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OPPO HA-2 Portable Headphone Amplifier/DAC Discussion Thread

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  1. grig
    keep me posted pls, very curios..
  2. mimizone
    So I got a iFi iDefender 3.0.
    Let me give some context.

    I use a Mac Mini Late 2012 for everything at my desk, including Hi-Res music. The mini has many external hard drives via USB and Firewire.
    - One Drobo Generation 2 via Firewire, with 4 drives
    - WD My Book via USB 3 directly to the Mini
    - WD Elements via USB 3 powered Hub
    - Generic external case for 3.5" drive (for Time machine) via USB 3 powered Hub
    - USB keyboard on the hub
    - Mouse on the hub
    - iPhone charger on USB 3 hub
    - Usually an external 2.5" case in USB 3 hub
    - HDMI to the display
    - 3.5mm audio out to cheap speakers and a spare 3.5mm ports for headphones if needed

    All plugged to the same Belkin Power strip

    I use the following for audio:
    - Oppo HA-2 SE via USB hub (or dedicated port on the mini), using a generic USB cable
    - I use the Oppo as both a DAC and an amplifier, or use a tube amp (Eddy Current ZDT Jr.) via line-out on the Oppo, using a generic RCA/3.5mm cable.
    - Headphone: Audeze LCD-XC using the 6.5mm cable with a cheap but good quality 3.5mm adapter if needed

    My problem was the following:
    When using the tube amp, I could hear all drives in the Drobo NAS starting/rotating when they wake up from sleep/standby.
    Like actually hear them, with a sound of acceleration, similar to the sound you would hear without headphone in the room. The volume on the amp had to be fairly loud, in the last quadrant (above 3/4). I was not experiencing the issue on the headphone output of the oppo itself.
    I also had a noise problem at loud volume. The ZDT Jr. amp is dead quiet normally, even for a tube. It's very dead quiet. (unless you make the tubes ring by knocking on the amp chassis...). That noise was more like a background/white noise, fairly faint but very present at 85-100% volume on the ZDT. The noise would disappear if I unplug the usb cable from the oppo.

    I've tried many tricks to avoid those noises before buying the iDefender.
    I first tried many usb cables I have, all generic. The noise+hard drive sound were different but always there.
    I've tried different generic RCA/3.5mm I had. Same noise+sound.
    I used a DLNA renderer instead of plugging the Oppo to the mac mini, trying to isolate the USB noise from the mini.
    the DLNA renderer is a very small PC based on Atom, with an SSD, no USB devices, running Volumio.
    the noise was still there, less present but still there. The hard drive sound was there too, unless I plugged the DLNA renderer in an outlet on the other side of the room. The hard drive sound would sill be there but less intense.

    So I was getting crazy by that time :)
    I also tried to plug the Drobo to different power outlets. Not changing much somehow.

    All the equipment is more or less in the same space/spot. Mac mini and drives are next to each other. The RCA cable running around the mac mini. The Drobo being under the desk, 3ft below the ZDT amp.

    I ordered the iDEfender 3.0 and a nice RCA/3.5mm cable (SKW brand). Very nice cable for not too much $26 or so.

    Using the new cable between the Oppo and the ZDT amp basically removed entirely the sound from the hard drives. nothing, dead quiet.
    the iDefender is a weird case.
    By itself, plugged on the hub and using the generic usb cable, there is still that white noise. It sometimes even seems louder.
    But once I use an external power supply for the iDefender (I think I use one that came from a Raspberry Pi), the noise is gone, entirely too. Dead quiet.

    The only thing I can hear, and frankly it's nothing, is the very faint noise the mac must be creating when Audirvana takes control of the Oppo DAC. I put the volume on the ZDT to the max, in Audirvana to the max. First, all music is off and stopped. If I pause a track, there is faint hiss barely above the tinnitus I have... If I press the stop button in audirvana instead of pause, the hiss disappears.

    I can only hear that if it's dead quiet at night in my house. And it may be in my head :)

    so TLDR is:
    - iDefender 3.0 with external power is good, without bad
    - better cables is the first thing to buy
    - the Oppo does something funky with power via the mini usb port, and also with its line out port.

    I am debating buying a simple Furman power conditioner instead of my cheap Belkin power strip. That may just also solve the noise coming from the Drobo.

    Sorry for the long text here... But I indeed was becoming crazy to remove that noise. Hearing the Drobo starting when in a middle of a quiet part of a track was dreadful/scary...
    Last edited: Jan 5, 2019
  3. Chris Ihao
    Just a bit of necroing here, but could also be a bit helpful considering its still available. Thanks a bunch for the link. Tried several alternatives in stores but no dice. Hopefully my Huawei will play nice with this one. A really good price and free shipping so I bought two. :)
  4. grig
    Thank you very useful this post !
  5. lucifero13
    How would you know if the power is being drawn from the USB and not from the battery? I asked a friend to make one just like yours
  6. MikeyFresh
    The DAC is always in all circumstances powered by it's battery and not by USB as stated by Oppo. That makes sense, there are not two different pathways for powering the circuit, only one, that being the battery.

    What the circumstance you quoted describes is a way to keep the battery from being charged all the time by the USB connection. If you cut the bus power via that UpTone USPCB adapter, the charging LED indicator lights on the HA-2 go out, it is no longer drawing any charge. The HA-2 sounds better with that charging circuit deactivated, and the noisy PC ground severed.
  7. abm0
    Ehh, it's easy until the included cable dies out because it's so rigid and deals so poorly with repeated bending. :) Then you discover almost nobody makes such cables, with OTG pin configuration at both ends.
    I tried making my own out of two regular OTGs by using the OTG side of each and soldering the wires together in the middle, but it's a mess - the wires are too thin to allow a solid and reliable connection and joint to form in the middle.
    My next idea is to get two regular OTGs with female USB-A connectors at the non-OTG ends, and strip the outer metal shell of one of the female As to turn it into a male A and just plug it into the other female A. :)
  8. MikeyFresh
    The above exchange was entirely related to connecting the HA-2 to a computer, not a phone, so no OTG requirements come into play there.

    The original posts were about the iFi iDefender and whether or not powering it was required with the HA-2 (it isn't), and that then morphed into a question about how to keep the PC from continuously charging the HA-2 when they are connected. There are various ways to do that including just putting a piece of tape on the host side VBUS pins of the USB cable.

    You can get good quality generic OTG cables properly wired for the HA-2 (both ends) on eBay for under $7, the seller is yourcharger, these are known to work fine with the HA-2:

    10cm Left Angle Micro USB to Type C Cable OTG at both ends for OPPO HA-2SE DAC

    He has other lengths as well, they all work with the HA-2 in my experience.
  9. abm0
    Not sure you looked at what I was replying to, and even so: OTG requirements always come into play when you want to use the HA-2 without charging it (it's not healthy for a Li-Ion battery to stay close to 100% for long periods of time). Plus any USB plug that's meant to go into a computer is always configured like an OTG (master-end), it was just never called that. :)

    Interesting. I would've never come up with that since I don't know enough about USB to declare the power supply pin useless for the data transfer scenario.

    Making an international order for something that's electrically so simple is unacceptable. That's why I'm exploring the options I mentioned above. I might also try what you said with the V+ line - thanks again!
  10. MikeyFresh
    $6.99 + free ePacket shipping from Hong Kong, I have received these in the mail in NY in as little as 4 days, however sometimes it can take more like 10 days depending on the time of year and how busy the postal system is. By comparison, there is some domestic mail in the U.S. that takes longer than 4 days, so the international aspect is no big deal. Obviously yours or anyone else's mileage may vary in that regard. To each his own.

    I too make cables, lots of them, but the linked OTG cables are so inexpensive (and actually very good generic quality) that I just order a couple at a time and don't bother with making anything as the USB spec is actually not as easy or trivial to meet in terms of the 90 Ohm characteristic impedance as one might think. That's one nice thing about the UpTone adapter, not only does it have the switch for defeating the VBUS, but it is also rigidly designed to adhere to the 90 Ohm impedance spec.

    Some DACs require bus power for the USB handshake to occur, others do not, including the HA-2.
    Last edited: Jan 23, 2019
  11. Chris Ihao
    Can confirm. Ordered two cables for an almost symbolic price, and free shipping. Works good. Really no reason not to get them.
    MikeyFresh likes this.
  12. abm0
    Well, I thought I'd keep that in mind as a source of last resort, but it turns out they don't actually offer anything like what I need right now: a single-cable direct replacement for the original micro-to-micro double-OTG that came with the HA-2. All they have specifically for the HA-2 are those Type-C ones. And all their micro-to-micros are OTG at only one end. Like I said, it's a b***h to find these, so I'd rather try to make one myself. :)
    Last edited: Jan 23, 2019
  13. MikeyFresh
    As @Chris Ihao mentions above, seller yourcharger's micro-to-micro OTG cables do work as intended with the HA-2 (pin 4/sense/ID tied to GND at both ends). I have them in about 4 or 5 different lengths, all from that seller, all work just as the stock Oppo cable does.

    12cm SHORT Right Angle Micro USB to Left Angle Micro USB Host OTG Adapter Cable

    It works, don't worry about the listing saying nothing about HA-2 compatibility, he only does that on the Type C cables because almost none of those are compatible with the HA-2, so he goes out of his way to point out that one is. Many of us have been buying the exact listing linked to above for several years now, it is the correct cable for the HA-2, and even the very long one yourcharger offers (1.5M/5 foot?) also works, I have that one too.
    Last edited: Jan 23, 2019
    abm0 likes this.
  14. alpovs
    abm0 quoted my post. Your reply is irrelevant. And abm0 needed a micro-B to micro-B cable, not USB-C, as pointed out later.
  15. alpovs
    The seller is a woman.
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