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O2 AMP + ODAC - Page 126

post #1876 of 3453

Asian Batman, in your previous post you said you used the 6.5x gain "once" before you changed it, and it made the bass all sloppy on your DT770s. That is not proof that SQ is 'always' better at low gain. Now you are telling me that you plugged in and used high gain with multiple sources. Which was it?

 

Either way, gain is not about SQ - it is about source matching and while it can affect SQ, it is not really the first place to go when summarizing an amps performance!

post #1877 of 3453
Quote:
Originally Posted by MrMateoHead View Post
 

Asian Batman, in your previous post you said you used the 6.5x gain "once" before you changed it, and it made the bass all sloppy on your DT770s. That is not proof that SQ is 'always' better at low gain. Now you are telling me that you plugged in and used high gain with multiple sources. Which was it?

 

Either way, gain is not about SQ - it is about source matching and while it can affect SQ, it is not really the first place to go when summarizing an amps performance!

 

Thanks for pointing that out. I only had my DT770 at the time I got my O2/Odac, so using it once with 6.5x with multiple sources in a day. I count that as once upon a time, but sorry for the confusion. Hope that clears that up. I never said anything about SQ or anything about it being better at low gain. I just said that I find 1x to be sufficient for the headphones I do have. 

post #1878 of 3453

Oh OK. I thought that you were equating gain levels with sloppy bass, which would have been strange.

post #1879 of 3453
Quote:
Originally Posted by MrMateoHead View Post
 

Oh OK. I thought that you were equating gain levels with sloppy bass, which would have been strange.

 

I can understand the confusion cause in a way I was stating that the DT770 had a bad bass response with the high gain level with the sources I tried it with. For bass heavy songs, the bass sounds like someone is holding their hands on a subwoofer as the bass hits. I was not trying to generalize 6.5x = sloppy bass. :beerchug:

post #1880 of 3453
Quote:
Originally Posted by MrMateoHead View Post
 

Don't go clipping your O2 right away because you think high gain = bad sound.

 

The 6.5x gain is still useful for HDR recordings and weak sources (i.e., virtually any common device you probably would use as a source aside from the ODAC).

 

Spend some more time listening and playing around before you do it. Better yet, plug an Mp3 player or cell phone into it with some classical to see what I mean.

 

You know what, you're absolutely right about needing the 6.5x gain for classical. Just turned on some Ravel Piano Concerto in G with Thibaudet. That 2nd movement especially is super quiet. I'm glad I've not changed the gain. The irony is I'm a classical trumpet player and it took me this long to turn on some classical music. 

post #1881 of 3453
Quote:
Originally Posted by nabwong View Post
 

You know what, you're absolutely right about needing the 6.5x gain for classical. Just turned on some Ravel Piano Concerto in G with Thibaudet. That 2nd movement especially is super quiet. I'm glad I've not changed the gain. The irony is I'm a classical trumpet player and it took me this long to turn on some classical music. 

No one ever just says I'm right! Glad to help.

 

High Dynamic Range soaks up power big time - and makes setting gain and volume levels tricky. Certainly what is about right for classical will brutalize your ears with pop. Try a Blu-Ray or DVD at some point also - much the same. That is why I would rather have a little too much gain than not enough - particularly with an amp like the O2 which is so perfectly silent!

post #1882 of 3453
Quote:
Originally Posted by nabwong View Post
 

I just received my o2+odac. Quick question, is it just me or is there a sound difference between 2.5x and 6.5x gain. I find the 6.5x to be more congested and bloated than the 2.5x. Also more sibilance. Yes, I reduced the volume when I went higher gain. My laptop volume is 100%. 

 

That's strange, cause I didn't hear any difference between 2.5x vs 6.5x with HD600 or HD800.

You just have to be sure to lower the volume in pc if you wanna use 6.5x, so the output from odac is 1V max, if using AC adapter. In case of batteries it's even lower (cca 0.7V). According to my measurements 1V is around 67-68% on windows volume slider, 0.7V is cca 55%


Edited by Dano91 - 1/13/14 at 1:40am
post #1883 of 3453

Does anyone know the maximum operating temperatures on this amp/dac? I put it on top of my PC that runs about 30-40 degrees celcius (chassis temps) when on max load. Then the heat transfers to my DAC that gets quite warm.

Edit: I use an infrared thermometer, the bottom of the ODAC is 33 degrees celcius.


Edited by Nec3 - 1/11/14 at 8:55am
post #1884 of 3453
Quote:
Originally Posted by Dano91 View Post
 

 

That's strange, cause I didn't hear any difference between 2.5x vs 6.5x with HD600 or HD800.

You just have to be sure to lower the volume in pc if you wanna use 6.5x, so the output from odac is 1V max, if using AC adapter. In case of batteries it's even lower (cca 0.7V). According to my measurements 1V is around 67-68% in windows volume slider, 0.7V is cca 55%


What were you measuring? Output from the ODAC at those system volume levels? It would seem that this is a useful thing to know.

post #1885 of 3453
Quote:
Originally Posted by MrMateoHead View Post
 


What were you measuring? Output from the ODAC at those system volume levels? It would seem that this is a useful thing to know.

 

Yes, I used simple DMM at 50Hz sine wave @ 0 dBFS.

post #1886 of 3453
Quote:
Originally Posted by Dano91 View Post
 

 

Yes, I used simple DMM at 50Hz sine wave @ 0 dBFS.

 

Something wrong there, with a 0db sine wave you should have measured ~2.8v or ~2v RMS.   Specs for the ODAC are, quote "Line Output: Approximately 2 Vrms into 5K ohms or higher"

post #1887 of 3453
Quote:
Originally Posted by mcandmar View Post
 

 

Something wrong there, with a 0db sine wave you should have measured ~2.8v or ~2v RMS.   Specs for the ODAC are, quote "Line Output: Approximately 2 Vrms into 5K ohms or higher"

That's correct - with volume slider at 100% I measured 1.999V, 

at 90% - 1.588V

80% - 1.336V

70% - 1.060V and so on

 

EDIT: I did full plot from 100% to 0% on volume slider in Win at 5% steps if anyone is interested:

Warning: Spoiler! (Click to show)
50 Hz, sine wave, 0 dBFS
 
100% 1.999 V
 95    1.774 
 90    1.588
 85    1.490
 80    1.336
 75    1.182
 70    1.060
 65    0.941
 60    0.838
 55    0.707
 50    0.561
 45    0.501
 40    0.398
 35    0.315
 30    0.250
 25    0.198
 20    0.141
 15    0.089
 10    0.050
  5     0.020

Edited by Dano91 - 1/13/14 at 1:24am
post #1888 of 3453

I never ever use 6.5....not needed at all.

 

Alex

post #1889 of 3453

I use 6.5X all the time. Even in my car, the gain is cranked (yikes!). Necasary in the day of having CD, USB, Aux Inputs and Radio etc. Its impossible to set amps properly for each source and still guarantee yourself ample headroom to push someone's crappy Mp3 player mix with justice. ;)

 

Thanks Dano 91 - Its geek gratification to know what my pre-outs are doing at a given volume on the Windows slider :beerchug:

 

I am actually a little surprised that its clearly non-linear volume adjustment - but pretty close.


Edited by MrMateoHead - 1/13/14 at 5:24pm
post #1890 of 3453
Quote:
Originally Posted by nabwong View Post
 

I just received my o2+odac. Quick question, is it just me or is there a sound difference between 2.5x and 6.5x gain. I find the 6.5x to be more congested and bloated than the 2.5x. Also more sibilance. Yes, I reduced the volume when I went higher gain. My laptop volume is 100%. 

Hi,
 

 

as has been said before, ODAC is rated to deliver 2V RMS at 0dB and this is too much for O2 at 6.5x gain, regardless of power option and O2 volume pot setting. This means that the O2 input stage will clip when driven by ODAC at 100% software volume and music going up to 0dB. 

 

So either turn down the volume in software (not so bad if you run ODAC at 24 bit) or change one of the gain modes to 3.5x which happens to be the max gain with ODAC and mains power - on battery it's 2.5x btw...

 

Joachim

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