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O2 AMP + ODAC - Page 143

post #2131 of 3408

Hey guys the thread starter in post one :

 

""As I was searching for a good amp/ dac, I decided to save myself the trouble of picking between numerous options and get an O2 amp/ dac. Now I have to choose between JDS Lab variant and the EHP variant. I can only see the rear view of the former (http://www.jdslabs.com/item.php?fetchitem=39) and the latter seems smaller than I thought (http://epiphany-acoustics.co.uk/wp-content/uploads/2012/04/Epiphany-Acoustics-EHP-O2-Reflection2.jpg). Why is it that the EHP variant is187 dollars and the JDS LAB variant is 285 dollars? P.S. Do I need an AC adapter for both? I would appreciate it if you guys can help me choose.""

 

Lets get back to the thread.....

 

Thanks

Alex

post #2132 of 3408
Quote:
Originally Posted by adydula View Post
 

Hey guys the thread starter in post one :

 

""As I was searching for a good amp/ dac, I decided to save myself the trouble of picking between numerous options and get an O2 amp/ dac. Now I have to choose between JDS Lab variant and the EHP variant. I can only see the rear view of the former (http://www.jdslabs.com/item.php?fetchitem=39) and the latter seems smaller than I thought (http://epiphany-acoustics.co.uk/wp-content/uploads/2012/04/Epiphany-Acoustics-EHP-O2-Reflection2.jpg). Why is it that the EHP variant is187 dollars and the JDS LAB variant is 285 dollars? P.S. Do I need an AC adapter for both? I would appreciate it if you guys can help me choose.""

 

Lets get back to the thread.....

 

Thanks

Alex

 

You might want to check the EHP price again - it's 187 UK pounds for the O2+ODAC combo, not dollars. Although right now it's on discount at 167 pounds.

The EHP offer includes the AC adapter and you can choose UK, EU or US versions. With the JDS offer the adapter is not included.

 

Joachim

post #2133 of 3408
Quote:
Originally Posted by jring View Post
 

 

You might want to check the EHP price again - it's 187 UK pounds for the O2+ODAC combo, not dollars. Although right now it's on discount at 167 pounds.

The EHP offer includes the AC adapter and you can choose UK, EU or US versions. With the JDS offer the adapter is not included.

 

Joachim

 

£167 works out to be around $280 (rounded up, at time of writing)  And with the adapter the JDS variation is $300 (rounded up, at time of writing).

 

Without postage costs, this works out well. But with postage, this is far more of a deal for people in the UK than for anyone else.

 

Add the O2 output booster board upgrade and a USB isolator, and you have a clear contender for for a dac+amp end game set-up fit for a starving student's budget.

post #2134 of 3408
Quote:
Originally Posted by JacobLee89 View Post

£167 works out to be around $280 (rounded up, at time of writing)  And with the adapter the JDS variation is $300 (rounded up, at time of writing).

Without postage costs, this works out well. But with postage, this is far more of a deal for people in the UK than for anyone else.

Add the O2 output booster board upgrade and a USB isolator, and you have a clear contender for for a dac+amp end game set-up fit for a starving student's budget.
Are JDS or epiphany going to manufacture the booster board O2 or are they not allowed?
post #2135 of 3408
Quote:
Originally Posted by James-uk View Post


Are JDS or epiphany going to manufacture the booster board O2 or are they not allowed?

 

The O2 output booster PCB is a DIY project by AGDR that's is on its 3rd revision. I found out about it in the DIY section of this forum:

 

http://www.head-fi.org/t/693300/o2-headamp-output-booster-modification-pcb

 

With it installed, I have noticed better clarity on certain instruments, and that transients (i.e: a drum being hit / staccato notes) became sharper and more "thumpier". Imagine it as a O2 which had a good meal and a hot shower.

 

The only downside is that the DIY project requires SMD soldering, requiring an additional flux pen/dispenser and at least tweezers of some sort. The good news is that everything is documented, and following the build instructions (read through everything once though) step by step has made the process easier. (This was also my first SMD project)

 

It'll be best to contact AGDR about obtaining the PCB, or the kit. I am however unsure when the next batch of PCB's will be available.

 

*edit*

 

I guess them (JDS / epiphany) "building" the PCB's may just be up to AGDR's decision. The design leaves much possibility for several tweaks (even a complete PCB overhaul), and the constant design changes could just discourage JDS or epiphany from including such a mod. 

 

Wouldn't hurt contacting them to raise their awareness of such a gem though.


Edited by JacobLee89 - 3/9/14 at 11:17am
post #2136 of 3408
Quote:
Originally Posted by JacobLee89 View Post
 

 

£167 works out to be around $280 (rounded up, at time of writing)  And with the adapter the JDS variation is $300 (rounded up, at time of writing).

 

Without postage costs, this works out well. But with postage, this is far more of a deal for people in the UK than for anyone else.

 

Add the O2 output booster board upgrade and a USB isolator, and you have a clear contender for for a dac+amp end game set-up fit for a starving student's budget.


Don't forget about HeadnHifi if in Europe. With just a few more, you can get the new revision which has the AC input and RCA output at the back with a 1/4" Headphone out in the front. Very clean-looking. If you want to save even more you can get the DIY kit. Keep in mind he is based in Switzerland, so you'll have to check the Germany(He ships it from Germany) shipping option to prevent paying the Royal Mail(If in the UK) pigs or your respective local post offices the extra fee and tax.


Edited by rikaldrey - 3/9/14 at 1:42pm
post #2137 of 3408
Quote:
Originally Posted by rikaldrey View Post
 


Don't forget about HeadnHifi if in Europe. With just a few more, you can get the new revision which has the AC input and RCA output at the back with a 1/4" Headphone out in the front. Very clean-looking. If you want to save even more you can get the DIY kit. Keep in mind he is based in Switzerland, so you'll have to check the Germany(He ships it from Germany) shipping option to prevent paying the Royal Mail(If in the UK) pigs or your respective local post offices the extra fee and tax.


Yeah, that's what I did; got the DIY kit shipped from Germany and incurred no further charges. :D Hopefully this coming week I can get the ODAC wired up and finally try the whole thing! :cool:

post #2138 of 3408
Quote:
Originally Posted by JacobLee89 View Post
 

I guess them (JDS / epiphany) "building" the PCB's may just be up to AGDR's decision. The design leaves much possibility for several tweaks (even a complete PCB overhaul), and the constant design changes could just discourage JDS or epiphany from including such a mod. 

 

Wouldn't hurt contacting them to raise their awareness of such a gem though.

 

Hey good question!  I have not copyrighted the O2 booster board in the spirit of the O2 designer's goals with the O2 amp.  The Gerber files to make PC boards are posted at the Google Drive link in that DIY thread (use the V3.0 which includes the headphone relay).  Anybody can make boards, including companies.  I know that the forum here keeps close watch over the commercial end of things.  Any company planning on selling the boards, either bare or assembled, better not make any mention of it here in the forum unless they are properly set up with Head-Fi as a commercial vendor.  But as far as license goes there isn't any, and I get no royalties the same as the O2's designer didn't for the O2.  Anybody can make the O2 booster board. :bigsmile_face:

 

As for DIY, the mods here will let me sell the stuff at-cost to help out with the minimum board order quantities at the PCB fabrication outfits. I have one board left from the existing batch and a parts kit (only for those overseas, in the US you have to use Mouser or Digikey direct) as per the DIY booster board thread.  Send me a PM if anyone is interested. I'll probably do another board run in the near future too.

 

EDIT: the last board from the current run just found a home.  I'll post in the DIY section thread when I do another board run.


Edited by agdr - 3/9/14 at 11:05pm
post #2139 of 3408
Quote:
Originally Posted by JacobLee89 View Post
 
Quote:
Originally Posted by James-uk View Post


Are JDS or epiphany going to manufacture the booster board O2 or are they not allowed?

 

The O2 output booster PCB is a DIY project by AGDR that's is on its 3rd revision. I found out about it in the DIY section of this forum:

 

http://www.head-fi.org/t/693300/o2-headamp-output-booster-modification-pcb

 

With it installed, I have noticed better clarity on certain instruments, and that transients (i.e: a drum being hit / staccato notes) became sharper and more "thumpier". Imagine it as a O2 which had a good meal and a hot shower.

 

The only downside is that the DIY project requires SMD soldering, requiring an additional flux pen/dispenser and at least tweezers of some sort. The good news is that everything is documented, and following the build instructions (read through everything once though) step by step has made the process easier. (This was also my first SMD project)

 

It'll be best to contact AGDR about obtaining the PCB, or the kit. I am however unsure when the next batch of PCB's will be available.

 

*edit*

 

I guess them (JDS / epiphany) "building" the PCB's may just be up to AGDR's decision. The design leaves much possibility for several tweaks (even a complete PCB overhaul), and the constant design changes could just discourage JDS or epiphany from including such a mod. 

 

Wouldn't hurt contacting them to raise their awareness of such a gem though.

 

Someone has developed an O2 booster board?  And you notice "better clarity," "transients ... became sharper," and now things "are more thumpier?"

 

Just curious, but was that a subjective or objective conclusion?

 

 

P.S. I am certain that agdr has come up with something worthwhile.  In no way am I attempting to state that it's not an improvement.  If I had an O2, I'd build his booster board, too. ;)


Edited by tomb - 3/9/14 at 6:11pm
post #2140 of 3408

The booster  board has a long and well worth reading thread on the diyaudio site.

I have heard no real world audio improvements that my ears can detect.

 

The booster board does reduce the dc offset voltage from 3mv to 10uv a 98% reduction in this voltage.

It also replaces the two NJM4556A output chips with a OP140 and LME49990 pair on each channel.

 

The booster board also allows for higher voltages for higher impedance and low-sensitivity headphones.

The O2 runs 12 volt rails. The booster board allows for this voltage to run at 15 vdc.

 

There is also a 18vdc modification if desired.

 

Another neat thing is the board reduces turn off thumps.

 

There are several other neat modifications, like being able to add a 1/4" Neutrik jack!

 

Enjoy

Alex

and Thanks to AGDR!

post #2141 of 3408
Quote:
Originally Posted by tomb View Post
 

 

Someone has developed an O2 booster board?  And you notice "better clarity," "transients ... became sharper," and now things "are more thumpier?"

 

Just curious, but was that a subjective or objective conclusion?

 

 

P.S. I am certain that agdr has come up with something worthwhile.  In no way am I attempting to state that it's not an improvement.  If I had an O2, I'd build his booster board, too. ;)

 

We can quite comfortably say that it's subjective. I sadly do not have any measuring equipment, and do not have another O2 to do any A/B testing with. Only my very likely biased memory of how it used to sound, and my ears. I may have been subjected to some mental voodoo magic in this case. I now have 2 additional green LED's I can oogle at though....

 

I'm not going to defend the O2, or the booster board though it did "feel" like it has some sort of improvement on my HD650s after the mod, and by no means (from what I've read so far) that the O2 can get any close to a BH Crack in terms of pairing with the HD650. Which of course will be my next acquisition to save up for.

 

I'm quite midway in this sort of topic: I find the subjective viewpoint as important as the objective. I could use analogies, but we are all of different backgrounds, perspectives, ear sizes, and appetite. 

post #2142 of 3408
Quote:
Originally Posted by tomb View Post
 

 

Someone has developed an O2 booster board?  And you notice "better clarity," "transients ... became sharper," and now things "are more thumpier?"

 

 

Obviously subjective, but i found exactly the same after building and testing one for myself. Regardless of measurements or semantics, it just sounds better.   ......IMO

 

Also i do have two O2's so i was able to do some side by side comparisons to satisfy my own curiosity.


Edited by mcandmar - 3/9/14 at 8:07pm
post #2143 of 3408
Quote:
Originally Posted by JacobLee89 View Post
 

 

We can quite comfortably say that it's subjective. I sadly do not have any measuring equipment, and do not have another O2 to do any A/B testing with. Only my very likely biased memory of how it used to sound, and my ears. I may have been subjected to some mental voodoo magic in this case. I now have 2 additional green LED's I can oogle at though....

 

I'm not going to defend the O2, or the booster board though it did "feel" like it has some sort of improvement on my HD650s after the mod, and by no means (from what I've read so far) that the O2 can get any close to a BH Crack in terms of pairing with the HD650. Which of course will be my next acquisition to save up for.

 

I'm quite midway in this sort of topic: I find the subjective viewpoint as important as the objective. I could use analogies, but we are all of different backgrounds, perspectives, ear sizes, and appetite. 

 

I think on a future upgrade my money may be spent on the BH Crack amp instead of the booster board. How does it compare to the O2? What is the cost involved with parts?

 

BG

post #2144 of 3408
Quote:
Originally Posted by adydula View Post
 

The booster  board has a long and well worth reading thread on the diyaudio site.

I have heard no real world audio improvements that my ears can detect.

 

Hi Alex!  This is good news, since you know what they say about medical doctors - "first do no harm". :regular_smile :   Alex and the other builders know I've stayed away from making any comments on how I think the booster board sounds or making any sound claims.  That is all your guy's jobs! :biggrin:   There are a lot of folks here on the foum with critical listening ears much better than mine.  I'm just the engineer. 

 

If the booster does make any headphones or IEMs sound better it is probably due to some combination of the stuff that is objective (measureable) with the booster board:

 

* Like Alex says that 93% or so reduction in output DC offset from 3mV for the standard O2 to 30uV or so with the booster means that the transducers in headphones or IEMs stay much closer to their natural mechanical "zero" resting point.  If this makes a difference at all in the sound it is more likely to be with sensitive IEMs than headphone.  In fact, for my fairly sensitive AKG-K550s, I wrote their tech support once about the issue.  The answer that came back was 3mV being no problem at all since the standard volume level is around 40mV and maximum around 130mV.  3mV just put the transducer diaphram slightly to one side.  But I've read posts where people with some IEMs swear it makes a huge difference to have the transducer resting in the middle.  So... you tell me from the listening! :regular_smile :

 

* The latest version 3.0 with the relay completely eliminates all O2 turn-on and turn-off thumps with the one wire addition going from the booster to the O2 board.  This won't change listening sound any, but at least the thumps are gone.  One anoyance nailed.

 

* Double the slew rate as mentioned in posts above from the O2 amp's 3V/uS to the 6V/uS limit of the O2's input NJM2068 gain chip.  As per the discussions above the digital 16/44 signal processing chain limits slew such that the O2's 3V/uS *should* be adequate, but there are certainly many other opinions here.  Again, you guys tell me from the listening if there is a difference.

 

* +/-15Vdc upgrade capability for folks with high impedance and low sensitivity phones that can't get enough volume from the O2.  This would be a fairly small subset of users.

 

* Those mezmerizing green LEDs! :biggrin:   They perform a couple of useful diagnositic functions.  The LEDs are hooked in after the O2's power management mosfets vs. the O2's red which is before the mosfets.  So when the green LEDs come on you know your mosfets have turned on and the O2 amp circutis are getting juice.  And since one LED is on each power rail, if only one LED ever comes on you know you have lost on power rail, and even know which one based on which LED went dark.  When the O2's batteries run down and the O2's power management circuit shuts it down, you finally have a way to know what has happened.  The O2 red LED will still be on but both green LEDs will go off.

 

* Should be slightly lower noise and distortion from the datasheet numbers, but this is yet to be fully measured.  I've recently bought one of the QA400 analyzers (essentially a USB soundcard in a box set up for distortion measurements) and ran some initial tests on both the standard O2 and one with the booster.  To the limit of the QA400, which is 10 or 20dB  noiser than a dScope or AP analyzer, the two looked essentially identical within the margin of error.  The booster was just a tad better in THD+N, but again figuring in the margin of error it is a wash.  But most likely both units are bumping up again that higher noise floor in the QA400.  I'm in the process right now of stuffing a notch filter PCB I built to try to take those noise THD+N numbers down further.  But again, the good news here is that the booster board did not appear to make the O2's THD+N any worse.  Even if the THD+N numbers eventually do measure better than the stock O2 there is a good argument to be made as to whether that would even be audible or not.  You tell me with the listening!

 

* Higher current drive capability for folks with low impedance low sensitivity headphones.  Again this is likely to be a small subset of headphones or IEMS out there.

 

* Zero output impedance capability.  The folks who have built booster boards should keep in mind they can short the four O2 1-ohm resistors straight across, as shown in the diagrams here, to get true zero ohms out.  The stock O2 needs those resistors to balance up the two paralleled sections of the NJM4556A output chips.  To make the booster board plug and play I designed it to use those 4 resistors as they sit when you plug in the board, so you still wind up with the O2's 0.5 ohm output resistance.  But the booster chips don't need any resistor.  You can just short those right across underneath the O2.  Whether having zero ohms out vs. 0.5 ohms makes any difference in the sound, well... you tell me with your listening! :regular_smile :

 

 


Edited by agdr - 3/10/14 at 8:11am
post #2145 of 3408
Quote:
Originally Posted by agdr View Post

 

* Zero output impedance capability.  The folks who have built booster boards should keep in mind they can short the four O2 1-ohm resistors straight across, as shown in the diagrams here, to get true zero ohms out.  The stock O2 needs those resistors to balance up the two paralleled sections of the NJM4556A output chips.  To make the booster board plug and play I designed it to use those 4 resistors as they sit when you plug in the board, so you still wind up with the O2's 0.5 ohm output resistance.  But the booster chips don't need any resistor.  You can just short those right across underneath the O2.  Whether having zero ohms out vs. 0.5 ohms makes any difference in the sound, well... you tell me with your listening! :regular_smile :

 

 

 

The Zero output impedance mod does seem to me like something that requires more fiddling than it's worth, therefore I've left the output impedance at 0.5. The booster board still (either subjectively or objectively) sounds like an improvement over the stock O2.

 

However I am now curious as to how an amplifier's output impedance would affect headphones. Currently reading up on Benchmark Media's article on it, which is convincing me to try it out.

 

*edit**

Done the mod and cannot hear any noticeable change. Might be noticeable with lower impedance headphones / IEMS


Edited by JacobLee89 - 3/10/14 at 9:40am
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