5 ms·

I followed this guy for a long time until it was obvious that he quit and did not mean to return. The design of that amp was frustrating. The power, the input

by steve19 13y ago

I followed this guy for a long time until it was obvious that he quit and did not mean to return. The design of that amp was frustrating. The power, the input and the output are all on the front of the amp. I always wondered why nobody cleaned that up and put power and input at the back. I also wished it used DC rather than 12 VAC. Now I know, it was the no-derivative license. When I was young I would mess around with audio circuits, trying different opamps, seeing if they changed the sound. These days I am far more concerned about connectivity. His Objective DAC is more interesting in my opinion. If I ever need a 24bit USB DAC, I will get one. Considering I think 256 bit MP3s sound just fine, and FLAC far to much effort, I probably will never need one. http://www.jdslabs.com/products/48/o2-odac-combo/ http://www.jdslabs.com/products/48/o2-odac-combo/ NwAvGuy proved what he wanted to do, that simple circuits are good enough and doing things like hand matching resistors with very expensive equipment is not required for a clean reproduction of audio. I still wonder if he really cared, or if he was a troll (he spend a good amount of time getting himself banned on forums).

nawitus 13y ago
Hmm, I thought it used DC rather than AC. It uses batteries.
- wfraser 13y ago
  Correct. It also needs a wall wart.
- makomk 13y ago
  It's got a built-in battery charger and can also run from a wall wart without using batteries at all. The reason the external power supply has to be AC is that it needs dual negative and positive power supply rails, which it gets from rectifying the AC and using that to charge a pair of batteries. Cheap, easy, and in theory gives decent audio performance. If you read NwAvGuy's blog, the modifications necessary to run it off DC are pretty much exactly what he wouldn't want people to do.
runeks 13y ago
> His Objective DAC is more interesting in my opinion. If I ever need a 24bit USB DAC, I will get one. FWIW I purchased his Objective DAC (from this site: http://www.headnhifi.com/odac-rca http://www.headnhifi.com/odac-rca) and I don't hear less noise from this than my internal sound card (Terratec Aureon 7.1-Space). So I was a bit disappointed. But perhaps my internal sound card was just that good, although I think the noise level is greater than is reported online. Audible noise at normal listening levels.
- josh-wrale 13y ago
  This sounds like a ground loop or otherwise interference from the power input. Have you tried these on a power conditioner or a UPS?
- ggreer 13y ago
  I have an ODAC and I can't detect any noise unless I max-out the volume knob with my ER-6is. Not that it matters, since playing anything at that volume with those headphones would be deafening and painful. I definitely hear more noise with my FiiO E7, and my laptop's headphone-out is even worse. In the hope that I have some idea of what I'm talking about, I've listed some possible reasons why you may be hearing noise and how to fix them. 1. Using analog inputs (RCA or line in) instead of USB. This will just amplify the noise from your input source. Analog inputs are enabled even if you're playing sound through USB, so be sure to disconnect any secondary source from your amp. 2. Nearby EMI. I found I could hear a high-pitched whining if I put my amplifier near the lower-right of my monitor. Repositioning your amplifier and/or headphone cable may fix the problem. 3. Grounding issue (unlikely). Try unplugging the amp's adapter and using the DAC-line output[1]. If there's no noise, the problem must be in amplification. That means either a defective amplifier circuit or a grounding/EMI issue. 4. Bad software (very unlikely). I once had a copy of VLC that output low-level noise when paused. This was when x86-64 was new. There were plenty of other problems with VLC on 64-bit at the time, since it used ints and longs as bitfields. You'd have this problem with all soundcards, not just the ODAC. It might also be useful to describe your set-up in more detail, including what headphones you've tried your amp with. Edit: Another thing you'll want to do to improve audio output: Make sure your OS is sending 24-bit audio to the ODAC. On OS X, open up Audio Midi Setup, then select the ODAC output and switch it to 24 bit. The default is 16-bit, which reduces dynamic range if you don't have the software volume at 100%. 1. It's the right-most output on mine: http://abughrai.be/pics/IMG_0594.JPG http://abughrai.be/pics/IMG_0594.JPG. I'm not sure where the DAC-out is on other versions.
sanoli 13y ago
Well, he got himself banned drom audiophile forums from pointing out their inconsistencies and ridiculous claims. I thought that was pretty cool of him, since he had the means to back it up. edit: I forgot to agree with you on the design of the damn amp. I never got one either, because everything was in the damn front of the little box. When friends ask my opinion, I just tell 'em to get a schiit modi/magni combo. Looks way nicer, is a little cheaper, and you won't be able to tell the difference in the audio anyway.
- calinet6 13y ago
  To be fair, his style was highly argumentative. He left no room for subjectivity or talking about subjectivity in anything. Which leaves out a fair portion about what audio really is to the human brain, whether or not you perfect its reproduction mathematically. His point of view, and his way of presenting it, were far too unbalanced and inhumane, regardless of their correctness. This was the reason he was not received well; not for the facts themselves. This fact generalizes to a great many technical problems.
  - ozy23378 13y ago
    I read him differently. He only criticized objective claims which were scientifically implausible or found to be untrue, e.g., that vinyl had higher fidelity than CD as a medium, that humans could hear a difference between cheap and expensive cables, or when his measurements differed remarkably from manufacturers' specs, i.e., false advertising. He did not criticize subjective preferences such as vinyl over CD, fancy cables over cheap ones or tube amps over op-amps. Only when false/implausible objective claims came into play did he refute them.
    - calinet6 13y ago
      This is true, he never argued against simple preference. His bedside manner in most discussions left a lot to be desired, is all.
  - makomk 13y ago
    From what I've seen, NwAvGuy and other objective-audio types generally tend to have a better understanding of the subjective parts of audio though. It helps if you don't treat it as a mystery that can be affected by changes in the audio we can't measure. (Also, they're rather less likely to design amplifiers that destroy the equipment they're connected to than certain audiophile companies...)
badsock 13y ago
In case you're wondering, everything was at the front because he was trying to hit a price point for DIYers, and the custom-cut end panels were a big line item. By putting everything in one panel, the other could be left unaltered at a savings. You can certainly argue that it was penny-wise pound-foolish, but that was the reasoning at least. Also a more liberal license would have allowed things to be moved around, true, but it wouldn't have been an O2 anymore - the routing of the board is very important to its performance. I think perhaps a better choice on the licence would have allowed derivatives, so long as they were renamed significantly.
ozy23378 13y ago
> If I ever need a 24bit USB DAC, I will get one. Considering I think 256 bit MP3s sound just fine, and FLAC far to much effort, I probably will never need one. He decided for a 24-bit DAC in order to have enough headroom for software volume adjustment, because lowering the volume in software reduces the effective number of bits and thereby maximum dynamic range. He didn't claim that humans could hear a difference between 16-bit and 24-bit bit depth under practical conditions.

by steve19 13y ago

nawitus 13y ago

Hmm, I thought it used DC rather than AC. It uses batteries.

wfraser 13y ago
Correct. It also needs a wall wart.
makomk 13y ago
It's got a built-in battery charger and can also run from a wall wart without using batteries at all. The reason the external power supply has to be AC is that it needs dual negative and positive power supply rails, which it gets from rectifying the AC and using that to charge a pair of batteries. Cheap, easy, and in theory gives decent audio performance. If you read NwAvGuy's blog, the modifications necessary to run it off DC are pretty much exactly what he wouldn't want people to do.

runeks 13y ago

> His Objective DAC is more interesting in my opinion. If I ever need a 24bit USB DAC, I will get one. FWIW I purchased his Objective DAC (from this site: http://www.headnhifi.com/odac-rca http://www.headnhifi.com/odac-rca) and I don't hear less noise from this than my internal sound card (Terratec Aureon 7.1-Space). So I was a bit disappointed. But perhaps my internal sound card was just that good, although I think the noise level is greater than is reported online. Audible noise at normal listening levels.

josh-wrale 13y ago
This sounds like a ground loop or otherwise interference from the power input. Have you tried these on a power conditioner or a UPS?
ggreer 13y ago
I have an ODAC and I can't detect any noise unless I max-out the volume knob with my ER-6is. Not that it matters, since playing anything at that volume with those headphones would be deafening and painful. I definitely hear more noise with my FiiO E7, and my laptop's headphone-out is even worse. In the hope that I have some idea of what I'm talking about, I've listed some possible reasons why you may be hearing noise and how to fix them. 1. Using analog inputs (RCA or line in) instead of USB. This will just amplify the noise from your input source. Analog inputs are enabled even if you're playing sound through USB, so be sure to disconnect any secondary source from your amp. 2. Nearby EMI. I found I could hear a high-pitched whining if I put my amplifier near the lower-right of my monitor. Repositioning your amplifier and/or headphone cable may fix the problem. 3. Grounding issue (unlikely). Try unplugging the amp's adapter and using the DAC-line output[1]. If there's no noise, the problem must be in amplification. That means either a defective amplifier circuit or a grounding/EMI issue. 4. Bad software (very unlikely). I once had a copy of VLC that output low-level noise when paused. This was when x86-64 was new. There were plenty of other problems with VLC on 64-bit at the time, since it used ints and longs as bitfields. You'd have this problem with all soundcards, not just the ODAC. It might also be useful to describe your set-up in more detail, including what headphones you've tried your amp with. Edit: Another thing you'll want to do to improve audio output: Make sure your OS is sending 24-bit audio to the ODAC. On OS X, open up Audio Midi Setup, then select the ODAC output and switch it to 24 bit. The default is 16-bit, which reduces dynamic range if you don't have the software volume at 100%. 1. It's the right-most output on mine: http://abughrai.be/pics/IMG_0594.JPG http://abughrai.be/pics/IMG_0594.JPG. I'm not sure where the DAC-out is on other versions.

sanoli 13y ago

Well, he got himself banned drom audiophile forums from pointing out their inconsistencies and ridiculous claims. I thought that was pretty cool of him, since he had the means to back it up. edit: I forgot to agree with you on the design of the damn amp. I never got one either, because everything was in the damn front of the little box. When friends ask my opinion, I just tell 'em to get a schiit modi/magni combo. Looks way nicer, is a little cheaper, and you won't be able to tell the difference in the audio anyway.

calinet6 13y ago
To be fair, his style was highly argumentative. He left no room for subjectivity or talking about subjectivity in anything. Which leaves out a fair portion about what audio really is to the human brain, whether or not you perfect its reproduction mathematically. His point of view, and his way of presenting it, were far too unbalanced and inhumane, regardless of their correctness. This was the reason he was not received well; not for the facts themselves. This fact generalizes to a great many technical problems.
- ozy23378 13y ago
  I read him differently. He only criticized objective claims which were scientifically implausible or found to be untrue, e.g., that vinyl had higher fidelity than CD as a medium, that humans could hear a difference between cheap and expensive cables, or when his measurements differed remarkably from manufacturers' specs, i.e., false advertising. He did not criticize subjective preferences such as vinyl over CD, fancy cables over cheap ones or tube amps over op-amps. Only when false/implausible objective claims came into play did he refute them.
  - calinet6 13y ago
    This is true, he never argued against simple preference. His bedside manner in most discussions left a lot to be desired, is all.
- makomk 13y ago
  From what I've seen, NwAvGuy and other objective-audio types generally tend to have a better understanding of the subjective parts of audio though. It helps if you don't treat it as a mystery that can be affected by changes in the audio we can't measure. (Also, they're rather less likely to design amplifiers that destroy the equipment they're connected to than certain audiophile companies...)

badsock 13y ago

In case you're wondering, everything was at the front because he was trying to hit a price point for DIYers, and the custom-cut end panels were a big line item. By putting everything in one panel, the other could be left unaltered at a savings. You can certainly argue that it was penny-wise pound-foolish, but that was the reasoning at least. Also a more liberal license would have allowed things to be moved around, true, but it wouldn't have been an O2 anymore - the routing of the board is very important to its performance. I think perhaps a better choice on the licence would have allowed derivatives, so long as they were renamed significantly.

ozy23378 13y ago

> If I ever need a 24bit USB DAC, I will get one. Considering I think 256 bit MP3s sound just fine, and FLAC far to much effort, I probably will never need one. He decided for a 24-bit DAC in order to have enough headroom for software volume adjustment, because lowering the volume in software reduces the effective number of bits and thereby maximum dynamic range. He didn't claim that humans could hear a difference between 16-bit and 24-bit bit depth under practical conditions.