Review: NwAvGuy's O2 DIY Amplifier
Mar 26, 2012 at 1:12 AM Post #1,486 of 1,550


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Alright, thanks. That ODAC is looking better all the time then, I hope it turns out to be good.
 


 



The ODAC will be USB only. Knowing the source, I'm sure it will be good.
smile.gif
  I assume your card has USB?
 
You could also get a DAC with Coax and/or Optical inputs. There are a number of good affordable ones.
 
Mar 26, 2012 at 2:37 AM Post #1,487 of 1,550
No, I meant for just completely bypassing the card all together. If the ODAC is higher quality than my soundcard (no double amping which will lead to less distortion and the DAC will probably be a lot nicer), I will just slide it inside my O2 and use that hooked up via a rear usb port on my pc. Unless I have misunderstood how external DACs and amps work.
 
My card uses the AK4396VF DAC so I'm sure the ODAC will be an improvement in many ways. 
 
Mar 26, 2012 at 6:06 AM Post #1,488 of 1,550
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If it's real, maybe the conflicting reports come from the behavior being different in different peoples' systems, what with different configurations and positioning of other add-in cards (particularly video cards) and the CPU power circuitry, and so on?


Maybe, although I would expect those factors to affect mainly the SNR, rather than the frequency response.
 
 
Mar 26, 2012 at 6:57 AM Post #1,491 of 1,550


Quote:
No, I meant for just completely bypassing the card all together. If the ODAC is higher quality than my soundcard (no double amping which will lead to less distortion and the DAC will probably be a lot nicer), I will just slide it inside my O2 and use that hooked up via a rear usb port on my pc. Unless I have misunderstood how external DACs and amps work.
 
My card uses the AK4396VF DAC so I'm sure the ODAC will be an improvement in many ways. 



Yes, you're right. Sorry, I misunderstood what you meant before.
 
You can plug an outboard DAC (like the ODAC) into the USB port and bypass your internal soundcard.
 
On the other hand, AKM makes some fine DAC chips and the AK4396 has been used in some very "high-end" gear. As long as the card is well designed, I would think it should perform as well as the ODAC. Double amping isn't nearly the problem that many people claim. As long as you're not driving the card into clipping (it may clip at 100% volume, and it may not - every card is different), there is no harm in driving the O2 direct from the cards headphone jack.
 
Or you could use the onboard DAC but bypass the amp stage by using a Coax or TOSLINK cable to an outboard DAC.
 
You have several options that really come down to subjective sound quality (for what that's worth) and money. If you are at all interested in the O2 and ODAC, you should read more of NwAvGuy's articles and discover more about what he thinks about DAC's, amps, subjective vs. objective, double amping, etc. It may help you decide what to do.
 
Mar 26, 2012 at 4:12 PM Post #1,494 of 1,550


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I think this is so incorrect I'm not even going to argue the point. Do "you all" really know anything about audio?

 
No need to get your panties in a bunch...  I wrote that at like 3 in the morning, OK? Yes, it is incorrect - My apologies. Obviously coax and optical outs bypass the card entirely (or at least the DAC and onboard amp).
 
May I suggest that in the future, if you have something constructive to contribute, then please do. Otherwise, at the very least, conduct yourself like a grown up and treat others the way you yourself would like to be treated.
 
 
Mar 26, 2012 at 4:43 PM Post #1,495 of 1,550


Quote:
 
No need to get your panties in a bunch...  I wrote that at like 3 in the morning, OK? Yes, it is incorrect - My apologies. Obviously coax and optical outs bypass the card entirely (or at least the DAC and onboard amp).
 
May I suggest that in the future, if you have something constructive to contribute, then please do. Otherwise, at the very least, conduct yourself like a grown up and treat others the way you yourself would like to be treated.
 


My comment led to a helpful correction on your part. And I I didn't insult your choice of undergarments. Please conduct yourself with civility.
 
 
Mar 26, 2012 at 5:24 PM Post #1,498 of 1,550
Can i use a 13v ac-ac transformer with the O2?
Will it do any damage to the amp?
If 13v is usable would a 16/18v supply make any difference for good?
 
I am unable to find 14-20 VAC, 13v is the best i could manage. Hence the questions.
Thanks much.
 
Mar 26, 2012 at 5:43 PM Post #1,499 of 1,550
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Maybe, although I would expect those factors to affect mainly the SNR, rather than the frequency response.


Yeah true, interference and noise should be affecting SNR and non-harmonic distortion artifacts, not really FR.
 
 


Can i use a 13v ac-ac transformer with the O2?
Will it do any damage to the amp?
If 13v is usable would a 16/18v supply make any difference for good?
 
I am unable to find 14-20 VAC, 13v is the best i could manage. Hence the questions.
Thanks much.


Check the current rating as well, though likely it's at least 200 mA or so and thus okay.
 
It may be okay.  If you have a multimeter to measure the voltage unloaded, then that should tell you.  The voltage you measure without the adapter plugged into the amp (so unloaded) should be about 13.5V AC or so.  In fact the "default" AC adapter recommended, the WAU12-200 (which I and many others use), is rated for 12V nominal but is more around 13.5V unloaded, so your 13V adapter may be okay.  It depends also on what exactly the voltage is you're getting from the wall.  Note that the transformer output voltage drops, the more power you pull from it.
 
If the rating is too low, then under sustained heavy power consumption, the voltage out of the transformer to the 12V regulators may drop close enough to 12V that the regulators get cranky and start to misbehave, meaning that the power supply rails have more noise on them, degrading the performance a little bit.  Heavy power consumption pretty much means bench testing max output into low impedances--this probably won't happen in practice unless you're listening really load on a planar magnetic headphone while charging batteries (which are depleted) simultaneously.  If not under sustained heavy power consumption, a suitable adapter on the "low" side is just as good, maybe even preferred since there will be less waste heat generated by the regulators.
 

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