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O2 AMP + ODAC
Oct 17, 2015 at 11:55 AM Post #4,726 of 5,671
kwangsun said:
  I have a question. I have a HIFIDIY ESS ES9023 USB DAC + Fiio E9 combo on my desk. Would it make sense for me to buy the ODAC+O2? Seems odd to drop so much clams on an amp+dac when I have a dac that has similar specs as the ODAC and an amp that isn't utter junk. The E9 isn't THAT great an amp though I'll admit. 
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Kwangsun, I would say that ODAC sounds better than HIFIDIY 9023 DAC. As for the Fiio E9 vs. O2, feel free to read Nwavguy's headamps compare webpage; I would say that that O2 is top notch at this price tag and Fiio E9 is not even close. You can also check Tyll's reviews and tests with many other headphone amplifiers; http://www.head-fi.org/t/670889/tyll-hersten-innerfidelitys-21-amp-measurements for details.
 
Oct 17, 2015 at 12:37 PM Post #4,728 of 5,671
raoultrifan said:
  Nec3, I was referring to NJM2068, the OPAMP dealing with voltage amplification. OPA2227 or LME49720 should work just fine, also MUSES8820 or MUSES02.
 
In case you want to swap the 2 x NJM4556 output buffers, then this is a bit more complicated. You can swap them with LME49720 or LME49860, but these will only drive 64-600ohms headphones.
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I went ahead for the LME49720HA (+ Adapter). I don't think the Muses02's price was justifiable for me :)
 
Oct 18, 2015 at 6:24 PM Post #4,729 of 5,671
It took me a while to realize that the O2+ODac truly is the most boring combo ever.
It's not that it's bad, it's just (like advertised), dead neutral. Can I use the word neutral? It's -/+0.1db across the 20hz/20khz board.
 
It can certainly drive my Q701's at 63ohms at something like 400mW (when the Q's are rated for 200mW).
but I would like to reiterate the Q701 + ODAC/O2 is a boring combo, but I love it.

Why? I don't know, the same reason I love the ER4S.
agdr said:
  ....The O2 designer noted in his blog that the LME49720 was similar to the NJM2068, with the major downside just being it was more expensive........
[Shortened quote for space-sake, sorry if I took your quoted quote out of context]
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Let's just hope NWAVGuy is wrong in my case. 
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Oct 20, 2015 at 10:34 AM Post #4,730 of 5,671
nec3 said:
  It took me a while to realize that the O2+ODac truly is the most boring combo ever.
It's not that it's bad, it's just (like advertised), dead neutral. Can I use the word neutral? It's -/+0.1db across the 20hz/20khz board.
 
It can certainly drive my Q701's at 63ohms at something like 400mW (when the Q's are rated for 200mW).
but I would like to reiterate the Q701 + ODAC/O2 is a boring combo, but I love it.

Why? I don't know, the same reason I love the ER4S.

Let's just hope NWAVGuy is wrong in my case. 
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I'm glad you like the boring combo, but in all honestly, are you sure it ain't yo headphones that are boring? The flatter I get my sound, the more amazing it becomes . . . . just sayin'. But if you really wanted to save some money, I'd skip the ODAC for now and just enjoy having a proper beastly little O2 amp. I always felt the ODAC was only that last "10%" of fidelity I've been enjoying for awhile now.
 
FYI I am half responding to this post because I have a new monitor with a mostly "flat" gamma response of 2.2, 90-100% sRGB color and fairly even lighting - I can't imagine asking for "oversaturation" and extra "backlight bleed" or IPS glow or whatever. Causes eye fatigue, you know, plus it isn't true to the images. Wonder why audio is so different to so many.
 
Oct 20, 2015 at 12:31 PM Post #4,732 of 5,671
mrmateohead said:
 
I'm glad you like the boring combo, but in all honestly, are you sure it ain't yo headphones that are boring? The flatter I get my sound, the more amazing it becomes . . . . just sayin'. But if you really wanted to save some money, I'd skip the ODAC for now and just enjoy having a proper beastly little O2 amp. I always felt the ODAC was only that last "10%" of fidelity I've been enjoying for awhile now.
 
FYI I am half responding to this post because I have a new monitor with a mostly "flat" gamma response of 2.2, 90-100% sRGB color and fairly even lighting - I can't imagine asking for "oversaturation" and extra "backlight bleed" or IPS glow or whatever. Causes eye fatigue, you know, plus it isn't true to the images. Wonder why audio is so different to so many.
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The problem for me is that the Q701 is very dry with the O2+ODAC. Notes don't tend to last very long (specifically the bass), so that's why I preferred the analogue tubes that somehow compensated for this. So even though the ER4S is supposed to be compensated for the Harman Target Response Curve, it still somehow has the perfect timbre and balance for overall enjoyment; which is "flat"
 
I somewhat realized that of course, the music is what make or breaks the final rating. Great masterings tend to compliment the ODAC+O2/Q701 Combo, but the average masterings leaves satisfactory enjoyment.
 
Unfortunately tube amps in my experience don't have the greatest durability so I'm switching back to full solid state.
 
The ODAC is the only DAC I have, other than the FiiO X5... I'll try that combo when I get home.
 
Oct 22, 2015 at 12:49 AM Post #4,734 of 5,671
It has been written for several times on this forum on how to modify gain on O2, also on nwavguy's blog.
 
There are 2 resistors you need to change, actually for gain of 1x you just need to unplug 1 resistor, but for for the gain of 3.5x you need to change the other resistor. I suggest you check nwavguy's blog for more details; there you'll see the schematic and it will be quite easy for you to understand it. (sorry I can't provide you with a direct link, but nwavguy has been banned on head-fi and we're not allowed to provide you links or copy-paste from his blog).
 
Cheers!
 
Oct 22, 2015 at 1:40 AM Post #4,735 of 5,671
Sorry for nitpickking, but there are actually two resistors for each gain setting. So he has to remove the two resistors for low gain and change the ones for high gain.
If 1x/2,5x is acceptable, only the two resistors for high gain have to be removed. I did that with my O2.
 
Edit: You will also get to the desired result if you remove only one resistor for low gain and change one resistor high gain. So it is totally correct what raoultrifan wrote. Many apologies.
 
Oct 23, 2015 at 9:27 AM Post #4,738 of 5,671
draulius said:
  Should I get the 250 Ohm or 600 Ohm version of a headphone for this DACAMP? I like to stay at 1x gain whenever possible.
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Both of them will work on O²/ODAC . (seams you are talking about Beyers ...) . Peraphs on some very quiet records you will have to switch to 2.5/3X gain with the 600 ohms version (depend on how loud you listen) .
 
Oct 23, 2015 at 3:51 PM Post #4,739 of 5,671
havoc-28 said:
   
Both of them will work on O²/ODAC . (seams you are talking about Beyers ...) . Peraphs on some very quiet records you will have to switch to 2.5/3X gain with the 600 ohms version (depend on how loud you listen) .
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If the question was about beyers, the 600 ohm version is usually the best - although the difference is not that big. So if you don't plan mobile use, get 600 ohms.
 
Joachim
 
Oct 23, 2015 at 5:26 PM Post #4,740 of 5,671

 
Hey guys! The o2 is my first amp so I was wondering if someone is kind enough to help me out.
 
I definitely wanna protect myself from hearing damage. I am using Audirvana with the O2. From the picture shown, is it safe to leave the Audirvana's volume at 0dB and the O2 low gain at 9 o' clock?
 
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