
- *oops* looking at the card more carefully, it appears op amp outputs are DC.
- can't tell if the MOSFETs (J1, 02N) are used as buffers or switches. (mute?)

Replaced Line-In, MC33078 (MIC-IN, mono-mode with 1/2 the opamp not used, not LINE-IN opamp) with LME49860.
- this op amp is coupled with bi-polar 10uf @ 16vdc.

While the card was out...
- replaced two Jamicon 100uf @ 16vdc (C16, C46) with Panasonic FC 220uf @ 25vdc

Picture of mod summary, to date:
http://www.esnips.com/doc/b1bf5a95-d.../X-FI-MOD-013b
post #1084 of 2194
Quote:
Originally Posted by trodas View Post
(X-Fi Fatal1ty Sanyo Os-con SEPC 820uF 2,5V for main chip voltage filtering used)
Get that 2.5vdc cap off and replace with unit rated at 6.3vdc or more!
- PCI bus/slot is feeding 5vdc.


EDIT:
*wait one*
- trodas
might have a point....
- the TI PS54352 is a switching down-regulator, 5vdc in, with an output of 1.2vdc.
- so the 2.5vdc he installed might be ok, depending on which side of the regulator its on.
- will have to yank and look at card again.....

EDIT 2:
- trodas is either lucky or knows what he's doing. (guessing the latter...)
- C177 is on the 1.2vdc side of the down-regulator!
- measured, card installed and powered-up, across C177, with Fluke 8012A
- thanks for the new data!

Texas Instruments PS54352:
http://www.ti.com/lit/gpn/tps54352
post #1085 of 2194
Quote:
Originally Posted by bichi View Post
I should have been more clear...
- not the polarized DAC facing caps, but the output facing coupling caps for line-out.
- *oops* looking at the card more carefully, it appears op amp outputs are DC.
- can't tell if the MOSFETs (J1, 02N) are used as buffers or switches. (mute?)

Replaced Line-In, MC33078 with LME49860.
- not much effect on RMAA tests.
- this op amp is coupled with bi-polar 10uf @ 16vdc.
- will have to test with live recordings, some future date.

While the card was out...
- replaced two Jamicon 100uf @ 16vdc (C16, C46) with Panasonic FC 220uf @ 25vdc

Picture of mod summary, to date:
http://www.esnips.com/doc/375f3914-8.../X-FI-MOD-013b
The nonpolarized caps might be line in coupling caps. Check the voltages on them. If there is substantial voltage do not remove if very little the Direct couple it. I can't see you picture clearle enough to determine which are polar & which are nonpolar caps.
post #1086 of 2194
Quote:
Originally Posted by germanium View Post
The nonpolarized caps might be line in coupling caps. Check the voltages on them. If there is substantial voltage do not remove if very little the Direct couple it. I can't see you picture clearle enough to determine which are polar & which are nonpolar caps.
eh?
- they are line-in coupling caps, as stated in post above.
- its a cluster of 4, non-polarized caps, most likely for L+R "line-in/mic-in" and L+R "aux-in"
- will most likely leave those alone for now...

ps: recognize the "blue" transistor in pix?
post #1087 of 2194
Anybody know the voltage swing the bypass caps face?
post #1088 of 2194
Quote:
Originally Posted by bichi View Post

ps: recognize the "blue" transistor in pix?
Not for sure.
post #1089 of 2194
Quote:
Originally Posted by LawnGnome View Post
Anybody know the voltage swing the bypass caps face?
Bypasses on the powersupply caps don't see much of any voltage swing. They do see fair amount of current swing though That is what makes my bypasses have such an effect on the sound as the signal has a lower impedance supply to return to.
post #1090 of 2194
Quote:
Originally Posted by bichi View Post
eh?
- they are line-in coupling caps, as stated in post above.
- its a cluster of 4, non-polarized caps, most likely for L+R "line-in/mic-in" and L+R "aux-in"
- will most likely leave those alone for now...

ps: recognize the "blue" transistor in pix?
After some research it appears to be an early Raytheon germanium transistor. Almost all of the early transistors of that period were germanium. Silicone came out in the second half of the 1950-1960 decade. It was germanium transistor failure rate that put Scott out of business. They couln't handle the back electromotive force generated when there was a poor connection at the speaker causing a flash voltage when a crossover coil suddenly discharged at the breaking of contact. Germanium transistors could really only survive well when they seen less than 50 volts across them. Ideally 35 volts max. This made for very low powered amplifiers by todays standards. One advantage germanium has though is very low forward voltage drop which can be beneficial in low voltage digital electronics. Germanium is used in newer processors to stretch the silicone molecules allowing the silicone to take on a lower foward voltage higher current characteristic of germanium without some of the drawbacks of germanium. This allowed higher switching speeds.
post #1091 of 2194
Quote:
Originally Posted by germanium View Post
Bypasses on the powersupply caps don't see much of any voltage swing. They do see fair amount of current swing though That is what makes my bypasses have such an effect on the sound as the signal has a lower impedance supply to return to.
Whoops, meant coupling caps. I have 6.3v oscons.
post #1092 of 2194
Quote:
Originally Posted by LawnGnome View Post
Whoops, meant coupling caps. I have 6.3v oscons.
They have about 2.5 volts D.C. on them & I have measuered .5 volt swing on them but that was tith music not a test signal so it is probably double that. 6.3 volt caps would be safe in that scenerio. May be a good option if you don't want to D.C. couple them. I personally have not had any problem with D.C. coupling though as the D.C. though not very very low is atill at a safe level for most equipment that a computer soundcard is likely to see.
post #1093 of 2194
FYI:
- two interesting articles on coupling caps, between DACs, op amps and general cap apps in audio engineering.
- doing an engineering "refresh" on audio freq coupling methods, before attacking more fun with X-FI.

Choose capacitor types to optimize PC sound quality
http://www.edn.com/index.asp?layout=...leid=CA6430345

Capacitor Characteristics (Audio Applications)
http://sound.westhost.com/articles/capacitors.htm

ps:
Quote:
Originally Posted by germanium View Post
After some research it appears to be an early Raytheon germanium transistor. Almost all of the early transistors of that period were germanium...
yep, Raytheon CK722
- rare, nowadays...
- thought you might know it off the top of yer head, considering your nickname...
- father was with embassy corps and lived in a few foreign countries, growing up.
- was "fekked," being a kid, reading Popular Electronics and trying build projects.
- try buying a CK722 in Brazil, in 1962...
- have collected quite a few old, germanium transistors, over the past years and use a "potted" one when interviewing new-grads seeking employment, along with an old 6L6 tube....
- still build one-of-a-kind "fuzz-boxes" with old, 2N404 germaniums for musicians.
- CK722 Museum: http://www.ck722museum.com/
post #1094 of 2194
Quote:
Originally Posted by bichi View Post
FYI:
- two interesting articles on coupling caps, between DACs, op amps and general cap apps in audio engineering.
- doing an engineering "refresh" on audio freq coupling methods, before attacking more fun with X-FI.

Choose capacitor types to optimize PC sound quality
http://www.edn.com/index.asp?layout=...leid=CA6430345

Capacitor Characteristics (Audio Applications)
http://sound.westhost.com/articles/capacitors.htm

Great links.

Also, here is something for the people who love to attach boutique capacitors, and allow long leads to get them to fit.

Quote:
With a 1uF cap (hardly massive), a mere 10mm of lead length (6nH) creates a series resonant circuit at close to 2MHz. Increase the capacitance to 10,000uF, and it is now 20kHz.
post #1095 of 2194
Quote:
Originally Posted by LawnGnome View Post
Great links.

Also, here is something for the people who love to attach boutique capacitors, and allow long leads to get them to fit.
I'm not a fan of boutique capacitors as many underperform when compared to a good milspec cap. I had a tube amp that had MIT Multicap capacitors for coupling & I had a problem of shifting bias current that was causing the tubes to overheat. This amp came from the factory with these caps. I suffered through this for some months then finally figured out it was the boutique caps that was causing this. I replaced them with milspec Sprague brand Orange drop film foil caps. The leakage stopped through the caps & the bias became rock stable & the amp sounded much much better to boot.
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