Cwtim01 has mentioned elsewhere that he is building a DAO circlotron with very low distortion figures.
http://www.diyaudio.com/forums/solid-state/301164-mosfet-source-follower-headamp-2.html#post4931546
A few of you have asked him for schematics.
Firstly thank you for your interest.
I can say that he is one of the two Alpha Testers currently building a fully balanced DAO.
One example has been tested functional and measured individually at module level, pending intergration.
This will be my Ultimo Headamp design, as I have no idea how to build something even better, at least for now.
You can read about the basic topology which has been posted multiple times before :
http://www.diyaudio.com/forums/pass...ce-follower-configurations-9.html#post3139052
But we shall probably not be publishing the fully schematics (actually any full schematics) here in the future.
We might consider it as a "public" project after Alpha Test, for a selected few.
As already mentioned here :
http://www.diyaudio.com/forums/pass-labs/295455-m2x-balanced-headamp.html#post4801198
it is a difficult project to do right, and require knowledge, skill, and measurement capability.
The M2X headamp shown in the link above is fully in the public domain.
It is also somewhat easier to build, the only difficulty being the 8x floating supply for 2 channels.
And you can use 1x 2SK369V with suitable heat sinking to replace 2x 2SK170BL.
I believe NicMac has matched device to offer.
So maybe an alternative to consider.
If you have further questions, please do not hesistate to post them here.
Patrick
http://www.diyaudio.com/forums/solid-state/301164-mosfet-source-follower-headamp-2.html#post4931546
A few of you have asked him for schematics.
Firstly thank you for your interest.
I can say that he is one of the two Alpha Testers currently building a fully balanced DAO.
One example has been tested functional and measured individually at module level, pending intergration.
This will be my Ultimo Headamp design, as I have no idea how to build something even better, at least for now.
You can read about the basic topology which has been posted multiple times before :
http://www.diyaudio.com/forums/pass...ce-follower-configurations-9.html#post3139052
But we shall probably not be publishing the fully schematics (actually any full schematics) here in the future.
We might consider it as a "public" project after Alpha Test, for a selected few.
As already mentioned here :
http://www.diyaudio.com/forums/pass-labs/295455-m2x-balanced-headamp.html#post4801198
it is a difficult project to do right, and require knowledge, skill, and measurement capability.
The M2X headamp shown in the link above is fully in the public domain.
It is also somewhat easier to build, the only difficulty being the 8x floating supply for 2 channels.
And you can use 1x 2SK369V with suitable heat sinking to replace 2x 2SK170BL.
I believe NicMac has matched device to offer.
So maybe an alternative to consider.
If you have further questions, please do not hesistate to post them here.
Patrick
To illustrate the effort that goes into this, here is a quad set of matched LU1014s to be used in the next Alpha proto.
We took 250x prematched LU1014s from Deep Surplus, all from the same Vgs group.
We then curve traced them all in a triode cell under full operating conditions, at 40 degC.
From those 250 devices, about 10 quads were hand picked for this application.
(2nd column from left is Vgs at bias, 3rd is Yfs at bias)
In addition, everything else in the triode cell (Cascode FETs, source resistors, Zener diodes) are hand matched to tight tolerances.
Patrick
.
We took 250x prematched LU1014s from Deep Surplus, all from the same Vgs group.
We then curve traced them all in a triode cell under full operating conditions, at 40 degC.
From those 250 devices, about 10 quads were hand picked for this application.
(2nd column from left is Vgs at bias, 3rd is Yfs at bias)
In addition, everything else in the triode cell (Cascode FETs, source resistors, Zener diodes) are hand matched to tight tolerances.
Patrick
.
Attachments
Correct about the transformers.
And this is only a prototype build using less well matched components.
There will be a final build with custom designed enclosures and perfectly matched devices later.
I am quite confident that we shall then have distortion level even lower than this prototype.
Very well built indeed (for a proto).
Patrick
And this is only a prototype build using less well matched components.
There will be a final build with custom designed enclosures and perfectly matched devices later.
I am quite confident that we shall then have distortion level even lower than this prototype.
Very well built indeed (for a proto).
Patrick
WOW! That looks more like a work of art than an amplifier.
Congratulations on such a nice build.
I'm sure some guys out there would gladly give up one of their testicles for an amplifier of that caliber!
By the way, what's the point of having through-hole pads on the PCBs for the axial leaded components if you aren't going to solder them from the top as well as the bottom sides of the board?
> I'm sure some guys out there would gladly give up one of their testicles for an amplifier of that caliber!
I definitely WILL NOT.
Not even for the balanced DAO which has < -104dB THD for the HAGS, and <-107dB for the circlotron.
All without any global feedback of course.
All of Stixx's amps look gorgeous.
In the end, you have to like the sound as well.
He certainly does.
http://www.diyaudio.com/forums/head...ss-zgf-headphone-amplifier-6.html#post4843421
Patrick
I definitely WILL NOT.
Not even for the balanced DAO which has < -104dB THD for the HAGS, and <-107dB for the circlotron.
All without any global feedback of course.
All of Stixx's amps look gorgeous.
In the end, you have to like the sound as well.
He certainly does.
http://www.diyaudio.com/forums/head...ss-zgf-headphone-amplifier-6.html#post4843421
Patrick
Beautiful work, Stixx!
