[williamhifi]

X3 actually used quite a decent parts. Mine became very hot after charging, then I traced the problem to a TI TPS 63000 regulator, which provide v+ and feed the LM 2662 negative voltage generator. I have no idea why it became hot so fast, but I will replace them to see how it will work. I might add a delay circuit to the ps in order to protect them.

 

[williamhifi]

The output section has a LMH op am which has an 100 ma output current capability. But from the dac, the signal goes thru an OP1612 low pass filter, then another Opa 1612, then used the LMH as an output buffer.
I took out the last op amp, the LMH type, the sound became greatly more transparent

 

[saratoga]

The output section has a LMH op am which has an 100 ma output current capability. But from the dac, the signal goes thru an OP1612 low pass filter, then another Opa 1612, then used the LMH as an output buffer.
I took out the last op amp, the LMH type, the sound became greatly more transparent

 
Is that with high impedance headphones?  Not sure you want to drive normal ones without the buffer amp.  

 

[j0p3Y]

Its not a liquid crystal display is it?

Hmmm

May just pop it out. I've just removed the mirror screens on my X2 's and they don't seem to need a new screen protector. Might try the same here. Dunno why I've not thought of that before...!

no, it's OLED if I'm well informed.
Popping it out will render your x3 useless... Errr.. Not useless but prone to dust and moisture getting inside. That transparent part keeps that out. Also it protects your OLEDscreen. Need a replacement which is clear.

 

[fredhubbard2]

no, it's OLED if I'm well informed.
Popping it out will render your x3 useless... Errr.. Not useless but prone to dust and moisture getting inside. That transparent part keeps that out. Also it protects your OLEDscreen. Need a replacement which is clear.

Yes I understand that, but my X2 's been without screens for a few months and no probs as yet. I have 2 X3 so may risk it for the glory of a bright screen. Will report back .

 

[thanderbird]

already tried to change the battery xduoo x3 ? maybe put a battery with greater durability ?

 

[williamhifi]

Is that with high impedance headphones?  Not sure you want to drive normal ones without the buffer amp.  

Well LMH is a cheap op amp.all my headphones are low impedence type. 1612 is never out of juice, at least at those gain level. You couldnchange to 1602 too, which has 50% more deive current

 

[saratoga]

Well LMH is a cheap op amp.all my headphones are low impedence type. 1612 is never out of juice, at least at those gain level. You couldnchange to 1602 too, which has 50% more deive current

 
How low?  I think the problem isn't running out of power, but rather the impedance presented.

 

[williamhifi]

How low?  I think the problem isn't running out of power, but rather the impedance presented.

I mainly use audio technica ath m70x, which is about 35 ohm. Those in the ear type with 16 ohms are easy to drive.
Opa 1612 can put out 50ma. I can drive my m70x to loud enough that will destroy my ear. At X3 gain level, 1612 can handle with no problem.
I removed the LMH op amp. Then connect the pin 2 with 3, and pin 5 with 6 in the remaining op amp traces. I think you dont even hv to remove the LMH op amp. Just short pin 2 with 3, and pin 5 with 6 with the op amp remain. The only different is that LMH will still use 2 to 3 ma of current

 

[saratoga]

Opa 1612 can put out 50ma. 

 
At 15v.  Ohms Law:  V/I=Z.  15/.05 = 300 ohms.  That is ok for a line out, but terrible for a headphone output.  
 

I can drive my m70x to loud enough that will destroy my ear. At X3 gain level, 1612 can handle with no problem.

 
 
Yes, because the X3 supports a high voltage.  But this has nothing to do with impedance, which is what you are changing.  You will still get a large voltage swing (although much smaller than normal), but it'll be badly degraded since you're basically trying to run headphones off a line out jack.  
 
I don't understand what you're hoping to accomplish by removing the current buffering.  Best case you are ruining your headphone output. 

 

[williamhifi]

At 15v.  Ohms Law:  V/I=Z.  15/.05 = 300 ohms.  That is ok for a line out, but terrible for a headphone output.  



Yes, because the X3 supports a high voltage.  But this has nothing to do with impedance, which is what you are changing.  You will still get a large voltage swing (although much smaller than normal), but it'll be badly degraded since you're basically trying to run headphones off a line out jack.  

I don't understand what you're hoping to accomplish by removing the current buffering.  Best case you are ruining your headphone output. 

I guess you have to try it out for yourself first.
Your ohm's law sud be using the output voltage rather that the ps'. Any way, if you are handy, you cud do some measurements first before making the assumption.. i wud not say things I have not done before.
I hv been working on a few x2 and x3. Destroying some n repaired them as well.

Cheers

 

[saratoga]

I didn't use the power supply voltages. I used the values in the data sheet for that amp.

If you want you can calculate the max output current though for a given voltage. Just apply ohms law and 300 ohms. Your iems are probably only getting microamps of current at comfortable volume. If you are OK with that, I wonder why you bought a brick of a DAP designed for high currents? An old iPod or Sansa would do better than that, and have much better battery life. Whole point of the x3 is the high current amp

 

[williamhifi]

I didn't use the power supply voltages. I used the values in the data sheet for that amp.

If you want you can calculate the max output current though for a given voltage. Just apply ohms law and 300 ohms. Your iems are probably only getting microamps of current at comfortable volume. If you are OK with that, I wonder why you bought a brick of a DAP designed for high currents? An old iPod or Sansa would do better than that, and have much better battery life. Whole point of the x3 is the high current amp

I have sent you a mail for my explaination... in short, please take a look at TI web site on opa 1622, the op amp they design just for headphones, there are ample explaination about the current needed to drive headphones..but most headphones are quite easy to drive with just 1612.
Last night I soldered across the +ve and -ve input of the LMH op amp, it work well as expected, with clearer sound. Of course now the output chip will be opa 1612. If you need higher current, replace it with opa 1602, but to most headphone, 1612 is ok..
Have fun!

 

[vapman]

I have sent you a mail for my explaination... in short, please take a look at TI web site on opa 1622, the op amp they design just for headphones, there are ample explaination about the current needed to drive headphones..but most headphones are quite easy to drive with just 1612.
Last night I soldered across the +ve and -ve input of the LMH op amp, it work well as expected, with clearer sound. Of course now the output chip will be opa 1612. If you need higher current, replace it with opa 1602, but to most headphone, 1612 is ok..
Have fun!

Any sound difference between 1602/1612/1622? Thinking I want to go with whatever allows largest current, but not sure yet.

 

[Rixsta]

any other players with dual MicroSD recommended?