The DAO SE all-FET Class-A ZGF Headphone Amplifier

A preliminary picture of the beta SE-amp during first listening tests. Everything working as expected, all numbers so far well within spec. More to follow soon.




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Thank you.

It was quite a challenge with a few set backs of all kinds, but well worth it. :)

Now doing some more listening (and comparing) before I post my impressions. Although already now I know that the DAO is a hell of a headphone amplifier.
To sum it up I just mention the title of one of my favourite test tracks: "In Heaven" (--> Michael Wollny Trio, small combo Jazz, the piano is dead beautiful!)
 
Have a few more days of listening to the DAO SE headphone amplifier so I might as well post
some more impressions. As some might know I have built quite a number of headphone amplifiers
of various topologies in the quest of... well, good sound. ;)
Coming from tube amps and hybrids I recently arrived at solid state amplifiers like The Wire,
Dynahi, and EUVL's F5 HA.

To my ears the DAO again betters them all. On good recordings it is as close to a live concert as
I could imagine with headphones on my head. The DAO is always in control and sounding absolutely
effortless, with a rich tonality and timbre that for the first time makes piano sound right (have it in
my ear with my daughter playing...) The Danyuk Crossfeed might be part of that positive experience
because it helps project a three-dimensional stage with remarkable depth where my other amplifiers
sound comparably flat and 2D. [For testing I often have two amps playing at a time to compare...]

Bass is dry and deep , highs are subtle and extremely detailed, it is fast and free of artificial "effects".
Of course these are my subjective impressions... not trying to sell anything here. But gents believe it,
this is something.

Anybody living close to me feel invited to come over and have a listen! ;)
 
Next will be to post a few images and notes about the process of building and things to consider...

I think I was lucky to be chosen as beta tester because I did not fully qualify with no electronic education
to speak of... but then it can be done with patience, the willingness to learn and a tiny bit of guidance (thanks P: !).

I will happily share all details about my build and answer build-related questions as fas as I can.
 
Following are a few images of the build process. For the technical questions please refer to the beginning of this thread where EUVL posted all the relevant information.
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Maybe a few words upfront: the DAO is not your typical all-on-one-pcb-and-be-done kinda amplifier. It employs a multitude of small circuit boards, some of them actually tiny, for maximum flexibility and freedom of choice. This involves quite a bit of drilling and tapping plus custom work, even in the ready-made case (2109H) that was chosen for the beta amplifier.

To be honest this case is what it is: chinese mass-production (no pun intended!), but it will house everything there is (17 boards in my build, and the custom wound toroid), requires no major modification and is quite inexpensive. As some know my case work usually is a bit more elaborate, but it took me almost a year to build the DAO (for several reasons), so it is the commercial case for now.
 
> To be honest this case is what it is: chinese mass-production (no pun intended!), but it will house everything there is (17 boards in my build, and the custom wound toroid), requires no major modification and is quite inexpensive.

Not everyone is so lucky as you and me who have access to CNC equipped workshops and good brushing and anodising.

Your photography is certainly better than mine.

:)


Patrick
 
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Great to hear about your success with this build! Really good pics too. Can't wait to get my build on.

A question for you, Stixx: Can you give us some info on the headphones you paired with the amp? Any ones sticking out as working really well with it? Any ones not benefiting from the pairing with the DAO as much as others?
 
Hi Rodeo,

I have an interesting observation here. My headphones for the last years are slightly modded Sennheiser HD800 and Hifiman HE-500. Before the DAO I did most of my listening with the Hifiman because it was more "pleasant" while the Sennheiser can be a bit too analytical on longer listening sessions.

Now with the DAO and the Xfeed things are almost opposite, because now everything comes together: the good imaging of the Senn's paired with their dry bass makes for the "live character" I mentioned in a previous post.
The Hifiman's in contrast are still pleasant but have a bit too much upper bass which starts masking detail. One can get really picky on that level... :p.
Nevermind.
 
No, not really. I know these measurements very well and have them saved on my computer.
The response shows a more pronounced treble peak for the Hifiman which cannot be heard as such. The Sennheiser has the most accurate bass of all headphones I ever owned/heard, so nothing is in the way of the midrange/treble region.

I also think they did a good job in positioning the drivers, hence the superb imaging (for Inneraudio still the best imaging headphone there is). That the Senn "lost" the slightly aggressive edge is due to the Xfeed mostly, IMO. When I switch amplifiers results are different.
 
The HD800 6/7Khz peak is an issue for many users.
Lots of mods (and the new HD800s) appeared for solving this problem.
Pairing this headphone to a solid state amp that doesn't make it harsh sounding is a big deal
I know users that turned to tube headphones amp because of this.

It's very good news that the DAO is a good match for this headphones, it may also be an indication that other headphones that suffer from "aggressiveness" in upper medium/ lower treble may benefit from DAO.

I've to agree with Stixx with HD800 imaging, for those who like "out of the head" wide and deep imaging, it's the best available... (but i've to warn that not everybody like huge soundstage, some prefer intimacy).

I followed this thread for years, and I may be tempted to build one for my Fostex, but I'm afraid it's a tougher work than my knowledge and skills can handle.
 
If there is an explanation then it is more likely the interaction between the DAO follower and the reactance of the HD800 driver at HF.

Technically you sure are the person to ask. I still have the impression that the way the DAO projects the stage in [my] head has to do with how I perceive the treble region.
Will be interesting to see how the F5 HA will behave with the Crossfeed added.
;)