[kiteki]

 
Okay, well I saw head-fi user leeperry say earlier today that the PCM270X DAC chip sounds horrible, he recommend the $30 "HA INFO U2" using Tenor TE7022L instead.
 
 
 

 

[DRUB]

 
Quote:

 
Okay, well I saw head-fi user leeperry say earlier today that the PCM270X DAC chip sounds horrible, he recommend the $30 "HA INFO U2" using Tenor TE7022L instead.
 

Leeperry isn't someone I'd rely upon for objective reviews of DACs or anything audio for that matter, he's a renowned troll in the Sound Science forum with a rabid pro-cable stance.
 
Regarding Cheapskate's situation, the most probable situation is that the O2 he ostensibly built was built incorrectly or has malfunctioning parts. I haven't seen the measurements for or heard/tested the grubDac so I can't comment on it.

 

[mikeaj]

Let's think about it this way:
 
Not too long ago, Voldemort criticized Mini^3 and 3 channel amp design.  Forums were in uproar.  Critics resort to ad hominem attacks and ask if he's ever designed any amps, and if he could do better.  Eventually he's banned, and a couple months later, he designs something with better performance and lower cost (though to be fair:  a little larger size and weight), and he releases it to the public.
 
Now, cheapskateaudio criticized O2 and TI reference / standard electrical building blocks on Wikipedia.  Forums are in uproar.  Critics ask if he's ever designed any amps, and if he could do better...then...
 
 
One can dream, right?

 

[kingpage]

One is an electrical engineer with many years of industry experience, another is a DIYer who never had any proper EE training. Pretty big difference there. He didn't even know enigeers use reference designs from datasheets all the time and that big companies like TI invest millions of dollors in R&D to get the best circuit implementation to be put in the specsheets so that combining with their product it will give the best results possible (in order to give them an edge in the market).
 
 

 

[kiteki]

 
I don't think Herr Voeldemaart is a Joe Schmoe from Cincinnatti that one day woke up and decided to make a blog about audio and teach himself how to build an amp from wikipedia and a TI pdf document.
 

 

[khaos974]

I wonder what happened to Cheapskateaudio to go from this
 
Quote:

I finished this to the point that I can turn it on. It worked with the 9v and hasn't caught on fire yet so I assume it's safe for use with the wall-wart. Right off the bat it sounds better than the uDac 2 in terms of overall sound balance. The music seems to come from a darker background compared to the uDac 2 headphone out, even via the uDac 2's line outs. 
 
Treble seemed more zingy at first, but on closer inspection is not just more zingy, but more clear, the two amps have similar tone in the treble region. Using the O2 I think the decay is better on cymbal crashes and overall there seems to be a bit more clarity to the treble.
 
Bass is where I'm hearing the biggest differences, not only quantity but quality. The bass is more pronounced and better defined with the O2. Bass is truly thunderous when called upon to be so and seems to come from outside your head.
 
Midrange is more full and more *real* sounding than the uDac 2. The uDac 2 can seem distorted or colored relative to the O2, although the uDac 2 can have a very musical tone that is appealing on certain tracks.
 
Dynamics seem improved with the O2, the uDac seems to be clipping during particularly loud passages, this is very evident when the digital volume is set to 0, knocking it down -2db alleviates that issue but clarity and that little extra oomph seem to be missing from the uDac 2 compared to the O2.
 
The O2 is very clean sounding, the uDac 2 is more musical sounding, the cello seems to have more music in it with the uDac 2, even as it sounds a little flat at times. The uDac 2 can sound flat in complex passages, and while it's musical tone is definitely appealing, it does not have nearly the clarity the O2 has, nor does it have nearly the power to drive a headphone like the HD650.
 
The above impressions are all at higher volumes, at lower volumes the clarity of the O2 is just too far beyond the uDac 2 to even warrant comparison. One is powered by AC and the other by a measly USB output, this is obvious to hear when listening at lower volumes... The uDac 2 is relegated to class F, for FAIL status at low volumes. 
 
Based on my initial impressions I hereby declare, officially, without reservation or psychic influences beyond my control or understanding, the O2 headphone amplifier superior in all respects to the uDac 2 headphone amplifier. It is a great sounding amplifier!
 
O2 >>> uDac 2
 
Objective > Subjective, most of the time
 
Thanks to the unnamed for providing this cheap and easy to build kit to the DIY community!
 
 
I'll post a more complete review of the amp in the appropriate forum at a later time. For now, enjoy these photos of the build process:
 
 
 
Resistors on:

 
Further along:

 
Almost done:

 
It worked...WOOT!

 

 
to this:


Quote:

Quote:

I finally got around to A/B'ing my "modded" O2 with my semi-stock O2 and I was able to easily pick out the two amps in a blind comparison with matched volume levels. The only things not-stock on the the semi-stock O2 are the power supply caps, and the mosfets (I switched everything else back to stock). Mosfets are the same on both amps. If the filter caps were stock the difference would be even more noticeable, I just didn't feel like changing them, so, whatever... I also used the WAU16-400 for both amps, using the WAU12-200 with the stock amp would have increased the difference.
 
I preferred the modded O2 in everyway, which still isn't operating at 100% of it's best possible sound because I had to compromise on parts to fit them on the board and/or avoid burning things up like sissy v-regs, still, it embarrasses the stock O2, with its K-Mart blue light special parts selection... The sad thing is that maybe $5-$10 worth of upgraded parts can drastically change the sound of the amp, taking it from harsh and deafness inducing, to at least being listenable over a longish period of time.
 
The differences are blatantly obvious on some tracks, and more subtle on others of course. The biggest difference is the bass, there is simply more of it in the modded version. Measurements using REW confirm this, the bass stays hugely better controlled under 50 hz. There are other differences throughout the FR curve, but nothing that really says "this is the difference you're hearing" the way the sub 50z curve clearly does. 
 
 
It's defacto for me at this point, the amp delivers better performance with better/different parts.

What else is defacto is that this amp is barely better than the headphone out on my computer. And it's toss up as to whether it's better than the uDac 2.

After this whole experience I am seriously questioning the legitimacy of the DIY audio scene here on head-fi. most of you are either deaf, or simply ignorant of what a good sounding amp is...

It's also a joke that NwAvGuy's design has been lauded when it is basically a TI datasheet and a wikipedia article connected by a volume pot, so... What's the big deal there? An input switch with 4 resistors? Is that what is the big deal?

Somebody help me understand what the big deal is with this amp because I don't hear it and I don't see it in the circuit.

For reference, cheapskate went back and edited his original post - here's the original version including the potshots at the DIY scene and his general capacity for ignorance. I think cheapskate might be 'de facto' insane.
 

 
 
 

 

[kingpage]

His head-fi account got hacked into? cheapskateaudio is not longer the real cheapskateaudio.

 

[deadlylover]

Quote:

His head-fi account got hacked into? cheapskateaudio is not longer the real cheapskateaudio.

 
Nah, I'm pretty sure he's under the Imperius Curse.
 
Take it easy guys.

 

[kingpage]

Or Polyjuice Potion?

 

[cheapskateaudio]

 
 
Quote:

 
I'm more willing to put faith in hard measurements done on proper equipment than the subjective raving of someone with a blatant antipathy toward others in this forum.
 
I think by now it is obvious that cheapskate hasn't managed to properly build his O2, and so far he's refused to post pictures of his PCBs or submit them to someone who can measure them properly. Every time he's asked to support and validate his inflammatory statements about this amp he merely responds with vague references to the design process being comprised of a wikipedia article and a PDF schematic (laughable). 

I have two properly built amps thank you very much, they're both noise free, and perfectly functional within the scope of the limitations in their design or parts.
 
 
 

 

[Head Injury]

Quote:

I have two properly built amps thank you very much, they're both noise free, and perfectly functional within the scope of the limitations in their design or parts.

Well, if you know that for a fact, demonstrate it for us.

 

[cheapskateaudio]

 
Quote:

I wonder what happened to Cheapskateaudio to go from this
 


 
to this:
 
 
 

Part of the reason why you folks piss me off so much is because I explained this (and many other things) in detail like 6 times in this thread. I stated unequivocally, I was WRONG before. Not to mention, the amps performance degrades over time due to sissy v-regs...
 
 
 

 

[mikeaj]

Just kidding around...btw both kingpage and kiteki missed the other part of the joke, or chose to ignore it.  After this stage, there was one thing Voldemort did (which you addressed), and another thing that happened to him.

 

[cheapskateaudio]

 
Quote:

 
I don't think Herr Voeldemaart is a Joe Schmoe from Cincinnatti that one day woke up and decided to make a blog about audio and teach himself how to build an amp from wikipedia and a TI pdf document.
 

Just because he isn't that person doesn't make the amp not that amp.

 

[SobbingWallet]

Quote:

Just kidding around...btw both kingpage and kiteki missed the other part of the joke, or chose to ignore it.  After this stage, there was one thing Voldemort did (which you addressed), and another thing that happened to him.

As a side note, I always thought his second choice of name was clever, since we could refer to him as "He Who Must Not Be Named."