[wdahm519]

Quote:

The designer of the O2 has done some very extensive measurements that would tend to disagree with with you.. Of course I would agree with you that a Discrete amplifier may have a performance advantage, but I take issue with blanket statements like:  "OA(opamp)s are not primaly designed to drive loads and if they do, their performance is not very good"  
 

This is what I was going to write.

 

[MrSlim]

Quote:

This is what I was going to write.

Heh, someone else usually beats me to the punch..  

 

[MrSlim]

Quote:

The Wire uses op amps and gets somewhat better performance than that...also it has slightly higher voltage swing (9.2V rms), for those 600 ohms vintage AKG models and so on.  I don't think like a couple dB of difference is make-or-break level though.

Well, it's output stage is more like an Opamp on Steroids(aka a Buffer)(LME49600) really, and its designed for high current output. I hope to hear one soon, if I would just get mine done...   

 

[wdahm519]

Quote:

Well, it's output stage is more like an Opamp on Steroids(aka a Buffer)(LME49600) really, and its designed for high current output. I hope to hear one soon, if I would just get mine done...   

That sounds a lot like a PIMETA V2.  It also uses buffers in the same configuration if I'm not mistaken.
 

 

[wakibaki]

Quote:

If you had a mastering-grade DAC (clean, transparent) and wanted to build an absolutely transparent headphone amp that can drive headphones up to 800 ohms, what would you build?

Given that you're asking this question, an O2 would be a good starting point. 
 
It's arguably distortion-free beyond the point of audibility.
 
The performance is verified on industrial-grade testgear (not the case for many designs, especially self-builds).
 
It will drive the very large majority of phones to adequate levels.
 
It's battery/mains operated
 
It's a comparatively easy build with all thru-hole components. Howto guides are being produced to complement the already comprehensive instructions. You can get help if you have a problem. You can easily replace the parts if you inadvertently destroy them. You can put NE5532s in it throughout as a temporary measure and it'll still work, albeit with reduced current drive capability
 
You can get a complete kit including enclosure from a group buy on DiyAudio.com.
 
It's probably the best value-for-money you'll get. 
 
The Wire is a good amp by all accounts, but you will have to make decisions about a volume control, power supply and other complications. Better to leave it for a second build.
 
Discrete amps are complex, more difficult to debug, offer no significant performance advantage at these power levels and many are designed using no more sophisticated testgear than a soundcard + RMAA (if that). You could spend six months picking through specifications and still be none the wiser. Many are boutique merchandise (fashion items). As such, they will have their adherents, but who asks a fashionista for advice about comfortable hard-wearing shoes?
 
Bear in mind that beyond a certain point paper performance improvements are almost certainly inaudible (the amps sound the same).
 
If you're looking for a lo-cost, lo-risk, straightforward, hi-performance build, the O2 is the way to go.
 
w

 

[mikeaj]

Hm, I interpreted the OP to be more of a hypothetical rather than a practical question, but I may be very wrong in that interpretation.  wakibaki makes very good points.  Particularly if you're looking for something relatively cheap and simple to start with and actually build, yet obtains a high level of performance that won't at all be embarrassed by a "mastering-grade DAC," the O2 is a very good idea.

 

[peppe]

 
There may also be the Objective Desktop Amp (ODA) from the O2 developer.  It has has similar goals as the O2 without the battery/portability requirement.  Something to keep your eye on...

 

[HiFi1972]

Thank you all again, I'm currently teaching myself how to read a diagram and the basics in DIY electronics. I've been building my own cables and making repairs to my gear (replacing connectors) over the last couple of years for the purpose of building myself a headphone amp. Hats off to all you folks for the knowledge you share on these forums!

 

[nikongod]

 
Quote:

Run like the wind from the first person who tries to sell you his $30 single-ended triode-ified monstrosity.
 

I don't buy my gear, I build it. 
 
Why discourage people from experimenting with different circuits? Different people like different things after all. Perhaps they will find something they like in a circuit you dont think will work well. 
 
Even implying that SET amps as a group are a "bizarre design" is an oxymoron. 

 

[shadow419]

 
Quote:

Thank you all again, I'm currently teaching myself how to read a diagram and the basics in DIY electronics. I've been building my own cables and making repairs to my gear (replacing connectors) over the last couple of years for the purpose of building myself a headphone amp. Hats off to all you folks for the knowledge you share on these forums!

+1 for the O2 recommendation since you're fairly new at building an amp.  The Wire diy amp measures even better and provides more voltage swing, but it's not as easy a build for a first timer imo.
 

 

[cheapskateaudio]

I'm sure it depends largely on what headphones you hook up to the thing, but I am unequivocal despite Willikans arguments, the O2 has that faux transparency that is common of low end high-fi gear that is trying to hard. The O2 also behaves very differently depending on the headphones, in other words, it colors different headphones in different ways, even in ways that are contrary to the general expectations of specific headphones. I've never heard an amp that was so bad in this regard, except maybe an OTL tube amp.
 
Its hard to believe that some are continuing to pretend that it's my amp and only my amp. If anyone wants to spend time and money on this, go ahead, but understand that this amp does nothing new, and there is no free lunch, nor has there been. It's worth $50 to build out a pcb but that's about it. You're not getting a thousand dollar amp for nothing, you're getting something that is more different than good really.
 
 

 

[Shamharoth]

Quote:

Its hard to believe that some are continuing to pretend that it's my amp and only my amp. 
 

Well, in all respects, that's the only explanation...
 

 

[Willakan]

For some reason, my post seems to have disappeared...
@Cheapskate:
 
Not a single other individual has reported the incredible variety of different problems that you have with the O2. Not a single individual has had problems with the regulators. Nobody else using it with the HD650s reported it was offensively bright. Nobody else tried to assert it was made by somebody mashing together datasheets and measuring it with a scope from a flea market.
And now we have a new one - the O2 is unhappy with certain headphones. It isn't. Let's just leave it at that.

What do you have against this amplifier? I thought you said the uDAC was worse - yet I fail to see you in every thread that mentions the uDAC shouting "IT'S CRAP"

 

[MrSlim]

Quote:

That sounds a lot like a PIMETA V2.  It also uses buffers in the same configuration if I'm not mistaken.
 

Yes, it looks like it does.. except the PIMETA is using a third (ground) channel configuration whereas the Wire is strictly two channel.. 

 

[MrSlim]

Quote:

I'm sure it depends largely on what headphones you hook up to the thing, but I am unequivocal despite Willikans arguments, the O2 has that faux transparency that is common of low end high-fi gear that is trying to hard. The O2 also behaves very differently depending on the headphones, in other words, it colors different headphones in different ways, even in ways that are contrary to the general expectations of specific headphones. I've never heard an amp that was so bad in this regard, except maybe an OTL tube amp.
 
Its hard to believe that some are continuing to pretend that it's my amp and only my amp. If anyone wants to spend time and money on this, go ahead, but understand that this amp does nothing new, and there is no free lunch, nor has there been. It's worth $50 to build out a pcb but that's about it. You're not getting a thousand dollar amp for nothing, you're getting something that is more different than good really.
 
 

Why don't you send your amp to someone else who has built the O2 (or other amps as well, (I've built Soha+Jisbos, CTH, CK2III and B22 and have a "Wire" in process)) and have them have a listen to your amp.  I have HD580's which are very similar sounding to the HD650's, as well as K601's and 240s MkIIs.  I think most people who know me here or on DIY consider me very fare and open minded, if you were willing to send it to me.