Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › O2 AMP + ODAC
New Posts  All Forums:Forum Nav:

O2 AMP + ODAC - Page 168

post #2506 of 3390
Quote:
Originally Posted by Xenophon View Post

I wouldn't get it either, even if I had the disposable income commensurate with it.  If nothing else, DAC-technology is still evolving at a reasonably fast pace, a top of the line DAC purchased 7 years ago would be less than mid-end now.

My advice/'philosophy':  a) take your time to get to know what you have and don't lose yourself in sites like this, there's always 'better' and many wizards promoting things they may not even have heard, far less compared to other gear. The taller the claim, the higher the burden of proof.  b) Invest in quality music material after all, that's what this is all about and if that stinks, no expensive gear will fix it. c) Learn what your sound signature preferences are, once again, this takes time. d) Many roads lead to Rome, what's right for me/my music may not be right for you. e) Audition gear there's no substitute for your own ears.  I had to purchase some items unheard due to my situation living in 2 countries and in retrospect, some things I'd have done differently.  

For the rest, personally I like source/amp to be as neutral as possible and adapt the sound to my liking via a judicious choice of headphones.  Just my opinion.  Also, neutrality is not the end all and certainly does not equate euphony in all cases.  

If I were you I'd take a break from tinkering, enjoy the music and then go out and audition something radically different to see how it compares.  Try a tube amp/dac for instance, that'll provide significant contrast.

I agree with everything you've said. In particular I like to think of having a wide range of headphones with different sound signatures as a very expensive EQ.

I will be investing in a valve amp, particularly since I read they can work particularly well with the HD650's.
post #2507 of 3390
Well, I managed to fix my wobbly power socket. I needed a T5 bit so I bought a set. The problem turned out to be a loose lock-nut on the back of the socket. I guess it happened in transit between Switzerland Scotland. I also took delivery of my Pyst phone cables. Much better looks but no discernible difference in sound.

I'm now waiting for my HD650's to be delivered and that'll be me set for a while. My wallet (and wife) can't take any more smily_headphones1.gif
post #2508 of 3390
Quote:
Originally Posted by Xenophon View Post

I wouldn't get it either, even if I had the disposable income commensurate with it.  If nothing else, DAC-technology is still evolving at a reasonably fast pace, a top of the line DAC purchased 7 years ago would be less than mid-end now.

My advice/'philosophy':  a) take your time to get to know what you have and don't lose yourself in sites like this, there's always 'better' and many wizards promoting things they may not even have heard, far less compared to other gear. The taller the claim, the higher the burden of proof.  b) Invest in quality music material after all, that's what this is all about and if that stinks, no expensive gear will fix it. c) Learn what your sound signature preferences are, once again, this takes time. d) Many roads lead to Rome, what's right for me/my music may not be right for you. e) Audition gear there's no substitute for your own ears.  I had to purchase some items unheard due to my situation living in 2 countries and in retrospect, some things I'd have done differently.  

For the rest, personally I like source/amp to be as neutral as possible and adapt the sound to my liking via a judicious choice of headphones.  Just my opinion.  Also, neutrality is not the end all and certainly does not equate euphony in all cases.  

If I were you I'd take a break from tinkering, enjoy the music and then go out and audition something radically different to see how it compares.  Try a tube amp/dac for instance, that'll provide significant contrast.
A damn fine post. smily_headphones1.gif
post #2509 of 3390
Quote:
Originally Posted by Zorrofox View Post

Well, I managed to fix my wobbly power socket. I needed a T5 bit so I bought a set. The problem turned out to be a loose lock-nut on the back of the socket. I guess it happened in transit between Switzerland Scotland. I also took delivery of my Pyst phone cables. Much better looks but no discernible difference in sound.

I'm now waiting for my HD650's to be delivered and that'll be me set for a while. My wallet (and wife) can't take any more smily_headphones1.gif
Very pleased to hear that the socket was an easy fix.
The O2 is a little wonder. I don't know if it beats amps costing hundreds or thousands but it is definitely worth the £80 I paid for it and that is good enough for me.
One thing though.
These comparisons to the Benchmark DAC may be a bit disingenuous.
I have read that the Benchmark is predominantly a DAC. Hence the name I guess!
Apparently it is available without an amp for only £150 less.
This would indicate that the amp being measured against the O2 only costs £150.
Or have I got this wrong?
Whatever. The O2 will do me until I have some serious cash to spare.
Edited by krismusic - 4/9/14 at 11:36am
post #2510 of 3390
Quote:
Originally Posted by krismusic View Post

These comparisons to the Benchmark DAC may be a bit disingenuous.
I have read that the Benchmark is predominantly a DAC. Hence the name I guess!
Apparently it is available without an amp for only £150 less.
This would indicate that the amp being measured against the O2 only costs £150.
Or have I got this wrong?

 

Couldn't be more wrong. DAC2 D version is without preamp (no analog inputs). There's always a world class (measuring) headphone amp (two of them).

 

Hmph I think my O2 broke or something. Left side has a loud hiss and sounds quieter.. time to open it up I guess.

post #2511 of 3390

I don't see anything funny at quick glance..

 

Exact symptom: No hiss at pot minimum position, hiss starts to get very loud the more I open the pot - but when I get from 95% to 100% full open pot, the hiss disappears completely. Any hints?

post #2512 of 3390
Quote:
Originally Posted by Zorrofox View Post

I wasn't implying the ODAC is garbage! I love it. I just want to know what more expensive DAC's bring to the party. Surely they must add something? This is why I pointed out that all the O2 has to be is transparent, ie transparent to the source data. That source data is surely variable depending on the DAC used?

Let me re-state; I think the ODAC / O2 work wonderfully together and if this truly is the pinnacle then great, I'll go on a better holiday smily_headphones1.gif

 

I think the odac is a great value but as others have noted, it isn't the pinnacle.  This whole hobby boils down to a line drawing exercise and diminishing marginal returns.  Everyone ultimately has to draw that line in the sand relative to their own ears, wallets and priorities.

 

I like my odac and listen to it frequently, but I also agree with some of the more serious dac reviewers on head-fi that sabre dacs seem to leave just a little something to be desired in terms of treble timbre and bass tonality.  The burrbrown dac chip in my Keces 131 doesn't measure quite as well as a sabre (although my recollection is that the dac on the whole measures slightly better than the odac), but this implementation sounds a little more real to me overall, particularly in the highs and deep bass.  You might give at least the first post of this thread a good read while noting that the authors are not particularly inclined towards sabre dacs.  http://www.head-fi.org/t/693798/ranking-of-21-dacs-and-dac-configurations-and-why-chocolate-ice-cream-must-die  They still rank the odac in a category entitled "recommended for others" and praise its value and incredible sonic similarity to benchmark's products.  But I tend to agree that objectively better sound is still out there, albeit on an exponential pricing curve. 

post #2513 of 3390
That's the thing. I'm not science-minded but I understand the rationale and criteria used to measure an amplifier. A DAC on the other hand is something else. DAC's surely come in different flavours?
post #2514 of 3390

These "flavours" are highly discussable, depends on one's approach to the hobby. What do you feel needs clarification about DAC measurements?

post #2515 of 3390
I think this is worth a watch. Highlights the kind of thinking some people have on digital. Makes me realise how people can get carried away when talking about dacs in general.

http://m.youtube.com/watch?v=cIQ9IXSUzuM
post #2516 of 3390
Quote:
Originally Posted by James-uk View Post

I think this is worth a watch. Highlights the kind of thinking some people have on digital. Makes me realise how people can get carried away when talking about dacs in general.

http://m.youtube.com/watch?v=cIQ9IXSUzuM

 

Makes me glad that I remained sceptical of DACS to this day - and counting - 

post #2517 of 3390
Quote:
Originally Posted by MaciekN View Post

These "flavours" are highly discussable, depends on one's approach to the hobby. What do you feel needs clarification about DAC measurements?

Hi. It's not that I doubt the testing of DAC's, I just don't really understand how it works. What is the reference point that DAC's are tested against?

It's as much to do with myself. If I open up my O2 I have an understanding of what I'm looking at. I understand how an amp works and I'm able to identify what I'm looking at. Open up an ODAC and I'm pretty much lost from the get-go. It's an age thing. Also my line of work in the real world takes my nowhere near this kind of subject.
post #2518 of 3390

DACs are supposed to convert digital signal to analog one. Many (not all) signals were first analog, then they were recorded and digitized, that is sinewaves representing amplitude and frequency were saved as ones and zeroes. Looking at it from another perspective: There is this Nyquist-Shannon theorem (you can check it on wikipedia) that states that any bandlimited signal can be reproduced if we have at least 2 points representing the original sinewave. The video posted above explains it nicely. So essentially DAC is supposed to reconstruct the original analog waveform, any deviation (called also artifacts) from the original will be a kind of distortion. There are many kinds of distortion, both in frequency domain (think THD, IMD measurements) and time domain (jitter) and granted that all of them remain low enough, your hearing will not be able to tell the difference between original and reconstructed signal, 100% the same in your perception. On paper ODAC (and many other DACs) achieves this. So any % of distortion in DAC measurements reflect how much it deviates from ideal.

 

Note that usually headphones have around 100x higher distortion levels than modern day D/A chips.

 

On the PCB side of things ODAC is very simple. First, you have the Tenor chip that takes 0s and 1s from USB at a rate determined by the PC and decodes it into i2s signal, where (as far as I remember) each channel and clock info run on separate buses (cables) into the ESS DAC chip. There each sample for each channel is taken at a very strict pace (determined by master clock), converted from current to voltage and amplified (all of this integrated into the chip) and then sent straight to the output as a set sinwaves that make up music.

 

Some designs use SPDIF for digital signal, where 0s and 1s representing samples and clock info are encoded into a single stream passed with controlled impedance coax or optical connection into a receiver chip, where it is broken down into i2s and sent to DAC. Supposedly this last step was a problem for older receiver chips, resulting in jitter (as sample info modulated clock info and vice versa), but modern chips handle it just fine. In ODAC this one step is omitted, so there is nothing to fix after decoding SPDIF.

 

There is also an inductor that probably filters high frequency noise from USB. All the rest are resistors and capacitors controlling chip functions, modes, and such.


Edited by MaciekN - 4/10/14 at 6:49am
post #2519 of 3390
Quote:
Originally Posted by MaciekN View Post

DACs are supposed to convert digital signal to analog one. Many (not all) signals were first analog, then they were recorded and digitized, that is sinewaves representing amplitude and frequency were saved as ones and zeroes. Looking at it from another perspective: There is this Nyquist-Shannon theorem (you can check it on wikipedia) that states that any bandlimited signal can be reproduced if we have at least 2 points representing the original sinewave. The video posted above explains it nicely. So essentially DAC is supposed to reconstruct the original analog waveform, any deviation (called also artifacts) from the original will be a kind of distortion. There are many kinds of distortion, both in frequency domain (think THD, IMD measurements) and time domain (jitter) and granted that all of them remain low enough, your hearing will not be able to tell the difference between original and reconstructed signal, 100% the same in your perception. On paper ODAC (and many other DACs) achieves this. So any % of distortion in DAC measurements reflect how much it deviates from ideal.

Note that usually headphones have around 100x higher distortion levels than modern day D/A chips.

On the PCB side of things ODAC is very simple. First, you have the Tenor chip that takes 0s and 1s from USB at a rate determined by the PC and decodes it into i2s signal, where (as far as I remember) each channel and clock info run on separate buses (cables) into the ESS DAC chip. There each sample for each channel is taken at a very strict pace (determined by master clock), converted from current to voltage and amplified (all of this integrated into the chip) and then sent straight to the output as a set sinwaves that make up music.

Some designs use SPDIF for digital signal, where 0s and 1s representing samples and clock info are encoded into a single stream passed with controlled impedance coax or optical connection into a receiver chip, where it is broken down into i2s and sent to DAC. Supposedly this last step was a problem for older receiver chips, resulting in jitter (as sample info modulated clock info and vice versa), but modern chips handle it just fine. In ODAC this one step is omitted, so there is nothing to fix after decoding SPDIF.

There is also an inductor that probably filters high frequency noise from USB. All the rest are resistors and capacitors controlling chip functions, modes, and such.

Wonderful post! Even more so because I now understand something I didn't this morning. Given those relative distortion figures it's amazing the DAC's relevant at all.

Thanks very much for this, I've pasted it into Evernote smily_headphones1.gif
post #2520 of 3390

DAC chips made by semiconductor companies are spec'd and used in reference circuits.

 

The ODAC was designed to try to meet or exceed the DAC chip specs....

 

In the process of the actual physical design and several layouts the designer indicates the issues of actual physical placement

on his attempts to meet or exceed these types of measurements.

 

So be carfeful on comparing specs on a DAC chip by itself.

 

Placing a chip into a circuit design on a physical board and depending on the bells and whistles outside of the chip can dramatically

affect the overall performance and measurements.

 

The minimilastic design and careful layout that are documented on the designers blog make the ODAC an exceptional DAC.

 

All the gory details are over there for all to read...

 

All the best

A.


Edited by adydula - 4/10/14 at 5:57pm
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › O2 AMP + ODAC