[diamondears]

O2 produces 613mW @ 33 ohms.


Modifying O2 breaks the license. Even disregarding the license, it makes no engineering sense to modify O2. A portable (or desktop) amp should be designed from the ground up with desired features and performance in mind. It's quite possible to design an amp with equal or greater performance than O2. We've done so several times in the past two years (sorry, cannot share R&D!).

Battery capacity is the greatest limitation when designing a portable amp. The market has shifted dramatically since 2011, and I think there's a strange obsession now with max output power. Sure, it's important to adequately power headphones, but most portable users have high sensitivity sets which are easily driven by an amp with much less power than O2:



[COLOR=000000][SPL Chart Data][/COLOR]

We could design a portable amp that blows away O2 in terms of max output power, but I think doing so is unnecessary. Run-time for 1W of output power would be incredibly short, even with a large Li-Ion battery; run time would be fine when driving efficient headphones and/or listening at moderate volumes. Again, portable users typically do not need more so much power. Driving truly demanding headphones necessitates AC power.

I'm with you re not needing too much power. Most portables out there are more than enough even for HPs.

What I wish is to have an O2 in a truly portable build. O2's present power and battery life is more than enough for me. What I think would be great is to use its excellent transparency into the usual/popular portable build plus its present battery life and power.

 

[jseaber]

I'm with you re not needing too much power. Most portables out there are more than enough even for HPs.

What I wish is to have an O2 in a truly portable build. O2's present power and battery life is more than enough for me. What I think would be great is to use its excellent transparency into the usual/popular portable build plus its present battery life and power.

 
Understood!
 
O2 is as small as possible with its dual 9V batteries. Fitting into a smaller case would require replacement of its entire power supply circuitry to accommodate a Li-Ion. This would mean a new design that should not carry the Objective name, in my opinion.

 

[diamondears]

Understood!

O2 is as small as possible with its dual 9V batteries. Fitting into a smaller case would require replacement of its entire power supply circuitry to accommodate a Li-Ion. This would mean a new design that should not carry the Objective name, in my opinion.

Is there something like that already in the works? Or is it out already (C5/C5D)? What's the differences between C5/C5D and O2/ODAC aside from the physical/build?

 

[HotIce]

When I compared the O2 and the FIIO E12, I could not tell them apart, sound wise.
I ended up with the E12 because of portability, and the ability to power/charge via USB.
I also like more the E12 design with the diamond buffer within the feedback loop, and the higher P2P voltage swing, but again, this made no practical difference as I could not have told them apart in a blind test.

 

[Peti]

What? The JDSLAbs C5/C5D use the same NWAVGuy stuff as in the O2/ODAC??

 

[Rajikaru]

The original design decision to go with dual 9V batteries have always appealed to me, because lithium ion batteries on competing solutions (such as the mentioned FiiO E12) have a finite lifespan. 

Unless they are sent back to the manufacturer for battery replacement, which would involve shipping and labor costs, along with cost of the battery, it would also make the lifespan of device itself shorter by inheritance.  

The O2s dual 9V batteries will of course have to be replaced eventually, but those are available everywhere, affordable, and easily user replaceable.  

That being said, I'm very interested in the AC powered ODA.
 
The O2 is currently a conditional recommendation for a 88-90dB/mW headphone such as the HE-560, with the conditions being that the gain settings are optimized to 7/input voltage (AC power only). An ODA with 3x the max continuous output and multiple gain settings would remove that condition.  

 

[HotIce]

Shouldn't be that bad on the E12. Remove two screws, slide the circuitry, and replace the battery pack.
According to FIIO info, the E12 has an 11V pack, charge pumped to create +/-11V rails.
 
 
 

 

[jseaber]

  What? The JDSLAbs C5/C5D use the same NWAVGuy stuff as in the O2/ODAC??

 
No, not at all! You'll see from benchmarks that C5D and O2+ODAC both perform extremely well. O2+ODAC has a more powerful amplifier.
 

Is there something like that already in the works? Or is it out already (C5/C5D)? What's the differences between C5/C5D and O2/ODAC aside from the physical/build?

 
Sorry, I cannot share our R&D projects. C5D has a completely different design topology than O2+ODAC. The main differences are portability and output power:
 
C5D

1. Single opamp per channel / Peak output of 
2. 63 step digital potentiometer; perfect channel balance
3. +/-7VDC operating voltage
4. USB rechargeable Li-Ion Battery
5. DAC: Self-powered SA9027 + PCM5102A
    

O2+ODAC

1. 3 Opamps per channel
2. Analog potentiometer
3. +/- 12VDC operating voltage
4. AC operation only
5. DAC: USB powered TE7022L + ES9023

 

[zealsoijun]

Light Harmonic Geek Out 1000 over all.

 

[castleofargh]

 they both use volts!!!!  you're caught red handed

 

[Rajikaru]

  Light Harmonic Geek Out 1000 over all.

 
 
Yeah it's cool...
 
Geek Out 1000: 4.3 Vrms
Output at 32 Ohms = 4.3²/32 = 577 mW
Output at 50 Ohms 4.3²/50 = 369 mW
 
But it's not exactly a power upgrade either. 

 

[diamondears]

No, not at all! You'll see from benchmarks that C5D and O2+ODAC both perform extremely well. O2+ODAC has a more powerful amplifier.


Sorry, I cannot share our R&D projects. C5D has a completely different design topology than O2+ODAC. The main differences are portability and output power:

C5D

• Single opamp per channel / Peak output of 
• 63 step digital potentiometer; perfect channel balance
• +/-7VDC operating voltage
• USB rechargeable Li-Ion Battery
• DAC: Self-powered SA9027 + PCM5102A
  
   

O2+ODAC

• 3 Opamps per channel
• Analog potentiometer
• +/- 12VDC operating voltage
• AC operation only
• DAC: USB powered TE7022L + ES9023

Thanks, John. Very looking forward to what your R&D is working on now.

Cheers.

 

[theodoro]

Hello guys, 
I finally got my O2 and i used it for about 5 days. I really like it  So far i used it with my HD600 and DT990 Pros (250omhs) and i can say it made both headphones sound more natural (which i didn't expect with the DT990s)  and more detailed. However i didn't hear a HUGE difference or that the headphones NEED the amplification since i don't believe it's a night/day difference. 
My DAC is the crappy PC on-board DAC, so my question is: will the Odac improve even more the sound quality or i should expect the same improvement?

 

[diamondears]

  Hello guys, 
I finally got my O2 and i used it for about 5 days. I really like it  So far i used it with my HD600 and DT990 Pros (250omhs) and i can say it made both headphones sound more natural (which i didn't expect with the DT990s)  and more detailed. However i didn't hear a HUGE difference or that the headphones NEED the amplification since i don't believe it's a night/day difference. 
My DAC is the crappy PC on-board DAC, so my question is: will the Odac improve even more the sound quality or i should expect the same improvement?

I suggest get an excellent DAC. It's where the "tweaking" happens. Suggest also to get a DAC with multiple digital filter options that you can toggle while listening to your music. There are digital-sounding filters, analogue-sounding, and there's somewhere in between... 

 

[theodoro]

I suggest get an excellent DAC. It's where the "tweaking" happens. Suggest also to get a DAC with multiple digital filter options that you can toggle while listening to your music. There are digital-sounding filters, analogue-sounding, and there's somewhere in between... 

I have no idea what "digital filters" are. I would get an Odac, but if you have an other suggestions at the same money with rcas, I would love to hear them