O2 AMP + ODAC
Jun 29, 2012 at 1:29 AM Thread Starter Post #1 of 5,663
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As I was searching for a good amp/ dac, I decided to save myself the trouble of picking between numerous options and get an O2 amp/ dac. 
 
Now I have to choose between JDS Lab variant and the EHP variant. I can only see the rear view of the former (http://www.jdslabs.com/item.php?fetchitem=39) and the latter seems smaller than I thought (http://epiphany-acoustics.co.uk/wp-content/uploads/2012/04/Epiphany-Acoustics-EHP-O2-Reflection2.jpg). Why is it that the EHP variant is187 dollars and the JDS LAB variant is 285 dollars? 
 
P.S. Do I need an AC adapter for both? 
 
I would appreciate it if you guys can help me choose. 
 
Jun 29, 2012 at 1:52 AM Post #3 of 5,663

alphaphoenix

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No.  Assuming the ODAC and O2 are separate, only the O2 amp needs the adapter.  The ODAC gets its source via the mini USB and the 1/8 or RCA to 1/8 on the ODAC feeds to the O2 amp.  If you have the O2/ODAC combo, you only need the one adapter to power the O2.
 
Jun 29, 2012 at 2:29 AM Post #5 of 5,663
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Quote:
No.  Assuming the ODAC and O2 are separate, only the O2 amp needs the adapter.  The ODAC gets its source via the mini USB and the 1/8 or RCA to 1/8 on the ODAC feeds to the O2 amp.  If you have the O2/ODAC combo, you only need the one adapter to power the O2.

I'm planning to get a O2 / ODAC combo. Have any of you guys purchased the O2 / ODAC? If so, which variant did you go with? 
 
Jun 29, 2012 at 2:38 AM Post #6 of 5,663

alphaphoenix

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If you're getting the O2/ODAC combo (ODAC installed inside the O2), there shouldn't be any difference between the two manufacturers except for distinct aesthetics.  Go for the all inclusive cheaper price.
 
If you're asking "should I go for the O2/ODAC integrated combo or separate combo" that depends on your setup.  I prefer a separate combo.  You may not care much for the O2, like me, but really fancy the ODAC that gives you much more flexibility.  All-in-one configurations has its advantages.  Again, it's all personal preference.
 
Jun 30, 2012 at 1:18 PM Post #7 of 5,663
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If you're getting the O2/ODAC combo (ODAC installed inside the O2), there shouldn't be any difference between the two manufacturers except for distinct aesthetics.  Go for the all inclusive cheaper price.
 
If you're asking "should I go for the O2/ODAC integrated combo or separate combo" that depends on your setup.  I prefer a separate combo.  You may not care much for the O2, like me, but really fancy the ODAC that gives you much more flexibility.  All-in-one configurations has its advantages.  Again, it's all personal preference.

Thanks! 
 
Jul 9, 2012 at 3:23 PM Post #9 of 5,663

lorriman

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JDS Lab ODAC usb DAC + JDS Lab O 2 head amp full modification with Black Gate Capasitors


Nice: did you have to do anything to the O2 electronics for that battery config?

Without the ODAC (which I've managed to slip in under the O2 board) do you think there would be enough room in a B03 enclosure?
 
Jul 9, 2012 at 6:40 PM Post #10 of 5,663

Zophiel

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I'm currently saving up for the O2 and the ODAC as separate entites from JDS.  I want them separate so that i can take the O2 with me to work/ other portability reasons, and when i come home i have a decent Desktop configuration.  The only question i have is, when i own just the O2, before i can afford the ODAC, what benefits will i see from taking the O2's input from my soundcard's output?  Just output impedance and max power?
 
Jul 10, 2012 at 12:29 PM Post #11 of 5,663

lorriman

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I'm currently saving up for the O2 and the ODAC as separate entites from JDS.  I want them separate so that i can take the O2 with me to work/ other portability reasons, and when i come home i have a decent Desktop configuration.  The only question i have is, when i own just the O2, before i can afford the ODAC, what benefits will i see from taking the O2's input from my soundcard's output?  Just output impedance and max power?


There are two other improvements depending on your setup.

1)In Win XP digital volume adjustment meant getting less than 16bits of info other than at max volume. The audio quality can audibly degrade at less than max volume. The O2 lets you set max volume at the laptop and use the O2 to turn the volume down. (The ODAC gives you back digital volume control so long as you set it to 24bit as there are enough bits to endure bit stripping.). It;s been said that Vista corrected this XP flaw.

2)Noise: some kinds of source noise do not increase with increased source volume. If this is the case then by whacking the laptop up to max volume you can get the audio so far away from that background noise that it is inaudible.

One issue with the above is that if you are feeding sensitive phones then even at 2.5x gain you can't get the pot higher than 9pm on the O2 which is in pot channel-imbalance territory (which happens at the lower end) especially if you are a quiet listener. As a loud listener using armatures I am often at 9pm and I believe I may have experienced this issue. It's one reason a lot of O2 users change the 2.5x gain to 1x (ie. no gain).I'm not sure what the situation is with max volume on the source but in some cases it is bound to be too much even for 6pm on the pot.

Possible 3rd: I'm lead to believe that an amp straining to produce current for a low impedance, high-current device can start distorting. I;m not sure that this is true. If so then that extra power will not just give more volume but also avoid distortion in some cases. Perhaps someone can correct that.


Keep in mind also that the Odac requires an amp. So if you haven't already then the O2 is a stunningly good value amp that you'll be needing.

Having said that: the Behringer UCA202 measures well, as done by guess who, and at half the price there's really there's no absolute need for an Odac unless you want the ultimate.(I wanted the ultimate.) It also has the advantage of not (technically) needing an amp. But it does have a very high output impedance so you'll be needing that amp anyway.
 
Jul 10, 2012 at 3:06 PM Post #12 of 5,663
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Quote:
There are two other improvements depending on your setup.
1)In Win XP digital volume adjustment meant getting less than 16bits of info other than at max volume. The audio quality can audibly degrade at less than max volume. The O2 lets you set max volume at the laptop and use the O2 to turn the volume down. (The ODAC gives you back digital volume control so long as you set it to 24bit as there are enough bits to endure bit stripping.). It;s been said that Vista corrected this XP flaw.
2)Noise: some kinds of source noise do not increase with increased source volume. If this is the case then by whacking the laptop up to max volume you can get the audio so far away from that background noise that it is inaudible.
One issue with the above is that if you are feeding sensitive phones then even at 2.5x gain you can't get the pot higher than 9pm on the O2 which is in pot channel-imbalance territory (which happens at the lower end) especially if you are a quiet listener. As a loud listener using armatures I am often at 9pm and I believe I may have experienced this issue. It's one reason a lot of O2 users change the 2.5x gain to 1x (ie. no gain).I'm not sure what the situation is with max volume on the source but in some cases it is bound to be too much even for 6pm on the pot.
Possible 3rd: I'm lead to believe that an amp straining to produce current for a low impedance, high-current device can start distorting. I;m not sure that this is true. If so then that extra power will not just give more volume but also avoid distortion in some cases. Perhaps someone can correct that.
Keep in mind also that the Odac requires an amp. So if you haven't already then the O2 is a stunningly good value amp that you'll be needing.
Having said that: the Behringer UCA202 measures well, as done by guess who, and at half the price there's really there's no absolute need for an Odac unless you want the ultimate.(I wanted the ultimate.) It also has the advantage of not (technically) needing an amp. But it does have a very high output impedance so you'll be needing that amp anyway.

What gain should I be using if I'm using a headphone of impendence 50 ohms? 2.5x gain or no gain? 
 
Btw I noticed that the Epiphany O2/ ODAC combo are encased in one compact form. Is the JDS Lab's combo of the O2/ ODAC also the same compact form as well? I did not see a picture from their website. 
 
Jul 10, 2012 at 4:17 PM Post #13 of 5,663

lorriman

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At 50 Ohms I think you'll be fine at 2.5x. However, I'm only going on other people's conversations on diyaudio: I can't do the maths.

Even for sensitive phones: at 9pm it's not so bad; I;m not really bothered by it. But let's say that the phones had a similar channel imbalance of their own as the pot on the O2, then that could be bothersome and the only solution would be to reverse the phones, L-R and viceversa to cancel them out, which may be annoying for some things (like films).
 
Jul 10, 2012 at 6:50 PM Post #14 of 5,663

Zophiel

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Quote:
What gain should I be using if I'm using a headphone of impendence 50 ohms? 2.5x gain or no gain? 
 
Btw I noticed that the Epiphany O2/ ODAC combo are encased in one compact form. Is the JDS Lab's combo of the O2/ ODAC also the same compact form as well? I did not see a picture from their website. 

 You are more interested in the interplay between impedance and sensitivity of the headphone rather than just the Ohms WRT Gain.  Just FYI the O2 is designed to be able to produce appropriate mW accross a LARGE (16-600) range of impedances.  what gain you want to use is your preference.  Once the music is playing at acceptable (your taste) levels, then you want to use the lowest gain you can do achieve this.  the O2 comes default with a 2.5X and 6.5X gain modes, but can be easily customized to 1X/2.5X/6.5X (pick any two).  Youre not going to really need 6.5X except for voltage HUNGRY headphones like HD 650 or the higher end Beyers.  
 
Jul 10, 2012 at 7:14 PM Post #15 of 5,663

lorriman

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I'm planning to get a O2 / ODAC combo. Have any of you guys purchased the O2 / ODAC? If so, which variant did you go with? 
I'm planning to get a O2 / ODAC combo. Have any of you guys purchased the O2 / ODAC? If so, which variant did you go with? 


Probably you are aware, but just in case: keep in mind that the combo means NO BATTERIES and so no portability. If you want this to do everything for you then it should be separates.
 

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