[MrMateoHead]

  There was no red in Audacity. I wasn't listening to smashed crap when I noticed it. I noticed the clipping on a -2 peak, 11 db of dynamic range, -20 RMS average keyboard track listening on HD 650s. I just tried it with "event mode" with some 5 db of dynamic range pop, -.05 peaks and yeah no clipping on my HD 25s as it doesn't have to be amplified as much but it clipped with dynamic classical music and 80s metal.

It's not the player, it's the output from the ODAC (powered from a USB port) clipping the O2 amp due to poor opamp design choices from nwavguy. He stuck the volume pot between the stages. It clips even on 1x gain sometimes. Then you have JDS Labs poor choice of letting the windows volume slider control the volume (power) to the ODAC despite that potentially allowing it to clip the O2 as they didn't set the firmware in the ODAC to bypass that when the DAC is set in exclusive mode with the standard drivers (ASIO and WASAPI) that bypass the Windows DirectSound mixer/resampler. This clipping is different from dirty USB power making the bus-powered ODAC not sound very good. This is the same clipping that comes up in 6.5x on the O2 when that gain setting is used with a normal 2 volt source like the ODAC.

I've never heard the O2 clip at less than 6.5X gain and 2V in on any quality of recording. To claim that it is clipping at unity gain doesn't make any sense. There is static / popping when using the volume knob, that is typical.
 
Are you using this thing from your Thinkpad? Are there other devices sharing the USB bus? Tried a different USB port or device yet? It sounds almost like it is a power issue, or even a defect.

 

[Psalmanazar]

  I've never heard the O2 clip at less than 6.5X gain and 2V in on any quality of recording. To claim that it is clipping at unity gain doesn't make any sense. There is static / popping when using the volume knob, that is typical.
 
Are you using this thing from your Thinkpad? Are there other devices sharing the USB bus? Tried a different USB port or device yet? It sounds almost like it is a power issue, or even a defect.

No other devices were on the bus. The DAC was performing well except for causing the O2 to clip. DirectSound makes the ODAC sound like a bad crossfeed plugin but wasn't clipping the O2. It's very easy to clip the O2. All of this is due to poor design choices.

 

[HaVoC-28]

  No other devices were on the bus. The DAC was performing well except for causing the O2 to clip. DirectSound makes the ODAC sound like a bad crossfeed plugin but wasn't clipping the O2. It's very easy to clip the O2. All of this is due to poor design choices.

So you are the first one here that come with clipping issue at unity gain and claim that the problem come from the O2 disign

. Sometimes there is deffective unites or wrong assembly like a resistance that is not correct etc etc .
 
Then at witch stage the O² clips , with witch recordings to see if the issue is easy to reproduce  with any o² , cause if this is a disign defect it will be easy to reproduce .

 

[Psalmanazar]

Well it's the poor driver implementation of the JDS Labs ODAC clipping the O2. ASIO and WASAPI event mode really shouldn't be clipping it in situations where WASAPI push doesn't and that clipping in situations where DirectSound doesn't. Nothing was posted about the various driver issues so I thought it best to share for consumers' future benefit.

Everyone knows nwavguy made the poor choice of sticking the potentiometer between the stages to lower the noise floor of the O2 and that the ODAC is bus-powered.

 

[HaVoC-28]

  Well it's the poor driver implementation of the JDS Labs ODAC clipping the O2. ASIO and WASAPI event mode really shouldn't be clipping it in situations where WASAPI push doesn't and that clipping in situations where DirectSound doesn't. Nothing was posted about the various driver issues so I thought it best to share for consumers' future benefit.

Everyone knows nwavguy made the poor choice of sticking the potentiometer between the stages to lower the noise floor of the O2 and the the ODAC is bus-powered.

 
The O²/ODAC are more than 3 years old now : / , and no one would have discovered O² clipping at 1x yet ? . Yes there is a clipping issue that happen only  when you exceed  7 v . At 1X with ODAC providing around 2.03v you can't possibly get it to Clip .
 
Something is clearly wrong with your combo or somewhere else .

 

[castleofargh]

There was no red in Audacity. I wasn't listening to smashed crap when I noticed it. I noticed the clipping on a -2 peak, 11 db of dynamic range, -20 RMS average keyboard track listening on HD 650s. I just tried it with "event mode" with some 5 db of dynamic range pop, -.05 peaks and yeah no clipping on my HD 25s as it doesn't have to be amplified as much but it clipped with dynamic classical music and 80s metal.
It's not the player, it's the output from the ODAC (powered from a USB port) clipping the O2 amp due to poor opamp design choices from nwavguy. He stuck the volume pot between the stages. It clips even on 1x gain sometimes. Then you have JDS Labs poor choice of letting the windows volume slider control the volume (power) to the ODAC despite that potentially allowing it to clip the O2 as they didn't set the firmware in the ODAC to bypass that when the DAC is set in exclusive mode with the standard drivers (ASIO and WASAPI) that bypass the Windows DirectSound mixer/resampler. This clipping is different from dirty USB power making the bus-powered ODAC not sound very good. This is the same clipping that comes up in 6.5x on the O2 when that gain setting is used with a normal 2 volt source like the ODAC.

makes little sense to me.
the DAC won't clip unless the track is clipped on the digital level before being sent to the DAC. when the digital value for te signal reaches 0db, the odac will output about 2V. there is no way it will try or be able to output more, and no reason why 2V would be too much.
then the O2 could be clipped if another DAC was used with a higher max voltage, and some unfortunate choices of gain for a given headphone, but again you're in a situation that cannot make it happen with a working ODAC/O2 and hd650. that's what I used for a few years now and I can't imagine a way to make it clip that wouldn't come directly from me messing up with the signal on the computer(pushing an EQ up without adjusting the global gain or anything that would be a digital clipping and would as such sound clipped on any source).
 
so you either do something very wrong on the computer side of things and you've decided to blame the ODAC/O2/nwavguy for what is 100% your misuse of something, or you have a damaged ODAC/O2. but the "nwavguy failed design" part is BS and has nothing to do with your situation.

 

[MrMateoHead]

  No other devices were on the bus. The DAC was performing well except for causing the O2 to clip. DirectSound makes the ODAC sound like a bad crossfeed plugin but wasn't clipping the O2. It's very easy to clip the O2. All of this is due to poor design choices.

The fact that the Audio File is not clipped does not prove the absence of square waves, which may have resulted from an overloaded microphone during the recording process, or EQing problems, and so on. In that case the "clipping" is passed through the ODAC, Amp and headphone.
 
It isn't clear that the headphones are not clipping as well, or distorting, given that they are the part of the signal chain with the highest distortion and some kind of SPL limit. Loose connections can also sound like clipping, and the inputs of the O2 / headphone cables surrounding me need a little "wiggle" once in awhile. In fact there is a chassis grounded wire hanging off the input that I had to re-seat to restore "buggy connections". I would check that, too.
 
Finally, when I upgraded to Windows 10, it broke my Realtek audio and various other drivers. I had audio through the ODAC but nothing else. Uninstalling / reinstalling drivers was required.
 
I hope you find a solution, or Opamps that work for you.

 

[Psalmanazar]

Blame who you want. JDS Labs for lack of driver testing or Nwavguy for making the problem possible. JDS Labs believing that ASIO and WASAPI are non-standard drivers is ridiculous.
 
I spent most of my free time Thursday through Saturday ruling out other variables such as USB cables, headphones, and recordings while solving a problem that shouldn't have arisen to begin with. I'm done. The end.

 

[raoultrifan]

  Well it's the poor driver implementation of the JDS Labs ODAC clipping the O2. ASIO and WASAPI event mode really shouldn't be clipping it in situations where WASAPI push doesn't and that clipping in situations where DirectSound doesn't. Nothing was posted about the various driver issues so I thought it best to share for consumers' future benefit.

Everyone knows nwavguy made the poor choice of sticking the potentiometer between the stages to lower the noise floor of the O2 and that the ODAC is bus-powered.

 
Hi, 
 
AFAIK there's no driver implemented by JDS, instead ODAC is using OS native driver, which should be perfect I'd say.
 
As for nwavguy's design, he choose to have the potentiometer between voltage input stage and output buffer instead having it placed before voltage input stage, because the noise-floor would be greatly decreased this way. In case you have a problem with the noise when rotating the potentiometer dial (only when playing the music), then feel free to change it with a Bournes and/or change the 50K resistors as well (for details, find agdr audio webpage or contact him directly here on Head-Fi).
 
Anyway, placing the potentiometer the way nwavguy did makes this headamp one of a kind into audiophile world, mostly because it's dead silent! And for a 59USD kit that's a steal.
 
ODAC is bus powered, like probably all of the existing Tenor7022/ESS9023 implementations (anyway, ODAC has a noise reduction circuit on +5V USB input). It's very cheap and sounds great, that's what it matters after all, so there's no reason to pay for a dedicated +5V PSU to power this chip. If you want, feel free to buy Schiit Wyrd or something else similar and let us know how audio improves here with ODAC. Anyway, ASUS Essence One, TEAC UD-501 and many other DACs are having their USB converter chip powered directly from the USB bus as well.
 
Regards!
 
L.E.: http://firev1.blogspot.ro/2014/11/schiit-wyrd-does-it-work.html - shows a little bit of improvement for the Tenor 7022 USB chip. Also, Wyrd is also powering the ESS9023 chip as well, so at least theoretically sound should get improved a bit, especially on noisy USB computer ports.

 

[bada bing]

  Blame who you want. JDS Labs for lack of driver testing or Nwavguy for making the problem possible. JDS Labs believing that ASIO and WASAPI are non-standard drivers is ridiculous.
 
I spent most of my free time Thursday through Saturday ruling out other variables such as USB cables, headphones, and recordings while solving a problem that shouldn't have arisen to begin with. I'm done. The end.

What are you using to power the O2 ?
 
I wouldn't go so far as to call it a defect, but the O2's has unusual clipping that depends on rail voltage and input signal voltage.
If you are sure you are clipping in the amp section, you have rails running too low for the input and gain. That is the only way the 
O2 clips and it is rather odd behavior. I'd check the rails in the amp, something is amiss.
 
The O2 is an interesting design and it is easy to get really good performance from it as long as you understand the design trade offs.
JMO, but I am surprised that it has become as widely adopted as it has, because the design trade offs make it a bit prone
to having issues with under informed users operating it outside of its design parameters. What you are describing isn't outside
the design unless you are operating it with defective/dead batteries or there is a problem in the wall wart / psu section.

 

[Takeanidea]

I sold my O2/Odac but I still consider to be right up there with the very best of small form Dac/Amps and anyone who has bought one well done and anyone who is thiking about getting one- get one! You cannot go wrong

 

[adydula]

I have stopped trying to help people that just dont understand the O2 design and clipping....there are so many folks that just will never understand circuit design especially with the O2.....Its been  around for a long time now and many, many people like what it does and do understand the why's of its design points and how good of an amp it is.....
 
Back to the music....happy clipping to you all!
 
Alex
:>)

 

[marios_mar]

Can the O2+ODAC combo work completely just with USB power?

 

[adydula]

Nope....the dac is powered via USB, the amp need an AC to AC walwart or batteries.
 
A.

 

[Meremoth]

Which company's version of the O2/ODAC do you guys prefer?  I did extensive research on the O2/ODAC a couple years ago, and I think I was going to go with JDS Labs, but since time has passed I was wondering if anything has changed that I should know about?  
 
Just purchased the Fostex TH-0XX, and I have no amp or dac - and after lots of past research I determined the O2/ODAC is what I want, I just need to know where I should purchase it from (I live in the US).  If there is no clear winner, any subjective opinions about where I should purchase it is very much appreciated.  Thanks.
 
Edit:  Also, it doesn't have to be the all-in-one combo, it can be the separate units as well.  I think I was planning on getting separate units in case I ever wanted to mix-and-match with other amps or dacs, but I'm open to suggestions.  
 
Edit #2:  Just read that there's a Rev B version of the ODAC from JDS Labs...  should that be of any concern to me?  Thanks.