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FiiO X3 mod - AD8397 to AD8620 - Page 7

post #91 of 213
will the opa1662 work?

Edited by chesterqw - 9/19/13 at 11:44pm
post #92 of 213
Quote:
Originally Posted by ClieOS View Post
 

 

Well, I think the more correct way of describing this will be, the amp section adds a touch of warmness to the line-out. Remember that the line-out isn't just an output on its own. The same line signal feeds into the amp section as well.

 

Yes, what this means is that if you are using an external amp on the line-out, there is absolutely no need to mod the AD8397.

 

Hi

 

I just got my X3 and love it, but have been intrigued by this thread. Thanks ClieOS! Having had and/or modified high end home audio equipment in the past, I am fully aware of the benefits and gains that can be made.

 

But before I rush into anything (i.e. Ripping open my X3 and performing major surgery) you mentioned that if using the Line out with a suitable amp may give similar results.  Do you or anyone have any suggestions of a suitable portable headphone amp that would make the sound more neutral?  I guess I should be posting this on the help and suggestions forum..

post #93 of 213
Thread Starter 
Quote:
Originally Posted by chesterqw View Post
 
will the opa1662 work?

 

On brief look, I don't see any problem.

 

Quote:
Originally Posted by csumm View Post
 

 

...

But before I rush into anything (i.e. Ripping open my X3 and performing major surgery) you mentioned that if using the Line out with a suitable amp may give similar results.  Do you or anyone have any suggestions of a suitable portable headphone amp that would make the sound more neutral?  I guess I should be posting this on the help and suggestions forum..

 

If you are planning on using an amp with X3, then getting a good quality amp will just save you all the trouble of modding and possibly better sounding than a mod'ed amp section.

post #94 of 213
Quote:
Originally Posted by ClieOS View Post
 

 

On brief look, I don't see any problem.

 

 

If you are planning on using an amp with X3, then getting a good quality amp will just save you all the trouble of modding and possibly better sounding than a mod'ed amp section.

 

Thank you, that was what I am after.

 

Are there any particular amps that you would suggest? While I have spent more years (and money) than I would care to remember in home audio, I am relatively new to high end portable sound. Any suggestions as to where to begin this new quest (ah, my wife will be angry at my new hobby, but at least it is not another woman!) would be appreciated. Any particular brands, models...?

 

Thanks again

post #95 of 213
Thread Starter 
Quote:
Originally Posted by csumm View Post
 

 

Thank you, that was what I am after.

 

Are there any particular amps that you would suggest? While I have spent more years (and money) than I would care to remember in home audio, I am relatively new to high end portable sound. Any suggestions as to where to begin this new quest (ah, my wife will be angry at my new hobby, but at least it is not another woman!) would be appreciated. Any particular brands, models...?

 

Thanks again

 

Depends on your budget and how much weight you are willing to carry, I'll say O2 (by JDS Labs, or other companies as it is an open source design) is one of the most colorless amp you can get for a very good price (~$150 or so). Meier Audio QuickStep is another amp I can wholeheartedly recommend for its balanced ground topology (similar to the sound of a balanced setup, I own the first gen. StepDance, QuickStep is the 3rd gen). Leckerton Audio UHA-6S MK2 is also a really good choice as well (I own the UHA-4, a stepdown with similar topology). UHA-6S MK2 also has SPDIF input that you can use with X3, though it doesn't support over 24/96. These will be my top three portable amp to recommend.

post #96 of 213
Quote:
Originally Posted by ClieOS View Post
 

 

Depends on your budget and how much weight you are willing to carry, I'll say O2 (by JDS Labs, or other companies as it is an open source design) is one of the most colorless amp you can get for a very good price (~$150 or so). Meier Audio QuickStep is another amp I can wholeheartedly recommend for its balanced ground topology (similar to the sound of a balanced setup, I own the first gen. StepDance, QuickStep is the 3rd gen). Leckerton Audio UHA-6S MK2 is also a really good choice as well (I own the UHA-4, a stepdown with similar topology). UHA-6S MK2 also has SPDIF input that you can use with X3, though it doesn't support over 24/96. These will be my top three portable amp to recommend.

 

Thank you so much, this makes the search much easier to begin. I will see what is available in Taiwan, then look online

 

Cheers for the advice!

post #97 of 213
Are there any websites where i could buy the ADA4896 or AD8620 opamps, that ships internationally? Google gives me nothing, and i wasn't planning on buying 100pcs.

-CH23
post #98 of 213
Quote:
Originally Posted by CH23 View Post

Are there any websites where i could buy the ADA4896 or AD8620 opamps, that ships internationally? Google gives me nothing, and i wasn't planning on buying 100pcs.

-CH23

 

Here it is....ready......>>> eBay <<<

 

http://www.ebay.com/itm/AD8620-Low-Noise-Wide-BandWidth-JFET-Precision-Dual-Op-Amp-AD8620ARZ-/171128413497?pt=LH_DefaultDomain_0&hash=item27d80c5d39

post #99 of 213

Yes it seems that eBay is my only choice then, thank you smily_headphones1.gif
post #100 of 213
Thread Starter 
Quote:
Originally Posted by CH23 View Post


Yes it seems that eBay is my only choice then, thank you smily_headphones1.gif

 

Don't buy opamp from eBay unless it is your ONLY / LAST choice, as there are too many fake opamp on there.

 

Try Element 14 or RS Component for international location. Digikey or Mouser for USA. These are all well respected electronic component suppliers.

post #101 of 213
Quote:
Originally Posted by ClieOS View Post

Don't buy opamp from eBay unless it is your ONLY / LAST choice, as there are too many fake opamp on there.

Try Element 14 or RS Component for international location. Digikey or Mouser for USA. These are all well respected electronic component suppliers.

Thank you very much, ClieOS!

Now i have one question regarding the AD8620:

There's an AD8620 A, and an AD8620 B, but apart from their price, i don't know the difference between them. Which one should i buy?
Edited by CH23 - 9/20/13 at 11:56pm
post #102 of 213
Thread Starter 
Quote:
Originally Posted by CH23 View Post


Thank you very much, ClieOS!

Now i have one question regarding the AD8620:

There's an AD8620 A, and an AD8620 B, but apart from their price, i don't know the difference between them. Which one should i buy?

 

'B' has a tighter spec than 'A', but for the content of the mod, A is totally fine.

 

Even on the same wafer, there are some chips on the board that will perform slightly ahead / average / worst than others. It is a common practice for chip manufacturer to test chip and sell the tighter spec batch (of the same chip) for a higher price, where the average batch will be sold at normal price and the worst batch be sold as a lower model number at cheaper price. That's how they maximize profit.

post #103 of 213
Quote:
Originally Posted by tomb View Post
 

I really don't understand this thread, unless the FiiO implementation of the AD8397 is suspect.

It might actually be. Output impedance for the X3 is very low (spec = <0.3 ohms), and the AD8397 does not like driving significant amounts of capacitance without some extra series resistance. 2.2 ohms is recommended for up to 470 pF in the datasheet, while otherwise 270 pF is the recommended maximum. Now your average 3m Sennheiser cable, for example, weighs in at about 1 nF. That may be enough to upset the chip.

 

By contrast, the AD8620 datasheet claims "excellent capacitive load driving capability" ... "can safely drive up to 10 nF". Ta-Dah.

 

AD8397 is a bit of a stupid chip. While it has significant current drive capability, it is not suitable for driving cans at very low output impedance, so it kinda falls flat in practice when you need to drive one of these super picky IEMs. A bit like the TPA6120A2 that requires a 10 ohm output resistor (well, rumor has it that this one was a failed DSL line driver anyway...).

 

Using an MSOP part (like the ADA4896) for a headphone output driver is something that I wouldn't feel comfortable recommending. Such a tiny package has like no power dissipation at all. SO-8 is bad enough, they didn't come up with power pads for no reason. If you can accept a temperature of 100K above ambient, the ADA4896 can still dissipate 450 mW, but I wouldn't really want the poor chip to get that hot. At 55K above ambient, we're talking about 250 mW. Idle PD would be about 60 mW in the X3.

post #104 of 213
Thread Starter 

On the topic of TPA6120A2 - actually it can be implemented with output impedance under 1 ohm, just not by the book.. iFi Audio did that in their iCAN and the result is excellent.

post #105 of 213
Quote:
Originally Posted by ClieOS View Post
 

 

Don't buy opamp from eBay unless it is your ONLY / LAST choice, as there are too many fake opamp on there.

 

Try Element 14 or RS Component for international location. Digikey or Mouser for USA. These are all well respected electronic component suppliers.

 

I bought many components on ebay without problems. Tubes from Russia, opamps, capacitors and pots from Thailand, PCBs and resistors from China. Be careful buying exotic transistors from China or parts known to be in short supply, but TPA6120 or PGA2320 from USA, or 50 NE5532 from Thailand, no problem at all. Some things just aren't worth counterfeiting. It's much less trouble, more convenient, and much less expensive than going to Farnell and having to buy £20 in components or have to pay shipping and handling. The one good thing about Farnell or RS is the next-day delivery.

 
I'm with tomb. Unless there are multiple reports of the Fiio failing or oscillating with high capacitance cables, and I don't see any evidence of that, then dragging a surface mount chip off its pads to replace it with one which will have less current drive, the AD8397 being unsurpassed in that package, just seems to me like going looking for trouble. I'd be careful myself about designing the part into an enclosure with a shorting output connector like a 3.5mm stereo jack, since the datasheet suggests no output short-circuit tolerance, but there are probably 10's of thousands of these Fiios sold worldwide and all the problem reports I can find relate to a firmware problem with not starting up on first power-on.

 

w

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