Tube output stage for voltage DAC ?

mgm31 · 27th January 2008, 08:12 PM

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 · 30th January 2008, 08:55 PM

No idea ?

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

FibCouple · 2nd February 2008, 01:08 PM

Quote:

Originally posted by 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

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 · 2nd February 2008, 03:01 PM

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 · 2nd February 2008, 03:41 PM

Quote:

Originally posted by mgm31
...............

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

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

http://www.fortunecity.com/rivendell...a/vasfda.html#

I tried a similar circuit, see the CD63/67 mods thread (http://www.diyaudio.com/forums/showt...ht=#post831469) around post 453

Andy

mgm31 · 3rd February 2008, 04:51 PM

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 · 3rd February 2008, 10:13 PM

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

mgm31 · 4th February 2008, 07:12 AM

Yes.....

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

chungtat · 5th February 2008, 01:59 AM

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:

Building the ultimate NOS DAC using TDA1541A

poynton · 5th February 2008, 08:22 AM

Further to my post above :-

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

http://www.diyaudio.com/forums/showt...ht=#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/showt...ht=#post831469 post 633

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

Andy

27th January 2008, 08:12 PM	#1
mgm31 diyAudio Member Join Date: Sep 2005 Location: Toulouse	Tube output stage for voltage DAC ? 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

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30th January 2008, 08:55 PM	#2
mgm31 diyAudio Member Join Date: Sep 2005 Location: Toulouse	No idea ? I will try Broskie's design and will see.....

2nd February 2008, 03:01 PM	#4
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	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.

3rd February 2008, 04:51 PM	#6
mgm31 diyAudio Member Join Date: Sep 2005 Location: Toulouse	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.

3rd February 2008, 10:13 PM	#7
JeroenR diyAudio Member Join Date: Jan 2005 Location: Amersfoort	try cd enhancer II on http://ultranalog.com/

4th February 2008, 07:12 AM	#8
mgm31 diyAudio Member Join Date: Sep 2005 Location: Toulouse	Yes..... Not very cheap (sowter transfos, £110 ) but innovative.....

5th February 2008, 01:59 AM	#9
chungtat diyAudio Member Join Date: Mar 2005 Location: HK	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: Building the ultimate NOS DAC using TDA1541A

5th February 2008, 08:22 AM	#10
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	Further to my post above :- Here is one suggestion, originally from HiFi World magazine :- http://www.diyaudio.com/forums/showt...ht=#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/showt...ht=#post831469 post 633 This last one, using Thorstens filter in differential mode, does work extremely well !!! Andy