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FiiO X3 mod - AD8397 to AD8620 - Page 8

post #106 of 238

Well, I searched google for AD8620 counterfeit, problem, fake, I could only find 4 references, and 2 of them were on Head-fi, you were the author, and you had no direct experience, you were relying only on reports from other people. The other references weren't well supported, one at least being based only on a suspicion that the price was too low.

 

You have to be careful about starting or propagating 'Internet Legends' especially when substituting opamps doesn't work out as well as hoped, an ill-advised opamp change can easily degrade performance.

 

Consider that the AD8397 will drive 310mA into a 32 ohm load, where the 8620 is good for 30mA only, and that into an unspecified load. This is a factor of 10+ in only a single parameter, albeit quite a significant one where driving low impedances is concerned. A little arithmetic suggests that (11.8V/0.03A = 393 ohms) the AD8620 will only happily drive just under 400 ohms before the output voltage starts to become restricted, whether it simply falls off or clips is open to speculation. What is certainly true is that with lower impedance loads the distortion will rise, perhaps giving rise to the differences detected in your 'blind testing'.

 

As for the necessity of taking risks, surely it would be a lot less risky to just leave the original opamp in place and not risk damaging the PCB?

 

w

post #107 of 238
Thread Starter 

I guess you didn't search in Chinese? Well, never mind that. Maybe I am just being overcautious there but as I have said - if you can get 100% genuine part without concern over how much you pay (or any other factors on that matter), why don't you? What is the bad in that?

 

Also, all of the downside of swapping the opamp has been mentioned, if you have read my posts in this thread more carefully. While RMAA test isn't exactly an industry standard like an AP machines, I did carry out measurement on multiple loads to at least confirm my mod didn't ruin the day, at least to the kind of load I was planning to use. Unless someone is willing to give / loan me an AP, I am afraid that isn't much I can do more. As for the risk management on mod'ing - I am sure that's mostly relate to individual's soldering skill more than anything? Last I checked,  I did warn people about it.


Edited by ClieOS - 9/21/13 at 6:14pm
post #108 of 238

Don't mean to bring this OT, but, Clieos which version of the AD8066 should I use when I want to do this mod (I'm new to Opamps, so I was wondering which would work the best on this list: http://components.arrow.com/part/search/ad8066?region=na)?

post #109 of 238
Thread Starter 
Quote:
Originally Posted by EuphonicArin View Post
 

Don't mean to bring this OT, but, Clieos which version of the AD8066 should I use when I want to do this mod (I'm new to Opamps, so I was wondering which would work the best on this list: http://components.arrow.com/part/search/ad8066?region=na)?

 

You don't want to order 1000 or 2000 opamp (under 'multiple' tab), so you can cross those out. That leaves you with 5 options. Then you don't want the evaluation board (-EBZ) for sure, so now there are only 4 options. Anything with an M (ARMZ and ARM) means it is MSOP8 instead of SOIC8, so we don't want those as well. The two choices left are the AD8066AR and AD8066ARZ - Z means RoHS compliance, which doesn't matter to us, so either one of them will do. But ARZ is cheaper, so that's the one to get.

post #110 of 238

I have done my mod. AD8397 replaced with OPA1602. OPA1612 and OPA1602 sounded very similar and OPA1602 is even less power hungry. Output current is the same for both, 30mA but plenty for IEMs.

 

I used flux, a temperature controlled soldering station, desoldering wick, leaded solder, tweezers, a screwdriver and a light.

 

I ran into some problems.

 

First I was not carefull with desoldering/removing the AD8397 and loosend a connection pin on the circuit board. I put it back into place and started soldering the OPA1602 but again screwed up and this time the pin broke. I thought this is the end but I saw the pin was connected to one end of a SMD-part and figured I could connect the opamp pin to that. After soldering the pins on the other side of the opamp, I put on enough solder to connect the two points and made sure they were connected without making other shorts. All was into place, the HOLD-button was another obstacle.

 

Luckely it works and now it sounds a lot better to my ears. There is almost no difference between my iBasso D4 with OPA1612 and my X3, using T5 is no longer required to get the sound I want.

 

The mod is not easy! The most difficult part is removing the AD8397, if you do that in a careless way, you can screw up hard. I have quite good soldering skills but at my previous job I had a better soldering iron (tip).

post #111 of 238
Thread Starter 
Quote:
Originally Posted by s0lar View Post
 

The mod is not easy! The most difficult part is removing the AD8397, if you do that in a careless way, you can screw up hard. I have quite good soldering skills but at my previous job I had a better soldering iron (tip).

 

Great that you find the reborn X3 better. Yep, this is definitely not for novice.

post #112 of 238

If you must attempt this mod, then it's better to cut the AD8397 off the board. You do this with the tip of a scalpel or craft knife, cutting the legs one-by-one, as close to the chip's body as you can get the knife. If you do it right the blade will come to rest on a tiny ledge on the chip instead of contacting the PCB. You have to press hard, holding the knife very firmly to avoid breaking the blade. You will hear a tiny 'click' when the chip leg parts. When the chip falls away from the board pick up all the legs on a hot soldering iron, they will stick to it, and tidy up the remaining solder on the pads with solder wick. Work quickly to avoid lifting a pad from the board.

 

Of course the AD8397 will be useless for any further electronics, but it's probably better not to try to re-use it anyway.

 

w

post #113 of 238

Ok, I'm almost ready for the mod myself. I'm loving X3 as DAP, but I still feel like I'm missing something there, but this is just my nature ;)

 

So I gathered all op-amps I had around and this is what I have left:

 

AD8599, AD8620, AD8022, LME49720 - all tested in my C-Moy at some stage, liked all of them, loved AD8599 and L49720

AD8512, OPA1662 - not tested.

 

I know that none of you have crystal ball to answer if above will sound good to me, but do you think that apart from AD8620 (which was already tested) can be fitted? I really want to try 8599 or/and 49720, but I'm aware that number of tries is limited.

What do you think about the rest?

 

Cheers

post #114 of 238

^.........:popcorn:

post #115 of 238
Quote:
Originally Posted by docentore View Post

Ok, I'm almost ready for the mod myself. I'm loving X3 as DAP, but I still feel like I'm missing something there, but this is just my nature wink.gif

So I gathered all op-amps I had around and this is what I have left:

AD8599, AD8620, AD8022, LME49720 - all tested in my C-Moy at some stage, liked all of them, loved AD8599 and L49720
AD8512, OPA1662 - not tested.

I know that none of you have crystal ball to answer if above will sound good to me, but do you think that apart from AD8620 (which was already tested) can be fitted? I really want to try 8599 or/and 49720, but I'm aware that number of tries is limited.
What do you think about the rest?

Cheers

I would suggest soldering some wires to the points where you would normally put the OPAMPs, and try each opamp, soldering them to the wires

This way you don't screw up the X3's board.
post #116 of 238
Quote:
Originally Posted by CH23 View Post


I would suggest soldering some wires to the points where you would normally put the OPAMPs, and try each opamp, soldering them to the wires

This way you don't screw up the X3's board.

 

Thanks for the suggestion, but:

1. I would be concerned about the noise, distance to the components (ie coupling caps), etc.

2. I actually screwed my last mod by using this method on my amp, I could test the op-amps ok, but the sq was deteriorated because of the reasons above and I messed up the board because I wasn't careful enough. Nothing that cannot be repaired but I would like to avoid this.

 

Hence I want to make the swap on the first, worst case scenario on the second try

post #117 of 238
Quote:
Originally Posted by docentore View Post

Thanks for the suggestion, but:
1. I would be concerned about the noise, distance to the components (ie coupling caps), etc.
2. I actually screwed my last mod by using this method on my amp, I could test the op-amps ok, but the sq was deteriorated because of the reasons above and I messed up the board because I wasn't careful enough. Nothing that cannot be repaired but I would like to avoid this.

Hence I want to make the swap on the first, worst case scenario on the second try

I wish you the best of luck.

I haven't bought components yet to mod mine, so i'm glad you're also willing to test it ;P
post #118 of 238
Quote:
Originally Posted by docentore View Post
 

 

Thanks for the suggestion, but:

1. I would be concerned about the noise, distance to the components (ie coupling caps), etc.

2. I actually screwed my last mod by using this method on my amp, I could test the op-amps ok, but the sq was deteriorated because of the reasons above and I messed up the board because I wasn't careful enough. Nothing that cannot be repaired but I would like to avoid this.

 

Hence I want to make the swap on the first, worst case scenario on the second try

I think the issues you described above were due to poor modding skills. Wires sounds like a proper bet to me. I mean we use wires on bread boards and it all works fine. Why won't it work in your case?

post #119 of 238
Quote:
Originally Posted by serious7 View Post
 

I think the issues you described above were due to poor modding skills. Wires sounds like a proper bet to me. I mean we use wires on bread boards and it all works fine. Why won't it work in your case?

 

 

I'm new to audio DIY and I assumed that wire testing of elements to choose the best op-amp in smd enviroment, were resistance of few ohms and capacitance difference of couple of pico-farrads on wires, which are also acting as antenna makes a difference. But obviously it was my poor modding skills made the sq bad as you noticed.

 

My modding skills are completely fine actually the only problem is I have trouble with attention to details. Because it isn't cMoy breadboard build anymore I prefer not to make any mistakes and not to choose the ic that cannot be rolled to many times carefully. 

 

Re:1 I'm not new to modding/building/repairing, I've fixed and modded tones of PC's and consoles (that's including reballing bga chips when I was doing this for living), but I'm completely new to DIY audio. I've build my first kind-o-cmoy 4 months ago with opamp I found on old tv pcb when I was bored. But as I've said sometimes I make stupid mistakes.

Re:2 I damaged it because I wasn't careful when taking off "the test wire installation" (lack of attention)

post #120 of 238
Quote:
Originally Posted by docentore View Post
 

I'm new to audio DIY and I assumed that wire testing of elements to choose the best op-amp in smd enviroment, were resistance of few ohms and capacitance difference of couple of pico-farrads on wires, which are also acting as antenna makes a difference. But obviously it was my poor modding skills made the sq bad as you noticed.

 

My modding skills are completely fine actually the only problem is I have trouble with attention to details. Because it isn't cMoy breadboard build anymore I prefer not to make any mistakes and not to choose the ic that cannot be rolled to many times carefully. 

 

Re:1 I'm not new to modding/building/repairing, I've fixed and modded tones of PC's and consoles (that's including reballing bga chips when I was doing this for living), but I'm completely new to DIY audio. I've build my first kind-o-cmoy 4 months ago with opamp I found on old tv pcb when I was bored. But as I've said sometimes I make stupid mistakes.

Re:2 I damaged it because I wasn't careful when taking off "the test wire installation" (lack of attention)

You must have access to oscilloscopes then? I'm sure you can design a test amplifier circuit where you can measure the impact a wire can have on the entire design. Have the oscilloscope point between the two outputs and see for yourself if the wire did any damage for your circuit.  My experiences with this is that there is no impact of introducing a wire whatsoever to an amplifier circuit. 

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