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O2 AMP + ODAC - Page 207

post #3091 of 3453

Hi. I'm new to this forum, and I'm thinking about purchasing a desktop O2/ODAC combo (1/4'' jack, RCA connectors) with a modified gain of 1x/2.5x.

 

Quote:

Originally Posted by jseaber
 
agdr and I have discussed this and believe NwAvGuy made a mistake here. With a 15VAC transformer, voltage drop across U5 and U6 is higher, resulting in another thermal issue. It's best to use 14VAC with O2 as far as heat is concerned.

 

Do O2/ODAC manufacturers stock ~14V >400mA power supplies (instead of the standard 12V 200mA power supply)? Or will it be cheaper to purchase separately?

 

The LEDs on the unit look extremely bright. Would this be easy to switch out for a dim orange/red LED? Or can I order it with this variant?

 

Are there any other options/modifications you can suggest before pulling the trigger?

post #3092 of 3453
Quote:
Originally Posted by Cyune View Post
 

 

Do O2/ODAC manufacturers stock ~14V >400mA power supplies (instead of the standard 12V 200mA power supply)? Or will it be cheaper to purchase separately?

 

The LEDs on the unit look extremely bright. Would this be easy to switch out for a dim orange/red LED? Or can I order it with this variant?

 

Are there any other options/modifications you can suggest before pulling the trigger?

 

The default Triad WAU12-200 and WAU12-1000 power adapters we stock for North American customers generate 13.50-13.95VAC depending on the specific line voltage of your home/building. A 14VAC adapter is non-standard since transformers must be produced at integer multiples of line voltage. For example:

 

120V:12V = 10:1

120V:15V = 8:1

 

Manufacturers tend to assume input line voltage of 115VAC. If you assume 115VAC, required ratio for 14VAC output is 8.2143....or for 120VAC input, 8.57143...

 

More importantly, O2 is internally limited to 12VAC. Its regulators require at least a 1.5V drop for normal performance. Extra voltage drop across a regulator is ideal as long as heat dissipation is acceptable! This is one of NwAvGuys minor oversights. Heat output at regulators U5 and U6 increase proportionally to supply voltage. Input of 14-15VAC is fine for most loads. With 16VAC+ input and a small load impedance (32 ohms) driven to high levels, it's possible to drive U5/U6 to dangerous IC temperatures.

 

tl;dr -- Stick with the supplies we recommend. Operating voltage is within expectations. When you increase voltage, it's wasted as heat.

 

The LEDs are high efficiency, low brightness. Changing the LED is discouraged since it's part of the power management circuit. If you wish to install a different LED, make sure to select a part with the same voltage drop as the standard part.

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post #3093 of 3453

Thank you for the thorough feedback!

post #3094 of 3453
Is it necessary to omit R1, R2, D2 and D6 in full desktop setup? Some instructions prescribe such action.
post #3095 of 3453
Quote:
Originally Posted by schmalgausen View Post

Is it necessary to omit R1, R2, D2 and D6 in full desktop setup? Some instructions prescribe such action.

 

The designer himself stated that those plus the battery terminals can be left out in the comments to the details article on his blog (which must not be named here), so it's probably safe. OTOH having them in doesn't hurt either.

 

Joachim

post #3096 of 3453
What....I think my O2 died on me. The power light is on, the DAC works, but upon plugging in headphones to the O2, I hear absolutely nothing, not even the "pop" upon turning it on/off. It was working earlier today. :/


Got it. It was running on batteries.
Edited by miceblue - 6/26/14 at 5:28pm
post #3097 of 3453

Wow!!

 

That's funny.....

 

 Batteries!!

 

A.

post #3098 of 3453

Head-Fi user RealMode took the following image of his O2+ODAC with a FLIR thermal camera. He says he's too new to post the picture himself:

 


Edited by jseaber - 6/27/14 at 10:37am
Reply
post #3099 of 3453

what were the parameters when this image was taken?

 

Alex

post #3100 of 3453

Ambient temp was around 21C.

Unit was on for a few hours of mild use then I turned it off, removed the case and powered it up on a piece of plastic and ran random tracks at 50% knob volume on the 2.5x setting for 5 min with a old pair of Sony MDR-V500DJ's and then took the shot from 5-7cm above.

 

I have a better lens on order that should make the shots much clearer. I plan on re-doing the test with a more extended burn when it shows up.

post #3101 of 3453
http://archimago.blogspot.ca/2014/06/24-bit-vs-16-bit-audio-test-part-ii.html?m=1

Another result in for the objective crowd . No surprises here.
post #3102 of 3453

Guyz, ODAC + O2, is the best ever with iems.  It beats everything I compare with.  The must transparent and detailed.  That ES9023 is cheap and well performing.  

 

Also, is there anyway to up my performance of the ODAC?  Noise isolation or stable PS?  I notice the ODAC degrades if I feed it my smartphone's OTG.  My guess is it lacks juice.  This makes me think that ODAC needs better power supply.   Any good suggestions? 

 

Thanks,

SE

post #3103 of 3453
You say the ODAC "degrades" but what are you comparing it with?
post #3104 of 3453
Quote:
Originally Posted by SilverEars View Post
 

Guyz, ODAC + O2, is the best ever with iems.  It beats everything I compare with.  The must transparent and detailed.  That ES9023 is cheap and well performing.  

 

Also, is there anyway to up my performance of the ODAC?  Noise isolation or stable PS?  I notice the ODAC degrades if I feed it my smartphone's OTG.  My guess is it lacks juice.  This makes me think that ODAC needs better power supply.   Any good suggestions? 

 

Thanks,

SE

 

Hi,

 

ODAC uses about 1 watt or 200mA at 5V USB power. If your smartphone cannot supply this, the voltage might get too low and this might create audible artifacts. Things you could try are the following:

 

- try to run ODAC at your smartphone OTG plug while the smartphone is being charged (if it's not the same plug) and see if ODAC performs as expected.

 

- plug a powered USB hub between you smartphone OTG and the ODAC and see if ODAC performs as expected.

 

Not sure what to do while on the go...

 

Joachim

post #3105 of 3453


I inserted an ammeter in a USB cable and and never saw more than 50ma or so of current draw...

 

Alex

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