[overhaze]

On advice I'm going to copy and paste a post I made elsewhere on the forum. Looking for advice on whether I have a ground loop. Also I accidentally used DirectSound for the direct connection test but I re-tested it with MME and the results are identical.



Hello

I'm looking to for help interpreting some RMAA results from an odac+O2 combo connected to one of my computers. I can't judge whether I am looking at an actual ground loop between my computer and the odac or one between the odac and my PCs line-in. Some large screenshots incoming.

This is what I get with a direct connection to my pc

And this is what I get with a hifimediy USB ground isolator

Also since I had one lying around here is what a direct USB connection to the pc looks like using a Behringer HD400 Hum destroyer instead of a standard audio cable

And here is the mess I get if I combine the Hd400 and the USB isolator

 

[raoultrifan]

Why don't you power the O2 from internal batteries? There will be no ground loop at all.

Also, O2 is powered from a transformer, so it's already isolated from mains, which is a good thing. However, try using a laptop...see if it measures better.

Have you tried listening with sensitive cans if there's an audible noise coming from O2 while connected to ODAC? Of course...no music playing.

 

[overhaze]

Why don't you power the O2 from internal batteries? There will be no ground loop at all.

Also, O2 is powered from a transformer, so it's already isolated from mains, which is a good thing. However, try using a laptop...see if it measures better.

Have you tried listening with sensitive cans if there's an audible noise coming from O2 while connected to ODAC? Of course...no music playing.

Its a combo unit so battery power isn't an option. I would say the most sensitive headphones I own are my Nighthawks, they are incredibly easy to drive. No hiss. I suppose I could dig out the IEMs that came with my phone.

 

[raoultrifan]

Sometimes RMAA tests are not conclusive, the 50/60Hz could get induced into the RCA cables with no reason and might compromise the results. Also, there are many other reasons that RMAA might be not the best way to measure the SNR or dynamics.

I would say that if no noise could be heard you should be fine with the O2/ODAC combo.

 

[overhaze]

Question about the hifimediy isolator and the odac. Is the 200mA its putting out enough to run the odac without audio degradation and is the 45 nanoseconds of added jitter within the range the odac can compensate for?

 

[adydula]

I measured the current draw years ago and it was less than 50 ma.

Alex

 

[wariwaro]

Hi, I was searching a power supply for the O2, and I've found a relatively cheap adapter here in my country (I'm from Spain and the adapter costs less than 10€), it's an european AC adapter, it has an output of 15V 400mA AC, 6VA... but there is something about this adapter that makes me wonder if it's suitable;
In the adapter, there is a sticker that has the symbol of: Safety isolating transformer for toys. (It has the form kinda of a train or a car).

Could this adapter work for the O2? Or maybe should I just go with one of the well known adapters for O2 without risks?

Can you help me please guys?

Ty!

 

[raoultrifan]

http://www.jdslabs.com/O2_poweradapters.php

Some pictures might be more helpful, but 15VAC/400mA sound OK.

The thing with the toys protection looks like advertising to me. After all such an AC/AC transformer will provide isolation from the 230V mains.

 

[wariwaro]

Oh, thank you, I'll upload an image of the power supply then!

 

[raoultrifan]

Looks fine to me: http://www.spelektroniikka.fi/kuvat/A20920G.pdf. Hope the plug will fit fine too.

 

[grig]

Boys is out there any real alternative to the O2 budget friendly and on the portable side more or less like the O2 ? In case no anyone than can help to find and buy all the components to build an O2 ?

 

[WilliamLeonhart]

Boys is out there any real alternative to the O2 budget friendly and on the portable side more or less like the O2 ? In case no anyone than can help to find and buy all the components to build an O2 ?

Closest I can think of is the JDS C5D. If you want to build yourself a (somewhat) portable O2+ODAC (it's possible), you can start with buying the O2 and ODAC boards from JDS too

 

[grig]

Closest I can think of is the JDS C5D. If you want to build yourself a (somewhat) portable O2+ODAC (it's possible), you can start with buying the O2 and ODAC boards from JDS too

jds is not exactly budget friendly, not to mention that i have to add import fees and shipping cost all the way to australia. when i was counting to source all the parts from third parties and save a lot by doing so...

 

[MrMateoHead]

jds is not exactly budget friendly, not to mention that i have to add import fees and shipping cost all the way to australia. when i was counting to source all the parts from third parties and save a lot by doing so...

How Much Power do you need?

There are products from Fiio that may also work just fine and they are not that costly. IF you can go without portability, there are good options that are affordable. The Schiit Fulla is about $100, AMP+DAC, for example. Not SUPER powerful, but more than enough for "normal" headphones.

What headphones are you using? Depending on their sensitivity / impedance etc. you may be better off using a good smartphone/computer on the run, and add a decent desktop setup at home. After all, the outside world can have a really poor signal to noise ratio.

 

[grig]

How Much Power do you need?

There are products from Fiio that may also work just fine and they are not that costly. IF you can go without portability, there are good options that are affordable. The Schiit Fulla is about $100, AMP+DAC, for example. Not SUPER powerful, but more than enough for "normal" headphones.

What headphones are you using? Depending on their sensitivity / impedance etc. you may be better off using a good smartphone/computer on the run, and add a decent desktop setup at home. After all, the outside world can have a really poor signal to noise ratio.

My dac at the moment is FiiO x5 III Gen, but i will add soon an SMSL Su-8 or a Topping D50. The headphones that i use most are the DT 1990 Pro, in general i need at least the power of an O2 or more just keep things more future proof. The important thing is a good amp that makes the music to shine sounding as best as possible. Now the O2 is very good amp i use to own the little own.... But perhaps out there in the china market i can find something as good but cheap, perhaps an Smsl SAP 2 could do the trick...?!