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O2 AMP + ODAC - Page 201

post #3001 of 5287
I suppose that's why we love the O2 . Totally transparent in every possible way !
post #3002 of 5287
Quote:
Originally Posted by James-uk View Post

I suppose that's why we love the O2 . Totally transparent in every possible way !

Ba-boom! smily_headphones1.gifsmily_headphones1.gifsmily_headphones1.gif
post #3003 of 5287
Quote:
Originally Posted by James-uk View Post

That kind of poor communication and engagement is enough to make me want to sell my HD800s!!! If you make the most advanced headphone ever at least have the confidence to be transparent with your information and employ someone to respond with facts rather than random bull**** and lack of understanding !

 

We could do a similar test with other headphone brands , and i guess that it will not be that different from sennheiser from most .:p

 

If you reply to them , and point that the informations are incorrect they will pass your email to tech 2 support or something like that where some one with a bit more knowledge on the subject will give you a "decent" response (i hope so) .

post #3004 of 5287
https://m.facebook.com/story.php?story_fbid=841752309179115&id=367116489976035

I just spotted this . Another example of why we can't trust our ears.
post #3005 of 5287

If you pay this much money or were anticipating on spending this much money on headphones I would hope you would get honest and accurate answers up front without having to play 20 questions in the first place!!.

 

Yes the O2 was very refreshing in that way and it indeed turned out to be a absolutely wonderful amp for 98% of the cans out there...and the ODA as I see it now rounds out the rest pretty much.

 

Soon we will have measurements and hope they meet and exceed the O2...

 

Alex

post #3006 of 5287

Is there going to be another version soon, and if so what would be the price?thanks.

post #3007 of 5287

As far as the ODA and follow on's there are a few "upgrades or improvement projects"...one is a O2 booster board that can plug into the sockets of an existing O2 amp The latest O2 booster board is 3.1.

 

Version 3.1 is:

 

The final circuit uses the OPA140 op-amp (FET input, DC precision, low THD+N) looped around an LME49600 audio current buffer on each channel to replace the O2 Headphone Amp's original NJM4556A output chips. Many other op amps would also work, such as the OPA827 and OPA627 with varying effects - see the full op amp rolling write-up in the build instructions. The board produces a 93% reduction in the O2 amp's DC output offset voltage to around 20uV from the O2's standard 3mV. Output current capability is increased from 120mA per channel to 200mA for "music power" (playing music rather than sine wave testing). The O2's power supply has limitations that would prevent continuous current draw above 200mA per channel.

 

Details on this can be found at DIYAUDIO.COM.

Boards and parts lists can be found there as well.

Link: http://www.diyaudio.com/forums/headphone-systems/244473-o2-headamp-output-booster-pcb.html

 

A desktop ODA is close to completion in (2) formats one with 12.5  volt rails and a second optional one :

 

 

The second "optional" build is for folks who specifically have 300 ohm or 600 ohm (or higher) headphones that almost have enough volume with the O2 headamp, but not quite. This build has +/-15Vdc power supply rails and uses a 5K volume pot (linear or log taper, either is fine) again for pot power dissipation reasons. The transformer with this +/-15Vdc build remains that same as up until now, 20Vac - 24Vac. This +/-15Vdc build should only be used with 300R or higher headphones for output chip power dissipation reasons.

Note that if you have 300R or 600R headphones that are nowhere near loud enough with the O2 then the +/-15Vdc rail option here isn't likely to help. You need a lot of additional voltage swing to get adequate dynamic range on music peaks, such as AMB's b22 headamp with +/-30Vdc rails or a tube amp.

 

The standard version is pretty much done and I have built one and have been using it for over a week and its a wonderful amp, as good as the O2 is and better in other respects.

 

Soon we will have lab measurements as well to benchmark against the O2 itself.

 

The booster board is a simple DIY mod that can be used with the current O2 amp and in the same enclosure. The ODA is more of a desktop not portable headphone amp.

 

The booster board can also be bought assembled and tested from agdraudio.com

 

All the best

Alex
 

post #3008 of 5287
Quote:
Originally Posted by James-uk View Post

That kind of poor communication and engagement is enough to make me want to sell my HD800s!!! If you make the most advanced headphone ever at least have the confidence to be transparent with your information and employ someone to respond with facts rather than random bull**** and lack of understanding !


 I've never in my life, never ever, and I've sent quite a few emails for technical support, had a proper answer to my question. Sometimes they don't answer at all (*cough* Musical Fidelity *cough*). It seems that people who answer these email's as a rule are totally clueless about the things you ask them about, and just have a pattern or a list of answers that they can offer you depending on the type of question you ask. They're most definitely not engineers of technically qualified for the job, they're usually people whose working potentials go no further than answering telephone calls or replying to emails.  I mean, if they guy who answered from Sennheiser doesn't even know that HD800's don't have a equal impedance across all frequencies, then how much does he know in general....not much. Probably never even put the HD800's on his head, and is probably not even interested in headphones.

 

That said, you can be damn sure that Sennheiser engineers know what they're doing, probably better than anyone else in the world when it comes to headphones considering how long they've been in the business and how many different types of headphones they produce,  so you can be sure that there's a good reason why their amps have an output impedance that they have, and that is to work with their high end headphones as good as possible.


Edited by derbigpr - 6/1/14 at 3:43am
post #3009 of 5287

You would hope....

 

Wonder why they call it tech support???

 

:)


A.


Edited by adydula - 6/1/14 at 4:48am
post #3010 of 5287

You need to be able to find guys who are passionate about what they do...and generally that means that if a company reaches a certain size you won't be able to reach those.  I contacted and got very detailed replies to questions from people like Fried Reim (Violectric) and Nelson Pass, just to name two who are active in the hifi/audio field.  And this was to questions that were really unrelated to a specific purchase I was contemplating.  Sure, they make a living out of it but that's almost a side effect for most of them.  Personally I couldn't imagine a greater hell than dragging myself to work to do a job I didn't care about.   Doesn't matter if it's about electronics, law, medicine, cultivating orchids, raising cattle or baking pastry, everyone has a talent but sadly, most people don't develop it.

 

Sitting back in my office in Delhi now, reading up on some stuff and looking worried at my ODAC/O2 that's sitting on my desk in the 37 centigrade heat (read an article on the plane about how every 10 centigrade increase in temp over average spec for certain components shortens their lifetime by half...poor capacitors).  Anyway, going to contact agdr tomorrow and place an order, spent my last hours in Europe yesterday building a power supply for it, damn those EU regulations.  

 

Off to bed now but first I'll do some more reading about impedance and load matching between tubes/output transformers/my HE-6 for a build I'm working on.  The deeper I delve the more complicated it becomes, reached a level where everything starts to matter if you want the best possible performance.  Gonna cost me 3 times what an off the shelf product would run but hey, that's why it's called a hobby I guess.

post #3011 of 5287

Xenophon,

 

Great!! Tell AGDR you know me etc....he is a really great person who has really gone out of his way to help me and others with the O2 Booster board DIY projects and the new ODA.

 

I am totally elated how the ODA turned out, its really a world class amp to me and it has made listening to my T90s a real pleasure.

 

Yes even with my listening tests with the O2 the sound is very very similar it has more current capacity and all those nice extras that make it a more functional and efficient unit.

 

Over at DIY the posted some info on torroidal transformers that can be used to build a ac supply for the ODA etc..

 

Alex

post #3012 of 5287

Ok folks AGDR just posted this at DIYAUDIO.COM

 

"I'm also going to let the cat out of the bag about something. John at JDS labs has agreed to dScope test the O2 booster board too, along with the ODA, and is in-process with that right now as time permits on his end. We will finally have some dScope measurements for the O2 booster board! A huge thanks goes out to John for the testing."

 

I knew this was in progress and had to wait until AGDR made this public....so hopefully we will have some discrete data soon!

 

Alex

post #3013 of 5287

Would be awesome to see JDSLabs include booster boards on their O2s.

post #3014 of 5287
Quote:
Originally Posted by adydula View Post

Ok folks AGDR just posted this at DIYAUDIO.COM

"I'm also going to let the cat out of the bag about something. John at JDS labs has agreed to dScope test the O2 booster board too, along with the ODA, and is in-process with that right now as time permits on his end. We will finally have some dScope measurements for the O2 booster board! A huge thanks goes out to John for the testing."

I knew this was in progress and had to wait until AGDR made this public....so hopefully we will have some discrete data soon!

Alex

**Fanboy Alert **

John is one heck of a guy who is outrageously committed to his customers too. There was a time I thought the problems I was having related somehow to the other product of his, the C5D. Boy, was I wrong. My apologies to John on that one.

I am very interested in how these DIY projects test out on the dScope, particularly the ODA. Thanks to AGDR, we have additional options. Options are always a good thing.

Bob

PS: I hope he received his evaluation unit back that he let me borrow.
post #3015 of 5287
I'm sorry about this but I'm going to ask a question that I know has been asked before (possibly by me) but ill be damned if I can find the answer via search.

I came so close to disaster last night when my 18 month old LaCie hard drive failed! I've always had my music backed up but it now exceeds the size of my largest backup disk.

I wasn't able to repair the disk so this morning I had to go to the city and buy another disk to transfer my files to and hopefully be able to reformat the LaCie.

Sorry, I digress. Anyway, because I'm sitting here twidling my thumbs waiting for my backup to complete I thought I'd review all my system settings.

I'm usiang a Mac (latest Mavericks) and as far as I remember I need to go into Audio Devices and choose my ODAC then set input & output to 96000Hz. I'm able to set the output no problem but the input is greyed out.

What am I missing here? And yes, this is most possibly a question for the software section but I find you guys here very reliable & knowledgeable.
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