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O2 AMP + ODAC - Page 87

post #1291 of 3145
Quote:
Originally Posted by ProTofik View Post

Ohms doesn't have much do to with the volume level . You may want to change your gain settings to 1x as I did for my hd600.


I'm not sure if that's a good idea. According to NwAvGuy, peaks in audio at standard listening volumes can be as high as 110 dB for which you will need ~2.5V from amp with HD 600 or 650. But O2 set to 1x gain with ODAC would be able to deliver only 2V.

I think it's just easier to lower volume in PC.. very probably you won't here any difference in terms of audio quality (Once I made a test with ODAC set to 5% at 16 bit and O2 at full volume, and I couldn't tell the difference with HD 600 vs ODAC at 100% volume @24 bit)


Edited by Dano91 - 4/26/13 at 11:08am
post #1292 of 3145
Quote:
Originally Posted by Dano91 View Post

Quote:
Originally Posted by ProTofik View Post

Ohms doesn't have much do to with the volume level . You may want to change your gain settings to 1x as I did for my hd600.


I'm not sure if that's a good idea. According to NwAvGuy, peaks in audio at standard listening volumes can be as high as 110 dB for which you will need ~2.5V from amp with HD 600 or 650. But O2 set to 1x gain with ODAC would be able to deliver only 2V.

I think it's just easier to lower volume in PC.. very probably you won't here any difference in terms of audio quality (Once I made a test with ODAC set to 5% at 16 bit and O2 at full volume, and I couldn't tell the difference with HD 600 vs ODAC at 100% volume @24 bit)

 

I don't quite understand this. The ODAC is supposed to deliver up to 2V RMS; it's not an amplifier. It doesn't have any user settings (like "5%").

post #1293 of 3145

OS volume control, probably.

 

Whatever 5% there maps to (probably neither 0.1 V nor 0.447 V), that is.

post #1294 of 3145
Quote:
Originally Posted by HamilcarBarca View Post

I don't quite understand this. The ODAC is supposed to deliver up to 2V RMS; it's not an amplifier. It doesn't have any user settings (like "5%").
You can set it to 5% via computer volume slider.
post #1295 of 3145
Quote:
Originally Posted by Limniscate View Post

Does the O2 start making a thumping sound or pulsating sound through the headphones when the battery is low?

 

Here is a circuit that fixes the low-battery thumping problem, for anyone into some DIY circuit building work.  

 

The circuit "latches" the O2 power management circuit when the batteries get low, so that "off" really means "off" rather than the thumping.  To reset this circuit the O2 has to be powered off for about 45 seconds to let the capacitor discharge.  Of course at that point the battery needs charging too since that is what tripped the O2 power management circuit in the first place, otherwise it will just re-latch if the battery is still low (or plug into AC). 

 

The circuit could just be built up on some cheap perfboard or home etched as shown, then soldered into the points indicated on the O2.  Just wrap a piece of electrical tape around the board to insulate it, with 4 small gauge wires running from the latch board to the O2 PC board.  Since it hooks onto resistors on the top side of the O2 PC board it is easiest to attach when building an O2 up from scratch. Otherwise just a dab of solder on the end of each resistor end to attach the wire.  I've tested the circuit on an O2 and it works well.

 

R1 and C1 form a time delay circuit to lock out the latch circuit for the first 20 seconds when the O2 is powered on since the O2 mosfets cycle for the turn-on thump prevention.  After that, when the power management mosfets cycle when the battery is low, Q1 turns on while Q2 is already on.  That then shorts out R9 on the O2 PCB, latching the power management circuit "off" as long as the power is still on.  When the O2 power is turned off for about 45 seconds C1 discharges through the power rails, resetting the latch circuit.

 

Have fun!

-agdr

 

 

 

latch circuit.png 10k .png file

 

 

 

 

 

latch layout.png 7k .png file

 

 

 

 

 

O2 attch points.png 25k .png file
Edited by agdr - 4/26/13 at 6:16pm
post #1296 of 3145
Quote:
Originally Posted by MrEleventy View Post

Quote:
Originally Posted by HamilcarBarca View Post

I don't quite understand this. The ODAC is supposed to deliver up to 2V RMS; it's not an amplifier. It doesn't have any user settings (like "5%").
You can set it to 5% via computer volume slider.

 

My point was there's nothing to set on the ODAC, from computer or otherwise. I replied to a rather confused post.

post #1297 of 3145
Quote:
Originally Posted by HamilcarBarca View Post

 

My point was there's nothing to set on the ODAC, from computer or otherwise. I replied to a rather confused post.


Of course you are right, you can't set anything on ODAC.

By "5% volume" I meant setting PC volume slider (labeled as odac) to 5%.

 

The point is, you get 2V RMS only when this slider is set to 100%. 

And by previous post I wanted to say, that with O2 amp with 1x gain, you get 2V RMS at best, which can be with some headphones (e.g. HD600, 650..) insufficient in terms of audio quality even when they seem to be loud enough.


Edited by Dano91 - 4/27/13 at 2:16am
post #1298 of 3145

im having some problems with my odac. sometimes i get crazy, massive, very noticeable distortion and i have to unplug the usb cable from my computer, and then plug it back in again. ive tried different usb outlets but it doesnt help, and im unplugging and replugging my odac almost every day now... on the info sheet provided by jds labs it says the cause is likely weak usb power or bad usb cable. as the cable came from jds labs, im assuming its the former. the solution suggested by jds is to use a powered usb hub, which i can see go for ~30$ on amazon. could anyone explain a little more about this please? is there any other way? my desk is cluttered enough as it is, i dont need another box connected to the mains sitting on it...(edit: or do they run on battery power?). is there a way to fix this through my computers settings or something?


Edited by adamlr - 4/27/13 at 12:43pm
post #1299 of 3145
it sounds like Windows is powering down the usb ports. try a different power setting in control panel.
post #1300 of 3145
Quote:
Originally Posted by MrEleventy View Post

it sounds like Windows is powering down the usb ports. try a different power setting in control panel.


thanks. im not very computer savvy im afraid, could you be more specific? im using a laptop on what it calls "high performance" option. the only other power options are all about battery saving and what not ("balanced", "energy saver" etc.). i tried looking around the "devices" section and all - i found no configurations about usb power control

post #1301 of 3145

Very Scary  Moments with the ODAC connected to the O2

 

Well, I've read in this thread that some of you experienced some buzzing, whining, etc with your O2 & ODAC.

I thought it would never happen to me, but unfortunately  it did happen, the buzzing that is. 

The buzzing was coming back and going away and coming back and so on every few minutes.

When there was  no buzzing I touched the volume knob on the O2 and the buzzing resumed.

I touched the top of the O2 and the buzzing resumed. I touched the ODAC and the buzzing came back.

The buzzing was on and off in the course of a few hours.

 

Does anyone  know why did the buzzing occur?

 

laptop -->  ODAC --> ODAC --> headphones

 

P.S.

In my next post (tomorrow?) I'll tell you what really happened.


Edited by JakeJack_2008 - 4/27/13 at 1:19pm
post #1302 of 3145
Quote:
Originally Posted by MrEleventy View Post

it sounds like Windows is powering down the usb ports. try a different power setting in control panel.


theres a setting called usb selective suspend setting - its enabled. is it this? should i disable it?

 

edit: some further google investigation indicates that this may be the solution. though im not 100% sure. oh well, fingers crossed.

thank you very very much for pointing me in the right direction, theres no way i would have thought of this by myself.


Edited by adamlr - 4/27/13 at 2:05pm
post #1303 of 3145
Quote:

Originally Posted by Dano91 View Post
 

Of course you are right, you can't set anything on ODAC.

By "5% volume" I meant setting PC volume slider (labeled as odac) to 5%.

 

That should have been obvious, so I must have been having a bad moment. Thanks.

 


Quote:

Originally Posted by Dano91 View Post
 

And by previous post I wanted to say, that with O2 amp with 1x gain, you get 2V RMS at best, which can be with some headphones (e.g. HD600, 650..) insufficient in terms of audio quality even when they seem to be loud enough.

 

No. If the ODAC's output is "loud enough", it's also neutral. There's no insufficiency.

post #1304 of 3145
Quote:
Originally Posted by adamlr View Post


theres a setting called usb selective suspend setting - its enabled. is it this? should i disable it?

edit: some further google investigation indicates that this may be the solution. though im not 100% sure. oh well, fingers crossed.
thank you very very much for pointing me in the right direction, theres no way i would have thought of this by myself.
Yeah, that should at least knock a variable out if it continues to act up. I think it should be fixed. let's hope. smily_headphones1.gif
post #1305 of 3145
Quote:
Originally Posted by adamlr View Post

im having some problems with my odac. sometimes i get crazy, massive, very noticeable distortion and i have to unplug the usb cable from my computer, and then plug it back in again. ive tried different usb outlets but it doesnt help, and im unplugging and replugging my odac almost every day now... on the info sheet provided by jds labs it says the cause is likely weak usb power or bad usb cable. as the cable came from jds labs, im assuming its the former. the solution suggested by jds is to use a powered usb hub, which i can see go for ~30$ on amazon. could anyone explain a little more about this please? is there any other way? my desk is cluttered enough as it is, i dont need another box connected to the mains sitting on it...(edit: or do they run on battery power?). is there a way to fix this through my computers settings or something?

I have this problem with my laptop, never could fix it.

I think it has to do with the windows usb drivers or the drivers that install when you plug in the dac. Try moving it to a different port or deleting the drivers and letting windows install them anew.

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