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Review: JDS Labs O2 (Black edition) + O2/ODAC discussion

Jun 26, 2013 at 1:18 PM Post #361 of 543
Quote:
jakejack_2008 said:
 
I am a bit confused.
I am using the JDS Labs ODAC and O2 (which has standard 2.5x &  6.5 X gain) as two seperates.
I always use the 2.5x gain with my Beyerdynamics DT 880 (250 Ohm).
(I never use the 6.5x gain because the sound is muddy and somewhat distorted.)
Well, the ODAC has about 2 V RMS output (and is connected via the USB cable to my laptop).
So the O2  will clip but not  
tongue_smile.gif
  too much?  There was a whole discussion about clipping in the ODAC/O2 thread.
It was suggested that to reduce clipping one should reduce the computer's  volume level to, say, 50%.  ...
...or to clip some resistors or capacitators or something else in the O2 amplifier. -
I am not a DIY'er or an engineer, so I don't know that at all.
 
On the other hand the instructions from the JDS Labs say that one should max
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 the volume on the computer to 100%...
but max volume causes clipping.
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your confusing two things:
1. "clipping" resistors: in order to change the gain settings of the (standard) O2, you need to open it up and cut out one of the resistors. depending on which you cut out, your gain settings will be changed to either x1 and x2.5, or x1 and x6. ive done it myself.
2."clipping" is also a term for when an amp reaches its limits:
 
Quote:
nothing4me said:
Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its published ratings.
Click to expand...

btw, i own dt770s, also 250 ohm. and on x2.5 gain i do believe youll deafen yourself before you reach into clipping... its more likely to occur as a result of improper eqing i think. but i may be wrong there.
 
Jun 26, 2013 at 7:34 PM Post #362 of 543
Hello,
 
I always have my windows player at 100%.
 
I use the lowest gain setting and adjust the volume control to the levels I want to listen to.
 
If the lowest gain allows you to play at sane levels there is no need to use any higher gain setting with your setup.
 
If not then you would try the higher gain setting again using the volume control to get to levels that are sane and wont cause hearing damage.
 
The amp was designed to be used with a wide variety of devices.
 
I have one O2 amp set to unity gain (clipping the resistor for the 6.5 gain setting)...and to 2.5 gain.
 
I mostly use unity gain with most of my cans and very rarelt use the 2.5 gain setting.....
 
If your using very sensitie cans or in ear devices, you most likely will never need the higher gain settings....you arent loosing anything.
 
Enjoy
A.
 
Jul 11, 2013 at 3:22 PM Post #364 of 543
orangecr said:
I have the JDS black edition, and I want to remove the resistors to have 1X and 2,5X gain settings. 

Is it as easy as it looks? Just cut and remove?

What's the worst case scenario?

I don't think it's necesary to say I know nothing about electronics 
confused_face.gif

 Thanks!
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Right, you want to electrically remove them from the circuit, which is achieved by physically severing the metal leads (and removing the things).

Worst-case scenario is... you cut the wrong parts, making the amp not work anymore?

It's R19 and R23 for the switch-in setting. They're right next to the volume control potentiometer. Those are the ones you'd remove.
 
Jul 11, 2013 at 3:45 PM Post #365 of 543
Quote:
mikeaj said:
Right, you want to electrically remove them from the circuit, which is achieved by physically severing the metal leads (and removing the things).

Worst-case scenario is... you cut the wrong parts, making the amp not work anymore?

It's R19 and R23 for the switch-in setting. They're right next to the volume control potentiometer. Those are the ones you'd remove.
Click to expand...

 
It's easy as long as you have diagonal cutters. Here's a PDF guide with an actual photo:
http://www.jdslabs.com/pdf/O2_LowGain.pdf
 
Jul 20, 2013 at 10:14 PM Post #368 of 543
If I'm not using LOD, would that affect volume level?  
 
i'm pairing the O2 with Beyer DT880 250Ω cans.  this is hooked directly to my iphone 5.  yes, i'm double amp'ing.  i'm on battery power and to get to something loud (not ear splitting), i can take it to 3/4 volume level.  obviously i dont need it this high for everyday use, but was just curious.  i figured you could get this to something unbearably loud and was surpised to see that it was at a level i'd still tolerate.
 
Jul 20, 2013 at 10:24 PM Post #369 of 543
iguanajm said:
If I'm not using LOD, would that affect volume level?  

i'm pairing the O2 with Beyer DT880 250Ω cans.  this is hooked directly to my iphone 5.  yes, i'm double amp'ing.  i'm on battery power and to get to something loud (not ear splitting), i can take it to 3/4 volume level.  obviously i dont need it this high for everyday use, but was just curious.  i figured you could get this to something unbearably loud and was surpised to see that it was at a level i'd still tolerate.
Click to expand...


Technically the LOD makes your iPhone at the maximum volume. If you set the iPhone volume at maximum without any volume limits, you get the same volume as what the LOD does.
 
Jul 20, 2013 at 10:32 PM Post #370 of 543
I thought LOD, was bypassing the amp/dac??  Maybe I'm getting my terms mixed up.  But basically the signal is still in digital form.  Line Out D......(device??)
 
And so if you want the purest form of audio, you would want to get a dac and an amp, or a dual amp/dac unit.  The O2 is amp only.  So I'd need a fiio or similar and use the dac portion.  Next i'd take my lightning connector and stick that in the USB of the dac.  take the line out of the dac, stick that in the amp, and then amp to my cans.  That would be purest audio possible.
 
What I'm doing is using my iphone's amp and dac, sticking that to the line in on the O2 (effectively double amp'ing my source) and then to my cans.  I also know there aren't any cheap solutions for the lightning connector.  I did read about mixed results using the 30pin connector....
 
Please correct me if I misspoke, I'm still learning  :)
 
Jul 20, 2013 at 11:36 PM Post #371 of 543
Yeah the Line Out Dock connector bypasses the internal amp only, but it outputs the same volume as maximum volume on the iPhone.

E.g. Set your O2's potentiometer at 9 o'clock, plug in the LOD to your iPhone, connect the LOD to the O2, and play some music. Your music's volume level will be the same as if you had set the iPhone volume level to maximum and double amped with the O2 with the potentiometer still in the 9 o'clock position.

You can bypass both the DAC and amp with a digital out connector with a USB-terminated end to connect the iPhone to a special "Apple certified" DAC. A Line Out Dock connector just has a 3.5 mm-terminated end.
 
Jul 21, 2013 at 2:04 PM Post #372 of 543
Gotcha.  Thanks for the explanation.  So, going LOD, is cheap and doable, BUT bypassing the DAC is what gets expensive (with lightning connectors at least)?  Obviously with time things will get cheap, but last I checked there were only a couple DAC's made specifically for lightning all were over $500 I believe....
Thanks again!
 
Jul 21, 2013 at 3:31 PM Post #373 of 543
The question is rather why bypass an excellent DAC and even great amp in the first place.
 
Jul 21, 2013 at 4:57 PM Post #375 of 543
miceblue said:
Because this is Head-Fi, where people need to spend $500+ USD on a portable rig to be considered an audiophile. Forget logic and common sense. XD
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You sir are a genius, you summed it up perfectly.
I try and keep it simple, iPod > LOD > amp > headphones, sometimes just iPod > headphones

DACs are too expensive for I devices, and the sound quality increase just doesn't justify the price for me anyway.
 
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