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FiiO X3 mod - AD8397 to AD8620 - Page 10

post #136 of 216
Quote:
Originally Posted by JuicyBruce View Post
 

Hi Folks - I have a chap lined up to do the soldering work and I was wondering if the ISL5502 would suit?

 

A link to the datasheet

http://www.ic-on-line.cn/view_online.php?id=1161594&file=0077\isl55020irz-t13_711159.pdf

 

Cheers! JB

 

100% not, the one that you have listed is in 16qfp packacge. Pin wise one you need is 8-SOIC

post #137 of 216
Quote:
Originally Posted by docentore View Post
 

 

100% not, the one that you have listed is in 16qfp packacge. Pin wise one you need is 8-SOIC

 

Sorry - probably sent that too quickly. This is it mounted on an adaptor inside my D10 (with class A mod).

Ill do a bit more hunting for specs...

 

 

Edit - right so im an idiot. Had a missing zero. Here are the specs:

 

http://www.intersil.com/en/products/amplifiers-and-buffers/all-amplifiers/amplifiers/ISL55002.html


Edited by JuicyBruce - 10/25/13 at 4:21am
post #138 of 216

hello guys

from what I understood, dac buffer opamp is in a single supply design. Am I right?

Does someone know why? could not they use negative rail of ad8387 also for the buffer opamp?

I think ad8692 is a very low quality chip, and it's the bottleneck of the player.

what do you think about it?

post #139 of 216
Quote:
Originally Posted by vale25 View Post
 

hello guys

from what I understood, dac buffer opamp is in a single supply design. Am I right?

Does someone know why? could not they use negative rail of ad8387 also for the buffer opamp?

I think ad8692 is a very low quality chip, and it's the bottleneck of the player.

what do you think about it?

 

 You are right - it is single supply op-amp. I didn't want to risk and connecting the -/+5.5V rail to it.

 

Any suggestions regarding which chip could we use? I was thinking of ADA4841-2 or ADA4896-2, but I don't have any experience with them. Which op-amp could be suitable that is considered as good for audio and DAC buffer?

post #140 of 216
Quote:
Originally Posted by docentore View Post
 

 

 You are right - it is single supply op-amp. I didn't want to risk and connecting the -/+5.5V rail to it.

 

Any suggestions regarding which chip could we use? I was thinking of ADA4841-2 or ADA4896-2, but I don't have any experience with them. Which op-amp could be suitable that is considered as good for audio and DAC buffer?

I checked in the data scheet. AD8692 does not accept negative voltage rail. I think that the only way to make a real improvement on  sonic performance is changing this opamp with an audio grade opamp and give it negative supply through a hard wire. Also a cap should be used near the opamp pin. But this is sci-fi for me.


Edited by vale25 - 10/27/13 at 5:03pm
post #141 of 216
Quote:
Originally Posted by vale25 View Post

hello ad8692 is a very low quality chip, and it's the bottleneck of the player.
what do you think about it?

Why do you think that? Because it says 'low cost' in the datasheet?

The 8692 is a high performance, single-supply device, intended for portable audio devices.

If you guys don't understand that cost and performance aren't synonymous, then it won't be any surprise to the rest of us when you end up breaking your DAPs.

Wiring in a dual-rail device and wiring in a negative supply will have unknown consequences in terms of the output DC offset of the DAC section without detailed knowledge of the circuit. This will have an unknown knock-on effect on the amplifier section. A single-rail supply device has been employed for some reason when a dual-rail supply was available. The DAC output is almost certainly a current one, and the opamp is being used for I-V conversion. Current-output DACs frequently have a DC output offset to keep the (dual-rail) opamp working in class A, but this may not have been considered desirable in a battery-powered device because of the drain on the battery, or there may have been some other reason, but whatever it is, you don't know.

Get a grip, and don't mess with what you don't understand.

w
post #142 of 216
Quote:
Originally Posted by wakibaki View Post


The 8692 is a high performance, single-supply device, intended for portable audio devices.

If you guys don't understand that cost and performance aren't synonymous, then it won't be any surprise to the rest of us when you end up breaking your DAPs.



Get a grip, and don't mess with what you don't understand.

w

 

Great advice, leave all learning and experimenting because we don't understand. Sorry, I wasn't born with this great knowledge so I need to learn if I want to know. And I'm learning by reading, asking questions and experimenting. And I'm experimenting on stuff that I own, if I'll break it - well life is hard but one needs to break some eggs to make an omelette.

 

Get a grip and share some of your great knowledge instead of criticise and patronise other members.

post #143 of 216
Quote:
Originally Posted by docentore View Post

Great advice, leave all learning and experimenting because we don't understand. Sorry, I wasn't born with this great knowledge so I need to learn if I want to know. And I'm learning by reading, asking questions and experimenting. And I'm experimenting on stuff that I own, if I'll break it - well life is hard but one needs to break some eggs to make an omelette.

Get a grip and share some of your great knowledge instead of criticise and patronise other members.

If you think that gets it then you obviously haven't read my other contributions to this thread.

w
post #144 of 216
Quote:
Originally Posted by wakibaki View Post


If you think that gets it then you obviously haven't read my other contributions to this thread.

w

 

Actually I did, and I found the one with using knife to extract ic quite useful, but the rest is just "manufacturer knows better what sound you like, leave this as is". 

post #145 of 216

Changing the AD8397 should have more influence than changing DAC output opamp (AD8692) I would think. 

 

You could ask James at Fiio, he responds quite fast to questions.

post #146 of 216
Quote:
Originally Posted by wakibaki View Post


Why do you think that? Because it says 'low cost' in the datasheet?

The 8692 is a high performance, single-supply device, intended for portable audio devices.

If you guys don't understand that cost and performance aren't synonymous, then it won't be any surprise to the rest of us when you end up breaking your DAPs.

Wiring in a dual-rail device and wiring in a negative supply will have unknown consequences in terms of the output DC offset of the DAC section without detailed knowledge of the circuit. This will have an unknown knock-on effect on the amplifier section. A single-rail supply device has been employed for some reason when a dual-rail supply was available. The DAC output is almost certainly a current one, and the opamp is being used for I-V conversion. Current-output DACs frequently have a DC output offset to keep the (dual-rail) opamp working in class A, but this may not have been considered desirable in a battery-powered device because of the drain on the battery, or there may have been some other reason, but whatever it is, you don't know.

Get a grip, and don't mess with what you don't understand.

w ,

I think it not for datasheet low cost indication. The reason is that when I use the DAP from line output, I notice a harshness and a grain in the treble that can't be attributed to wolfson wm8740. (I know there are a lot of other possible reasons for this, but buffer opamp appear to be the most probable)

 

WM8740 is a voltage output dac.

I believe single supply op amp was chosen to keep low the power consumption, but if there is any reason would be nice to know.

I'm always ready to learn; maybe my poor mastery of english language gave you a different impression, but when I wrote "what do you think about", I really wanted to know your thought about it. A little less arrogance from your side would have been great.

Said this, unless James fiio say to me " change that opamp, it was placed there only for long battery life", I'd never open my x3


Edited by vale25 - 10/28/13 at 6:34am
post #147 of 216
Quote:
Originally Posted by s0lar View Post
 

Changing the AD8397 should have more influence than changing DAC output opamp (AD8692) I would think. 

 

You could ask James at Fiio, he responds quite fast to questions.

 

You are right it does affects the sound more than DAC output, but changing the ad8692 does change the signature of the DAP significantly. I was able to say straight away that there is something different, better or worse (tried 3 or 4 differents chips already).

 

I'm not going to mod anymore until someone more experienced could advise in polite way what are good candidates for the DAC output op-amp.

post #148 of 216

I just checked and my iBasso D4 uses AD8616 as DAC output opamp. It works single supply 2.7V to 5V and is a CMOS rail-to-rail opamp, just like the AD8692.

AD8066 is a FET opamp.

iBasso D4 has dual DACs though.

You should be carefull since clipping can occur at the DAC output when you swap the opamp. I have no idea about the signal that the DAC puts out, safest is to ask Fiio directly.

post #149 of 216

So sorry to trample on your delicate sensitivities. My advice, grow a thicker skin and just push ahead with the 'experiment' next time without asking. Wire in a dual-rail opamp, after all the worst that it can cost you is the price of a new X3...   :smile: 

 

w

post #150 of 216
Quote:
Originally Posted by wakibaki View Post
 

So sorry to trample on your delicate sensitivities. My advice, grow a thicker skin and just push ahead with the 'experiment' next time without asking. Wire in a dual-rail opamp, after all the worst that it can cost you is the price of a new X3...   :smile: 

 

www

 

Or the price of whatever headphone that you choose to test the sound with.  :veryevil:

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