Tube output stage for voltage DAC ?

[mgm31]

Hi,

I got a CS4398 evaluation board. The XLR output sound great but I would try a tube output stage.

I did not found a lot of example :

Broskie cathode follower : http://www.tubecad.com/2006/08/blog0075.htm (no gain required)

Thorsten Loesch design (can't find the link, I got only a paper copy).

Does someone have experience in balanced voltage output dac with tubes ? What advice could you give ?

Thanks a lot

 

[mgm31]

No idea ?

I will try Broskie's design and will see.....

 

[FibCouple]

Hi,

I got a CS4398 evaluation board. The XLR output sound great but I would try a tube output stage.

I did not found a lot of example :

Broskie cathode follower : http://www.tubecad.com/2006/08/blog0075.htm (no gain required)

Thorsten Loesch design (can't find the link, I got only a paper copy).

Does someone have experience in balanced voltage output dac with tubes ? What advice could you give ?

Thanks a lot

Hi

Have a look at Lukasz Fikus's site at:

http://www.lampizator.eu

He has extensive experience with current & voltage out DACs & has on his site mods done to dozens of players. I have changed my Arcam 70.2 discrete output stage to a tube output stage as per the lampizator circuit, and the difference is huge. And this is considering that I already had various mods done including audiocom clock 4, BG NXs in powesupply, some NX hiQ caps for DAC decoupling, super regulators, disabling digital out etc etc.

He also has a step-by-step guide which is excellent. However, you need to make sure you feel safe with dealing with high tube voltages which can kill.

Regards

Fib

 

[Bernhard]

You want a tube output stage because you think tubes sound better than opamps but if that DAC is voltage out, it is already the poison inside.

 

[poynton]

...............

Thorsten Loesch design (can't find the link, I got only a paper copy).

............

http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html#


I tried a similar circuit, see the CD63/67 mods thread (http://www.diyaudio.com/forums/showthread.php?s=&postid=831469&highlight=#post831469) around post 453

Andy

 

[mgm31]

Many thanks, especially for the lampizator link I didn't know

Yes, Opamp inside DAC are poison but at this time I got Opamp for filtering too. I can't throw my CS4398 eval board to the dust bin.....

The lampizator schematics seems not to deal with Vout+ AND Vout- but use only one output (Vout+ ?).

I'm searching a real differential schematic as explained in the tubecad journal.

The project is on my working table : I modified an aikido to this purpose. I'm waiting some parts for the power supply.

 

[JeroenR]

try cd enhancer II on http://ultranalog.com/

 

[mgm31]

Yes.....

Not very cheap (sowter transfos, £110 ) but innovative.....

 

[chungtat]

You might already read this but just in case you miss it.

Aikido differential amp for DAC:

http://www.tubecad.com/2006/08/blog0077.htm

Or you could also try another design by member in this forum:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=79452&perpage=25&highlight=&pagenumber=14

 

[poynton]

Further to my post above :-

Here is one suggestion, originally from HiFi World magazine :-


http://www.diyaudio.com/forums/showthread.php?s=&postid=831469&highlight=#post831469 post 504


and the one I went with, very simple and could be improved, based on Thorsten's work,


http://www.diyaudio.com/forums/showthread.php?s=&postid=831469&highlight=#post831469 post 633

This last one, using Thorstens filter in differential mode, does work extremely well !!!

Andy