24 bit / 192 kHz Tube DAC questions

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i would like to build a 24/192 DAC with a tube output stage but am not really sure where to begin looking for project guidlines. although i have some experience with electronics i am pretty much a newbie when it comes to D/A conversion. i have found a few Tube dac projects that have circuit boards available here and here for example but both seem to be built for 16/44 operation. are there any plans out there for the type of projet i'm looking for? i am not against learning the theory and applying it to create my own design but i have no idea where to begin. usually i learn details about my project as i'm building...but i feel like with this kind of thing it may require a lot more background knowledge then what i have at the moment.

thanks for any help

~Nasser
 
Well, I can tell you I've been having a tough time trying to design a tube output stage into an AD1955. Seems like this DAC doesn't like passive I/V conversion according to the manufacturer. That rules out a simple I/V resistor. I guess an omp amp I/V convertor feeding a tube stage is the best I could do. I even looked into a Zap Filter but that won't work well either due to high current output of this Dac. This according to the desinger anyway. A delta sigma design DAC with voltage outputs would be much much easier to match a tube stage up to I think.

-Ed
 
Overlord said:
oh ok...yeah i was thinking about using the CS43122 chip...which is a Delta sigma design. but i'm trying to find info on creating the digital conversion portion of the overall DAC...i think that if i can cmoe up with a decent design for that then i can borrow other peoples tube output stage and be ok...at least in theory...


The R-2R ladder dac is probably the only feasible dac for diy, if you really are determined to design your own conversion stage.
Laser trimming the resistors for the current sources might prove
a bit tricky for a diy'er though.

ray.
 
hmmm...yeah after a lot of research i'm having quite a bit more trouble then expected...then again a few days of research isnt really a whole lot. especially while trying to learn this stuff from scratch. maybe i can use a predefined conversion stage. but i'm not sure if i have the general idea down or not...

this the gist of what i am trying to do....please correct me if something is screwy...


SPDIF ->Transformer ->reciever chip(CS8416) -> ??? (not sure if i need to reclock or something at this stage -> DAC chip (CS43122) -> since it has a voltage output i should be able to couple it directly to a Tube Output stage right? since i dont have to worry about I/V conversion?
 
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