[dudebrah]

Could someone point me to where I could find a good, short M-M 3.5mm cable to connect my separate O2 and ODAC units? Would really appreciate it!!

 

[adydula]

http://www.jdslabs.com/item.php?fetchitem=L2
 
I have a few of these and they work well
 
Alex
 
also: http://www.amazon.com/3-5mm-Stereo-Reinforced-Premium-Quality/dp/B004LGNB0A/ref=sr_1_3?ie=UTF8&qid=1363043982&sr=8-3&keywords=3.5mm+6inch

 

[adydula]

I know of nobody that has actual proof of how detrimental a poor, bad, crappy, dirty, USB power source affects the capabilities of the ODAC.
 
There are lots of IMHO comments...
 
Here are the published specs:
 

1. Frequency Response: +/- 0.1 dB (10 hz - 19 Khz 24/44)
2. THD+N 100 hz 0 dBFS: 0.0029%
3. THD+N 20 hz -1 dBFS: 0.003%
4. THD+N 10 Khz -1 dBFS: 0.003%
5. IMD CCIF 19/20 Khz -3 dBFS: 0.0011%
6. IMD SMPTE -1 dBFS: 0.0004%
7. Noise A-Weighted dBu 24/44: --102.8 dBu
8. Dynamic Range: > 111 dB A-Weighted
9. Linearity Error -90 dBFS 24/44: 0.0 dB
10. Crosstalk 0 dBFS Line Out 100K: --93.5 dB
11. USB Jitter 11025 hz J-test 24/44: Excellent
12. Maximum Output Line Out 100K: 2.0 Vrms
13. Distortion: < 0.005%
14. PCB Dimensions: 49.0 x 58.0 mm

 
I wish I could post links to the actual discussions about the O2 and ODAC but we cant here.
 
There is a lot of very good discussion on why and how the ODAC was designed and why certain parts were used and why not others etc...take a good slow read on the March 1 ODAC blog updates on the ODAC. It will hopefully enlighten a lot of us. It did me.
 
Alex

 

[dudebrah]

Quote:

http://www.jdslabs.com/item.php?fetchitem=L2
 
I have a few of these and they work well
 
Alex
 
also: http://www.amazon.com/3-5mm-Stereo-Reinforced-Premium-Quality/dp/B004LGNB0A/ref=sr_1_3?ie=UTF8&qid=1363043982&sr=8-3&keywords=3.5mm+6inch

 
Thanks! Also http://www.amazon.com/FiiO-L2-3-5mm-Stereo-Cable/dp/B003UCC78I has the FiiO L2 cable for a couple bucks cheaper + free shipping w/Prime. 

 

[chrislangley4253]

Quote:

Could someone point me to where I could find a good, short M-M 3.5mm cable to connect my separate O2 and ODAC units? Would really appreciate it!!

The Fiio L2's and L8's are popular. I have been using a 1ft monoprice premium lately, the fiio's are a bit too flimsy for my liking, doesn't help that one of my L8's was DOA.

 

[adydula]

Testing.....
 

 
 

 
Always makes me smile...
 
Alex

 

[autoteleology]

RustA, if you like KMPlayer, try using PotPlayer instead. It's basically just as powerful with a much cleaner and organized interface.
 

---

 
Would it be possible on the O2 to, say, swap out the resistors to set different gains, or the opamps for a higher quality piece that can handle higher loads?

 

[mikeaj]

Quote:

Originally Posted by Tus-Chan /img/forum/go_quote.gif
 
[...]
Would it be possible on the O2 to, say, swap out the resistors to set different gains, or the opamps for a higher quality piece that can handle higher loads?

 
As for swapping resistors for gain, yes, it's described on the designer's blog.  It's just an elementary textbook non-inverting amplifier setup with an op amp, where you're adjusting what's R1 there in the diagram.  Gain is pretty much (1 + R2 / R1).  Remove R1 and it becomes pretty much infinity, so you get 1x gain.  
 
R2 in the diagram is 1.5 kohm in the O2.
 
R1 in the diagram corresponds to:
R17 -> low gain (switch out), L channel
R19 -> high gain (switch in), L channel
 
R21 -> low gain (switch out), R channel
R23 -> high gain (switch in), R channel
 
They're on the PCB close to the gain switch.  Swap all you please.  Actually, you could install holders that allow you to insert and change resistors without resoldering.  It's kind of a disappointment that the major builders don't offer this by default and send you extra resistors, which would cost under $1.
 
 
 
You can change the gain-stage op amp, but the fundamental limitation is not being able to handle voltages past some physical (electrical) limit.  They can't output anything past what the power supply voltage is, and then an additional margin due to the workings of the internal electronics, some junction forward voltage drops.  With a different op amp that can swing closer to the rails, you'd be able to handle slightly higher inputs, but not by a lot.  Definitely not near or past 8.5V rms, where the default limit is around 7V rms.
 
You could raise the power supply rails from say +/- 12V to +/- 15V, which would make a more significant difference, but again, it's not going to be a lot.  And that would cause higher power consumption and heat—default O2 runs pretty cold though.

 

[autoteleology]

What do you think is the highest gain that the O2 can theoretically handle without clipping?

 

[mikeaj]

Quote:

What do you think is the highest gain that the O2 can theoretically handle without clipping?

 
It's not really theoretical, as it's been tested and confirmed.  Again, check the blog or ask around.
 
With a little wiggle room depending on exactly what you define as the clipping point, it's about 7 / X, where X is the output level of whatever source you're using, in volts rms (assuming sine wave as usual).  Or roughly 19.8 / Y, where Y is the peak-to-peak output voltage, if you please.  That's on AC power.  On battery, depends on the battery charge level and battery, but expect more like 4.5 / X.
 
Pretty much the input level multiplied by the gain can't be larger than 7V on AC, 4.5V or so on battery.
 
 
All the above is what causes the gain stage to clip.  If the output level is very high (this is controlled by the volume control and not related to the gain issue), then output stage could also clip.  Clipping point depends on the headphones impedance.  Unless you listen really really loud, you're probably not going to drive the amp output into clipping for any traditional dynamic transducer headphone and even most of the planar magnetics.

 

[JakeJack_2008]

Quote:

My ears and my head are telling me the unity gain setting is sooo much better....but I know thats not totally accurate.
 
I do notice that with unity gain you have to crank the volume knob much farther to get things to liven up so shall we say...
 
I dont think there is any reason for me to used anything but unity gain with my setup...
 
I run from a destop pc, usb to the ODAC etc....mostly listen with batteries until I have to charge them up,
 
I would say that a pair of LCD2's and the O2 and ODAC is pretty much up there with the best....it would be hard for me to imagine anything being an orde of magnitude better than this setup...
 
And this is not even considering the cost....which we all know it this case is the deal of the century for head amps and dacs....
 
Alex

 
Thanx, Alex and others.
 
I would call it the steal of of the century. Just for under $300 

the awe-inspiring sound​

 of the​

​

ODAC and O2. 

 

[autoteleology]

It's not really theoretical, as it's been tested and confirmed.  Again, check the blog or ask around.

 
I'm not saying your advice is theoretical, as you clearly know what you're talking about. I'm confused by more than the basics myself when it comes to electrical engineering. I'm not questioning your knowledge in the slightest. 

 
I was simply asking what the maximum gain I could shoot for was if I decided to do some tweaking of the board.

Speaking of, I may or may not be selling my custom O2 and ODAC combo, so be sure to check out my listing, especially if you'd like a version that could be proudly displayed on a desk.
 
http://www.head-fi.org/t/655211/custom-built-o2-odac-combo-fiio-cable-extendable-usb-cable-and-triad-wall-wart-included

 

[mikeaj]

Quote:

I'm not saying your advice is theoretical, as you clearly know what you're talking about. I'm confused by more than the basics myself when it comes to electrical engineering. I'm not questioning your knowledge in the slightest. 

 
Oh np I didn't interpret it like that (though you'd be surprised how much people like me don't really know).  I was just making a distinction between the kinds of information or statements people throw out there.  Sometimes people are just speculating based on theory.  Sometimes people do calculations or run simulations based on certain models and assumptions.  You could call statements or conclusions from these things "theoretical" I guess, with the implication that maybe it's not certain or known for sure.  When you're talking about a system that's been built and tested and measured to perform as expected and that agrees with well-established and textbook theory, then "theoretical" maybe has the wrong connotation.
 
 
So with ODAC as source, ~3.5x gain max (use standard resistor value of ~620 ohms), probably, assuming you're making full use of its output.  Good luck on the sale.

 

[RustA]

Maybe someone could be interested in purchasing great DESKTOP O2/ODAC combo (1/4 headphone out, RCA outputs etc.)...

 
http://www.head-fi.org/t/656371/unique-o2-odac-desktop-combo-for-sale

 

[miceblue]

Quote:

Maybe someone could be interested in purchasing great DESKTOP O2/ODAC combo (1/4 headphone out, RCA outputs etc.)...

 
http://www.head-fi.org/t/656371/unique-o2-odac-desktop-combo-for-sale

This has been kind of bugging me for a while (not just to pick on you, but in general):
Quote:

As for the sound, this unit sounds a bit more transparent

 
How does one define what transparent "sounds like"? The O2 was designed to "sound transparent", so how can one justify something "sounds more transparent" and how can one actually actually confirm this? The designer of the O2 says it's transparent, but how does he know? I have heard multiple people say a Leckerton amp sounds more detailed than the O2; does this mean it's more coloured than the O2?