Valve DAC from Linear Audio volume 13

[Yasioo]

HI.

Someone have a PCB for this project? 🙂 (RAW DSD)

Thanks

 

[MarcelvdG]

For many years, Jan Didden, the former Editor of Linear Audio, has been so kind to make both the valve DAC article and the zip files of versions 1 and 2.1 freely accessible via his website. Now that he has decided to shut down the Linear Audio website, he has given me permission to post the article here, even though some of the copyright is his.

See the attachments for the article and the zip files of versions 1 and 2.1. For version 3, which is the LX45 version, see posts #1519, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6569767 and #1525, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6570538 .

 

[MarcelvdG]

Question to people who use RM8 cores: what exact core type and what wire diameter do you use?

 

[carlos269]

Other than by ear and by trial & error, has anyone determined the most efficient way to adjust the relative alignment values between the RV3 and RV4 potentiometers for the lowest residual background noise at DSD512x48 on the Raw-DSD version of the ValveDac?

I played around with adjusting the two potentiometers but it is hard to find the lowest noise level by ear or to know when the two potentiometers’ settings are optimized.

Any and all guidance, general directions and thoughts are greatly appreciated.

 

[MarcelvdG]

I can't tell you more than I wrote in the document attached to post #713, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6316095 , except that the optimum for RV₃ and RV₄ is supposed to be rather broad. If there is a range in which you don't notice any change, just put them somewhere halfway that range. On the other hand, the noise minimum you hear when adjusting RV₁ and RV₂ is fairly sharp, especially with single-turn trimming potmeters.

Maybe @nautibuoy can tell you more.

 

[carlos269]

Thanks Marcel. I think that after reading the paper you published, listening to a “digital silence” track at DSD512x48 and adjusting while listening through headphones is the key. I have been adjusting through high efficiency speakers as my set up is not set up for headphones but I can see how headphones would make this task much more efficient. Will try that. Ray had my ValveDac sounding with no background noise at DSD256 but when I went to DSD512 that is when the noise became noticeable though the high efficiency speakers.

When adjusting these potentiometers while wearing headphones, hearing protection is key as the sound dramatically jumps up and increase in level when you hit those misalignment spots along the range of the two potentiometers’ settings

 

[MarcelvdG]

Indeed, that's why I recommend a low powered headphone amplifier. You could also use some big series resistors to limit the maximum volume, or indeed good hearing protection with a reasonably flat frequency response.