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

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Oh yes.... Thanks Stixx, apreciate that, coming from you...

I have been too busy listening to it, giving it a serious burn-in and can say that sound only gets better, more relaxed and natural....

Have been listening with a pair of biwired AKG 7xx ( Massdrop Red ) and simply love it...

Also tried BeyerDynamic T90 and loved them as well, Fostex sounded good too, ....of course none of these are Focal Clear...but we might get there ......

In principle next week, after a solid understanding of the "stock" sound will do the modification to adjust second harmonic level.....

The lid will get some ventilation slots, as the case gets quite warm ( all of it ! ) after an evening's listening and as a bi product will probably add visualization for the DC-offset led's.

I find it very informative and reasuring seeing the progression of the led's intensity going down slowly prior to switch on of the output !

We shall see if i like the aesthetics of my 3D simulations....
:D
 
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Have you built SHPP ? it has 2 red leds showing dc status of each channel .
The intensity if these goes down progressively as DC level on output goes down when amp warms up initially.
When they go out , relay switches load ( headset ) on as does the blue front led on DAO faceplate.

C
 
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I did build the SHPP, but did not implement it yet in my balanced DAO build.
As the LEDs are smd I did not consider their use as indicators of DC in the cased build. Would be kind of nice with these LEDs on the faceplate next to the HP socket:rolleyes:

Anyway, great work as usual Carlos and Patrick!!!
 
Only when you have a large offset at startup that they will light up.
For smaller offsets (say <100mV), they remain unilluminated.

If I remember correctly, Carlos has 120mV offset at startup, which drops ti below 20mV after 2 minutes.
You can of course run them off board (e.g. to the front panel) with two thin wires.


Patrick
 
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Correct ,

My amp starts off cold at around 120mv dc off/set which quickly drops and leds start to go out at around 40mv....

But progression is very visible so i thought of using them outside case....
Also if something goes wrong one knows immediately which channel is at fault.

Some very usefull visual feedback but i will not change this faceplate, most probably a thin transparent strip under front connected to leds as lightpipe....TBD.....:D

C
 
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hehe...coming from you i will bet that is exactly what you have already done...:p

I know you are recasing your DAO so it makes sense.

am i right ? :joker:


I equated other options like on top of front plate like the lights on those big TIR trucks of old....row on top of cab....but nahh too gaudy.

So i think this solution is more fitting to the case style.

...you have great design sense so i am happy we are on same track....;)
 
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Not really - my progress on the new case is close to zero and it will take me years at this speed:mad:
The road from buying a CNC to making a case is long and expensive...
But I kind of like the idea of a tiny red warning LED close to the socket to indicate the presence of a defined DC offset.
What I have planned is to have a switch to bypass the cross-feed.
 
I could not resist posting for CeeVee.

Such nice CNC machining.
If you have milled transparent acrylic you know how tricky it is.


Patrick

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Thanks Patrick,
There are still a few internal details to complete so it resists closer inspection....this Naked DAO :)

Here it is warming up and singing.....I want to tone down the "fire inside" but it is quite a show in the evening.....:)

There is also a Aluminium lid version , i will keep that for the all balanced version, this is the SE version.
 

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