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Hotrodding the X-Fi: A Layman's Guide (No 56k) - Page 72

post #1066 of 2194
Quote:
Originally Posted by spiftacu1ar View Post
HI, i did this mod, but i only did one opamp to start. I was about to order more opamps for the rest of the mod, when i found this: LME49720

I was wondering if it is also a drop in replacement, because it is better than the other one which is recommended in the tutorial.
LME49720 and LME49860 announced July 23, 2007
Press Release: http://www.edn.com/pressRelease/2140057957.html

From the datasheets, there are no "technical" audio performance differences between the parts and are "interchangeable," relative to X-FI mod
- both LM4562 and LME49720 can use Vs(+/-) (supply voltage) of 2.5 to 17vdc
- LME49860 uses Vs(+/-) (supply voltage) of 2.5 to 22vdc
- op amp section of X-FI uses (+/-) 5vdc, therefore, there is no advantage (larger voltage swing only at higher Vs)
- LM4562 and LME49720 at about $2.83 USD and LME49860 about $3.54 USD each, budgetary pricing

Human "perception" of how the newer parts sound, is another matter
- only time will tell, since the new parts have only recently been released.....

I installed a new LME49860, only because it came in a "design sample" pack (see post #1062 above)
- if I were to design for a Vs(+/-) 5vdc, most likely would have selected either LM4562 or LME49720

REF:
National Semiconductor: LM4562 - http://www.national.com/pf/LM/LM4562.html
National Semiconductor: LME49720 - http://www.national.com/pf/LM/LME49720.html
National Semiconductor: LME49860 - http://www.national.com/pf/LM/LME49860.html
post #1067 of 2194
bichi,

Your rmaa tests results are worse than a stock x-fi xtrememusic.

Sure you didn't make any mistakes?
post #1068 of 2194
Quote:
Originally Posted by LawnGnome View Post
bichi,

Your rmaa tests results are worse than a stock x-fi xtrememusic.

Sure you didn't make any mistakes?
They seem to me to be within a margin of exceptable tolerance for a new card. 1 or 2 thousandths differance isn't going to make or break the sound of the card. You can get that much variance between new cards in other words & be acceptable. Most of those specs are already good enough so as not to contribute to the actual quality of the audible sound. There are many other factors that determine the actual sound that the spec sheet just cannot truthfully address. Zero feedback class A1 push pull vacumm tubes have much poorer specs but still sound worlds better than most transistor amps.

It is the going after the spec sheet that has in many ways damaged the enjoyment of music when listening to amps that use tons of feedback in order to get those nice beautifull specs. feedback squashes in many cases the dynamics that make music sound live. So does poor power supply design especially with transistors.This is especially true when driving speakers or headphones as these are highly reactive loads. It's not so bad when driving a purely resistive load. I have head this with my own ears comparing different levels of feedback on an amp with variable feedback with the option of no feedback. On Class A1 push pull tubes you can choke the power supply till the cows come home & not negatively effect the sound. All the chokes do in this case is knock down the hum very significantly, especially the harmonics..
post #1069 of 2194
Quote:
Originally Posted by germanium View Post
They seem to me to be within a margin of exceptable tolerance for a new card. 1 or 2 thousandths differance isn't going to make or break the sound of the card. You can get that much variance between new cards in other words & be acceptable. Most of those specs are already good enough so as not to contribute to the actual quality of the audible sound. There are many other factors that determine the actual sound that the spec sheet just cannot truthfully address. Zero feedback class A1 push pull vacumm tubes have much poorer specs but still sound worlds better than most transistor amps.

It is the going after the spec sheet that has in many ways damaged the enjoyment of music when listening to amps that use tons of feedback in order to get those nice beautifull specs. feedback squashes in many cases the dynamics that make music sound live. So does poor power supply design especially with transistors.This is especially true when driving speakers or headphones as these are highly reactive loads. It's not so bad when driving a purely resistive load. I have head this with my own ears comparing different levels of feedback on an amp with variable feedback with the option of no feedback. On Class A1 push pull tubes you can choke the power supply till the cows come home & not negatively effect the sound. All the chokes do in this case is knock down the hum very significantly, especially the harmonics..
I understand that, however according to the chips spec's, it should perform better than it is. Especially the THD+Noise. It shouldn't be limited by the DAC either, since the DAC is rated for higher than that.

I think it may have something to do with the voltage. I don't think either the DAC or the opamp is receiving enough voltage to reach its full potential.

If this was the case, it is something that could be easily remedied with a TREAD. Hook the TREAD up to the 12v rail, and have the TREAD regulate to 18V, then cut the trace feeding the opamp/dac and solder on the lead from the TREAD.

There also might be an easier way. The mosfet near the bottom of the card may be for regulating the voltage to the opamps, if this is fed from the 5V line, you could lift the leg of the FET and solder a lead from 12V.

I have done this before on motherboards and videocards for overclocking. And I'd bet DIMM slot power management is more complex than feeding an opamp.
post #1070 of 2194
Quote:
Originally Posted by LawnGnome View Post
bichi,
Your rmaa tests results are worse than a stock x-fi xtrememusic.
Sure you didn't make any mistakes?
No, no mistakes...
- only did the op amp and power cap mods, which is too simple to fek-up. (will not work or have missing channel)
- what I failed to do is take RMAA measurements prior to doing mod to compare against. (yeah, yeah, sux2bme)
- to germanium's point about "component tolerance" between individual cards, or any mass-produced product, is absolutely true. (ie., Jamicon couple/decouple caps have tolerance of +/- 20%)
- only "valid" way to measure performance improvements is using the same card (SB0460 F1), system, X-FI drivers, RMAA and mixer settings, etc., before and after.
- secondly, I used the newer LME49860 with Vs range of 2.5~22vdc, instead of 2.5~17vdc and might be out of performance "sweet-spot," relative to older, lower voltage LM4562 or newer LME49720.
- just for curiosity's sake, might change to LME49720 and do comparison, if I have time. (relative to LME49860)

Subjectively, I can hear/feel a difference with my simple, "stereo" setup in "tighter bass" and "cleaner highs," compared to original NJM4556. (better slew rate)
- Playback: http://www.m-audio.com/products/en_u...BX5a-main.html
post #1071 of 2194
Quote:
Originally Posted by LawnGnome View Post
I understand that, however according to the chips spec's, it should perform better than it is. Especially the THD+Noise. It shouldn't be limited by the DAC either, since the DAC is rated for higher than that.

I think it may have something to do with the voltage. I don't think either the DAC or the opamp is receiving enough voltage to reach its full potential.

If this was the case, it is something that could be easily remedied with a TREAD. Hook the TREAD up to the 12v rail, and have the TREAD regulate to 18V, then cut the trace feeding the opamp/dac and solder on the lead from the TREAD.

There also might be an easier way. The mosfet near the bottom of the card may be for regulating the voltage to the opamps, if this is fed from the 5V line, you could lift the leg of the FET and solder a lead from 12V.

I have done this before on motherboards and videocards for overclocking. And I'd bet DIMM slot power management is more complex than feeding an opamp.
Bear in mind also that you have 2 major systems you are testing, the DAC & the ADC. You have the combined noise & distortion of both with the RMAA test if you want to isolate the DAC you will have to go to an external tester which should give substantially better readings of the DAC. The ADC is the weak link in the RMAA tests. The tests I've run on the Elite pro seem to indicate that I'm at the true limit of the ADC which is slightly worse than the DACS spec wise but very very close.
post #1072 of 2194
Quote:
Originally Posted by bichi View Post
No, no mistakes...
- only did the op amp and power cap mods, which is too simple to fek-up. (will not work or have missing channel)
- what I failed to do is take RMAA measurements prior to doing mod to compare against. (yeah, yeah, sux2bme)
- to germanium's point about "component tolerance" between individual cards, or any mass-produced product, is absolutely true. (ie., Jamicon couple/decouple caps have tolerance of +/- 20%)
- only "valid" way to measure performance improvements is using the same card, system, RMAA and mixer settings, etc., before and after.
- secondly, I used the newer LME49860 with Vs range of 2.5~22vdc, instead of 2.5~17vdc and might be out of performance "sweet-spot," relative to older, lower voltage LM4562 or newer LME49720.
- just for curiosity's sake, might change to LME49720 and do comparison, if I have time. (relative to LME49860)

Subjectively, I can hear/feel a difference with my simple, "stereo" setup in "tighter bass" and "cleaner highs," compared to original NJM4556.
- Playback: http://www.m-audio.com/products/en_u...BX5a-main.html
The higher voltage power input yields higher voltage signal out putential & the specs will reflect this in the noise & distortion tests. If one were to give the noise & distortion as a actual voltage instead of a percentage the specs would be very very close indeed no matter what the power supply voltage. The readings as such are taken at such high output levels that they will never see those output voltages in any real usefull design for audio purposes.

CD output voltage is 2 volts by design
Most power amps with few exceptions will clip before they reach 2 volt input.

This is to say the voltage they test at are in fact meaningless to the average consummer. They should measure it at the CD max output voltage of 2 volts if they want to be truely honest with thier measurements. That way the percentage reading would actually mean something to the actuall consummer even if it doesn't make any real difference sound wise.
post #1073 of 2194
Quote:
Originally Posted by germanium View Post
The higher voltage power input yields higher voltage signal out putential & the specs will reflect this in the noise & distortion tests. If one were to give the noise & distortion as a actual voltage instead of a percentage the specs would be very very close indeed no matter what the power supply voltage. The readings as such are taken at such high output levels that they will never see those output voltages in any real usefull design for audio purposes.

CD output voltage is 2 volts by design
Most power amps with few exceptions will clip before they reach 2 volt input.

This is to say the voltage they test at are in fact meaningless to the average consummer. They should measure it at the CD max output voltage of 2 volts if they want to be truely honest with thier measurements. That way the percentage reading would actually mean something to the actuall consummer even if it doesn't make any real difference sound wise.
Agreed, but thats the art of "specmanship," and if it were standardized, all the "engineers-turned-product/marketing" and "validation engineers" would be out of a job.....

And it sounds like you have had "analog-engineering" experience and know the "internal" dark secrets of "optimization," which can mean "compromise..." (meaning the ability to handle larger Vsupply range, based on the same "core" amp and its "possible" impact on "best-performance" window, or in a design assessment meeting, where the new-grad engineer mumbles: "but the specs say....")
post #1074 of 2194
Quote:
Originally Posted by bichi View Post
Agreed, but thats the art of "specmanship," and if it were standardized, all the "engineers-turned-product/marketing" and "validation engineers" would be out of a job.....

And it sounds like you have had "analog-engineering" experience and know the "internal" dark secrets of "optimization," which can mean "compromise..." (meaning the ability to handle larger Vsupply range, based on the same "core" amp and its "possible" impact on "best-performance" window, or in a design assessment meeting, where the new-grad engineer mumbles: "but the specs say....")
Unfortunately none of the above. Just the experiance that comes with age & having been in this hobby since I was young, with exception of the time I was in the foster home of which abuse seemed to be the name of the game & I was at the receiving end of it all. Before that time of my life I was into stereo as early as 7 years old. I went into the foster home when I was 9. I left when I was 19. I wanted to run away many times but didn't know where to go & was afraid that if I was returned to them after having run away things would be even worse for me. I'm 50 now. I've had a chance to see & hear a lot out there & had a friend that was a very high up audio engineer for a while until he passed away a couple of years ago due to cancer. He built one of the most fantastic sounding & accurate zero feedback vacumm tube amps. Unfortunately he had to sell the design to cover medical expenses & passed away shortly thereafter. He never seen it marketed & I don't know who he sold it to though he did tell me at one time.

Jack sold it to Red Rock Audio. They unfortunatele changed his design considerably from the original. The original was much nicer than the production from Red Rock Audio & a lot less expensive had he been able to market it even though he used much better parts. The output transformers on jacks amps were nearly 2x the size of the Red Rock ones & were wound completely different. There were no taps to speak of on Jacks Amps but plugs that when inserted rewired the connections of the internal windings of the output transformer. The 4 ohm plug actually Split & paralelled the 16ohm windings providing 2X the current capability in the associated windings than a simple 4 ohm tap would ensuring that the winding resistance would not be a factor in the output impedance of the amp. The Red rock amp is way over priced considering Jack before he got sick was going to sell them for 3500 dollars & Red Rock wants almost 39,000 dollars. Let me assure you there is nothing in that amp that justifies the 35,500 dollar increase in price. The parts quality in many cases is lower than Jack used.

Oops,,,,, I mentioned the would be price of the ATP TA-25 instead of the ATP TA-50 with would have been 7000 dollars. adjusted very very generously for inflation it still would have been less than 10,000 with is still 1/4th of what Red Rock is charging. The ATP TA-50 would have been directly comparable power wise but the parts quality was much much higher on the ATP TA-50 than Red Rocks amp. Unfortunately these models never reached mass production. Only about 5 ATP TA-25s were made & only 2-3 ATP TA-50s were made before Jack became ill.
post #1075 of 2194
Quote:
Originally Posted by germanium View Post
Bear in mind also that you have 2 major systems you are testing, the DAC & the ADC. You have the combined noise & distortion of both with the RMAA test if you want to isolate the DAC you will have to go to an external tester which should give substantially better readings of the DAC. The ADC is the weak link in the RMAA tests. The tests I've run on the Elite pro seem to indicate that I'm at the true limit of the ADC which is slightly worse than the DACS spec wise but very very close.
But that doesn't explain why a better spec'd opamp would lead to lower results.

A stock card measures better than a card with the upgraded opamp.

This leads me to think that the amp stage is more complicated that people expect, and a simple drop in part needs more research.



The card SHOULD measure better after the opamp upgrade, but it doesn't. The ADC or DAC wont matter, since they stay unchanged.
post #1076 of 2194
Quote:
Originally Posted by LawnGnome View Post
But that doesn't explain why a better spec'd opamp would lead to lower results.

A stock card measures better than a card with the upgraded opamp.

This leads me to think that the amp stage is more complicated that people expect, and a simple drop in part needs more research.



The card SHOULD measure better after the opamp upgrade, but it doesn't. The ADC or DAC wont matter, since they stay unchanged.
Unfortunately the stock card was never tested by Bichi so we have no clue as to how the actual stock card of his performed in RMAA But then again does it really matter if the sound is better. Again RMAA is no indicator of the actual sound. I no longer have the X-Fi Platinum only the Elite Pro. This he admits himself but the specs that he has provided are in tolerance for a stock card so nothing to really worry about. I can radically change the sound of a card with very little change in the RMAA specs & I have measured wide variances in specs yet very little change in sound.
post #1077 of 2194
Quote:
Originally Posted by germanium View Post
"...I'm 50 now. I've had a chance to see & hear a lot out there & had a friend that was a very high up audio engineer for a while until he passed away a couple of years ago due to cancer..."
An old fart, eh?
- then you might recognise the "blue" part in the first "size" reference picture.
- gives you a clue on my age and experience... LOL
- http://www.esnips.com/doc/1b9968af-0.../X-FI-MOD-000b


Quote:
Originally Posted by LawnGnome View Post
But that doesn't explain why a better spec'd opamp would lead to lower results.
A stock card measures better than a card with the upgraded opamp.
This leads me to think that the amp stage is more complicated that people expect, and a simple drop in part needs more research.
The card SHOULD measure better after the opamp upgrade, but it doesn't. The ADC or DAC wont matter, since they stay unchanged.
Don't get too caught up in "paper" specs and simple RMAA test results.
- most of the improvements are subjective in nature.
- too many variables involved.
- maybe post your RMAA test results for comparison sake?

Its always assumed, (at least I do), that Creative's design is optimised for a NJM4556.
- since circuit design details are not known, ie., passive component values governing gain, impedance, freq equalization, etc., there is always risk of causing "undesireable" side effects by a simple "op amp" swap.
- since I didn't take "reference" RMAA results before doing the mod, I have no "objective" comparision reference to play with.
- bottom line, it "subjectively" sounds better to me....

- will probably replace the "line-in" op amp with an LME49860 and might replace coupling caps with "bi-polar" electrolytics
- have loads of RMAA test results to compare against, based on LME49860
- just cheap entertainment for me and since it keeps me at home, Wifey is chuffed too...
post #1078 of 2194
Quote:
Originally Posted by bichi View Post
An old fart, eh?
- then you might recognise the "blue" part in the first "size" reference picture.
- gives you a clue on my age and experience... LOL
- http://www.esnips.com/doc/1b9968af-0.../X-FI-MOD-000b




Don't get too caught up in "paper" specs and simple RMAA test results.
- most of the improvements are subjective in nature.
- too many variables involved.
- maybe post your RMAA test results for comparison sake?

Its always assumed, (at least I do), that Creative's design is optimised for a NJM4556.
- since circuit design details are not known, ie., passive component values governing gain, impedance, freq equalization, etc., there is always risk of causing "undesireable" side effects by a simple "op amp" swap.
- since I didn't take "reference" RMAA results before doing the mod, I have no "objective" comparision reference to play with.
- bottom line, it "subjectively" sounds better to me....

- will probably replace the "line-in" op amp with an LME49860 and might replace coupling caps with "bi-polar" electrolytics
- have loads of RMAA test results to compare against, based on LME49860
- just cheap entertainment for me and since it keeps me at home, Wifey is chuffed too...
I have a thread of my rmaa results, its a few threads down.

And the simple fact is, it SHOULD measure better, but its NOT.

All of this "on paper" stuff like its useless is BS.

Circuits are built around these data sheets. The data sheets provide the TESTED AND PROVEN performance of a part.

The opamp you replaced the stock opamp with is TESTED AND PROVEN to electrically perform better.

Yet performance decreases with the better spec'd opamp. So either it was damaged during install, or not soldered properly.

Or the new opamp does not just drop in.


either way, its extra time and money for a measured downgrade in performance.

Your results themselves prove this.
post #1079 of 2194
Quote:
Originally Posted by bichi View Post
An old fart, eh?
- then you might recognise the "blue" part in the first "size" reference picture.
- gives you a clue on my age and experience... LOL
- http://www.esnips.com/doc/1b9968af-0.../X-FI-MOD-000b




Don't get too caught up in "paper" specs and simple RMAA test results.
- most of the improvements are subjective in nature.
- too many variables involved.
- maybe post your RMAA test results for comparison sake?

Its always assumed, (at least I do), that Creative's design is optimised for a NJM4556.
- since circuit design details are not known, ie., passive component values governing gain, impedance, freq equalization, etc., there is always risk of causing "undesireable" side effects by a simple "op amp" swap.
- since I didn't take "reference" RMAA results before doing the mod, I have no "objective" comparision reference to play with.
- bottom line, it "subjectively" sounds better to me....

- will probably replace the "line-in" op amp with an LME49860 and might replace coupling caps with "bi-polar" electrolytics
- have loads of RMAA test results to compare against, based on LME49860
- just cheap entertainment for me and since it keeps me at home, Wifey is chuffed too...
Of note I decided at the beginning not to change the opamps. I felt that I could get the results I wanted with D.C. coupling & powersupply mods as I have had great success with this in the past. I was not denied either in this case.

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.

The ADC already uses nonpolarized caps but I sugest getting rid of these too as you will see an actual improvement in the signal to noise & distortion in the ADC circuit + sound better.The spec sheet for the ADC tells me that it is not sensitve to D.C. offset & cancels it within the ADC.

Oops, forgot you arn't talking the Elite pro so do not D.C. couple the lower X-Fi ADCs. The above only applies to the Elite Pro as far as the ADCs are concerned.
post #1080 of 2194
Quote:
Originally Posted by germanium View Post
Of note I decided at the beginning not to change the opamps. I felt that I could get the results I wanted with D.C. coupling & powersupply mods as I have had great success with this in the past. I was not denied either in this case.
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.
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