[dennistdk]

 
Hi Yobster. Thanks for the reply. The reason why I asked this is because the only way to use my QC15 is to connect it to the Line-Out. 

 
Why is that? It's supposed to go in the headphone jack... 

 

[Voss]

   
Why is that? It's supposed to go in the headphone jack... 

Hi dennis. Here is the reason:
http://www.head-fi.org/t/755879/oppo-ha-2-portable-headphone-amplifier-dac-discussion-thread/990#post_11550372

 

[dennistdk]

 
Hi dennis. Here is the reason:
http://www.head-fi.org/t/755879/oppo-ha-2-portable-headphone-amplifier-dac-discussion-thread/990#post_11550372

Ok - sounds strange. I'll try that with some QC15's at work next time (I have some QC25's here that work fine, but never used the Oppo with them as you don't really gain much).
 
If the problem is that there is too little impedance then you can just buy a trrs impedance add'er like this... or is it because there is too much impedance? 
 

 

[Voss]

If the problem is that there is too little impedance then you can just buy a trrs impedance add'er like this... or is it because there is too much impedance?

 
Hi dennis. I agree with you - it really sounds strange (pun intended). 

Thanks for sharing this impedance adder but I don't think it would this. It is more likely the TRRS standard being followed by Oppo. Based on their reply to my email, they confirmed that the the sleeve contact in both Headphone Out and Line Out is being used as GND. Based on this website and Wikipedia, Oppo seems to be following the OMTP standard. On the other hand, latest earphones are using the CTIA/AHJ standard thus resulting is "misconnection".
 
I would greatly appreciate if you would be able to test your HA-2 Line-Out with a non-Oppo TRRS cable.
 
Thanks.

 

[dennistdk]

   
Hi dennis. I agree with you - it really sounds strange (pun intended). 

Thanks for sharing this impedance adder but I don't think it would this. It is more likely the TRRS standard being followed by Oppo. Based on their reply to my email, they confirmed that the the sleeve contact in both Headphone Out and Line Out is being used as GND. Based on this website and Wikipedia, Oppo seems to be following the OMTP standard. On the other hand, latest earphones are using the CTIA/AHJ standard thus resulting is "misconnection".
 
I would greatly appreciate if you would be able to test your HA-2 Line-Out with a non-Oppo TRRS cable.
 
Thanks.

Ah ok - makes sense. The impedance was mentioned in the post, but your explanation sounds much more likely.
Maybe just get one of these for a quick fix then?
 
http://www.ebay.co.uk/itm/Audio-AUX-3-5mm-TRRS-Plug-Adapter-CTIA-AHJ-OMTP-Connector-Swap-Converter-Cable-/291596150253

 

[Voss]

 
Ah ok - makes sense. The impedance was mentioned in the post, but your explanation sounds much more likely.
Maybe just get one of these for a quick fix then?
 
http://www.ebay.co.uk/itm/Audio-AUX-3-5mm-TRRS-Plug-Adapter-CTIA-AHJ-OMTP-Connector-Swap-Converter-Cable-/291596150253

 
Thank you so much for your suggestions. This would do the trick. But I'll just stick with the included TRS cable when using the QC15. I'm mostly using the Headphone Out anyway. I was just so curious about the differences between the two output ports.
 
Cheers!

 

[abm0]

  I am not sure about other apps, but the UAPP app will not respond if you activate it before plugging in the DAC, AND turning the DAC on.

Works for me though, on a CyanogenMod 12.1. I've done A/B testing with UAPP permanently active, by hotplugging/unplugging the DAC and the headphones and it worked fine.

 

[abm0]

 
I am wondering if I try a USB A connector to USB C and use the 'A' port from the Oppo if this will have the same effect?

No. The Oppo doesn't charge through the large A connector, only through the micro. The A is for supplying charge when you want the Oppo itself to act as a power bank for something else.
 

I just went an purchased an Amicroe OTG cable adapter - Micro USB to USB. I tried the Micro USB end with my Micro USB - USB C adapter and then my cable to the Oppo but nothing. Tried it the other way around and also nothing. 3rd cable I've had refunded this weekend haha.
The search continues!

What end of which cable did you connect to what? It's unclear from this description. Also not clear what you're trying to accomplish - if it's charging the Oppo through its large USB A connector, it will never work because the device itself is not built that way.
 
 
As far as I can see from my usage so far, the HA-2 will charge through its micro-USB port (labeled "B") whenever it's connected to another device that can supply power and when the micro-USB connector plugged into the HA-2 has a "floating" ID pin (pin 4), i.e. pin not connected to anything, i.e. not an OTG USB-Host type of connector. If the plug has the ID pin shorted to GND, it's indicating to the HA-2 that it should act as USB-Host (which is what OTG cables are supposed to do, normally only at the audio source end = the phone or tablet) and the HA-2 interprets that as "I shouldn't charge from the device at the other end". So what's different between a normal OTG cable and the short micro-to-micro OTG cable that comes with the HA-2 is that the latter has USB-Host connectors at both ends (ID pin 4 shorted to GND at both ends). This allows you to tell your phone to act as USB Host and send music to the HA-2 while at the same time instructing the HA-2 to not charge from your phone.
 
So a normal OTG cable looks something like this, electrically:

... whereas the HA-2's included micro-to-micro cable has the ID-pin-to-GND thing going on at both ends. This allows you to play music without charging the DAC, and also to plug the cable in either way and still have it work (not possible with a regular OTG).

 

[MadAudio]

  Works for me though, on a CyanogenMod 12.1. I've done A/B testing with UAPP permanently active, by hotplugging/unplugging the DAC and the headphones and it worked fine.

Let me be more exact - the UAPP will work if activated before turning on the HA-2, but in android mode - it reports not seeing any USB DAC connection.  It will still send audio to the DAC but I believe the android device/app have done the decoding, and what goes out to the HA-2 is analogue (I am happy to be corrected on the "analogue out" if anyone knows differently, but I do know the UAPP app does report a failure to detect a USB audio device when turned on before turning on the HA-2).
 
This means the signal out will not be any better than 44.1/16bit, or maybe 48.1/16bit, regardless of the source file.
 
My own experience (non-rooted android 5.02 on Samsung Galaxy Note Pro) is that in order for the UAPP to utilize the hi-res capabilities of the HA-2 (and hi-res source files - eg flac 96k/24bit or better) I need to make all physical connections, turn on my Note Pro, then turn on the HA-2, upon which the UAPP app starts automatically, and reports using a DAC usb device.
 
Using a rooted android device running CyanogenMod may give different results.

 

[abm0]

  It will still send audio to the DAC but I believe the android device/app have done the decoding, and what goes out to the HA-2 is analogue

LOL, no it won't - you can't send anything analog via USB. If UAPP is playing and you can hear sound from the Oppo's headphone-out, the Oppo got a digital signal and converted it to analog itself, there's no other way that can go with just a USB between the phone and the Oppo.
 
 

This means the signal out will not be any better than 44.1/16bit, or maybe 48.1/16bit, regardless of the source file.

Ah, that may be true, I never had any reason to care about anything better than 16/44.1, so I haven't been paying attention to that.

 

[vigotone]

After owning the HA-2 for a little over a month now, I wanted to weigh in on the RFI issue. I have been using the HA-2 connected to an iPhone 6S Plus via the Zeskit USB to Lightning cable. When riding the subway while listening to music (stored locally on the iPhone), there is no cell signal and everything works flawlessly. Then, as the train pulls into a station that has cell reception, the handshake is lost, the music stops, and I hear RFI noise. It usually re-establishes the handshake quickly, at which point I restart the music. Then as we leave the subway station and the cell reception once again goes away, the music stops again, the handshake is lost, and I hear RFI noise.

This happens so often, it is clear that the HA-2 cannot maintain the handshake when going through areas of intermittent cell reception. As others have said, the only solution would be to switch to airplane mode, but surely Oppo must be aware that this is a real problem requiring a proper solution.

 

[MadAudio]

  LOL, no it won't - you can't send anything analog via USB. If UAPP is playing and you can hear sound from the Oppo's headphone-out, the Oppo got a digital signal and converted it to analog itself, there's no other way that can go with just a USB between the phone and the Oppo.

LOL at myself - of course a USB connection is digital!!! Idiot (me, that is)!!! I think I knew that when I said I "was prepared to be corrected on the analogue" part, just hadn't thought it through.
 

This happens so often, it is clear that the HA-2 cannot maintain the handshake when going through areas of intermittent cell reception. As others have said, the only solution would be to switch to airplane mode, but surely Oppo must be aware that this is a real problem requiring a proper solution.

 
Are we sure here that it its the Oppo that loses the handshake, and not the host device and the software??  I know that I have all sorts of problems re-establishing UAPP's recognition of my HA-2 if a cable or plug is momentarily jarred.  I have to completely stop the (UAPP) app, turn off my HA-2 (sometimes even power down my android tablet, and power it back up again) before UAPP will once again recognise the HA-2 is connected when I turn it back on.
 
Just as others have suggested that the HA-2 is well shielded, and the connecting cables (acting as aerials?) are the problem?

 

[BrutalLegend]

Anybody know what the power output is for a 80 ohms headphone? Thanks in advance!

 

[abm0]

  Anybody know what the power output is for a 80 ohms headphone? Thanks in advance!

It's not the impedance alone that tells you your power requirements, it's also the sensitivity.

 

[rickydenim]

  No. The Oppo doesn't charge through the large A connector, only through the micro. The A is for supplying charge when you want the Oppo itself to act as a power bank for something else.
What end of which cable did you connect to what? It's unclear from this description. Also not clear what you're trying to accomplish - if it's charging the Oppo through its large USB A connector, it will never work because the device itself is not built that way.
 
 
As far as I can see from my usage so far, the HA-2 will charge through its micro-USB port (labeled "B") whenever it's connected to another device that can supply power and when the micro-USB connector plugged into the HA-2 has a "floating" ID pin (pin 4), i.e. pin not connected to anything, i.e. not an OTG USB-Host type of connector. If the plug has the ID pin shorted to GND, it's indicating to the HA-2 that it should act as USB-Host (which is what OTG cables are supposed to do, normally only at the audio source end = the phone or tablet) and the HA-2 interprets that as "I shouldn't charge from the device at the other end". So what's different between a normal OTG cable and the short micro-to-micro OTG cable that comes with the HA-2 is that the latter has USB-Host connectors at both ends (ID pin 4 shorted to GND at both ends). This allows you to tell your phone to act as USB Host and send music to the HA-2 while at the same time instructing the HA-2 to not charge from your phone.
 
So a normal OTG cable looks something like this, electrically:

... whereas the HA-2's included micro-to-micro cable has the ID-pin-to-GND thing going on at both ends. This allows you to play music without charging the DAC, and also to plug the cable in either way and still have it work (not possible with a regular OTG).

Thanks for the info! Yes, the issue for me is to find a cable that is setup the same as the Oppo provided cable so it does not charge the phone. The only cable that has allowed UAPP to work is a standard Micro USB cable with a Micro USB - USBC adpater (came with my Note 7) but as I say, this charges the phone. I have tried my original Oppo Micro USB cable with the provided MicroUSB - USB C adapter however I get no connection at all.
 
I thought the Amicro OTG adapter cable might work as it clearly states OTG however this won't connect to the phone also.
 
The only cable I have found on the internet that people have got to work is the Anker MicroUSB - USB C cable however I can't find anywhere that will ship to Australia