耳机大家坛老帖 » 电脑音频 » 动手打磨X-Fi任何版本,都可以让低端的extreme music模拟输出超过外置DAC01!(多图)
«12 3 45» Pages: ( 3/5 total )
本页主题: 动手打磨X-Fi任何版本,都可以让低端的extreme music模拟输出超过外置DAC01!(多图) 打印 | 加为IE收藏 | 收藏主题 | 上一主题 | 下一主题

ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的extreme music模

AD9631 is worth trying. Might be better than the LM4562.

Why not use the AD8620 for the opamps ? It's meant to work with low voltages(like the +/- 2.5V supplied to them from the card) and it has a max current output of 60mA with much better slew rate,THD,distortion,lower crosstalk.
I have replaced the stocks with AD8620s for your information.

i have tried the AD8620 and AD8066, but the LM4562 sounds better to my ears. the AD8620 is thin and bright.

If you guys are driving headphones directly, the AD9632 would be a better choice than the LM4562.

I can't say I noticed a lack of bass, though I wouldnt be surprised if the 8599 has more emphasis on the mids and highs compared to the 4562. On Chesky's reference CD i noticed things the AD8599 does particularly well but most of that doesnt happen in the bass-end . Since you asked, I put on some bass-heavy music and it does seem a bit less bassy. I suppose preference would be atleast partly based on the kind of music played. The AD8066 reportedly has a very nice bass response if thats what youre looking for. I may or may not be bothered to try one of those on that position aswell, since I do have a few of them around. For hooking headphones straight into the soundcard the AD8066 just might be better then both the 4562 and the 8599, but thats speculation until I tried it.
顶端 Posted: 2007-07-24 18:58 | 40 楼
frui



头衔:主区650党前主席 主区650党前主席

级别: 蝙蝠侠
精华: 0
发帖: 3587
威望: 961
金钱: 4174
在线时间:1836(小时)
注册时间:2004-09-28
最后登录:2013-09-18

一个中国最早用SB卡的人

无论有否改善都狂顶!
顶端 Posted: 2007-07-24 22:41 | 41 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的extreme music

original poster已经有1000条回复了。。。
这里太冷清,大家还是看original poster和reply吧。。。

http://www.head-fi.org/forums/showthread.php?t=229350
顶端 Posted: 2007-07-25 21:50 | 42 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的extreme

I have not personally had a problem with my x-fi, but I have heard of more then one person who has had serious problems because theirs overheated. I am not sure if I do not have that problem because I have a good card, or because I have about $400 invested into cooling my rig.


The op-amps would not benefit you if you use the digital output, but the OP said doing all the mods makes the x-fi sound better then the Benchmark DAC1 so unless you are using a better DAC it might be worthwhile to make these changes

-
Originally Posted by Liver 
Cotdt,

What amplifier are you using with your modded card?

Also, has anyone tried this mod with the breakout (large) one? I have an elite pro with all the goodness on the card, but the breakout box has the same opamps as the standard xfi line up. I never understood that. Have better opamps on the xfi elite pro and then the breakout box negates the benefit of having the elite pro.

So, either I do the mod on the breakout box. Or on the card itself and get a good headphone amp.

Either way, I assume that only one opamp needs to be replaced to achieve the mod if you are only using it for headphones (even with CMSS). Is that correct?
I'm using a Doge 6210 tube amp for my K701s, while my other headphones don't need any amp and are driven straight out of the X-Fi. I would just mod the card and use an amp (if you need an amp at all). The Elite Pro should be even better than the regular X-Fi because of the better DACs.

To add to that, for digital you want to do a different set of mods. This is taken from Empirical Audio's website for the E-MU but it applies to any sound card including the X-Fi:

Digital Sound Card Mods
===================================
This E-MU PCI card has several opportunities to improve the S/PDIF out, including reducing the output voltage (3X the spec), improving power delivery and precisely matching to 75 ohms. After the mod is installed, the S/PDIF output is 500mV peak-to-peak. The impedance is perfectly matched to 75 ohms and the risetime is an unprecedented 5 nsec, allowing use of very short S/PDIF cables. The manufacturer cannot design it this way because they would likely fail emissions testing. However, most audiophiles are expected to use high-quality S/PDIF cables, so the emissions should not be an issue.

S/PDIF mod Details:

1. Change pulse transformer
2. Impedance match to 75 ohms
3. Add power decoupling to decoder and driver chips
4. Improve digital coupling caps
5. Remove various filter components


If you've read the above post you'd notice that its technically flawed.

Shorting (power) decoupling capacitors would essentially blow your DAC supply. There they are not decouplers as suspected.

Coupling capacitors if shorted would allow DC to pass onto the gain stage (the OPAMPs). Given the single positive supply to the OPAMPs, DC offset would manifest itself on the outputs if they couple between output and OPAMP. If they couple between DAC and OPAMP, it would introduce additional DC into the OPAMP which would happily amplify it with your rest of the audio signal. Given that timeslicing DACs are popular for such application, there would be some 2.5V of DC offset. Remember that an average line level output from your card is 2.0V.

The BG was added to the DSP which would benefit from a low ESR capacitor. The length of the extra legs of the BG further serves to act as antennas to pickup noise within the PC and adding it to the DSP supply. Whatever noise added by the DSP chip into the loop is also radiated, defeating the purpose of a capacitor decoupling no matter what is the sheer capacity. Using something like a SP or SEC OSCON would do a better job. You can save the money to use it on smaller BGs/ZA/ZL/RJH/RJJ on the OPAMP and DAC decoupling side, which promises more audible changes.

Not to forget a better output coupling capacitors which cannot be eliminated especially if DC coupled (majority of highend amplifiers) amplification is used.

Proceed with care.


The LM4562NA-POBD I use on the Meridian is 8-DIP size whereas on X-Fi it's SOIC.


Here's the long story short, I originally started with stock opamps on the Meridian which they're already preety decent. Then shortly after I switch the stock ones to Burr Brown OPA2134PA (recommanded from Auzen's support page) and sadly I hardly notice any difference despite many rave user reviews on them. Gladly I found the LM4562 in the forums and after the quick mod with them, I'm glad I was able to tell the difference right away. The sound is even cleaner, especially all instruments and each music notes are well seperated and defined. In the bass compartment, it's relatively better defined as well but not by a whole lot. Overall I'd say LM4562 op-amps are truely great and it's definetely a better upgrade over your stock SC's op-amps (NO placeable effect intended)

I've being wondering ever since the beginning I started doing op-amp mod and that's how will I be able to tell one of the op-amps goes faulty? As I mentioned earlier, there is one op-amp for each channel and a total of 4 opamps (front, side surround, centre subwoofer and rear surround) The front is also used for headphones, stated in the manual. So that's like I'm only using one of the 4 opamps (front output) is that right? And how will I know that the opamps are still performing at its optimal state?? Any comments are appreciated

Thanks Tiramisu. The X-Meridian does make it easier to swap opamps, especially without a solder iron, although to me replacing SOIC opamps are still pretty quick and easy. But in my mods I've discovered that changing the opamps is only a fraction of the total improvements. Removing the output capacitors and the Blackgate mod makes just as big a difference, as did the ERS paper which made it noticeably warmer. You should try these things on your card! I've never had an opamp go bad, especially not with the voltages used on sound cards. If the sound degrades noticeably, then it's probably faulty, but i've never come across it.

=
I'm glad you are able to find the supplies for this mod. If you want, you can replace all the remaining capacitors with Panasonics. But it won't be for sound quality, but for durability, since Jamicons are not reliable.
=
Be aware that the card puts out about 30millivolt D.C. with stock op amp at output with the coupling caps shorted. This may not seem like a lot & in most cases its not but if you have D.C. coupled amps upstream without D.C. offset compensation you can cause the amp to over heat & possably damage you amp & speakers.

You will also notice some popping sounds as the computer is booting up & shutting down.

That said the mod is really worth it especially if you have D.C. coupled amps that have D.C. offset protection. I'v done this to mine over a year ago & all my amps are D.C. coupled but with D.C. offset protection in my preamp. The sound is as good or better than my SACD player (SCD222ES).

What germanium did was DC-couple all his equipment, which is very good for sound quality but not as safe (although this can also be safe). If you use stock amp, 99% of the gear I've come across comes with input filter capacitors so you should be safe. To be absolutely safe, it's best to change opamps and the capacitors at the same time. I'm quite sure that with the LM4562s installed, you should get less than 10mV DC which is not a problem at all. Seriously though, even with the stock opamps the chances of equipment damage is small.

Edit: The Corda Headfive should be safe. If I remember correctly, he used WIMAS in the signal path.

The prospect of making a dull sound card sound great is intriguing. The safe handling of the ERS paper also seems to be a vague art form. Why not just insert big sheets of it inside the computer case to separate the card form everything else? I am in the market for the best DAC in the $700 or less category and the more reviews I read (many good ones on head-fi) the more I go round and round.

Opinions differ greatly. It seems the benchmark can be beat for less $$. The Audio Note kits are $2,000+. Maybe the new Stello DA100? Which dealers sell Stello in America???

-
Yes I agree that the Benchmark is not too hard to beat these days. When it first came out it was a giant killer, but now it itself has become the giant that new cheaper DACs aim to kill.

Stello DA100 does look like a killer because it has discrete outputs and a very good AKM DAC chip, but I wonder why it is priced so cheap. Maybe it is indeed a killer, or maybe they cut corners somewhere. I am trying to find someone who has this DAC so I can do a shootout against my modded Zhaolu, which is my reference because it has beaten the Aqvox, Apogee, and Lavry in shootouts. My Zhaolu has the Zapfilter discrete output which is a proven and famous design.

--
For clarification on the opamp model number from national semiconductor, it's the LM4562MA SOIC NARROW, right?
Yes, the number is LM4562MA. The other one is the DIP8 version which is much bigger and require a Browndog adaptor to work. Yes, use the Audigy as your test subject! But you'll be more than happy with the X-Fi. They did a much better job on the drivers and software aspect of it, and it doesn't resample anymore. The X-Fi is a good product, and I used to be a Creative basher but now they do an excellent job.

-
im not sure about terminology like opamps and stuff like that, but i was wondering, aside from cleaner sound, does this mod increase the amount of current that the card can put out, or is it strictly a mod to increase the quality of the sound that it puts out?
sound quality. although it does use a larger power supply capacitor so it might also help deliver more current. you'll still need an amp or maybe just a dedicated buffer to drive most full-sized headphones. the card can directly drive the AKG K701, but it's clearly not getting enough current so dynamics suffers.

kinda off topic, but what's a dedicated buffer?
Amps increase the voltage, but for headphones this is almost never needed. Portable sources already have enough voltage swing for almost any headphone, and sound cards usually have double that. What is needed is not amplification (more volume), but more current delivery(more oomph and dynamics). While many sound cards already have a built-in buffer, they are weak compared to the buffers in amps. A dedicated current buffer is what is needed. I don't know any companies that sell them, though. If they did, I would definately buy one.

cotdt, how does running the modded X-Fi alone compare with your modded Zhaolu? Obviously putting the Zapfilter in the Zhaolu costs quite a bit of money so I'm curious about what you think.

Also, I ordered my Xtrememusic and all the parts for this mod so I look forward to trying it out in a week or so. However, could you possibly go into a little more detail about how you used the ERS paper because I have never used any before and I'm a little confused about how you have placed it on the soundcard. If I am understanding right you used part of a mousepad placed on the backside of the soundcard and then put ERS (adhesive?) paper on top of it. In a regular case setup this might work but for me my motherboard is upside down in my case and so unless you are adhering the mousepad to the sound card in some way this won't work for me. Also some clarification on how it is on top of the card would be helpful too. Sorry, I'm sure it's really simple but I'm just not getting it fully.

I'm adhering the mousepad onto the back of the X-Fi using 3M spray glue, but used tape while I was still testing the mods. Basically you want the shielding to be between any potential sources of EMI/RFI and your sound card. The brute force way to do this is to shield both the front and the backside of the card. It's strange because I used to be able to hear this radio station from my amplifier, but I applied a bunch of ERS paper and it was gone. This made me a beleiver, even though a lot of the ERS paper stuff sounded like voodoo before I started using it.

As far as the Zapfiltered Zhaolu, nothing I've heard has beaten it. It's hard to compare it to the hotrodded X-Fi, because the sound is completely different. The main difference is that the Zapfilter has more weight to the tones, and it is more dynamic than any opamp-based DAC. It also has a wider soundstage than any other DAC by quite a margin, and very detailed lows, mids, highs. It has no weaknesses at all, but this is also what people said about the Benchmark when it first came out. Maybe one day an even better DAC would come along and show weaknesses, but it's hard for me to imagine right now. One DAC that people rave about is the EMM Labs, and I've never heard it but it's a candidate for the ultimate DAC since it has propietary processing. I would love to hear that one and compare it against my modded Zhaolu.

I like the modded X-Fi because it sounds really good already, making external DACs unneccesary. Even getting a high-end DAC would merely be something different tonally but not better. And besides, the X-Fi has 7.1 surround sound and can do recording.

Thats one nice looking mod you done there!

The capacitor shorting method, could you not remove them and short the connectors with wire or solder? ive never left a component in then soldered the connections up, made it a right arse to take it out :P

And the thing that Germanium said about the DC upflow is not to be concerned about right? I am looking for an amp eventually, but for now, running the HD595 straight into the back of the card with this mod is not gonna blow my ears out or damage the cans with this DC flow problem is it?

And! I take it this mod is as good or better than an external DAC via USB? or is it still behind that in SQ?

Cheers!

--
hmm... how much of a difference is there between the cs4382 DAC in the xtrememusic etc vs the cs4398 in the elite pro? and is there any difference between the xtrememusic etc that would matter?

also, for the option of getting different caps and replacing all of the caps on the soundcard, am i interpreting this wrong or do you mean replace all 20+ capacitors on the soundcard? (unless i'm stupid and am thinking of the wrong thing as capacitors)
you're going to have to hear them for yourself, because no one has ever modded an Elite Pro that i know of. however, there are some modded Zhaolu's with CS4398 and LM4562s and it should sound the same.

Yes, you can replace all the Jamicon capacitors. There are probably 20-30 on the board but half of them are coupling capacitors which you want to short anyway. I beleive you short almost a dozen capacitors if you do the surround channels and certain others, so in reality you're only replacing a dozen or so capacitors. This is entirely optional anyway, it doesn't affect sound quality. Personally, I would only replace the larger capacitors.

Would these S/PDIF mods be worthwhile? Has anyone done these and reported on the outcome?
I'm pretty sure it would make a difference, but personally for digital I would use an I2S connection. Most modern DACs can be modified to accept I2S. This would be good for minimizing jitter. This is only worth it if the DAC was very high-end. Most budget external DACs would probably be beaten by a analog-modded X-Fi.
=
How would you get I2S out of a computer and which sub $1000 dacs will already accept it?
For output, dddac.de has instructions on making a USB-to-I2S convertor, and empirical audio also has several solutions for it.

As far as DACs go, most of them can be modified to accept I2S, and you can look at schematics provided by the DAC chip company.

the non-DIY solution is to wait a few years for I2S to become more standard, but sadly it might not ever happen.
__________________

Originally Posted by Gilly 
you mention replacing the shorted caps, i take it that caps of any grade will degrade the audio, so if you have DC isolated stuff your fine to short it, and will sound best shorted?

If i want to replace them, are blackgates of the same type as the power filter fine, just with a lower rating? i cant take my card out right now to look :P
blackgates are not high enough quality as output filter caps. i recommend ~3uF teflon capacitors, or at the very least film capacitors like mundorf supreme. the best for sound quality is to not have the capacitor at all.

From what I gather I have labeled this pic
The OpAmp to replaced, and the three surrounds below it. The Power Filter Cap, and the CS4398s have been labeled. But what capacitors to short?

you want to short the 16 capacitors closest to each of the 4 opamps.



Attached in the pdf is the output circuit that I have traced on an X-Fi Platinum. I cannot see any of the 22uF electrolytic caps in the ouput at all but have traced some connected to +5v and -5v rails. Replacing the op amps are a great idea but could more be done replacing the transistors Q2,Q3,Q4,Q5 that are all marked J1X on the front outputs and on the other outputs a different set of transistors are used marked O2NR. Anyone know what who makes the J1X and O2NR transistors?
amazing work! you sure entered head-fi with a bang. on the newer X-Fi cards, the transistors are J1(infinity) instead of J1X and O2N- instead of 02NR. any idea what they can be replaced with?

Originally Posted by ]|[ GorE 
Those capacitors dont block DC ! They are connected to the +5 and -5V lines and are meant as current reservoirs. The reason there are 4 for each opamp is to keep the capacitors impedance low . I would add a higher valued cap in parallel to the existing caps,not short them.

And,instead of doing such a hokey mod,i would look up the datasheets of the dac and add the capacitors Creative has left out.
hmmmz... you sure? i'll trace the board and see...

Edit: Updated about the DC-coupling caps. I traced the opamp outputs and the 22uF are not part of the DC-coupling after all. Apparently, the X-Fi does things different from other sound cards. I still prefer the sound with those 22uF caps shorted though.

hmmm interesting, the from what you guys are saying, is it better not the short them out, since they might cause damage to the chips?  No damage will be caused to any chips;we aren't sure what is the exact use of those 22uF caps . If they are reservoir/decoupling caps for the V+ and V- of the opamps and shorting them seems to improve the sound(according to the OP),then perhaps the Jamicons should be replaced with lower ESR caps.

Originally Posted by ReTiCuLe 
Anyone found a site that takes Paypal for the Blackgate 2200uF 16V?
The only site I found is OOS.

P.S. Thanks for the headsup AngryGuy, I ordered 3.
partsconnexion.com accepts paypal. i think percy audio does also.
=
Hi,

I have changed the full set of op-amps from my X-fi (no more mods at the moment).

My impressions:

- Treble is cleary improved. The digital sound is gone and the sound is much more pleasant. I can raise the volume without obtaining harsh highs.

- Bass is tighter and with more detail.

- With multichannel music the singer IS in the room. Soundstage is also more deep and imaging more wide.

- The outputs can reasonabely drive directly my dt990, maintaining the characteristics described. The improvement in this aspect with respect to the unamped output of the stock x-fi is enourmous. However, I suppose that an external amp is always needed for a 250 ohms cans.

I have approximately traced the correspondence between surround op-amps and the two physical tri-pole jack outputs. From up to down (with respect to the first pic in the first post):

- Upper surround op-amp corresponds to one side surround and one back surround (not sure if it is left or right). All go to the second line out.

- Mid surround op-amp correspons to the other side surround (second line-out) and center/or sub (third line-out).

- Lower surround op-amp correspons to the other back surround and the center/or sub (complementarily to the previous one). All go to the third line-out

The conclusion is that, even with a 5.1 setup, you have to change all 4 op-amps due to the ad-hoc configuration.

I'm going to try further mods. I have ordered the blackgate and the ERS paper.

With respect to the op-amp caps, I preffer not to sort them but replace the full set of 16 caps with higher value ones.

Which cap value do you recommend (that can fit in the available room)?

As they seem to provide current and not transport signal, does high quality cap is really needed in this case (I suppose exchanging 16 blackgates will be quite expensive)? Do standard nichicons may be enough?

Thanks again to cotdt for this awesome thread!

http://www.head-fi.org/forums/showpost.php?p=2797799&postcount=89

unfortunately, no one is sure what exactly these capacitors do, so there is no definitive answer. i know some DAC chip engineers at CS so maybe i can ask them when i get the chance. however, the card does sound a little better shorted. if they were "critical" then if you short them then they shouldn't work at all, or sound strange. to be safe, you can try 22uF 16V Blackgates in that position. if there is any improvement then let us know. if not, then all you lose is a few dollars. i suppose 22uF polypropellenes would be too big, but the actual value does not seem to be critical.

==
Before

Testing chain: External loopback (line-out - line-in)
Sampling mode: 24-bit, 96 kHz

Summary
Frequency response (from 40 Hz to 15 kHz), dB: +0.01, -0.09 Excellent
Noise level, dB (A): -112.8 Excellent
Dynamic range, dB (A): 112.5 Excellent
THD, %: 0.0006 Excellent
IMD + Noise, %: 0.0012 Excellent
Stereo crosstalk, dB: -110.5 Excellent
IMD at 10 kHz, %: 0.0012 Excellent

General performance: Excellent

After mod, change opamp, ERS paper, new capacitor

Testing chain: External loopback (line-out - line-in)
Sampling mode: 24-bit, 96 kHz

Summary
Frequency response (from 40 Hz to 15 kHz), dB: +0.01, -0.09 Excellent
Noise level, dB (A): -113.1 Excellent
Dynamic range, dB (A): 112.9 Excellent
THD, %: 0.0006 Excellent
IMD + Noise, %: 0.0011 Excellent
Stereo crosstalk, dB: -110.9 Excellent
IMD at 10 kHz, %: 0.0012 Excellent

General performance: Excellent


A little more info about caps roles:

http://www.avsforum.com/avs-vb/showthread.php?p=10070526&&#post10070526


Cap modding for an Elite pro (sadly in japanese, but the pics may help):

http://www.geocities.jp/tag627/X-Fi.html

"Anyway, I shorted out the capacitors for the front 2 channels using small pieces of wire between the capacitor pins. I would say that the sound was a bit brighter and sounded a bit more real - especially for vocals. I measured dc voltages of less than 1mV for both front channels (with no sound playing)."

Very interesting, and in fact bclare's findings mirror mine exactly. Although the caps make the DAC more stable, they are not needed in this situation. Since capacitors degrade sound, they should be removed if they are not required. Manufacterers like Creative don't care about sound quality as much as a potential lawsuit where they could lose millions, and they have no idea what kind of equipment will be used with their card, so I can understand why they would want to play it safe.

Since 3 different X-Fi cards have had their caps shorted with no ill effects but in fact an improvement in sound quality, I would definately recommend shorting these caps.

I just modded the output opamp. I did not touch the input stage. Perhaps that is a source of distinct limitations.

The card is an elite pro. All parameters were that same (bit perfect, with all audio "enhancements" off, and volume at 90%).

I have listened to the card, before and after. The biggest changes for me was to plug my headphones directly into the card itself and not into the breakout box. Large difference between breakout box and direct out from sound card.

[rant]

This is a nice card. I have not heard the uber expensive DAC or DAC / Amp combos, but I like the sound. I like the music it makes.

Perhaps this is due to the eilte pro's inherent quality to begin with? I think Creative has made a very very good product here. I do not think it is a trade off any more between gaming and audio fidelity (at least with Windows XP). From my perspective, get the elite pro and then use it with all bells and whistles for gaming and switch to audio creation mode for the audio fidelity.

I keep wondering about all the questions here at headfi on what DAC or Amp to upgrade to (assuming upgrading from Xfi). I think this is a great card. Creative has made bad first impressions with a lot of the sound blaster line, but the elite pro is something else.

[/rant]

I have to admit my own personal limitations. If the modded card and the stock card were to be A/B tested, I may (low probability) be able to tell the difference. Not being able to A/B test, I can not make a statement that it is that different. That is a personal limitation.

While I was making the mod I fired up the integrated audio on the Bad Axe 2. It is the Intel HD audio. Now that was a huge difference from the modded elite pro and the integrated audio! My lord, I was modding as fast as I could to get away from that!

Can I ask why you chose a 2200uF standard Blackgate? Why not a 3300 or 4700uF? These are also available for 16V.
probibly no benefit/ cost outlay.

2200uF is a lot of capacitance, and its being fed DC power, which in theory should be relativly clean with modern switching transistors and vregs etc.

the massive HT amps normally have 2x 33000 uF capactiors running maybe 8x170w DIN or whatever, so 2200uF is already overkill imo

yes Gilly is right the 2200uF is already overkill.

a 4700uF Blackgate would be enormous and cost more! the general practice is to use something that is 10x the original value. any more than that will probably not yield any improvement. most people use the card with an amp which has a ton of capacitance, so actually with an amp the original value of 220uF is already enough. However, Blackgates have much better specs than Jamicon so the capacitor should still be replaced. I just picked the larger value because for some headphones I don't use a dedicated amp.

btw, there are other good choices for capacitor besides Blackgates, to those who care about every dollar in their wallet. Just be sure to not use too high voltage ratings, since electrolytic capacitors work best near their voltage rating. Thus we would use a 16V capacitor for 10-16V.
__________________

Till page 8
顶端 Posted: 2007-07-26 20:33 | 43 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的

  集成运算放大器,最早应用于电路信号的运算,简称为运放。随着运放技术的发展,目前运放的应用几乎渗透到电子技术的各个领域,它成为组成电子系统的基本功能单元,在简化了电路设计难度的同时,大大提高了电路的性能。近十年来,各大半导体公司也不遗余力地研发各种性能优异的运放,低失真、低噪声、低漂移、高速度、高精度,各显神通。
举个例子来说,在音频电路的设计中,就有专门的“运放发烧友”,喜欢在电路设计时,不断地改变所采用的运放的型号以及电路组态,比较不同运放、不同工作条件下的声音表现。在一些音响发烧的论坛网站上,如果你只知道NE5532、LF356,而不知道AD827、OPA2604、INA217等“靓声”运放的大名,都不好意思和人家打招呼。
  前不久,美国国家半导体公司在新闻发布会上,推介了两款音频集成电路,一款是大功率音频驱动电路LM4702(详见本刊2006年第11期“赠送样片活动”和本期文章介绍),另一款就是超低失真率的运放,型号是LM4562,从它的产品手册上看,最低失真率达到了0.00003%。《无线电》杂志特地组织了一批的LM4562样片,准备赠送给部分读者。
  如果您是一位电路设计应用高手,想体验一下新器件带来的快感,或者想PK一下以往作过的运放电路,就请认真填写好刊中附加的“新型元器件索取表”,尽快寄回到编辑部,就有机会获赠一片LM4562运放,这或许是目前能找到的失真最低的运算放大器了。
  需要说明的是,一个电路设计是否优秀,仅仅依靠指标高级的器件是不够的,出色的系统电路设计、外部元器件的选择、合理的布线、电源供给、屏蔽以及安装结构等等都是相当重要的因素。我们这次活动的目的,并不仅仅是为了推广某一个型号的集成电路,而是要征集一批运放应用设计的文章,征集一批理论与实践相结合的作者,建立一个高水平的作者队伍,给读者提供更多、更“解渴”的实用文章。同时也欢迎广大的无线电设计制作高手为我刊撰写各类新颖实用、深入浅出、图文并茂的文章。比如:电路设计应用、安装调试经验、名机电路分析、维修经验随笔等等。
  在2007年的《无线电》杂志中,每一期都将组织一些新型元器件的样片,供部分电子产品设计人员和无线电爱好者索取试用。
  “赠人玫瑰,手留余香”,欢迎大家继续订阅2007年的《无线电》杂志,邮发代号2-75,全年定价81.6元。


附: 超低失真音频运放LM4562简介
  美国国家半导体公司 (简称国半公司)新近推出型号为 LM4562的高保真双运放只有0.00003%的总谐波失真及噪声(THD+N),换言之,这款运算放大器的失真几乎可以忽略不计,它与新推出的LM4702高压立体声驱动器均属于同一系列的全新音频产品。
  LM4562芯片具有极低失真率、低噪声、高转换速率、很宽的工作电压范围以及较大输出电流等优点,性能之高是前所未有的。由于这款运算放大器具有这些优点,因此适用于专业级及高端的音频系统,如音像系统接收器、前置放大器、音频解码器和高保真功放以及各种医疗成像系统及工业设备。
  LM4562芯片的设计非常独特,不但内置高速的6MHz单位增益带宽运算放大器,而且另外还加设了一个专有的立体声音频驱动放大器,后者更是整套音频系统的关键电路,其具备了信号调节功能,确保音频系统可以发挥卓越的音响效果。标准工作状态下,这款运算放大器的输入噪声密度低至2.7nV/√Hz,中频的噪声转角 (noise corner) 达60Hz,输出电流达26mA,可驱动600Ω的负载。LM4562芯片的转换速率达20V/μs,增益带宽积高达55MHz。
  LM4562芯片可以在±2.5V至±17V之间的供电电压范围内保持工作稳定,最大输出电流高达45mA。该款芯片在上述的供电电压范围内操作时,其输入电路的共模抑制比(CMRR)及电源抑制比(PSRR)都高达108dB以上,而输入偏置电流则低至10μA(典型值)。在输出级的全力支持下,LM4562运算放大器的音频功能可以得到充分的发挥。
  LM4562运算放大器即使驱动高达100pF的容性负载,也可充分发挥其性能。这款芯片设有可抑制开关/切换噪声的静音功能,可使放大器的输出降低至等同静态电流,对节省用电很有帮助。此外,这款芯片也设有过热保护及输出短路等保护功能。
  LM4562芯片有三种封装形式,8脚DIP封装和SOIC封装的零售价约40元人民币,现已有大量现货供应。采用金属TO-5封装的芯片零售价约为160元人民币。可浏览http://www.national.com/pf/LM/LM4562.html进一步查询相关资料以及了解有关订购样品和评估电路板的手续。
顶端 Posted: 2007-07-26 23:01 | 44 楼
bigfoot_13


级别: 蜘蛛侠
精华: 0
发帖: 3403
威望: 1096
金钱: 4014
在线时间:2128(小时)
注册时间:2005-04-18
最后登录:2013-01-27

手里刚好有两颗AD8599

顶端 Posted: 2007-07-26 23:16 | 45 楼
bigfoot_13


级别: 蜘蛛侠
精华: 0
发帖: 3403
威望: 1096
金钱: 4014
在线时间:2128(小时)
注册时间:2005-04-18
最后登录:2013-01-27

发现AD8599的THD很高啊

600ohm负载20k就到了0.002%了
顶端 Posted: 2007-07-26 23:26 | 46 楼
ciyahu


级别: 侠客
精华: 0
发帖: 369
威望: 23
金钱: 339
在线时间:551(小时)
注册时间:2007-03-16
最后登录:2013-08-26

Re:动手打磨X-Fi任何版本,


good
顶端 Posted: 2007-07-26 23:30 | 47 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的

前天刚花了13.5刀在national的网页上定了5个LME49860MA运放。。。

Hi xxxx,

Thank you for your sample order from National Semiconductor
for the following device.

NSID: LME49860MA
Quantity: 5

****************************************************************
*  Your reference order number is:                            *
*                                                              *
*          xxxxxx                                    *
*                                                              *
*  This order has shipped from our warehouse in Singapore.    *
****************************************************************

Please expect the delivery window within 3-15 days after this
ship date depending on your destination.

Shipment status for all your sample orders is available at:
http://www.national.com/order/status/index.html

Other reference Information
==================================================
Email:          xxxxxxxx@hotmail.com
PO Number:      xxxxxx             
Packlist #:    xxxxx
Waybill #:      xxxxxxxx
Carrier:        PIMS

Order Date:    Jul 26 2007
Ship Date:      Jul 27 2007
Destination:    China
NSID:          LME49860MA    NOPB
Quantity:      5
==================================================

Thank you,


==============================


LME49860MA是本文中LM4562的第二代产品,有更好的电压适应性。。。等来了之后就开始打磨我的X-Fi Elite Pro啦!!!
顶端 Posted: 2007-07-28 22:03 | 48 楼
bigfoot_13


级别: 蜘蛛侠
精华: 0
发帖: 3403
威望: 1096
金钱: 4014
在线时间:2128(小时)
注册时间:2005-04-18
最后登录:2013-01-27

怎么付款?

怎么付款?Visa、Master?
这个价钱包含邮费吗?
顶端 Posted: 2007-07-29 12:56 | 49 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:怎么付款?

Quote:
引用第49楼bigfoot_13于2007-07-29 12:56发表的 怎么付款? :
怎么付款?Visa、Master?
这个价钱包含邮费吗?


我用的Visa卡,13.5刀是handling fee,那5个运放是free sample,没有额外的postage。



现在求Blackgate 2200uF 16v的cap两个!!哪位有的话我想买!!多谢!
顶端 Posted: 2007-07-29 15:48 | 50 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的extreme

bump...

blackgate cap可以从下面网站购买:http://www.partsconnexion.com/catalog/CapacitorsElectrolytic.html
顶端 Posted: 2007-07-31 18:26 | 51 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都

opamp的免费sample可以从下面网站购买,可能会收取handling fee:

http://www.national.com/
顶端 Posted: 2007-08-03 22:31 | 52 楼
心旷神怡




级别: 新手上路
精华: 0
发帖: 19
威望: 2
金钱: 9
在线时间:49(小时)
注册时间:2006-01-11
最后登录:2013-07-14

Re:Re:动手打磨X-Fi任何版本,都可以让低端的

Quote:
引用第48楼ter1于2007-07-28 22:03发表的 Re:动手打磨X-Fi任何版本,都可以让低端的 :
前天刚花了13.5刀在national的网页上定了5个LME49860MA运放。。。

Hi xxxx,

Thank you for your sample order from National Semiconductor

.......



为什么不用一个金封LM4562HA在两声道上呢?
顶端 Posted: 2007-08-04 02:59 | 53 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的extreme music

=============
One of the other mods I did to my X-Fi card, besides D.C. coupling, was bypass the power supply caps. I bypassed the large one 220uf with 3.3uf metalized film & the 2 power supply caps closest to the D.A. converter with 3.3uf metalized film caps. This improves the dynamics across the board, from the highest treble well into the bass. I believe this has much more effect than replacing the electrolytics with any kind of higher grade electrolytic including the black gates. I venture to say that it would even trump the opamp replacement. The distortion level of the JRC opamp while nothing to write home about is not of any real consequence either. Much more improvement can be had elsewhere soundwise without compromizing it's ability to drive headphones to a reasonable level. The highest distortion componant with my soundcard set up the way it is is below -100db for THD & below -90 DB for the TID. Niether of these distortion levels would be audible. .0012% THD is not going to be any more audible than .00006%. Both are well below the hearing threshhold.

The thing with the antielectrostatic paper backed with foam is the glue used to hold it to the soundcard can have negative effects on the sound (loss of detail & fuzziness to the sound in some cases at least temporarely anyway).

These are besides the D.C. coupling mods.
=============
顶端 Posted: 2007-08-04 23:43 | 54 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的

图片:
图片:
图片:
图片:
上几张xfi elite pro的图,不知道哪位知道这些答案。。。
顶端 Posted: 2007-08-05 09:10 | 55 楼
ter1




级别: 禁止发言
精华: 0
发帖: 514
威望: 138
金钱: 581
在线时间:329(小时)
注册时间:2006-10-13
最后登录:2011-06-04

Re:动手打磨X-Fi任何版本,都可以让低端的

图片:
背面截图。。。。。。。。。。。。。。。。
顶端 Posted: 2007-08-05 09:12 | 56 楼
sghong




级别: 侠客
精华: 0
发帖: 682
威望: 86
金钱: 395
在线时间:734(小时)
注册时间:2006-10-16
最后登录:2013-05-17

Re:动手打磨X-Fi任何版本

lm4562淘宝上才卖20多
为什么要去国外买呢?
顶端 Posted: 2007-08-06 11:45 | 57 楼
孤岛




级别: 骑士
精华: 0
发帖: 970
威望: 117
金钱: 959
在线时间:405(小时)
注册时间:2005-10-02
最后登录:2013-06-03

Re:动手打磨X-Fi任何版本,都可以让低端的extreme music模拟输出超过外置DAC01

谈何容易啊!

没有这方面知识和技能啊
顶端 Posted: 2007-08-07 00:44 | 58 楼
kobecao

头衔:shop34722517.taobao.com shop34722517.taobao.com

级别: 禁言
精华: 0
发帖: 3128
威望: 135
金钱: 1357
在线时间:1109(小时)
注册时间:2006-05-31
最后登录:2012-01-11

http://www.erji.net/read.php?tid=423659

顶端 Posted: 2007-08-08 12:25 | 59 楼
«12 3 45» Pages: ( 3/5 total )
耳机大家坛老帖 » ????

Powered by PHPWind 网友所发文章不代表本站立场,耳机大家坛版权所有,未经许可不得转载。 www.erji.net 浙icp备08008246号
战略合作伙伴:深圳市恒之瑞科技有限公司 《中华人民共和国增值电信业务经营许可证》粤B2-20120704
耳机大家坛成立于2002年  《耳机大家坛》图形LOGO及文字均为注册商标