[ClieOS]

AD825 isn't rail-to-rail but it is close. However, it is still a mono channel and there is the concern over its 8 ohm output impedance. AD827 doesn't have a lot of voltage swing on low impedance load or current output as well. Also the output impedance is 15 ohm, worst than AD825.
 
These are the kind of opamp that are more suitable if there is a buffer stage followed.

 

[hoichi]

15 ohm is sad news. I don't plan on using anything more than 50 ohm any time soon.

 

[wiser87]

ClieOS, say, sound good headphones VSonic GR-01 with the player FiiO X3?

 

[ClieOS]

Quote:

ClieOS, say, sound good headphones VSonic GR-01 with the player FiiO X3?

 
They sound pretty good together.

 

[wiser87]

Thank you very much!

 

[chengsta]

"The result is as I have expected, a much more neutral and detail presentation. I can almost compare it to the X3's line-out + O2"
 
so if I'm using the lineout I don't need this mod?  This is my takeaway from your tutorial.  So does that also mean that the line out is more neutral than the built in amp?

 

[ClieOS]

Quote:

"The result is as I have expected, a much more neutral and detail presentation. I can almost compare it to the X3's line-out + O2"
 
so if I'm using the lineout I don't need this mod?  This is my takeaway from your tutorial.  So does that also mean that the line out is more neutral than the built in amp?

 
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.

 

[CH23]

Subscribed.

Thanks for the mod&info, ClieOS!

And also thank you for all your reviews and advise

 

[wiser87]

ClieOS may I say stupid, because not very good at that. What do you think of mod in the THS4082?

 

[ClieOS]

Quote:

ClieOS may I say stupid, because not very good at that. What do you think of mod in the THS4082?

 
The opamp meets the minimum voltage and has a decent swing, so it might work. However, it does seem it need a higher output resistance to be stable so I am not sure if this is a safe choice.

 

[wiser87]

What is the output resistance at the THS4082 compared to the AD8397 and AD8620?

 

[ClieOS]

Open loop resistance for THS4082 is 13 ohm. Also, a minimum of 20 ohm output resistor is suggested to avoid any oscillation. The actual output impedance will be over 20 ohm.
 
In comparison, output impedance on AD8397 and AD8620 are all under 1 ohm.

 

[wiser87]

What opamp you have any advice for replacement AD8397?

 

[ClieOS]

Quote:

What opamp you have any advice for replacement AD8397?

 
ADA4896 has been suggested by the FiiO R&D team to be suitable replacement.

 

[cyberalpha11]

Quote:

 
ADA4896 has been suggested by the FiiO R&D team to be suitable replacement.

Will James (Fiio) consider to use ADA4896 for the new production batch of X3?