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  #41  
Old 08-08-2011, 06:34 PM
Mikerman Mikerman is offline
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With all due respect, one thing bothers me here:

I truly wish that the creator, NwAvGuy, was accepting donations for all of his hard efforts. (Well, assuming that the amp works! ) It is rare to see the amount of dedication that has gone into this--the length, alone, of the considerate documentation, which I in fact just read (well, as much as I can, as a mere mortal non-engineer).

It seems to me that it would not be untoward for contributions of, let's say, US$10, to come NwAvGuy's way by those building on and from his creative and inventive engineering spirit. I can't imagine that the vast majority of the audience would have any objection and anything but admiration.

And should NwAvGuy, by chance, be a trust-fund baby, how about a worthy charitable cause?

Really, the effort here is nothing but astounding. And, indeed, good can come from the Internet . . . .

Kudos.
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  #42  
Old 08-09-2011, 01:40 AM
F900EX F900EX is offline
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I would love to be able to build one, but with the many excuses I could give you I will spare them. BUT if the off chance someone offers to build them or it goes commercial, put me down for one
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  #43  
Old 08-09-2011, 11:06 AM
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I'm going to give a subjective review to this objective amp.

The bass is like a new flower - it does not bloom.
The treble is like a powerful shower - there is too much sss.
The mids is like Rapunzel's tower - they are too cold
Where I listen to it I want to cower,
Because my ears have been destroyed by so much power.

Review copyrighted by the Union of Audiophiles (AKA The Borg - "Resistance to subjectivity is futile").

I predict this amp will sound cold and lifeless like the DAC1. IME the best amps are ones where the designers spent hours listening to every single component in the entire Digikey catalog to find the best sounding ones. All this measurement, objectivity, and thinking stuff is BS. You listen with your ears, not your brain.

Before somebody starts cursing me, be aware that all of the above is a joke.

I'm glad to see finally see a product like this! This really is a great contribution to the community of headphone fans. Thanks NwAvGuy!
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  #44  
Old 08-09-2011, 02:03 PM
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Thanks guys. Yeah, I'm sure "cold", "sterile", "clinical" and similar words will be used by the subjectivists to describe the O2. It's obviously threatening to a lot of more expensive amps so it's expected they will find ways to justify their much more expensive purchases.

And, to Mikerman, I'm not a "trust fund baby". I simply believe the world is better off saving their money. Lots of things are a waste of money. When you focus on everything that matters, you're left with fairly modest requiremento of the O2s. If someone knows of a device that outperforms the O2 please post a comment here.
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  #45  
Old 08-09-2011, 05:02 PM
Soaa Soaa is offline
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Head-fi, or Deaf-hi?

I kid with that. Head-fi has its value but I've never counted on it or its members for truly unbiased reviews.

This O2 amp is really interesting to me. I'd build one if I had the time, but sadly, it appears that I'll have to wait for pre-made amps to appear on the market. I have an idea for a tagline though, that could be tastefully printed on the enclosure:

Objective 2
Performance made to measure.

Enough with the small talk. Any plans for a version of this amp that includes a USB DAC? I'd be really interested in something a bit like the FiiO E7, but with the audio circuitry of the O2.
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  #46  
Old 08-09-2011, 05:50 PM
saratoga saratoga is offline
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Given the frequencies involved, I don't think its feasible to DIY USB devices. You could just pair an amp like this with a typical external USB DAC via line out though.
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  #47  
Old 08-09-2011, 05:53 PM
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IIRC NwAvGuy said it might be possible to include a commercial (not DIY) DAC in it.

"INTEGRATED DAC - I think that could work. I'd probably use a commercial DAC (even if it's just the PCB) rather than a DIY DAC (most of which I think are rather half baked and not sufficiently well tested--RMAA just doesn't cut it). Having the DAC on a different board should keep the noise issues at bay."

http://nwavguy.blogspot.com/2011/07/...phone-amp.html
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  #48  
Old 08-09-2011, 06:13 PM
saratoga saratoga is offline
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Thats what I mean. Just buy whatever DAC you want and then put it in the same box as the amp, then solder in the line out.
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  #49  
Old 08-09-2011, 06:20 PM
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I've got the equipment and the soldering experience I could whip one of these together fairly easy from the looks of it.

Of course I would have to get one for myself and put it together before I could make any deals with anyone.
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  #50  
Old 08-09-2011, 07:11 PM
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I could do a full USB headphone DAC project but it would be more complex and require a lot more development time than the O2. It would also have at least some surface mount components and be less DIY friendly.

I designed the O2 because I was unable to find any reasonably priced headphone amps that met my criteria for good sound and headphone compatibility. But there are several decent DACs available that measure very well. And it's very difficult to compete on price against something mass produced in China. So I don't see much point in spending more trying to build your own DAC.

I also at least somewhat agree with Saratoga. Unless someone follows the chip manufacture's reference design exactly, including the PC board layout, few DIY DAC designers have the expensive equipment necessary to know if they got their DAC design correct or not. And, for reasons I don't understand, I've yet to see any of the designers follow the reference designs. I have, however, seen them make plenty of mistakes that have easily measurable, and sometimes audible, consequences.

The DIY designers, including the most popular ones, seem to assume you can just plop a DAC chip down on a PC board, connect everything up, and expect to get the impressive numbers on the datasheet. But that's far from reality. I have examples that prove that's not the case sitting on my test bench right now.

And, finally, there's only one DIY friendly USB DAC interface right now--the ancient TI PCM27xx and PCM29xx family chips. They're OK, but not that great. Better USB solutions, especially if you want to support anything beyond CD quality (i.e. 24/96), are costly and much less accessible for DIYers. The Benchmark DAC1, for example, uses licensed USB technology with custom firmware. The initial license payment will buy a nice car.

So, in reality, the commercial DAC manufactures have many advantages over the DIY guys. And, unlike with reasonably priced headphone amps, several of them get it right. I'll be reviewing more DACs in the near future.
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  #51  
Old 08-09-2011, 08:48 PM
Soaa Soaa is offline
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Thanks for the input. Are there any good compact DACs that you recommend? Any opinions on Headstage's DAC cable?

I look forward to more articles on DACs from you.
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  #52  
Old 08-09-2011, 09:07 PM
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The Stereophile test of the HRT Music Streamer II shows it's a great DAC for $149. I'm going to be testing the Asus Xonar U3 which is only $39 but I don't yet know how it will perform. Other Xonar products have tested very well.

If the Xonar U3 is disappointing I might try one of the relatively inexpensive Creative USB DACs. I know the NuForce uDACs are flawed so they're off the list.

If anyone else has other suggestions for USB powered DACs under $150 that might be a good match with the O2, please let me know?
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  #53  
Old 08-09-2011, 09:46 PM
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Where did Stereophile test the MSII? I want to read that.

dfkt mentioned some similar products to the U3 here. Would you be willing to test those too? That would be cool. . .
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  #54  
Old 08-09-2011, 09:55 PM
odigg odigg is offline
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Quote:
Originally Posted by saratoga View Post
Given the frequencies involved, I don't think its feasible to DIY USB devices. You could just pair an amp like this with a typical external USB DAC via line out though.
I agree with you 100%. I don't think there is a need for a DAC. I'll explain why I think this by first talking about the O2.

The O2 fills a need in the headphone world. For a long time a number of people (me included) have been looking for a nicely priced headphone amp that is capable of working in a wide variety of situations and that can also drive a wide variety of headphones. There have been amps you can buy that can do this, but they are expensive and have only been tested by ear. So you don't really know what you are paying for.

If I had to fault the O2 for something, it would be portability. HOWEVER, I think most "portable" amps have the same issue - they are not all that portable. All these "portable" amps are interesting, but a lot of people eventually get tired of them and switch to a different setup, maybe ditching the amp altogether.

As already stated, the O2 fills a gap in the market.

There is no such gap in the DAC market. There are a number of inexpensive DACs available. An example can be seen with the Behringer UCA202 - Review by NwAVGuy. Edirol and EMU also make nice products for decent prices.

I normally hear two major critiques about these products. I'll address both. There are other critiques (e.g. they sound cold and sterile) but I won't get into that.

1. Limited to 16/44. First of all, most music is only available in 16/44. Even if you did buy 24/96 or 24/192, it can be easily converted to 16/44 in a transparent manner (when compared in a blind test at sane volume levels).

2. These DACs are not portable. The popular PMPs (ipod, iphone, Clip, Cowon) are all able to convert a digital file to an audio signal in a transparent manner. There is no reason to have a DAC for these.

Plus, I imagine the type of person who is willing to carry around a portable DAC+AMP is not looking at the $30 UCA202

On a totally different note, I'd like to thank NwAvGuy for something. For a really long time now the headphone community has been obsessed with amps with pointlessly expensive components. Expensive and esoteric op-amps, "audiophile" capacitors, fancy potentiometers, etc. You name it, somebody found a way to raise the overall cost of products with it. Even many DIY designs use parts that are too expensive and not needed. So much of it is just marketing and providing a BS sense psychological security.

It's refreshing to see a BOM with components that are all sensibly priced. It's a welcome change for a community that typically supports products and components simply because they are marketed well and really expensive.

Quote:
If anyone else has other suggestions for USB powered DACs under $150 that might be a good match with the O2, please let me know?
Roland has the UA-11 DUO-Capture and UA-1G. I used an older version of the UA-1G a few years ago and it seemed to be fine. I never measured it. I suspect the headphone's output impedance is higher than zero, but you are interested in the DAC, not the headphone out. If you search for them on Froogle, just use "UA-11" and "UA-1G" since Roland is also Edirol which is also Cakewalk and this messes up the search.
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  #55  
Old 08-09-2011, 10:37 PM
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Hmmm... I just looked and can't seem to find the HRT MS II reviewed at Stereophile. I can only find the original Music Streamer (which had some issues) and the Pro version. I'll have to do some more research as I know I've seen real measurements on the II somewhere.

And thanks Odigg. A big part of the O2 was to show you don't need esoteric expensive parts. It's much more about the implementation. And, in fact, the expensive parts offer no advantage in the sorts of half-baked designs you so often see them in. Not having any way to properly measure their creations, designers using esoteric parts are often unaware how poorly their implementations perform. This has proven true for companies like Audio-GD, NuForce, Schiit Audio, AMB, HiFiMan, etc.

As for DACs there are indeed many nicely performing USB audio interfaces aimed at professional use. My complaint is many require proprietary drivers which I consider unacceptable these days for someone who just wants to listen to music. And some of what you're paying for in the pro interfaces is their A/D and the recording hardware like mic preamps, etc.

I'm hoping to find a simple, reasonably priced USB DAC optimized for playback that performs even better than the Behringer UCA202 and doesn't require any special drivers. But someone could do a lot worse than a UCA202 and the O2.

And, as dfkt correctly points out in his write up of the Xonar U3, a lot of people have perfectly acceptable DACs built into their PCs or laptops. The biggest problem with built-in sound is usually the headphone amp having limited output, a high output impedance, capacitor coupled outputs, etc. Using the O2 entirely (or largely) corrects for most of those limitations--no DAC required.
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  #56  
Old 08-09-2011, 10:46 PM
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Quote:
Originally Posted by NwAvGuy View Post
And, as dfkt correctly points out in his write up of the Xonar U3, a lot of people have perfectly acceptable DACs built into their PCs or laptops. The biggest problem with built-in sound is usually the headphone amp having limited output, a high output impedance, capacitor coupled outputs, etc. Using the O2 entirely (or largely) corrects for most of those limitations--no DAC required.
Don't you need a line out though? My laptop's sound is quite mediocre and I don't think it has such a thing.

P.S. Do I have your permission to post the O2's measurements in the Head-Fi thread? (without linking, it's not allowed) Or is that unacceptable?
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  #57  
Old 08-09-2011, 11:09 PM
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Quote:
Originally Posted by Satellite_6 View Post
Don't you need a line out though? My laptop's sound is quite mediocre and I don't think it has such a thing.

P.S. Do I have your permission to post the O2's measurements in the Head-Fi thread? (without linking, it's not allowed) Or is that unacceptable?
You probably don't need a line out unless the heapdhone amp really sucks. The O2 presents a 10,000 ohm load to the laptop. And, for reasons I won't try to explain, that's about a thousand times easier for the headphone amp to deal with than a typical pair of headphones. Even the issues with a capacitor coupled output disappear into 10,000 ohms. The thing that won't disappear is noise. So if the laptop's headphone jack has noise issues an external DAC is the only solution.

I don't mind if someone wants to quote, in what they write, a spec or two on Head-Fi, but I'd like to to direct those interested to more open forums where I'm not banned such as here at ABI. I just don't agree with Head-Fi's sponsor oriented bias and policies. I think it's best to encourage anyone there interested in the O2 to get their information from somewhere that encourages open discussion without ridiculous restrictions and randomly enforced draconian rules.
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  #58  
Old 08-09-2011, 11:16 PM
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OK. Gotcha.

I think it's good for interested ppl on Head-fi tho.
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  #59  
Old 08-09-2011, 11:29 PM
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Marvin the Martian Marvin the Martian is offline
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A budget way to eliminate the internal noise from a PC....http://www.turtlebeach.com/products/...ii.aspxhttp://

Whether or not it would be something good to combine with the O2, I couldn't say....I'm no engineer. But this little device made quite a difference with my desktop. Maybe it would be an interesting thing for NwAvGuy to test?
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  #60  
Old 08-09-2011, 11:33 PM
Soaa Soaa is offline
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Well noise is definitely my main problem with built-in jacks. Both of my computers have very audible levels of noise caused by close proximity USB ports.
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